HK1245054B - Method and apparatus for tissue ablation - Google Patents

Description

Methods and apparatus for tissue ablation

This application is a divisional application of an application filed on June 3, 2012, with application number 201280027522.X and invention name “Method and apparatus for tissue ablation”.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application also relies for priority on U.S. Provisional Patent Application No. 61/493,344, filed June 3, 2011, entitled “Method and Apparatus for Tissue Ablation,” assigned to the applicant of the present invention, which is hereby incorporated by reference in its entirety.

Field of the Invention

The present invention relates to medical devices and medical procedures. More particularly, the present invention relates to a device for ablating tissue that includes a centering or positioning attachment for positioning the device at a constant distance from the tissue to be ablated.

Background of the Invention

Almost 25% of people over the age of 50 have colon polyps. Although most polyps can be detected by colonoscopy and easily removed with a snare, sessile, flat polyps are difficult to remove using the snare technique and carry a high risk of complications such as bleeding and perforation. Advances in imaging technology in recent years have allowed more flat polyps to be detected. Polyps that cannot be removed endoscopically require surgical removal. Most colon cancers develop from colon polyps, and to prevent colon cancer, these polyps must be removed safely and completely.

Barrett's esophagus is a precancerous condition affecting 10-14% of Americans with gastroesophageal reflux disease (GERD) and has been shown to be a precursor to esophageal adenocarcinoma, the fastest-rising cancer in the developed world. Cancer incidence has increased more than sixfold over the past two decades, while mortality has increased sevenfold. The five-year mortality rate for esophageal cancer is 85%. Ablation of Barrett's epithelial cells has been shown to prevent progression to esophageal cancer.

Dysfunctional uterine bleeding (DUB), or menorrhagia, affects 30% of women of childbearing age. These associated symptoms significantly impact women's health and quality of life. This condition is typically treated with endometrial ablation or hysterectomy. Surgical intervention rates are very high among these women. Nearly 30% of American women will undergo a hysterectomy by the age of 60, with 50-70% of these women undergoing surgery for menorrhagia or DUB. The FDA has approved endometrial ablation as effective for women with abnormal uterine bleeding and intramural fibroids smaller than 2 cm. The presence of submucosal uterine fibroids and large uterine size have been shown to reduce the efficacy of standard endometrial ablation. Of the five FDA-approved global ablation devices (i.e., the Uterine Thermal Balloon Therapy System, Hot Water Infusion, NovaSure, Her Option, and Microwave Ablation), only microwave ablation (MEA) has been shown to be effective for submucosal uterine fibroids smaller than 3 cm that do not occlude the endometrial cavity, and for uteri up to 14 cm in size.

Known ablative treatments for Barrett's esophagus include laser therapy (Ertan et al., Am. J. Gastro., 90-2201-2203 [1995]), ultrasonic ablation (Bremner et al., Gastro. Endo., 43:6 [1996]), photodynamic therapy (PDT) using photosensitizer drugs (Overholt et al., Semin. Surq. Oncol., 1:372-376 (1995), multipolar electrocoagulation such as using a Bicap probe (Sampliner et al.), argon plasma coagulation (APC), radiofrequency ablation (Sharma et al., Gastrointest Endosc), and cryoablation (Johnston et al., Gastrointest Endosc). Treatment is performed with the aid of an endoscope and a device passed through a channel or along the endoscope.

However, conventional technologies have some inherent defects and have not been widely used clinically. First, most handheld ablation devices (Bicap probes, APC, cryoablation) are fixed-focus devices (point and shoot devices) that produce a small ablation focus. This ablation mechanism is operator-dependent, cumbersome, and time-consuming. Second, because the target tissue moves due to patient movement, respiratory movement, normal peristalsis, and vascular pulsation, the ablation depth of the target tissue is inconsistent and uneven ablation will occur. Surface ablation will produce incomplete ablation, leaving residual tumor tissue. Deeper ablation results in complications such as bleeding, stenosis, and perforation. These shortcomings and complications have been reported in conventional devices.

For example, radiofrequency ablation utilizes rigid bipolar balloon-based electrodes and radiofrequency heat energy. By delivering heat energy by bringing the electrodes into direct contact with the diseased Barrett's esophagus, ablation can be performed relatively uniformly over a large area. However, rigid electrodes do not adapt to changes in esophageal size and are ineffective for ablating lesions in a curved esophagus, proximal esophageal lesions as the esophagus narrows towards the top, and lesions in the esophagus at the gastrointestinal junction due to changes in esophageal diameter. Tumor-like diseases in Barrett's esophagus cannot be treated using rigid bipolar radiofrequency electrodes either. Due to their size and rigidity, the electrodes cannot pass through this range. In addition, adhesion of sloughed tissue to the electrodes can hinder the delivery of radiofrequency energy, resulting in incomplete ablation. Electrode size is limited to 3 cm, so repeated applications are required when treating Barrett's esophagus of greater length.

Photodynamic therapy (PDT) is a two-step procedure involving the infusion of a photosensitizer that is absorbed and retained by tumor and pre-neoplastic tissue. This tissue is then exposed to light of a selected wavelength, which activates the photosensitizer and causes tissue destruction. PDT carries complications such as stricture formation, and its photosensitivity limits its use to the most advanced stages of the disease. Furthermore, irregular absorption of the photosensitizer can result in incomplete ablation and residual tumor tissue.

Cryoablation of esophageal tissue using direct contact with liquid nitrogen has been studied in animal models and humans (Rodgers et al., Cryobiology, 22:86-92 (1985); Rodgers et al., Ann. Thorac. Surq. 55:52-7 [1983]) and has been used to treat Barrett's esophagus (Johnston et al., Gastrointest Endosc) and early esophageal cancer (Grana et al., Int. Surg., 66:295 [1981]). Injection catheters that directly inject liquid _N2 or _CO2 (cryoablation) or argon (APC) to ablate Barrett's tissue in the esophagus have been described. These techniques suffer from the disadvantages of conventional handheld devices. Treatment using the probe is cumbersome and requires the operator to control the operation by directly viewing the endoscope. Continuous movement of the esophagus due to breathing, cardiac or arterial pulsation or movement can cause uneven distribution of the ablative agent and produce uneven and/or incomplete ablation. Close proximity or direct contact of the catheter with surface epithelial cells can cause deep tissue damage, resulting in perforation, bleeding, or stricture formation. Placing the catheter too far into the esophagus due to esophageal movement can result in incomplete Barrett's ablation, necessitating multiple treatment sessions or masking the lesion, with the continued risk of esophageal cancer. The expansion of cryogenic gas in the esophagus can cause uncontrollable nausea, potentially leading to esophageal tears or perforations, necessitating continuous cryogen aspiration.

Colon polyps are typically removed using snare resection, with or without monopolar electrocautery. Following snare resection, flat polyps or residual polyps are treated with argon plasma coagulation or laser therapy. Both of these treatments are inadequate due to the aforementioned drawbacks. Therefore, most flat polyps undergo surgical resection due to the high risk of bleeding, perforation, and residual disease using traditional endoscopic resection or ablation techniques.

Most conventional balloon catheters traditionally used for tissue ablation heat or cool the balloon itself or a heating element such as a radiofrequency (RF) coil mounted on the balloon. This requires the balloon catheter to be in direct contact with the surface to be ablated. When the balloon catheter is deflated, epithelial cells adhere to the catheter and slough off, thereby producing bleeding. The blood interferes with the delivery of energy and thus reduces the energy. In addition, the reapplication of energy can produce deeper burns in areas of the surface lining that have sloughed off. Moreover, balloon catheters cannot be used to treat non-cylindrical organs, like the uterus or sinuses, and balloon catheters cannot provide non-circumferential or focal ablations in hollow organs. In addition, if a cryogen that expands exponentially upon heating is used as an ablative agent, the balloon catheter may create a closed cavity and capture the escaping cryogen, resulting in complications such as perforations and tears.

Therefore, there is a need in the art for an improved method and system for delivering an ablative agent to a tissue surface so as to provide consistent, controllable, and uniform ablation of the target tissue and minimize adverse side effects of introducing the ablative agent into a patient.

SUMMARY OF THE INVENTION

In one embodiment, the present specification discloses a device for use in conjunction with a tissue ablation system, comprising: a handle having a pressure-resistant port at its distal end, a flow channel through which an ablative agent can travel, and one or more connection ports at its proximal end for inlet and RF supply of the ablative agent; an insulated catheter attached to the pressure-resistant port of the snare handle, comprising an axis through which the ablative agent can travel and one or more ports along its length for releasing the ablative agent; and one or more positioning elements attached to the catheter axis at one or more different locations, wherein the positioning elements are configured to position the catheter at a predetermined distance from the tissue to be ablated.

Optionally, the handle has one pressure resistant port for attaching both the ablative agent inlet and the RF supply.The handle has one separate pressure resistant port for attaching the ablative agent inlet and one separate port for attaching the RF supply or electrical supply.

In another embodiment, the present specification discloses a device for use in conjunction with a tissue ablation system, comprising: a handle having a pressure-resistant port on its distal end, a flow channel passing through the handle, and a connection port on its proximal end for RF supply or electrical supply, the flow channel being continuous with a pre-attached cord through which an ablative agent can pass; an insulated catheter attached to the pressure-resistant port of the handle, comprising a shaft through which an ablative agent can pass and one or more ports along its length for releasing the ablative agent; and one or more positioning elements attached to the catheter shaft at one or more different locations, wherein the positioning elements are configured to position the catheter at a predetermined distance from the tissue to be ablated. Optionally, the distal end of the catheter is designed to pierce a target.

In another embodiment, the present specification discloses a device for use in conjunction with a tissue ablation system, comprising: an esophageal probe having a pressure-resistant port on its distal end, a flow channel through which an ablative agent can travel, and one or more connection ports on its proximal end for an inlet for the ablative agent and an RF supply or an electrical supply; an insulated catheter attached to the pressure-resistant port of the esophageal probe, comprising an axis through which the ablative agent can travel and one or more ports along its length for releasing the ablative agent; and one or more inflatable positioning balloons disposed at either end of the catheter beyond the one or more ports, wherein the positioning balloons are configured to position the catheter at a predetermined distance from the tissue to be ablated.

Optionally, the catheter is dual lumen, wherein a first lumen facilitates delivery of an ablative agent and a second lumen contains electrodes for RF ablation.The catheter has differential thermal insulation along its length.

The present specification also relates to a tissue ablation device comprising: a liquid reservoir, wherein the reservoir includes an outlet connector capable of resisting a pressure of at least 1 atm for attaching a reusable cord; a heating component comprising: a length of coiled tubing housed within a heating element, wherein activation of the heating element causes the coiled tubing to increase from a first temperature to a second temperature and wherein the increase causes the liquid within the coiled tubing to convert into vapor; and an inlet connected to the coiled tubing; an outlet connected to the coiled tubing; and at least one pressure-resistant connector attached to the inlet and/or outlet; a cord connecting the outlet of the reservoir to the inlet of the heating component; a single-use cord connecting a pressure-resistant inlet port of a vapor-based ablation device to the outlet of the heating component.

In one embodiment, the liquid reservoir is integrated into the operating room equipment generator.In one embodiment, the liquid is water and the vapor is steam.

In one embodiment, the compression resistant connector is a Luer lock connector. In one embodiment, the crimped tubing is copper.

In one embodiment, the tissue ablation device further comprises a pedal switch, wherein steam is generated and directed into the single-use cord only when the pedal switch is depressed. In another embodiment, steam is generated and directed into the single-use cord only when pressure is removed from the pedal switch.

In another embodiment, the present specification discloses a vapor ablation system for supplying vapor to an ablation device, comprising: a single-use sterile fluid container to which is attached a compressible tubing for connecting a fluid source to a heating unit within a handle of a vapor ablation catheter. The tubing passes through a pump that delivers the fluid to the heating unit at a predetermined rate. A mechanism such as a one-way valve is present between the fluid container and the heating unit to prevent backflow of vapor from the heating unit. The heating unit is connected to the ablation catheter to deliver vapor from the heating unit to the ablation site. The flow of vapor is controlled by a microprocessor. The microprocessor uses a pre-programmed algorithm in an open-loop system or uses information from one or more sensors incorporated into the ablation system in a closed-loop system, or both, to control the delivery of vapor.

