JP2014516608A - Radiofrequency ablation catheter device - Google Patents

Abstract

  A cylindrical shaped wire frame that supports a circular RF electrode can contact the inner surface of the aorta at the renal artery ostium, and the electrode ablate nerve activity around the renal artery ostium. The wire frame has a shape memory effect and is placed in the undeployed position folded at the end of the catheter, enclosed in a sheath, can be advanced through the blood vessel to the relevant location in the body cavity, the sheath is withdrawn, The frame is expanded to the deployed position to fit the lumen wall and allow the electrode to contact the lumen wall for ablation. The RF element can be placed around the opening to the renal artery using an imaging catheter that passes through the hole in the RF electrode and at least partially enters the entrance of the renal artery, and a balloon is placed in the kidney for positioning and stabilization. A proximal portion of the artery can be placed through the imaging catheter. When the device is deployed, the sheath is withdrawn, the wire frame is expanded, and the RF electrode is placed in the renal artery ostium.

Description

  In a broad sense, the present invention relates to a medical device and a method for treating vascular tissue by applying high frequency energy. In particular, it relates to an ablation device that treats patient tissue by delivering therapeutic radio frequency energy through a catheter and / or stent to a specific lesion for nerve ablation or atherosclerotic ablation.

  An artery is a tubular blood vessel that carries blood from the heart to body tissues and organs, and is composed of an outer fiber layer, a smooth muscle layer, a connective tissue, and an intimal cell (endothelium). Certain arteries have complex structures that perform multiple functions. For example, the aorta, a complex structure that performs multiple functions, contains a neural network that serves to maintain vascular tone throughout the body and each individual organ, excretion or reabsorption of sodium and water, and blood pressure control. These nerve electrical activities originate in the brain and the peripheral nervous system.

  The kidney has a dense afferent sensory innervation and efferent sympathetic innervation, thereby strategically positioned to be the origin and target of sympathetic nerve activity. Communication with essential structures in the central nervous system takes place via afferent sensory renal nerves. The renal afferent nerve projects directly into many areas in the central nervous system and indirectly projects into the anterior hypothalamus and posterior hypothalamus that contribute to arterial pressure regulation. Renal sensory afferent nerve activity directly affects sympathetic outflow to the kidney and other highly innervated organs involved in cardiovascular control, such as the heart and peripheral blood vessels, by modulating posthypothalamic activity Effect. These afferent and efferent nerves traverse through the aorta to their destination end organ site.

  Several studies have suggested that conditions such as renal ischemia, hypoxia, and oxidative stress increase renal afferent activity. Metabolites such as adenosine formed during ischemia, uremic toxins such as urea, or renal afferent stimulation, which can be caused by electrical stimulation, increases sensory nerve activity and blood pressure reflexes.

  Increased renal sympathetic nerve activity increases renin secretion rate, decreases renal urinary excretion by increasing renal tubular sodium reabsorption, and decreases renal blood flow and glomerular filtration rate. As nerve activity to the kidneys increases, sodium and water are reabsorbed, afferent and efferent arteries narrow, renal function decreases, and blood pressure increases.

  Release of renin can be suppressed using sympathetic blockers such as clonidine, moxonidine, and beta blockers. Angiotensin receptor blockers substantially improve blood pressure control and cardiovascular effects. However, these treatments have limited effectiveness and are detrimental. In addition, many hypertensive patients exhibit resistant hypertension with uncontrolled blood pressure and end organ damage due to the patient's hypertension.

  Patients with renal failure and those undergoing hemodialysis therapy show sustained activation of the sympathetic nervous system, which contributes to increased hypertension and cardiovascular morbidity and mortality. The signal that occurs in renal failure appears to result in sympathetic activity in chronic renal failure. Toxins circulating in the blood as a result of renal failure can cause excitement of the renal afferents, resulting in sustained activation of the sympathetic nervous system.