In one embodiment, the handle of the ablation device is made of a thermally insulating material to protect the operator from thermal injury. A heating element is enclosed within the handle. After the catheter is passed through the endoscope's channel, the handle locks into place. The operator can manipulate the catheter by gripping the thermally insulating handle or by manipulating the catheter near the handle.

The present specification also relates to a vapor ablation system comprising: a container having a sterile liquid therein; a pump in fluid communication with the container; a first filter disposed between the container and the pump and in fluid communication with the container and the pump; a heating element in fluid communication with the pump; a valve disposed between the pump and the heating container and in fluid communication with the pump and the heating container; a conduit in fluid communication with the heating element, the conduit comprising at least one opening at its operating end; and a microprocessor in operably communication with the pump and the heating element, wherein the microprocessor controls the pump to control the flow rate of the liquid from the container through the first filter, through the pump and into the heating element, wherein the liquid is converted into vapor via heat transfer from the heating element to the fluid, wherein the conversion of the fluid into the vapor results in volume expansion and an increase in pressure, wherein the increase in pressure forces the vapor into the conduit and out of the at least one opening, and wherein the temperature of the heating element is controlled by the microprocessor.

In one embodiment, the vapor ablation system further comprises at least one sensor on the catheter, wherein information obtained by the sensor is transmitted to the microprocessor, and wherein the information is used by the microprocessor to regulate the pump and the heating component and thereby regulate vapor flow. In one embodiment, the at least one sensor comprises one or more of a temperature sensor, a flow sensor, or a pressure sensor.

In one embodiment, the vapor ablation system further comprises a screw cap on the liquid container and a piercing needle on the first filter, wherein the screw cap is pierced by the piercing needle to provide fluid communication between the container and the first filter.

In one embodiment, the liquid container and catheter are disposable and configured for single use.

In one embodiment, the fluid container, the first filter, the pump, the heating element, and the conduit are connected by sterile tubing and wherein the connection between the pump and the heating element and the connection between the heating element and the conduit are pressure resistant.

The present specification also relates to a tissue ablation system comprising: a catheter having a proximal end and a distal end and a lumen therebetween, the catheter comprising: a handle proximal to the proximal end of the catheter and housing a fluid heating chamber and a heating element surrounding the chamber, a wire extending distally from the heating element and leading to a controller; an insulating sheath extending and covering the length of the catheter and disposed between the handle and the heating element at the distal end of the catheter; and at least one opening proximal to the distal end of the catheter for passing vapor; and a controller operably connected to the heating element via the wire, wherein the controller is capable of regulating the energy supplied to the heating element and further wherein the controller is capable of regulating the flow rate of liquid supplied to the catheter; wherein liquid is supplied to the heating chamber and is then converted into vapor within the heating chamber by heat transfer from the heating element to the chamber, wherein the conversion of the liquid into vapor causes volume expansion and a pressure increase within the catheter, and wherein the pressure increase propels the vapor through the catheter and out of the at least one opening.

In one embodiment, the tissue ablation system further comprises a pressure-resistant fitting attached to the fluid supply and a one-way valve within the pressure-resistant fitting to prevent backflow of vapor into the fluid supply.

In one embodiment, the tissue ablation system further comprises at least one sensor on the catheter, wherein information obtained by the sensor is transmitted to the microprocessor, and wherein the information is used by the microprocessor to regulate the pump and the heating component and thereby regulate vapor flow.

In one embodiment, the tissue ablation system includes a metal frame within the catheter, wherein the metal frame is in thermal contact with the heating chamber and conducts heat to the catheter lumen, thereby preventing condensation of the vapor. In various embodiments, the metal frame includes a metal skeleton, a metal spiral, or a metal mesh having fins extending outwardly at regularly spaced intervals, and wherein the metal frame includes at least one of copper, stainless steel, or other ferrous material.

In one embodiment, the heating element comprises a heating block, wherein the heating block is powered by the controller.

In various embodiments, the heating element uses one of magnetic induction, microwaves, high intensity focused ultrasound, or infrared energy to heat the heating chamber and the fluid therein.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will be further appreciated as they are better understood by reference to the detailed description considered in conjunction with the accompanying drawings, in which:

FIG1 illustrates an ablation device according to one embodiment of the present invention;

FIG2A illustrates a longitudinal cross-section of an ablation device having ports distributed thereon;

FIG2B illustrates a cross-section of a port on an ablation device according to one embodiment of the present invention;

FIG2C illustrates a cross-section of a port on an ablation device according to another embodiment of the present invention;

FIG2D illustrates a catheter of an ablation device according to one embodiment of the present invention;

FIG2E illustrates an ablation device in the form of a catheter extending from a conventional snare handle, according to one embodiment of the present invention;

2F illustrates a cross-section of an ablation device in the form of a catheter with a pre-attached tether extending from a conventional snare handle in accordance with another embodiment of the present invention;

FIG2G illustrates an ablation device in the form of a catheter extending from a conventional esophageal probe, according to one embodiment of the present invention;

3A illustrates an ablation device positioned in the upper gastrointestinal tract having Barrett's esophagus to selectively ablate Barrett's tissue, according to one embodiment of the present invention;

3B illustrates an ablation device positioned in the upper gastrointestinal tract having Barrett's esophagus to selectively ablate Barrett's tissue according to another embodiment of the present invention;

FIG3C is a flow chart illustrating basic procedural steps for using an ablation device according to one embodiment of the present invention;

FIG4A illustrates an ablation device positioned in the colon to ablate a flat colon polyp, according to one embodiment of the present invention;

FIG4B illustrates an ablation device positioned in the colon to ablate a flat colon polyp according to another embodiment of the present invention;

FIG5A illustrates an ablation device having a coaxial catheter design according to one embodiment of the present invention;

FIG5B illustrates a partially deployed positioning device according to one embodiment of the present invention;

FIG5C illustrates a fully deployed positioning device according to one embodiment of the present invention;

FIG5D illustrates an ablation device having a tapered positioning element according to one embodiment of the present invention;

FIG5E illustrates an ablation device having a disc-shaped positioning element according to one embodiment of the present invention;

FIG6 illustrates an upper gastrointestinal tract with a bleeding vascular lesion being treated using an ablation device according to one embodiment of the present invention;

FIG7 illustrates endometrial ablation performed on a female uterus using an ablation device according to one embodiment of the present invention;

FIG8 illustrates sinus ablation performed on a nasal passage using an ablation device according to one embodiment of the present invention;

FIG9 illustrates bronchial and bullous ablation performed on the pulmonary system using an ablation device according to one embodiment of the present invention;

FIG10 illustrates prostate ablation performed on an enlarged prostate in a male urinary system using an ablation device according to one embodiment of the present invention;

FIG11 illustrates fibroid ablation performed on a female uterus using an ablation device according to one embodiment of the present invention;

FIG12 illustrates a vapor delivery system utilizing an RF heater to supply vapor to an ablation device according to one embodiment of the present invention;

FIG13 illustrates a vapor delivery system utilizing a resistive heater to supply vapor to an ablation device according to one embodiment of the present invention;

FIG14 illustrates a vapor delivery system utilizing a heating coil to supply vapor to an ablation device according to one embodiment of the present invention;

FIG. 15 illustrates a heating component and coiled tubing of the heating coil vapor delivery system of FIG. 14 , according to one embodiment of the present invention;

16A illustrates an unassembled interface connection between a single-use cord and an ablation device of the heating coil vapor delivery system of FIG. 14 , in accordance with one embodiment of the present invention;

16B illustrates an assembled interface connection between a single-use cord and an ablation device of the heating coil vapor delivery system of FIG. 14 , in accordance with one embodiment of the present invention;

FIG17 illustrates a vapor ablation system utilizing a heater or heat exchanger unit to supply vapor to an ablation device according to another embodiment of the present invention;

FIG18 illustrates the fluid container, filter member, and pump of the vapor ablation system of FIG17;

FIG19 illustrates a first view of the fluid container, filter member, pump, heater or heat exchanger unit, and microcontroller of the vapor ablation system of FIG17;

FIG20 illustrates a second view of the fluid container, filter member, pump, heater or heat exchanger unit, and microcontroller of the vapor ablation system of FIG17;

FIG21 illustrates an unassembled filter assembly of the vapor ablation system of FIG17, depicting a filter disposed therein;

FIG22 illustrates one embodiment of a microcontroller for the vapor ablation system of FIG17;

FIG23 illustrates one embodiment of a catheter assembly for use with the vapor ablation system of FIG17;

FIG. 24 illustrates one embodiment of a heat exchanger unit for use with the vapor ablation system of FIG. 17 ;

FIG25 illustrates another embodiment of a heat exchanger unit for use with the vapor ablation system of the present invention;

Figure 26 illustrates the use of induction heating for heating chambers;

FIG. 27A illustrates one embodiment of a coil for use with induction heating in the vapor ablation system of the present invention;

FIG27B illustrates one embodiment of a catheter handle for use with induction heating in the vapor ablation system of the present invention;

FIGURE 28A is a schematic front cross-sectional view illustrating one embodiment of a catheter for use with induction heating in the vapor ablation system of the present invention;

FIG28B is a schematic longitudinal cross-sectional view illustrating one embodiment of a catheter for use with induction heating in the vapor ablation system of the present invention;

FIG28C is a schematic longitudinal cross-sectional view illustrating another embodiment of a catheter having a metal spiral for use with induction heating in the vapor ablation system of the present invention;

FIG28D is a schematic longitudinal cross-sectional view illustrating another embodiment of a catheter having a mesh for use with induction heating in the vapor ablation system of the present invention; and

FIG. 29 illustrates one embodiment of a heating unit for converting fluid into vapor using microwaves in the vapor ablation system of the present invention.

Detailed Description of the Invention

The present invention relates to an ablation device comprising a catheter having one or more centering or positioning attachments at one or more distal ends of the catheter to secure the catheter and its infusion port at a fixed distance from the tissue to be ablated, which is not affected by organ movement. The arrangement of the one or more injection ports allows for uniform injection of an ablative agent, thereby producing uniform ablation over a large area, such as that encountered in Barrett's esophagus. The flow of the ablative agent is controlled by a microprocessor and depends on one or more of the length or area of tissue to be ablated, the type and depth of tissue to be ablated, and the distance of the infusion port from the tissue to be ablated or the distance of the infusion port in the tissue to be ablated.

The present invention also relates to a device for use in conjunction with a tissue ablation system, comprising: a handle having a pressure-resistant port at its distal end, a flow channel through which an ablative agent can travel, and one or more connection ports at its proximal end for an inlet for the ablative agent and an RF supply or an electrical supply; an insulated catheter attached to the pressure-resistant port of the handle, comprising an axis through which the ablative agent can travel and one or more ports along its length for releasing the ablative agent; and one or more positioning elements attached to the catheter axis at one or more different positions, wherein the positioning elements are configured to position the catheter at a predetermined distance from or in the tissue to be ablated.

In one embodiment, the handle has one pressure resistant port for attaching the ablative agent inlet and the RF supply.In another embodiment, the handle has a separate pressure resistant port for attaching the ablative agent inlet and a separate port for attaching the RF supply or electrical supply.

The present invention also relates to a device for use in conjunction with a tissue ablation system, comprising: a handle having a pressure-resistant port on its distal end, a flow channel passing through the handle, and a connection port on its proximal end for RF supply or electrical supply, the flow channel being continuous with a pre-attached cord through which an ablative agent can travel; an insulated catheter attached to the pressure-resistant port of the handle, comprising a shaft through which an ablative agent can travel and one or more ports along its length for releasing the ablative agent; and one or more positioning elements attached to the catheter shaft at one or more different locations, wherein the positioning elements are configured to position the catheter at a predetermined distance from or in the tissue to be ablated. In one embodiment, the distal end of the catheter is designed to pierce the target tissue to deliver the ablative agent to a precise depth and location.

The present invention also relates to a device for use in conjunction with a tissue ablation system, comprising: an esophageal probe having a pressure-resistant port on its distal end, a flow channel through which an ablative agent can travel, and one or more connection ports on its proximal end for inlet and RF supply of the ablative agent; an insulated catheter attached to the pressure-resistant port of the esophageal probe, comprising an axis through which the ablative agent can travel and one or more ports along its length for releasing the ablative agent; and one or more inflatable positioning balloons arranged at either end of the catheter beyond the one or more ports, wherein the positioning balloons are configured to position the catheter at a predetermined distance from the tissue to be ablated.

In one embodiment, the catheter is double lumen, wherein a first lumen facilitates delivery of an ablative agent and a second lumen contains electrodes for RF ablation.

In one embodiment, the conduit has varying insulation along its length.

The present invention also relates to a vapor delivery system for supplying vapor to an ablation device, comprising: a liquid reservoir, wherein the reservoir includes a pressure-resistant outlet connector for attaching a reusable cord; a reusable cord connecting the outlet of the reservoir to the inlet of a heating component; a powered heating component, the heating component comprising a length of coiled tubing therein for converting liquid into vapor and pressure-resistant connectors at the inlet and outlet ends of the heating component; and a single-use cord connecting the pressure-resistant inlet port of a vapor-based ablation device to the outlet of the heating component.

In one embodiment, the liquid reservoir is integrated into the procedure room device generator.

In one embodiment, the liquid is water and the resulting vapor is steam.

In one embodiment, the compression resistant connection is of the Luer lock type.

In one embodiment, the convoluted tubing is copper.

In one embodiment, a vapor delivery system for supplying vapor to an ablation device further includes a pedal switch used by an operator to deliver more vapor to the ablation device.

"Treat," "treatment," and variations thereof refer to any lessening in the extent, frequency, or severity of one or more symptoms or signs associated with a health condition.

"Duration" and variations thereof refer to the time course from the start to the end of a prescribed treatment, regardless of whether the treatment ends because the health condition improves or the treatment is discontinued for other reasons. During the duration of treatment, a number of treatment cycles may be prescribed, during which one or more prescribed stimuli are administered to the subject.

A "cycle" refers to the time over which a "dose" of stimulation is administered to a subject as part of a prescribed treatment plan.

The term "and/or" refers to one or all of the listed elements or a combination of any two or more of the listed elements.

The terms "comprises" and "comprising" and variations thereof do not have a limiting meaning where they appear in the description and claims.

Unless otherwise specified, "a," "an," "the," "one or more," and "at least one" are used interchangeably and mean one or more than one.

For any method disclosed herein comprising discrete steps, the steps may be performed in any feasible order. Furthermore, any combination of two or more steps may be performed simultaneously, where appropriate.

Also herein, the recitation of numerical range endpoints includes all numbers contained within that range (e.g., 1-5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). Unless otherwise specified, all numbers used in the specification and claims to indicate the number of components, molecular weight, etc. should be understood to be modified by the term "about" in all instances. Therefore, unless otherwise specified, the numerical parameters mentioned in the specification and claims are approximate values and can vary depending on the expected performance to be obtained by the present invention. It is not intended to limit the doctrine of equivalents to the scope of protection of the claims, and each numerical parameter should at least be interpreted based on the number of significant figures provided and the number obtained by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. However, all numerical values inherently contain the standard deviation necessarily resulting from the found in their respective testing measurements.

Ablative agents such as steam, heated gas, or cryogens such as but not limited to liquid nitrogen are inexpensive and readily available and are introduced onto the tissue via an infusion port, maintained at a fixed and constant distance, and aimed for ablation. This allows the ablative agent to be evenly distributed over the target tissue. The microprocessor controls the flow of the ablative agent according to a predetermined method based on the characteristics of the tissue to be ablated, the depth to which ablation is required, and the distance of the port from the tissue. The microprocessor can use temperature, pressure, or other sensed data to control the flow of the ablative agent. In addition, one or more suction ports are provided to aspirate the ablative agent from the vicinity of the target tissue. The target segment can be treated by continuous infusion of the ablative agent, or by a cycle of infusion and removal of the ablative agent determined and controlled by the microprocessor.

It should be understood that the devices and embodiments described herein are implemented in accordance with a controller comprising a microprocessor that executes control instructions. The controller can be any form of computer device, including desktop, laptop, and mobile devices, and can communicate control signals with the ablation device via wired or wireless communication.

The present invention relates to multiple embodiments. The following disclosure is provided to enable those skilled in the art to practice the invention. The language used in this specification should not be interpreted as a general rejection of any one specific embodiment or as a means of limiting the claims beyond the meaning of the terms used herein. The general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of the present invention. In addition, the terms and expressions used are used for the purpose of describing exemplary embodiments and should not be considered to have a limiting effect. Therefore, the present invention should be given the widest scope of protection including various modifications, improvements and equivalent replacements consistent with the disclosed principles and features. For the sake of simplicity, the relevant details of the technical materials known in the relevant technical fields of the present invention have not been described in detail to avoid unnecessary confusion of the present invention.

FIG1 illustrates an ablation device according to one embodiment of the present invention. The ablation device includes a catheter 10 having a distal centering or positioning attachment for an inflatable balloon 11. The catheter 10 is made of or covered with an insulating material to prevent ablative energy from escaping the catheter body. The ablation device includes one or more infusion ports 12 for infusing an ablative agent and one or more suction ports 13 for removing the ablative agent. In one embodiment, the infusion port 12 and the suction port 13 are identical. In one embodiment, the infusion port 12 can direct the ablative agent at different angles. The ablative agent is stored in a reservoir 14 connected to the catheter 10. The delivery of the ablative agent is controlled by a microprocessor 15 and the initiation of treatment is controlled by the treating medical staff using an input device such as a pedal switch 16. In other embodiments, the input device can be a voice recognition system (which responds to commands such as "start", "more", "less", etc.), a mouse, a switch, a footpad, or any other input device known to those skilled in the art. In one embodiment, the microprocessor 15 converts a signal from an input device, such as pressure placed on a pedal switch or a voice command to provide "more" or "less" ablative agent, into a control signal that determines whether to dispense more or less ablative agent. Optional sensors 17 monitor changes in or near the ablated tissue to direct the flow of ablative agent. In one embodiment, the optional sensors 17 also include a temperature sensor. Optional infrared, electromagnetic, acoustic, or radiofrequency energy emitters and sensors 18 measure the dimensions of the hollow organ.

In one embodiment, a user interface comprising a microprocessor 15 allows a medical professional to define the device, organ, and health conditions, which in turn generates default settings for temperature, circulation, volume (sound), and standard RF settings. In one embodiment, these defaults can be further modified by the medical professional. The user interface also includes standard displays for all key variables and alarms for values exceeding or falling below certain levels.

The ablation device also includes safety mechanisms to protect the user from burns while manipulating the catheter, including thermal insulation and, optionally, a cool air purge, a cool water purge, and alarms/sounds to indicate the start and end of treatment.

In one embodiment, the inflatable balloon has a diameter between 1 mm and 10 cm. In one embodiment, the inflatable balloon can be spaced apart from the port by a distance of 1 mm to 10 cm. In one embodiment, the port opening has a size between 1 μm and 1 cm. It should be understood that the inflatable balloon is used to secure the device and is therefore configured to not contact the ablation area. The inflatable balloon can have any shape that contacts the hollow organ at three or more points. Those skilled in the art will understand that the distance of the catheter from the lesion can be calculated using triangulation. Optionally, an infrared, electromagnetic, acoustic, or radio frequency energy emitter and sensor 18 can measure the size of the hollow organ. Infrared, electromagnetic, acoustic, or radio frequency energy is emitted from the emitter 18 and reflected from the tissue to a detector in the emitter 18. The reflection data can be used to determine the size of the hollow cavity. It should be understood that the emitter and sensor 18 can be combined into a transceiver that can both transmit energy and detect reflected energy.

FIG2A illustrates a longitudinal section of an ablation device illustrating the distribution of infusion ports. FIG2B illustrates a cross-sectional view of the distribution of infusion ports on an ablation device according to one embodiment of the present invention. The longitudinal section and cross-section of the catheter 10 illustrated in FIG2A and FIG2B , respectively, illustrate one arrangement of infusion ports 12 for producing a uniform distribution of ablative agent 21 to provide a circumferential ablation zone in a hollow organ 20. FIG2C illustrates a cross-sectional view of the distribution of infusion ports on an ablation device according to another embodiment of the present invention. The arrangement of infusion ports 12 illustrated in FIG2C produces a concentrated distribution of ablative agent 21 and a concentrated area of ablation in the hollow organ 20.

For all embodiments described herein, it should be understood that the size of the ports, the number of ports, and the distance between the ports will be determined by the amount of ablative agent required, the pressure that the hollow organ can withstand, the size of the hollow organ as measured by the port-to-surface distance, the length of the tissue to be ablated (which is roughly the surface area to be ablated), the characteristics of the tissue to be ablated, and the depth of ablation desired. In one embodiment, there is at least one port opening with a diameter between 1 μm and 1 cm. In another embodiment, there are two or more port openings with a diameter between 1 μm and 1 cm and spaced equidistantly around the circumference of the device.

Figure 2D illustrates another embodiment of the ablation device. The vapor ablation catheter includes an insulated catheter 21 having one or more positioning attachments 22 of known length 23. The vapor ablation catheter has one or more vapor infusion ports 25. The length 24 of the vapor ablation catheter 21 having the infusion ports 25 is determined by the length or area of the tissue to be ablated. Vapor 29 is delivered through the vapor infusion ports 25. The catheter 21 is preferably positioned in the center of the positioning attachment 22, and the infusion ports 25 are arranged circumferentially to ablate and deliver vapor in a circumferential direction. In another embodiment, the catheter 21 can be positioned toward the periphery of the positioning attachment 22, and the infusion ports 25 can be arranged non-circumferentially, preferably linearly on one side for focal ablation and vapor delivery. The positioning attachment 22 is one of an inflatable balloon, a wire mesh disk with or without an insulating membrane covering the disk, a conical attachment, a ring attachment, or a free-form attachment designed to fit the desired hollow body organ or hollow body passage, as further described below. Optional infrared, electromagnetic, acoustic or radio frequency energy emitters and sensors 28 may be incorporated to measure the dimensions of hollow organs.

The vapor ablation catheter may also include an optional coaxial sheet 27 to constrain the positioning attachment 22 in a manner similar to a coronary metal stent. In one embodiment, the sheet is made of a memory metal or memory material that has a shape of the positioning attachment in a compressed linear form and a non-compressed form. Optionally, the channel of the endoscope can perform the function of constraining the positioning attachment 22 by, for example, acting as a constraining sheath. An optional sensor 26 is configured on the catheter to measure changes related to vapor delivery or ablation. The sensor is one of a temperature, pressure, image, or chemical sensor.

Alternatively, one or more infrared, electromagnetic, acoustic, or radiofrequency energy emitters and sensors 28 can measure the dimensions of hollow organs. Infrared, electromagnetic, acoustic, or radiofrequency energy is emitted from emitter 28 and reflected from tissue back to a detector within emitter 28. The reflected data can be used to determine the dimensions of the hollow cavity. Measurements are taken at one or more points to obtain an accurate estimate of the dimensions of the hollow organ. The data can also be used to generate topographical images of the hollow organ. Additional data from diagnostic tests can be used to confirm or supplement the data from the above measurements.

2E illustrates an ablation device 20 in the form of a catheter 21 extending from a conventional handle 22, according to one embodiment of the present invention. The catheter 21 is of the type described above and extends from and is attached to the handle 22. In one embodiment, the catheter 21 is thermally insulated to protect the user from burns that may result from the hot vapor heating the catheter. In one embodiment, the catheter is constructed of a material that ensures that the external temperature of the catheter will remain below 60° C. during use. The handle 22 includes a pressure-resistant port at the location where it is attached to the catheter 21. The handle 22 also includes a flow channel within which vapor is directed through the catheter 21.

In one embodiment, the snare handle 22 includes a single attachment port 23 for connecting the steam flow and RF supply. In another embodiment (not shown), the snare handle includes two separate attachment ports for connecting the steam flow and RF supply. The attachment port 23 is connected to the steam supply cord via a pressure-resistant connector. In one embodiment, the connector is a Luer lock type. In one embodiment, the catheter 21 is a double-lumen catheter. The first lumen serves to deliver steam to the ablation site. In one embodiment, the steam is released through a small port 24 provided near the distal end of the catheter 21. The distal end of the catheter 21 is designed so that it can pierce tissue to deliver steam to the desired depth and position within the target tissue. In one embodiment, the distal end of the catheter 21 gradually narrows to a sharp point. The second lumen accommodates electrodes for RF ablation. In one embodiment, the delivery of steam or RF waves is achieved by using a microprocessor. In another embodiment, the user can release steam or subject the target tissue to RF waves by using an actuator (not shown) on the handle 22. In one embodiment, the catheter has varying or different insulation along its length. In one embodiment, ablation device 20 includes a mechanism in which a snare that grasps the tissue to be ablated and sizes the tissue within the snare is used to determine the amount of vapor to be delivered.