  Elimination of renal sensory afferent nerves and renal efferent nerves has been demonstrated to reduce specific blood pressure and organ damage caused by chronic sympathetic hypersensitivity in various experimental models. Thus, by targeting both efferent sympathetic and afferent sensory nerves, functional denervation of the human kidney is characterized by an increase in overall neural activity, and in particular an increase in renal sympathetic nerve activity. It appears to be a valuable treatment for hypertension and possibly other clinical situations. Functional denervation in humans may also reduce the potential for end organ damage associated with hypertension.

  In-situ destruction of tissue or reduction in size of tissue has been used to treat a number of diseases and conditions both alone and as an adjunct to surgical removal surgery. This surgery is often not as traumatic as a surgical procedure and may only be an alternative if other procedures are not safe or effective. This method, known as ablation treatment, applies appropriate heat to the tissue, causing the tissue to shrink and stiffen. Ablation therapy devices have the advantage of using destructive energy that is rapidly dissipated and reduced to non-destructive levels by the conduction and convection forces of the circulating fluid and other natural biological processes.

  In many medical procedures, it is important to be able to ablate unwanted tissue in a controlled and focused manner without adversely affecting the surrounding desirable tissue. Over the years, a number of minimally invasive methods have been developed to selectively destroy certain areas of undesired tissue as an alternative to resection surgery. There are a variety of techniques with specific advantages and disadvantages, which have been suggested and contraindicated for various applications.

  In one technique, elevated temperature (heating) is used to ablate the tissue. When the temperature exceeds 60 ° C., cellular proteins quickly denature and coagulate, resulting in damage. This damage can be used to ablate and remove tissue or simply destroy tissue, leaving the ablated tissue in place. Thermal ablation can also be performed at multiple locations to perform a series of ablations, thereby killing and necrosing the target tissue. After heating, necrotic tissue is absorbed or excreted by the body.

  Electric current can be used to generate heat to ablate the tissue. Radiofrequency ablation (RF) is a high temperature minimally invasive technique in which an active electrode is introduced into undesired tissue and high frequency alternating current up to 500 kHz is used to heat the tissue to coagulate. Radio frequency (RF) ablation devices work by transmitting an alternating current through tissue, creating an increase in intracellular temperature and localized intervening heat.

  RF treatment is performed after first identifying the tissue site for treatment, with minimal side effects and risk to the patient. When coupled with a temperature control mechanism, RF energy is accurately delivered to the site of contact between the device and the tissue to obtain the desired temperature for treating the tissue. The tissue is ablated by heating the tissue with RF power applied via an electrode tip from a controlled radio frequency (RF) device.

  Background theory of RF heating damage and its practice has been known for decades, and there are a wide range of RF generators and electrodes to realize such practice. When used by electrophysiologists for the treatment of tachycardia, when used by neurosurgeons for the treatment of Parkinson's disease, and other RF surgeries such as gussel ganglion resection for trigeminal neuralgia, and intractable RF treatment protocols have been found to be very effective when used by neurosurgeons and anesthesiologists for percutaneous high cervical anterior cervical collateral destruction for sexual pain.

  Renal denervation can be achieved through the renal artery ostium of the aorta, that is, through a hole that branches the aorta open to the renal artery. Ablation of nerve activity at the renal artery ostium does not adversely affect blood flow from the aorta to the renal arteries, but does have the desired effect on denervation of the kidney. However, one problem in the art is providing a treatment surface that can reach the entire desired treatment area, such as the area surrounding the renal artery ostium. Although it may be known to use a catheter to deploy energy, it may be possible to achieve ablation around the entire ostial opening of the branch vessel of the aorta, such as the renal artery, to provide optimal uniform treatment It was difficult.

  There is an urgent need in the art to develop a technique for effectively ablating nerve function in the kidney by inhibiting nerve activity leading to the kidney. This mechanism can be realized by ablation of neural activity at the aortic level, specifically at the renal artery ostium level. Such an approach provides the advantages of improving the volume state in the body and reducing blood pressure.