FIG2F illustrates a cross-section of an ablation device 27 in the form of a catheter 21 extending from a conventional handle 22 with a pre-attached tether 25 according to another embodiment of the present invention. The tether 25 is attached directly to the vapor delivery system, eliminating an interface between the system and the ablation device and thereby reducing the chance of system failure due to disconnection. In this embodiment, the handle 22 includes a separate attachment port (not shown) for RF or electrical supply.

2G illustrates an ablation device 29 in the form of a catheter 21 extending from a conventional esophageal probe 26 according to one embodiment of the present invention. In one embodiment, the catheter 21 is thermally insulated and receives vapor from a flow channel contained in the probe 26. The catheter 21 includes a plurality of small ports for delivering vapor to the target tissue. The delivery of the vapor is controlled by a microprocessor. In one embodiment, the catheter 21 also includes two inflatable balloons 28, one at its distal end beyond the last vapor port 24 and another at its proximal end, near the location where the catheter 21 is attached to the probe 26. All vapor ports are disposed between the two balloons. Once the device 29 is inserted into the esophagus, the balloons 28 expand to keep the catheter 21 in place and to contain vapor within the desired treatment area. In one embodiment, the balloons must be separated from the ablation area by a distance greater than 0 mm, preferably 1 mm and ideally 1 cm. In one embodiment, the diameter of each balloon when inflated is in the range of 10 to 100 mm, preferably 15-40 mm, but one skilled in the art will appreciate that the exact size depends on the size of the patient's esophagus.

In one embodiment, the catheter 21 attached to the esophageal probe 26 is a double lumen catheter. The first lumen serves to deliver vapor to the ablation site, as described above. The second lumen houses the electrodes for RF ablation.

3A illustrates an ablation device placed in the upper gastrointestinal tract having Barrett's esophagus to selectively ablate Barrett's tissue according to one embodiment of the present invention. The upper gastrointestinal tract includes Barrett's esophagus 31, the gastric cardia 32, the gastroesophageal junction 33, and the displaced squamocolumnar junction 34. The area between the gastroesophageal junction 33 and the displaced squamocolumnar junction 34 is the Barrett's esophagus 31 targeted for ablation. Distal to the cardia 32 is the stomach 35, and proximal to the cardia 32 is the esophagus 36. The ablation device is passed through the esophagus 36 and the positioning device 11 is positioned in the gastric cardia 32, adjacent to the gastroesophageal junction 33. This secures the ablation catheter 10 and its port 12 in the center of the esophagus 36 and allows for uniform delivery of the ablative agent 21 to the Barrett's esophagus 31.

In one embodiment, prior to performing ablation, the positioning device is first secured to an anatomical structure that is not undergoing ablation. If the patient is undergoing peripheral ablation or is undergoing ablation for the first time, the positioning attachment is preferably placed in the gastric cardia, adjacent to the gastroesophageal junction. If the patient is undergoing focal ablation of any residual disease, the catheter system shown in Figure 4B is preferably used, as described below. In one embodiment, the positioning attachment must be spaced apart from the ablation area by a distance of more than 0 mm, preferably 1 mm, and ideally 1 cm. In one embodiment, the size of the positioning device is in the range of 10-100 mm, preferably 20-40 mm, but those skilled in the art will understand that the exact size depends on the size of the patient's esophagus.

The delivery of the ablative agent 21 is controlled by a microprocessor 15 connected to the ablation device through the infusion port 12. The delivery of the ablative agent depends on the tissue to be ablated and the desired ablation depth, and is guided by predetermined program instructions. In one embodiment, the target program temperature will need to be approximately -100-200 degrees Celsius, preferably 50-75 degrees Celsius, as further explained in the table below. In one embodiment, the esophageal pressure should not exceed 5atm and is preferably less than 0.5atm. In one embodiment, the target program temperature is achieved in less than 1 minute, preferably in less than 5 seconds, and can be maintained for up to 10 minutes, preferably 1-10 seconds, and then cooled to body temperature. Those skilled in the art will understand that repeated treatments can be performed until the desired ablation effect is achieved.

Optional sensor 17 monitors intraluminal parameters such as temperature and pressure and can increase or decrease the flow of ablative agent 21 through infusion port 12 to obtain sufficient heating or cooling to produce sufficient ablation. Sensor 17 monitors intraluminal parameters such as temperature and pressure and can increase or decrease the removal of ablative agent 21 through optional suction port 13 to obtain sufficient heating or cooling to achieve sufficient ablation of Barrett's esophagus 31. Figure 3B illustrates an ablation device placed in the upper gastrointestinal tract with Barrett's esophagus to selectively ablate Barrett's tissue according to another embodiment of the present invention. As shown in Figure 3B, the positioning device 11 is a wire mesh disk. In one embodiment, the positioning attachment must be separated from the ablation area by a distance of more than 0 mm, preferably 1 mm, and ideally 1 cm. In one embodiment, the positioning attachment is removably fixed at the cardia or gastroesophageal (EG) junction (for distal attachments) or fixed in the esophagus more than 0.1 mm, preferably about 1 cm above the approximate highest extent of the Barrett's tissue (for proximal attachments).

FIG3B illustrates another embodiment of a Barrett's ablation device in which the positioning element 11 is a wire mesh disk. The wire mesh may have an optional thermal insulation film to prevent the ablative agent from escaping. In the current embodiment, two wire mesh disks are used to position the ablation catheter in the center of the esophagus. The distance between the two disks is determined by the length of the tissue to be ablated, which in this case is the length of Barrett's esophagus. Optional infrared, electromagnetic, acoustic, or radiofrequency energy emitters and sensors 18 may be incorporated to measure the diameter of the esophagus.

FIG3C is a flow chart illustrating the basic procedural steps for using an ablation device according to one embodiment of the present invention. In step 302, a catheter of the ablation device is inserted into the organ to be ablated. For example, to ablate a patient's Barrett's esophagus, the catheter is inserted into the patient's esophagus via the esophagus.

In step 304, the positioning element of the ablation device is deployed and the size of the organ is measured. In one embodiment, if the positioning element is a balloon, the balloon is inflated to position the ablation device at a known predetermined distance from the tissue to be ablated. In various embodiments, the diameter of the hollow organ can be predetermined by using radiological tests such as barium x-rays or computed tomography (CT) scans, or can be predetermined by using pressure-volume cycles, i.e., by determining the volume required to increase the pressure in a fixed volume balloon to a fixed level (e.g., 1 atm). In another embodiment, if the positioning device is disc-shaped, a peripheral ring is provided to provide a visual understanding of the diameter of the hollow organ to the operating medical staff. In various embodiments of the present invention, the positioning device enables the catheter of the ablation device to be centered in a non-cylindrical body cavity, and the volume of the cavity is measured by the length of the catheter or a uterine sound.

Alternatively, the dimensions of hollow organs can be measured using one or more of infrared, electromagnetic, acoustic, or radiofrequency energy emitters and sensors. Infrared, electromagnetic, acoustic, or radiofrequency energy is emitted from the emitter and reflected from tissue to a detector within the emitter. The reflected data can be used to determine the dimensions of the hollow cavity. Measurements can be taken at one or more points to obtain a precise estimate of the dimensions of the hollow organ. Data from multiple points can also be used to generate a topographical image of the hollow organ or to calculate the volume of the hollow organ.

In one embodiment, the positioning attachment must be spaced from the port by a distance of 0 mm or more, preferably greater than 0.1 mm, and more preferably 1 cm. The size of the positioning device depends on the hollow organ being ablated and is in the range of 1 mm to 10 cm. In one embodiment, the diameter of the positioning element is between 0.01 mm and 100 mm. In one embodiment, the first positioning element comprises a circular body having a diameter between 0.01 mm and 10 cm.

In step 306, the organ is ablated by automatically delivering an ablative agent, such as steam, through an infusion port provided on the catheter. The delivery of the ablative agent through the infusion port is controlled by a microprocessor connected to the ablation device. The delivery of the ablative agent is guided by predetermined program instructions, depending on the tissue to be ablated and the depth of ablation required. In one embodiment of the present invention, if the ablative agent is steam, the dose of the ablative agent is determined by performing a dose measurement study to determine the dose for ablating endometrial tissue. The variable that can determine the total dose of the ablative agent is the volume (or mass) of the tissue to be treated, which is calculated using the length of the catheter and the diameter of the organ (for cylindrical organs). The determined dose of the ablative agent is then delivered using a microprocessor-controlled steam generator. Optionally, the delivery of the ablative agent can be controlled by an operator using predetermined dose measurement parameters.

In one embodiment, dosage is provided by first determining the treatment condition and desired tissue effect, and then finding the corresponding temperature, as shown in Tables 1 and 2 below.

Table 1

Temperature Organizational Effect 37-40 No obvious organizational effect 41-44 Cell damage reversible within hours 45-49 Irreversible cell damage within a short period of time 50-69 Irreversible cell damage in a short period of time - ablation necrosis 70 Threshold temperature for tissue shrinkage and H-bond breaking 70-99 Coagulation and hemostasis 100-200 Drying and carbonization of tissue >200 Carbonization of tissue glucose

Table 2

Nasal polyps 60-80 Turbinate resection 70-85 Bullous diseases 70-85 Lung repositioning 70-85 Heavy menstrual bleeding 80-90 Endometriosis 80-90 Uterine fibroids 90-100 Benign prostatic hyperplasia (BPH) 90-100 Barrett's esophagus 60-75 Esophageal dysplasia 60-80 Vascular GI disorders 55-75 Flat polyps 60-80

Furthermore, the desired ablation depth determines the maximum temperature hold time. For surface ablation (Barrett's), the maximum temperature hold time is very short (rapid burning) and does not allow heat to be delivered to deeper layers. This prevents damage to deeper normal tissues and, therefore, prevents patient discomfort and complications. For ablation of deeper tissues, the maximum temperature hold time is longer, thus allowing heat to penetrate deeper.

Figure 4A illustrates an ablation device placed in the colon for ablation of a flat colon polyp according to one embodiment of the present invention. An ablation catheter 10 is passed through a colonoscope 40. A positioning device 11 is arranged in the normal colon 42 relative to the patient's GI tract near a flat colon polyp 41 to be ablated. The positioning device 11 is one of an inflatable balloon, a wire mesh disk with or without an insulating membrane covering the disk, a conical attachment, a ring attachment, or a free-form attachment designed to fit into the colon lumen. The positioning device 11 positions the catheter 10 toward the periphery of the positioning device 11, placing it closer to the polyp 41 for non-circumferential ablation. Thus, the positioning device 11 secures the catheter to the colon 42 at a predetermined distance from the polyp 41 for uniform and focused delivery of the ablative agent 21. The delivery of the ablative agent 21 through the infusion port 12 is controlled by a microprocessor 15 connected to the ablation device and depends on the tissue and the depth of ablation required. The delivery of ablative agent 21 is guided by pre-programmed instructions, depending on the tissue to be ablated and the desired area and depth of ablation. Optional infrared, electromagnetic, acoustic, or radiofrequency energy emitters and sensor 18 are incorporated to measure the diameter of the colon. The ablation device allows for focused ablation of the diseased polyp mucosa without damaging the normal colon mucosa located away from the catheter port.

In one embodiment, the positioning attachment must be spaced from the ablation zone by a distance greater than 0.1 mm, ideally more than 5 mm. In one embodiment, the positioning element is proximate to the colon polyp relative to the patient's GI tract.

FIG4B illustrates an ablation device placed in a colon 42 to ablate a flat colon polyp 41, according to another embodiment of the present invention. As shown in FIG4B , positioning device 11 is a tapered attachment located at the tip of catheter 10. The tapered attachment has a known length "l" and diameter "d," which are used to calculate the amount of thermal energy required to ablate flat colon polyp 41. Ablative agent 21 is introduced from infusion port 12 to polyp 41 via positioning device 11. In one embodiment, positioning attachment 11 must be separated from the ablation region by a distance greater than 0.1 mm, preferably 1 mm, and more preferably 1 cm. In one embodiment, length "l" is greater than 0.1 mm, preferably between 5 and 10 mm. In one embodiment, diameter "d" depends on the size of the polyp and can be between 1 mm and 10 cm, preferably between 1 and 5 cm. Optional infrared, electromagnetic, acoustic, or radiofrequency energy emitters and sensor 18 are incorporated to measure the diameter of the colon. This embodiment can also be used to ablate residual neoplastic tissue at the margins following endoscopic snare removal of larger, sessile colon polyps.

FIG5A illustrates an ablation device having a coaxial catheter design according to one embodiment of the present invention. The coaxial design comprises a handle 52a, an infusion port 53a, an inner sheath 54a, and an outer sheath 55a. The outer sheath 55a is used to constrain a positioning device 56a in a closed position and surrounds the port 57a. FIG5B illustrates a partially deployed positioning device 56b, with the port 57b still located within the outer sheath 55b. The positioning device 56b is partially deployed by pushing the catheter 54b away from the sheath 55b.

Figure 5C illustrates the fully deployed positioning device 56c. The infusion port 57c exits the sheath 55c. The length "l" of the catheter 54c containing the infusion port 57c and the diameter "d" of the positioning element 56c are predetermined/known and are used to calculate the amount of thermal energy required. Figure 5D illustrates the conical design of the positioning element. The positioning element 56d is a cone with a known length "l" and a diameter "d", which are used to calculate the amount of thermal energy required for ablation. Figure 5E illustrates the disc design of the positioning element 56e, including a circumferential ring 59e. The circumferential ring 59e is set at a fixed predetermined distance from the catheter 54e and is used to estimate the diameter of a hollow organ or hollow passage in the patient's body.

FIG6 illustrates an upper gastrointestinal tract with a bleeding vascular lesion being treated using an ablation device according to one embodiment of the present invention. The vascular lesion is a visible vessel 61 in the base of an ulcer 62. An ablation catheter 63 is passed through the channel of an endoscope 64. A conical positioning element 65 is arranged above the visible vessel 61. The conical positioning element 65 has a known length "1" and diameter "d", which are used to calculate the amount of thermal energy required to coagulate the visible vessel to achieve hemostasis. The conical positioning element has an optional insulating membrane that prevents heat or vapor from escaping from the diseased area.

In one embodiment, the positioning attachment must be spaced from the ablation region by a distance greater than 0.1 mm, preferably 1 mm, and more preferably 1 cm. In one embodiment, the length "1" is greater than 0.1 mm, preferably between 5 and 10 mm. In one embodiment, the diameter "d" depends on the size of the lesion and can be between 1 mm and 10 cm, preferably between 1 and 5 cm.

FIG7 illustrates endometrial ablation of a female uterus using an ablation device according to one embodiment of the present invention. A cross-sectional view of the female reproductive tract, including vagina 70, cervix 71, uterus 72, endometrium 73, fallopian tubes 74, uterine sheaths 75, and uterine fundus 76, is illustrated. A catheter 77 of the ablation device is inserted through cervix 71 and into uterus 72. In one embodiment, catheter 77 has two positioning elements: a conical positioning element 78 and a disc-shaped positioning element 79. Positioning element 78 is conical and has an insulating membrane covering it. Conical element 78 positions catheter 77 in the center of cervix 71, and the insulating membrane prevents heat or ablative agent from escaping through cervix 71. A second disc-shaped positioning element 79 is deployed near uterine fundus 76, positioning catheter 77 in the center of the uterine cavity. Ablative agent 778 is delivered uniformly into the uterine cavity through infusion port 777. The predetermined length "1" of the ablation section of the catheter and the diameter "d" of the positioning element 79 allow for an estimation of the cavity size and are used to calculate the amount of thermal energy required to ablate the endometrial lining. An optional temperature sensor 7 disposed proximate to the endometrial surface can be used to control the delivery of the ablative agent 778. Optional local radiographic mapping using multiple infrared, electromagnetic, acoustic, or radiofrequency energy emitters and sensors can be used to define the cavity size and shape in patients with an irregular or deformed uterine cavity due to conditions such as fibroids. Additionally, data from diagnostic tests can be used to determine the uterine cavity size, shape, or other characteristics.

In one embodiment, the ablative agent is a vapor or steam that contracts as it cools. Steam becomes water, which has a smaller volume, compared to a refrigerant that expands, or a hot fluid used in hydrothermal ablation that remains constant in volume. For both refrigerants and hot fluids, increasing energy delivery is associated with increasing the volume of the ablative agent, which in turn requires a mechanism to remove the ablative agent or complications from the drug delivery, such as perforation. However, steam, when cooled, becomes water, which occupies a significantly smaller volume; therefore, increased energy delivery is not associated with an increase in the volume of remaining ablative agent, eliminating the need for continued removal. This further reduces the risk of thermal energy leaking through the fallopian tubes 74 or cervix 71, thereby reducing the risk of thermal damage to nearby healthy tissue.

In one embodiment, the positioning attachment must be spaced greater than 0.1 mm, preferably 1 mm, and more preferably 1 cm from the ablation region. In another embodiment, the positioning attachment can be positioned within the ablation region as long as it does not cover a significant surface area. For endometrial ablation, 100% of the tissue does not need to be ablated to achieve the desired therapeutic effect.

In one embodiment, a preferred distal positioning attachment is an uncovered wire mesh positioned proximal to the central body region. In one embodiment, a preferred proximal positioning device is a covered wire mesh that is pulled into the cervix to center the device and seal the cervix. One or more such positioning devices may be advantageous for compensating for anatomical variations in the uterus. The proximal positioning device is preferably elliptical, having a major axis between 0.1 mm and 10 cm (preferably 1 cm to 5 cm) and a minor axis between 0.1 mm and 5 cm (preferably 0.5 cm to 1 cm). The distal positioning device is preferably circular, having a diameter between 0.1 mm and 10 cm, preferably 1 cm to 5 cm.

FIG8 illustrates sinus ablation performed in a nasal passage using an ablation device according to one embodiment of the present invention. A cross-sectional view of the nasal passage and sinuses is shown, including a nostril 81, a nasal passage 82, a frontal sinus 83, an ethmoid sinus 84, and diseased sinus epithelial cells 85. A catheter 86 is inserted through the nostril 81 and nasal passage 82 into the frontal sinus 83 or the ethmoid sinus 84.

In one embodiment, catheter 86 has two positioning elements: a conical positioning element 87 and a disc-shaped positioning element 88. Positioning element 87 is conical and covered with an insulating membrane. Conical element 87 positions catheter 86 in the center of sinus opening 80, and the insulating membrane prevents thermal energy or ablative agent from escaping through the opening. A second disc-shaped positioning element 88 deploys in either the frontal sinus cavity 83 or the ethmoid sinus cavity 84, positioning catheter 86 in the center of either sinus cavity. Ablative agent 8 is delivered uniformly into the sinus cavity through infusion port 89. The predetermined length "1" of the catheter's ablation segment and the diameter "d" of positioning element 88 allow for estimation of sinus cavity size and calculation of the amount of thermal energy required to ablate diseased sinus epithelial cells 85. An optional temperature sensor 888 is positioned near the diseased sinus epithelial cells 85 to control the delivery of ablative agent 8. In one embodiment, the ablative agent is a vapor that contracts upon cooling. This further reduces the risk of thermal leakage, thereby minimizing the risk of thermal damage to nearby healthy tissue. In one embodiment, the size range of the positioning elements is similar to that used in endometrial applications, with a preferred maximum range of half that. Optional localized photographic mapping using multiple infrared, electromagnetic, acoustic, or radiofrequency energy emitters and sensors can be used to define lumen size and shape in patients with irregular or deformed lumens due to conditions such as nasal polyps.

Figure 9 illustrates ablation of a bronchus and bullae in a lung system using an ablation device according to one embodiment of the present invention. A cross section of a lung system is illustrated with bronchus 91, normal alveoli 92, bullous lesions 93, and bronchial ulcers 94.

In one embodiment, a catheter 96 is inserted through the channel of a bronchoscope 95 into a bronchus 91 and into a bullous lesion 93. Catheter 96 has two positioning elements: a conical positioning element 97 and a disc-shaped positioning element 98. Positioning element 97 is conical and covered with a thermally insulating membrane. Conical element 97 positions catheter 96 in the center of bronchus 91, while the thermally insulating membrane prevents heat energy or ablative agent from escaping through the opening into the normal bronchus. A second disc-shaped positioning element 98 deploys within the bullous cavity 93, positioning catheter 96 in the middle of the cavity. Ablative agent 9 is delivered uniformly into the sinus cavity through an infusion port 99. The predetermined length "1" of the ablation segment of catheter 96 and the diameter "d" of positioning element 98 allow for estimation of the size of the bullous cavity and are used to calculate the amount of thermal energy required to ablate the diseased bullous cavity 93. Alternatively, the cavity size can be calculated using radiological assessments of chest CAT scans or MRI. An optional temperature sensor is placed near the surface of the bullous cavity 93 to control the delivery of the ablative agent 9. In one embodiment, the ablative agent is a vapor that contracts when cooled. This further reduces the risk of thermal energy leaking into the normal bronchi, thereby reducing the risk of thermal damage to nearby normal tissue.

In one embodiment, the positioning attachment must be spaced more than 0.1 mm, preferably 1 mm, and more preferably 1 cm from the ablation zone. In another embodiment, the positioning attachment can be located within the ablation zone as long as it does not occupy a significant surface area.

In one embodiment, two positioning attachments are preferably provided. In another embodiment, an endoscope is used as a fixed point with a positioning element. The positioning device is between 0.1 mm and 5 cm (preferably 1 mm to 2 cm). The distal positioning device is preferably circular, with a diameter of 0.1 mm to 10 cm, preferably 1 cm to 5 cm.

In another embodiment of ablating a bronchial tumor 94, a catheter 96 is inserted into a bronchus 91 through a channel of a bronchoscope 95 and advanced through the bronchial tumor 94. A positioning element 98 is disc-shaped and has an insulating film covering. The positioning element 98 positions the catheter in the center of the bronchus 91, and the insulating film prevents heat energy or ablative agent from escaping through the opening into the normal bronchi. The ablative agent 9 is delivered uniformly to the bronchial tumor 94 through the infusion port 99 in a non-circular manner. The predetermined length "1" of the ablation segment of the catheter and the diameter "d" of the positioning element 98 are used to calculate the amount of heat energy required to ablate the bronchial tumor 94.

Using endoscope, laparoscope, stereo guide or radiological guidance, the catheter can be advanced to the desired ablation site. Optionally, using magnetic navigation, the catheter can be advanced to the desired location.

FIG10 illustrates prostate ablation performed on an enlarged prostate in the male urinary system using a device according to one embodiment of the present invention. A cross-section of the male urogenital tract is illustrated, including an enlarged prostate 1001, a bladder 1002, and a urethra 1003. The urethra 1003 is compressed by the enlarged prostate 1001. An ablation catheter 1005 is passed through a cystoscope 1004 placed in the urethra 1003 distal to the obstruction. A positioning element 1006 is deployed to position the catheter in the center of the urethra 1003 and one or more insulating needles 1007 are passed through to penetrate the prostate 1001. A vapor ablative agent 1008 is passed through the insulating needles 1007, thereby ablating the diseased prostate tissue and shrinking the prostate.

The size of the enlarged prostate can be calculated using the difference between the intraprostatic urethra and the extraprostatic urethra. Standard values can be used as a benchmark. Additional ports for infusing cooling fluid into the urethra can be provided to prevent damage to the urethra when ablative energy is delivered to the prostate for ablation, thereby preventing complications such as stricture formation.

In one embodiment, the positioning attachment must be spaced greater than 0.1 mm, preferably 1 mm to 5 mm, and no more than 2 cm from the ablation area. In another embodiment, the positioning attachment can be deployed in the bladder and pulled back into the urethral opening/bladder neck to secure the catheter. In one embodiment, the diameter of the positioning device is between 0.1 mm and 10 cm.

FIG11 illustrates uterine fibroid ablation performed on a female uterus using an ablation device according to one embodiment of the present invention. A cross-section of the female urogenital tract is illustrated, including a uterine fibroid 1111, a uterus 1112, and a cervix 1113. An ablation catheter 1115 is passed through a hysteroscope 1114, which is positioned within the uterus distal to the uterine fibroid 1111. The ablation catheter 1115 has a piercing tip 1120 that facilitates penetration into the uterine fibroid 1111. A positioning element 1116 is deployed to position the catheter in the center of the fibroid, while an insulated needle 1117 is passed through the needle 1117 to pierce the fibroid tissue 1111. A vapor ablative agent 1118 is passed through the needle 1117, thereby ablating the uterine fibroid 1111 and causing it to shrink.

FIG12 illustrates a vapor delivery system that utilizes an RF heater to supply vapor to an ablation device according to one embodiment of the present invention. In one embodiment, vapor is used as the ablative agent used in the ablation device described herein. An RF heater 64 is located near a pressure vessel 42 containing a liquid 44. The RF heater 64 heats the vessel 42, which in turn heats the liquid 44. The liquid 44 increases in temperature and begins to evaporate, causing the pressure in the vessel 42 to increase. The pressure in the vessel 42 can be maintained fairly constant by providing a thermal switch 46 that controls the resistance heater 64. Once the temperature of the liquid 44 reaches a predetermined temperature, the thermal switch 46 turns off the RF heater 64. The vapor generated in the pressure vessel 42 can be released via a control valve 50. As the vapor exits the vessel 42, a pressure drop occurs in the vessel, causing the temperature to drop. The thermal switch 46 measures the temperature drop, and the RF heater 64 resumes heating the liquid 44. In one embodiment, the target temperature of the vessel 42 can be set to approximately 108° C., providing a continuous supply of vapor. As the vapor is released, it experiences a pressure drop that reduces the temperature of the vapor to approximately 90-100° C. As the liquid 44 in the vessel 42 evaporates and the vapor exits the vessel 42, the amount of liquid 44 slowly decreases. Optionally, the vessel 42 is connected to a reservoir 43 containing the liquid 44 via a pump 49, which is activated by the controller 24 after sensing a decrease in pressure or temperature in the vessel 42 to deliver additional liquid 44 to the vessel 42.

Vapor delivery conduit 16 is connected to vessel 42 via fluid connector 56. When control valve 50 is open, vessel 42 is in fluid communication with delivery conduit 16 via connector 56. Control switch 60 can be used to turn vapor delivery on and off via actuator 48. For example, control switch 60 can physically open and close valve 50 via actuator 48 to control the delivery of vapor flow from vessel 42. Switch 60 can be configured to control other properties of the vapor, such as direction, flow rate, pressure, volume, spray diameter, or other parameters.

As an alternative to physically controlling the properties of the steam or in addition to physically controlling the properties of the steam, the switch 60 can also be electrically connected to the controller 24. The controller 24 controls the RF heater 64, which in turn controls the properties of the steam in response to the operator's actuation of the switch 60. In addition, the controller 24 can control the valve temperature or pressure regulator associated with the conduit 16 or the vessel 42. The flow rate, pressure or volume of the steam delivered via the conduit 16 can be measured using a flow meter 52. The controller 24 controls the temperature and pressure in the vessel 42, as well as the time, rate, flow rate and volume of the steam flowing through the control valve 50. These parameters are set by the operator 11. With a target temperature of 108°C, the pressure generated in the vessel 42 can be approximately 25 pounds per square inch (Psi) (1.72 bar).

FIG13 illustrates a vapor delivery system utilizing a resistive heater to supply vapor to an ablation device according to one embodiment of the present invention. In one embodiment, the vapor generated is used as an ablative agent for the ablation device described herein. A resistive heater 40 is positioned adjacent to a pressure vessel 42. Vessel 42 contains a liquid 44. Resistive heater 40 heats vessel 42, which in turn heats liquid 44. As a result, liquid 44 heats and begins to vaporize. As liquid 44 begins to vaporize, the vapor in vessel 42 increases the pressure within the vessel. The pressure within vessel 42 can be maintained relatively constant by providing a thermal switch 46 that controls resistive heater 40. When the temperature of liquid 44 reaches a predetermined temperature, thermal switch 46 turns off resistive heater 40. The vapor generated within pressure vessel 42 can be released via control valve 50. As the vapor exits vessel 42, vessel 42 experiences a pressure drop. This pressure drop in vessel 42 causes the temperature to decrease. Thermal switch 46 measures the temperature drop, and resistive heater 40 resumes heating liquid 44. In one embodiment, the target temperature of vessel 42 can be set to about 108°C, providing a continuous supply of steam. As the steam is released, it experiences a pressure drop that reduces the temperature of the steam to a range of 90-100°C. As the liquid 44 in vessel 42 evaporates and the steam exits vessel 42, the amount of liquid 44 slowly decreases. Vessel 42 is connected to another vessel 43 containing liquid 44 via pump 49, which is activated by controller 24 after sensing a decrease in pressure or temperature in vessel 42 to deliver additional liquid 44 to vessel 42.

The steam delivery conduit 16 is connected to the vessel 42 via a fluid connector 56. When the control valve 50 is opened, the vessel 42 is in fluid communication with the delivery conduit 16 via the connector 56. A control switch 60 can be used to turn steam delivery on and off via the actuator 48. For example, the control switch 60 can physically open and close the valve 50 via the actuator 48 to control the delivery of the steam flow from the vessel 42. The switch 60 can be configured to control other properties of the steam, such as direction, flow, pressure, volume, jet diameter or other parameters. As an alternative to physically controlling the steam properties or in addition to physically controlling the steam properties, the switch 60 can also be electrically connected to the controller 24. The controller 24 controls the resistance heater 40, which in turn controls the properties of the steam in response to the operator's actuation of the switch 60. In addition, the controller 24 can control the valve temperature or pressure regulator associated with the conduit 16 or the vessel 42. The flow meter 52 can be used to measure the flow, pressure, or volume of the steam delivered via the conduit 16. Controller 24 controls the temperature and pressure in vessel 42, as well as the time, rate, flow rate, and volume of vapor flowing through control valve 50. These parameters may be set by operator 11. Using a target temperature of 108° C., the pressure generated in vessel 42 may be approximately 25 pounds per square inch (psi) (1.72 bar).

Figure 14 illustrates a vapor delivery system that utilizes a heating coil to supply vapor to an ablation device according to one embodiment of the present invention. In one embodiment, the vapor generated is used as an ablative agent for use with the ablation device described herein. The vapor delivery system includes a conventional generator 1400, which is typically used in an operating room to power a specialized tool, namely a cutter. Generator 1400 is modified to include an integrated liquid reservoir 1401. In one embodiment, reservoir 1401 is filled with room temperature pure water. The reservoir 1401 portion of generator 1400 is connected to a heating element 1405 via a reusable active cord 1403. In one embodiment, reusable active cord 1403 can be used up to 200 times. The two ends of cord 1403 are fixedly attached via connectors to withstand operating pressures, and preferably withstand maximum pressures so that the cord will not break. In one embodiment, the connector can withstand a pressure of at least 1 atm. In one embodiment, the connector is a Luer lock type. The cord 1403 has a lumen through which the liquid flows to the heating element 1405. In one embodiment, the heating element 1405 includes a coiled length of tubing 1406. As the liquid flows through the coiled tubing 1406, it is heated by the surrounding heating element 1405 in a manner similar to a conventional heat exchanger. When the liquid is heated, it is vaporized. The heating element includes a connector 1407 that accommodates the outlet of the vapor from the coiled tubing 1406. One end of a single-use cord 1408 is attached to the heating element 1405 at the connector 1407. The connector 1407 is designed to withstand the pressure generated by the vapor within the coiled tubing 1406 during operation. In one embodiment, the connector 1407 is a Luer lock type. The ablation device 1409 is attached to the other end of the single-use cord 1408 via a connector that can withstand the pressure generated by the system. In one embodiment, the ablation device is integrated with a catheter. In another embodiment, the ablation device is integrated with a probe. The single-use cord 1408 has a specific lumen diameter and a specific length to ensure that the contained vapor does not condense into liquid, while providing sufficient slack for the user to operate. In addition, the single-use cord 1408 provides sufficient thermal insulation so that personnel will not be burned if they come into contact with the cord. In one embodiment, the single-use cord has a lumen diameter of less than 3 mm, preferably less than 2.6 mm, and a length of no more than 1 meter.

In one embodiment, the system includes a pedal switch 1402 that allows the user to supply more vapor to the ablation device. Pressing the pedal switch 1402 causes liquid to flow from the reservoir 1401 into the heating element 1405, where it is converted into vapor within the coiled tubing 1406. The vapor then flows to the ablation device via a single-use cord 1408. The ablation device includes an actuator that allows the user to open a small port on the device, releasing the vapor and ablating the target tissue.

FIG15 illustrates a heating element 1505 and a coiled tubing 1506 of the heating coil vapor delivery system of FIG14 according to an embodiment of the present invention. Liquid passes through a reusable active cord (not shown) and reaches a connector 1502 on one side of the heating element 1505. The liquid then travels through the coiled tubing 1506 within the heating element 1505. The coiled tubing is made of a material and is specifically configured to provide optimal heat transfer to the liquid. In one embodiment, the coiled tubing 1506 is copper. The temperature of the heating element 1505 is set within a range such that the liquid is converted into vapor when passing through the coiled tubing 1506. In one embodiment, the temperature of the heating element 1505 can be set by the user using a temperature setting dial 1508. In one embodiment, the heating element includes an on/off switch 1509 and is powered using an attached AC power cord 1503. In another embodiment, the heating element receives electricity through an electrical connector integrated into and/or facilitated by the active cord connected to the reservoir. The vapor passes through the end of the coiled tubing 1506 and exits the heating element 1505 through a connector 1507. In one embodiment, the connector 1507 is located on the opposite side of the heating element 1505 from the inlet connection 1502. A single-use cord (not shown) is attached to the connector 1507 and supplies the vapor to the ablation device.

FIG16A illustrates an unassembled interface connection between an ablation device 1608 and a single-use cord 1601 of the heating coil vapor delivery system of FIG14 , in accordance with an embodiment of the present invention. In this embodiment, the ablation device 1608 and the single-use cord 1601 are connected via a male-to-male dual Luer lock adapter 1605. The end of the single-use cord 1601 is threaded to form a female end 1602 of a Luer lock interface and is connected to one end of the adapter 1605. The ablation device 1608 includes a small protrusion at its non-operative end that is also threaded to form a female end 1607 of a Luer lock interface and is connected to the other end of the adapter 1605. The threaded Luer lock interface provides a secure connection and is capable of withstanding the pressure generated by the heating coil vapor delivery system without disconnecting.

FIG16B illustrates the assembled interface connection between ablation device 1608 and single-use cord 1601 of the heated coil vapor delivery system of FIG14 , according to an embodiment of the present invention. A male-to-male dual Luer lock adapter 1605 is depicted securing the two components together. The dual Luer lock interface provides a stable seal, allows interchangeability between ablation devices, and enables the user to quickly replace the single-use cord.

FIG17 illustrates a vapor ablation system that utilizes a heater or heat exchanger unit to supply vapor to an ablation device according to another embodiment of the present invention. In the depicted embodiment, water for conversion to vapor is supplied in a disposable, single-use sterile fluid container 1705. Container 1705 is sealed by a sterile screw cap 1710, which is pierced by a connector 1715 disposed on a first end of a first filter member 1720. A second end of the first filter member 1720, opposite the first end, is connected to a pump 1725 to draw water from the fluid container 1705, through the first filter member 1720, and then into a heater or heat exchanger unit 1730. The system includes a microcontroller or microprocessor 1735 to control the operation of the pump 1725 and the heater or heat exchanger unit 1730. The heater or heat exchanger unit 1730 converts the water into vapor (steam). The increase in pressure generated during the heating step drives the vapor through an optional second filter member 1740 and into the ablation catheter 1750. In one embodiment, the heater or heat exchanger unit 1730 includes a one-way valve at its proximal end to prevent vapor from returning to the pump 1725. In various embodiments, an optional sensor 1745 disposed near the distal end of the conduit 1750 measures one or more of the temperature, pressure, or flow rate of the vapor and sends the information to the microcontroller 1735, which in turn controls the speed of the pump 1725 and the level of vaporization energy provided by the heater or heat exchanger unit 1730.

FIG18 illustrates the fluid container 1805, first filter member 1820, and pump 1825 of the vapor ablation system of FIG17. As seen in the depicted embodiment, the system includes a water-filled, disposable, single-use sterile fluid container 1805 and a pump 1825 with a first filter member 1820 disposed therebetween. The first filter member 1820 is connected to the container 1805 and the pump 1825 by two, respectively, first and second, lengths of sterile tubing 1807, 1822, and comprises a filter for purifying water used in the ablation system.

19 and 20 illustrate first and second views, respectively, of the fluid container 1905, 2005, first filter member 1920, 2020, pump 1925, 2025, heater or heat exchanger unit 1930, 2030, and microcontroller 1935, 2035 of the vapor ablation system of FIG 17. Container 1905, 2005 is connected to first filter member 1920, 2020 via a first length of sterile tubing 1907, 2007, and first filter member 1920, 2020 is connected to pump 1925, 2025 via a second length of sterile tubing 1922, 2022. A third length of sterile tubing 1927, 2027 connects pump 1925, 2025 to heater or heat exchanger unit 1930, 2030. The microcontroller 1935, 2035 is operably connected to the pump 1925, 2025 via a first set of control lines 1928, 2028 and to the heater or heat exchanger unit 1930, 2030 via a second set of control lines 1929, 2029. Arrows 1901, 2001 depict the direction of water flow from the container 1905, 2005 through the first filter member 1920, 2020 and the pump 1925, 2025 and into the heater or heat exchanger member 1930, 2030, where the water is converted into vapor. Arrows 1931, 2031 depict the direction of vapor flow from the heater or heat exchanger unit 1930, 2030 into an ablation catheter (not shown) used in an ablation procedure.

FIG21 illustrates an unassembled first filter member 2120 of the vapor ablation system of FIG17 , depicting a filter 2122 disposed therein. In one embodiment, the first filter member 2120 includes a proximal portion 2121, a distal portion 2123, and a filter 2122. The proximal portion 2121 and the distal portion 2123 are secured together and house the filter 2122 therein. FIG21 also depicts a disposable, single-use sterile fluid container 2105 and a first length of sterile tubing 2107 connecting the container 2105 to the proximal portion 2121 of the first filter member 2120.

Figure 22 illustrates one embodiment of a microcontroller 2200 for the vapor ablation system of Figure 17. In various embodiments, the microcontroller 2200 includes a plurality of control lines 2228 connected to the pump and heater or heat exchanger unit for controlling said components and a plurality of transmission lines 2247 for receiving flow, pressure, and temperature information from an optical sensor positioned near the distal end of the ablation catheter.

FIG23 illustrates an embodiment of a catheter assembly 2350 for use with the vapor ablation system of FIG17 . Vapor is delivered from a heater or heat exchanger unit to the catheter assembly 2350 via a tube 2348 attached to the proximal end of a connector component 2352 of the assembly 2350. A disposable catheter 2356 having a disposable length of flexible tubing 2358 fixedly attached at its distal end is assembled to the connector component 2352. A second filter member 2354 is disposed between the connector component 2352 and the disposable catheter 2356 to purify the vapor supplied by the heater or heat exchanger unit. The connector component 2352 includes two gaskets 2353 spaced a short distance apart at its distal end to engage the covered disposable catheter 2356 and form a double-stage seal, thereby preventing vapor from leaking between the components. Once the disposable catheter 2356 is assembled to the distal end of the connector component 2352, the catheter connector 2357 is slid over the disposable flexible tubing 2358 and the disposable catheter 2356 and then snapped into place on the connector component 2352. The catheter connector 2357 serves to hold the disposable catheter 2356 in place and also helps prevent vapor leakage. In various embodiments, the disposable flexible tubing 2358 includes one or more holes or ports 2359 at or near its distal end to facilitate delivery of ablation vapor to the target tissue.

FIG24 illustrates one embodiment of a heat exchanger unit 2430 for use with the vapor ablation system of FIG17 . The heat exchanger unit 2430 includes a length of coiled tubing 2435 surrounded by a heating element 2434. Water 2432 enters the coiled tubing 2435 of the heat exchanger unit 2430 at an inlet port 2433 near a first end of the heat exchanger unit 2430. As the water 2432 flows within the coiled tubing 2435, the water is converted into vapor (steam) 2438 by heat dissipated from the coiled tubing 2435, which has been heated by the heating element 2434. The vapor 2438 exits the coiled tubing 2435 of the heat exchanger unit 2430 at an outlet port 2437 near a second end of the heat exchanger unit 2430 and is then delivered to an ablation catheter (not shown) for use in an ablation procedure.

Figure 25 illustrates another embodiment of a heat exchanger unit 2560 for use with the vapor ablation system of the present invention. In the depicted embodiment, the heat exchanger unit 2560 comprises a cylindrical, pen-sized "clamshell" type heating block. The heating block of the heat exchanger unit 2560 comprises a first half 2561 and a second half 2562 firmly attached along one side by a hinge 2563, wherein the halves 2561, 2562 are folded together and connected on opposite sides. In one embodiment, the side of the half opposite to the side with the hinge includes a clamp for holding the two halves together. In one embodiment, one of the halves includes a handle 2564 for manipulating the heat exchanger unit 2560. When the two halves are folded together, the heat exchanger unit 2560 snugly encloses a cylindrical catheter fluid heating chamber 2551, which is attached to the proximal end of the ablation catheter 2550, aligned with the proximal end and in fluid communication with the proximal end. Each half 2561, 2562 of the heat exchanger unit 2560 includes a plurality of heating elements 2565 for a heating block. The heating blocks are positioned and assembled so as to be in close thermal contact with the catheter fluid heating chamber 2551. When in operation, the heating elements 2565 heat the heating blocks, which transfer heat to the catheter fluid heating chamber 2551, which in turn heats the water within the chamber 2551, converting the water into steam. The heating blocks do not directly contact the water. In one embodiment, the catheter fluid heating chamber 2551 includes a plurality of linear recesses 2591 that extend along the length of the component and parallel to the heating elements 2565. When the halves 2561, 2562 are closed, the heating element 2565, which optionally protrudes from the inner surface of the halves 2561, 2562, contacts and fits within the linear recess 2591. This also increases the contact surface area between the heating block and the heating element, improving the efficiency of heat exchange.

A Luer fitting coupler 2549 is provided at the proximal end of the catheter fluid heating chamber 2551 for connection to a tube supplying sterile water. In one embodiment, a one-way valve is included at the proximal end of the catheter fluid heating chamber 2551, distal to the Luer fitting 2549, to prevent steam from being transferred under pressure to the water source.

As described above, the catheter fluid heating chamber is designed to be part of the ablation catheter and is single-use and disposable along with the rest of the catheter. In another embodiment, the chamber is reusable, in which case the Luer fitting is positioned between the catheter shaft and the chamber. The heating block is designed to be axially aligned with the heating chamber during use, is reusable and will not be damaged if it is dropped to the ground. In one embodiment, the weight and size of the heating block are designed so that it can be integrated into a pen-sized and shaped handle of the ablation catheter. The handle is insulated to prevent operator injury.

In one embodiment, the heating block receives its power from the console, and the console itself is line-powered and designed to provide a power of 700-1000W, determined by the fluid vaporization rate. The heating block and all output connectors are electrically insulated from line voltage. In one embodiment, the console includes a user interface, which allows the adjustment power to mate with the fluid flow rate. In addition, in one embodiment, a pump such as a syringe pump is used to control the flow of fluid to the heating chamber and the heating element. In one embodiment, the injection volume is at least 10ml and ideally 60ml.

In the above-described embodiments, the catheter used with the vapor ablation system is designed using materials that are expected to minimize cost. In one embodiment, the tubing used with the catheter is capable of withstanding temperatures of at least 125°C and can be bent through the bend radius of the endoscope (approximately 1 inch) without collapsing. In one embodiment, the section of the catheter that passes through the endoscope is 7 French (2.3 mm) in diameter and has a minimum length of 215 cm. In one embodiment, heat resistance is provided by the catheter shaft material, which shields the endoscope from the superheated vapor temperatures. In one embodiment, the heat exchanger unit is designed to be in direct contact with or very close to the biopsy channel of the endoscope to minimize the possibility of medical personnel handling heated components. Having the heat exchanger unit very close to the endoscope handle also minimizes the length of catheter that the vapor needs to travel through, thereby minimizing heat loss and pre-condensation.

In various embodiments, other means are used to heat the fluid within the conduit fluid heating chamber. FIG26 illustrates the use of induction heating to heat chamber 2605. When an alternating current passes through a coil of wire within chamber 2605, the coil generates a magnetic field. The magnetic lines of flux 2610 cut through the air surrounding the coil. When chamber 2605 comprises a ferrous material such as iron, stainless steel, or copper, currents known as eddy currents are induced to flow within chamber 2605, resulting in localized heating of chamber 2605.

FIG27A illustrates one embodiment of a coil 2770 used with induction heating in the vapor ablation system of the present invention. The coil is positioned around a catheter fluid heating chamber 2751. An alternating current passing through the coil generates a magnetic field and causes the catheter fluid heating chamber 2751 to heat. The heated chamber heats the fluid within, converting it into vapor, which enters the catheter 2750 for use in the ablation process. The coil itself does not heat, making it safe to touch. A Luer fitting connector 2749 is provided at the proximal end of the catheter fluid heating chamber 2751 for connecting to a tube supplying sterile water. In one embodiment, a one-way valve (not shown) is included at the proximal end of the catheter fluid heating chamber 2751, distal to the Luer fitting 2749, to prevent vapor from being transferred to the water source. In one embodiment, insulation material (not shown) is provided between the coil 2770 and the heating chamber 2751. In another embodiment, the chamber 2751 is suspended in the center of the coil 2770, with no physical contact between the two. In this embodiment, the air between them acts as insulation. The design of the chamber is optimized to increase its surface area to maximize contact and heat transfer, which in turn leads to more efficient vapor generation.

FIG27B illustrates one embodiment of a catheter handle 2772 for use with induction heating in the vapor ablation system of the present invention. Handle 2772 is thermally insulated and incorporates an induction coil. In one embodiment, handle 2772 includes an insulated tip 2773 at its distal end, which engages the endoscope channel after the catheter is inserted into the endoscope. Catheter 2750 is connected to a heating chamber 2751, which in turn is connected to a pump via an insulated connector 2774. In one embodiment, the length and diameter of heating chamber 2751 are smaller than those of handle 2772 and the induction coil, allowing heating chamber 2751 to slide coaxially within handle 2772 while maintaining a constant position within the magnetic field generated by the induction coil. An operator can manipulate catheter 2750 by grasping insulated connector 2774 and moving catheter 2750 into and out of handle 2772, which in turn moves the catheter tip into and out of the distal end of the endoscope. In this design, the heated portion of the catheter 2750 is within the channel of the endoscope and within the insulated handle 2772, and therefore does not contact the operator at any time during operation. An optional sensor 2775 on the insulated tip 2773 can sense when the catheter is not engaged with the endoscope and temporarily disable the catheter's heating function to prevent accidental activation and thermal injury to the operator. With reference to FIG27B , the catheter 2750 and heating chamber 2751 are the heated components of the system, while the handle 2772, insulated tip 2773, and insulated connector 2774 are cool components and therefore safe for the user to touch.

Figures 28A and 28B are front and longitudinal cross-sectional schematic diagrams, respectively, illustrating an embodiment of a catheter 2880 used with induction heating in the vapor ablation system of the present invention. The catheter 2880 includes an insulated handle 2886, which includes a heating chamber 2851 and an induction coil 2884. The heating chamber 2851 includes a Luer lock 2849 at its proximal end. The Luer lock 2849 has a one-way valve that prevents vapor from flowing back from the chamber 2851. The vaporization of the fluid in the chamber causes volume expansion and increased pressure, which pushes the vapor out of the chamber 2849 and into the catheter body. The induction coil 2884 includes a wire 2886 extending from the proximal end of the catheter 2880 to deliver an alternating current. The handle 2886 is connected to the catheter 2880 and has an outer insulating sheath 2881 made of an insulating material.

In various embodiments, the insulating material is polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), polyether block amide (PEBA), polyimide, or a similar material. In various embodiments, an optional sensor 2887 positioned near the distal end of the catheter 2880 measures one or more of the temperature, pressure, or flow rate of the vapor and sends the information to a microprocessor, which in turn controls the flow rate of the fluid and the vaporization energy provided to the chamber 2851. The microcontroller adjusts the fluid flow rate and chamber temperature based on the sensed information, thereby controlling the flow rate of the vapor and, in turn, the ablation energy flowing to the target tissue.

In one embodiment, the conduit 2880 includes an internal flexible metal skeleton 2883. In various embodiments, the skeleton 2883 comprises copper, stainless steel, or other ferrous materials. The skeleton 2883 is in thermal contact with the heating chamber 2851 such that heat from the chamber 2851 is passively conducted through the metal skeleton 2883 to heat the interior of the conduit 2880, thereby maintaining the steam in a vaporized state at a relatively constant temperature. In various embodiments, the skeleton 2883 extends through a specific portion or the entire length of the conduit 2880. In one embodiment, the skeleton 2883 includes regularly spaced fins 2882 that maintain the skeleton 2883 in the center of the conduit 2880 to uniformly heat the conduit lumen.

In another embodiment, as shown in FIG28C , the catheter includes an internal metal coil 2888 in place of the skeleton. In yet another embodiment, as shown in FIG28D , the catheter includes an internal metal mesh 2889 in place of the skeleton. Referring to FIG28B , 28C , and 28D , water 2832 enters the Luer lock 2849 at a predetermined rate. The water is converted into vapor 2838 within the heating chamber 2851 . The metal skeleton 2883, coil 2888, and mesh 2889 all conduct heat from the heating chamber 2851 into the catheter lumen to prevent vapor condensation within the catheter and ensure that the ablation vapor will exit the catheter from one or more holes or ports at its distal end.

FIG29 illustrates an embodiment of a heating unit 2990 that uses microwaves 2991 to convert fluid into vapor in a vapor ablation system of the present invention. The microwaves 2991 are directed to a catheter fluid heating chamber 2951, which heats the chamber 2951 and converts the fluid therein into vapor. The vapor enters the catheter 2950 for use in the ablation procedure. A Luer fitting connector 2949 is provided at the proximal end of the catheter fluid heating chamber 2951 to connect a tube supplying sterile water. In one embodiment, a one-way valve (not shown) is included at the proximal end of the catheter fluid heating chamber 2951, distal to the Luer fitting 2949, to prevent the vapor from being transferred to the water source.

In various embodiments, other energy sources such as high intensity focused ultrasound (HIFU) and infrared energy are used to heat the fluid within the catheter fluid heating chamber.

One advantage of steam delivery systems that utilize heating coils is that the steam is generated closer to the point of use. Conventional steam delivery systems typically generate steam near or directly at the location where the liquid is stored within the system. The steam must then travel through a long length of tubing, sometimes exceeding two meters, before reaching the point of use. Due to this distance, the system can sometimes deliver hot liquid as the steam cools from ambient temperature within the tubing.

The devices and methods of the present invention can be used to achieve controlled, centralized or peripheral ablation of target tissue to varying depths in a completely healing manner that can re-epithelialize. In addition, steam can be used to treat/ablate benign and malignant tissue growth, resulting in destruction, liquefaction, and absorption of the ablated tissue. The dosage and mode of treatment can be adjusted based on the type of tissue and the depth of ablation required. The ablation device can be used not only to treat Barrett's esophagus and esophageal dysplasia, flat colon polyps, gastrointestinal bleeding lesions, endometrial ablation, and lung ablation, but can also be used to treat any mucosal, submucosal, or peripheral lesions, such as inflammatory lesions, tumors, polyps, and vascular lesions. The ablation device can also be used to treat lesions or peripheral mucosal or submucosal lesions of any hollow organ or hollow body passage in the body. The hollow organ can be one of the gastrointestinal tract, pancreatic tract, reproductive tract, respiratory tract, or vascular structures such as blood vessels. The ablation device can be arranged endoscopy, radiation, surgery, or direct visual inspection. In a number of embodiments, a wireless endoscope or a single fiber endoscope can be incorporated as a part of the device. In another embodiment, magnetic navigation or stereo guidance navigation can be used to guide the catheter to the desired position. Radiopaque or ultrasound transparent materials can be incorporated into the catheter body for radioactive localization. Ferrous materials or magnet materials can be incorporated into the catheter to help magnetic navigation.

Although exemplary embodiments of the present invention have been described and illustrated herein, it should be understood that these embodiments are for illustrative purposes only. Those skilled in the art will appreciate that various modifications may be made to form and details without departing from the spirit and scope of the present invention.

Claims (23)

1. A device adapted to treat Barrett's esophagus in a patient's esophagus by ablating esophageal tissue, the device comprising: a fluid container configured to provide a fluid for conversion into an ablative agent; a heating chamber configured to generate the ablative agent; a catheter having an outer sheath and an inner shaft through which the ablative agent is capable of traveling, wherein the heating chamber is in physical communication with the catheter and is disposed in line with the catheter and between the fluid container and the catheter; a first positioning element attached to the outer sheath at a distal end of the outer sheath, wherein the first positioning element comprises a wire mesh disk configured to be positioned in the patient's gastric cardia to position the catheter at a fixed distance from esophageal tissue to be ablated; a pump configured to draw fluid from the fluid container and direct the fluid into the heating chamber; an infusion port in fluid communication with the inner shaft and configured to receive the fluid, wherein the heating chamber is configured to convert the fluid into the ablative agent within the heating chamber, and wherein the inner shaft comprises one or more ports through which the ablative agent can be released from the inner shaft, wherein each of the one or more ports is positioned along and circumferentially around the inner shaft between the infusion port and a distal end of the inner shaft and separated from the wire mesh disk by a distance of at least 1 mm; and A controller configured to control the heating chamber and the pump and programmed to determine the amount of thermal energy required to ablate the esophageal tissue, programmed to limit the maximum dose of the ablative agent based on the type of condition being treated, wherein the type of condition includes Barrett's esophagus, and programmed to limit the amount of thermal energy delivered so that the pressure in the patient's esophagus does not exceed 5 atm. 2. The device of claim 1, wherein the device is configured to generate the pressure within the patient's esophagus. 3. The device of claim 1, wherein the ablative agent has a temperature between 100 degrees Celsius and 200 degrees Celsius. The device of claim 1 , wherein the catheter further comprises a temperature sensor. 5. The device of claim 1, wherein the catheter further comprises a pressure sensor. The device of claim 1 , wherein the first positioning element has a diameter between 0.01 mm and 100 mm. 7. The device of claim 1, wherein the first positioning element comprises a circular body having a diameter between 0.01 mm and 10 cm. 8. A device adapted to treat Barrett's esophagus in a patient's esophagus by ablating esophageal tissue, the device comprising: a fluid container configured to provide a fluid for conversion into an ablative agent; a heating chamber, wherein a fluid in the heating chamber can be heated to generate steam; a conduit having a hollow inner shaft through which steam can be transported, wherein the heating chamber is in physical communication with the conduit and is disposed in line with the conduit and between the fluid container and the conduit; a first positioning element attached to the catheter at a distal end of the catheter, wherein the first positioning element comprises a wire mesh disk configured to abut the gastroesophageal junction when placed in the gastric cardia; a pump configured to draw fluid from the fluid container and direct the fluid into the heating chamber; an infusion port in fluid communication with the hollow inner shaft and configured to receive the fluid, wherein the heating chamber is configured to convert the fluid into the vapor within the heating chamber, and wherein the hollow inner shaft comprises more than one port through which the vapor can be released from the hollow inner shaft, wherein each of the more than one port is positioned along and circumferentially around the hollow inner shaft between the infusion port and a distal end of the hollow inner shaft and separated from the wire mesh disk by a distance of at least 1 mm; and A controller configured to control the heating chamber and the pump and programmed to determine the amount of thermal energy required to ablate the esophageal tissue, programmed to limit the maximum dose of the steam based on the type of condition being treated, wherein the type of condition includes Barrett's esophagus, and programmed to limit the amount of thermal energy delivered so that the pressure in the patient's esophagus does not exceed 5 atm. 9. The apparatus of claim 8, further comprising a temperature sensor, wherein the temperature sensor is used to control the release of the steam. 10. The device of claim 8, wherein the first positioning element is separated from each of the more than one ports by a distance of at most 10 cm. 11. The device of claim 8, wherein the diameter of the first positioning element is between 10 mm and 100 mm. 12. An apparatus adapted to treat an enlarged prostate in a patient by ablating prostate tissue, the apparatus comprising: a fluid container configured to provide a fluid for conversion into an ablative agent; a heating chamber, wherein a fluid in the heating chamber is capable of being heated; a catheter having a hollow inner shaft adapted to receive said ablative agent, wherein said ablative agent is said fluid in vapor form, wherein said heating chamber is in physical communication with said catheter and is disposed in line with said catheter and between said fluid container and said catheter such that said heating chamber receives said fluid and converts said fluid into said vapor before said vapor enters said hollow inner shaft; a first positioning element attached to the catheter at a distal end of the catheter, wherein the first positioning element is configured to position one or more needles of the catheter in a prostate of a patient; a pump configured to draw fluid from the fluid container and direct the fluid into the heating chamber; the one or more needles configured to pierce the prostate and configured to receive and deliver the ablative agent from the hollow inner shaft, wherein each of the one or more needles is positioned proximal to the first positioning element and extends radially from the hollow inner shaft; and A controller is configured to control the heating chamber and the pump and is programmed to determine an amount of thermal energy required to ablate the prostate tissue and is programmed to limit a maximum dose of the ablative agent based on a type of lesion being treated, wherein the type of lesion includes an enlarged prostate. 13. The device of claim 12, further comprising a second positioning element attached to the catheter proximal to the one or more needles, wherein the second positioning element comprises a wire mesh disk, the wire mesh disk of the second positioning element being configured to be positioned in the patient's urethra. 14. The device of claim 12, wherein the one or more needles are thermally insulated. 15. The apparatus of claim 12, wherein the first positioning element is configured to be positioned at a distance in the range of 0.1 mm to 2 cm from the area to be ablated. 16. The device of claim 12, wherein the first positioning element has a diameter between 0.1 mm and 10 cm. 17. An apparatus adapted to treat an enlarged prostate in a patient by ablating prostate tissue, the apparatus comprising: a fluid container configured to provide a fluid for conversion into an ablative agent; a heating chamber, wherein a fluid in the heating chamber is capable of being heated; a catheter having a hollow inner shaft adapted to receive said ablative agent, wherein said ablative agent is said fluid in vapor form, wherein said heating chamber is in physical communication with said catheter and is disposed in line with said catheter and between said fluid container and said catheter such that said heating chamber receives said fluid and converts said fluid into said vapor before said vapor enters said hollow inner shaft; a first positioning element attached to the catheter at a distal end of the catheter; a pump configured to draw fluid from the fluid container and direct the fluid into the heating chamber; one or more needles configured to pierce the prostate and configured to receive and deliver the ablative agent from the hollow inner shaft, wherein each of the one or more needles is positioned proximal to the first positioning element and extends radially from the hollow inner shaft; and A controller configured to control the heating chamber and the pump and programmed to determine an amount of thermal energy required to ablate the prostate tissue is programmed to limit a maximum dose of the ablative agent based on a type of lesion being treated, wherein the type of lesion includes an enlarged prostate. 18. The device of claim 17, further comprising a second positioning element attached to the catheter proximal to the first positioning element, wherein the second positioning element comprises a wire mesh disk configured to be positioned in the patient's urethra. 19. The device of claim 17, wherein the one or more needles are thermally insulated. 20. The apparatus of claim 17, wherein the first positioning element is configured to be positioned at a distance in the range of 0.1 mm to 2 cm from the area to be ablated. 21. The device of claim 17, wherein the first positioning element has a diameter between 0.1 mm and 10 cm. 22. The apparatus of claim 17, further comprising a sensor configured to measure a physiological parameter of the prostate, wherein the sensor is any one of a temperature sensor, a pressure sensor, a photoelectric sensor, or a chemical sensor. 23. The device of claim 22, wherein the sensor is a temperature sensor and the amount of thermal energy delivered to the prostate is based on a measured temperature of the prostate.