  It would be desirable to provide an apparatus and system that ablate nerve function in the kidney by attacking the renal nerve through the renal artery ostium of the aorta.

  SUMMARY OF THE INVENTION Broadly speaking, it is an object of the present invention to provide a method and an improved medical ablation device that generates heat to effectively ablate nerve function toward and within the kidney of a subject or patient. .

  Another object of the present invention is to deliver electrical energy, such as RF (radio frequency) energy, to the inner layer of the aortic wall to ablate aortic nerve activity.

  A further object of the present invention is to deliver electrical energy, such as RF (radio frequency) energy, to the inner layer of the aortic wall in order to ablate the aortic nerve activity, specifically through the aortic renal artery portal to the kidney. .

  A further object of the present invention is to measure the location of the aorta and neural activity within the renal arteries to determine the success of the ablation procedure.

  The present invention is directed to an apparatus, system and method for delivering high frequency energy to a body cavity, particularly the inner layer of the aorta, specifically the renal artery ostium of the aorta, using a non-conductive catheter.

  According to one embodiment, the device comprises a wire frame or stent, for example of a cylindrical shape, that can conduct RF energy and supports one or more electrodes that contact body tissue. According to one embodiment, the one or more electrodes have a circular structure on one side of the wire frame. When more than one electrode is used, the circular electrodes are arranged concentrically. The wire frame is brought into contact with the inner surface of the aorta at the renal artery ostium, and circular electrodes ablate the nerve activity around the circumference of the renal artery ostium.

  The wire frame or stent can be transitioned between an undeployed position and a deployed position. In the undeployed position, the wire frame is not expanded, i.e. folded. A wire frame that is folded into the undeployed position at the end of the catheter can be enclosed within a sheath. This device is advanced longitudinally, for example along a guide wire, through a blood vessel, to a relevant location in a body cavity such as within the aorta, and to a desired location within the inner circumference of the blood vessel, such as at the renal artery portal of the artery. Can be put.

  The sheath is then withdrawn, exposing the wire frame or stent member, allowing the wire frame to be expanded to the deployed position, which fits into the lumen wall and thereby around the wire frame. The placed electrode can contact the lumen wall. Heat is then generated at the electrodes by supplying an appropriate source of RF energy to the device, specifically ablation of neural activity, such as neural activity leading to the kidney.

  In one embodiment where the wire frame can be expanded to the deployed position, the wire frame is formed from a shape memory material. The natural shape of the wire frame is an expanded, generally cylindrical configuration, where the wire frame is placed within the sheath in a folded configuration. When the sheath is withdrawn, the wire frame restriction that keeps the wire frame in the folded configuration is released, and the wire frame spontaneously enters a memorized expanded configuration where the wire frame contacts the wall of the aorta. It becomes possible to expand.

  Arranging the RF element so that the circularly configured RF element is located around the circumference of the opening to the renal artery ensures improved delivery of RF energy to the designated location at the position of the arterial wall. To be. By including multiple RF elements in a single catheter system, a more complete nerve ablation results.

  In addition, the catheter design provides a mechanism for placing and securing the catheter at a desired location in the blood vessel, for example, within the aorta, so that the electrodes can be operated at the correct location, i.e., around the renal artery portal. Yes. This mechanism properly centers a circularly configured RF electrode around the circumference of the opening to the renal artery. If this device is not properly placed, the electrodes can ablate tissue that is not intended to be damaged, causing irreversible damage to other aorta or arterial structures.

  According to one embodiment, the positioning mechanism includes an imaging catheter that allows the user to properly center and position the RF electrode around the circumference of the opening to the renal artery. The imaging catheter allows the user to see exactly where the renal artery portal is located. The distal end of the imaging catheter extends from the proximal direction into the wire frame and exits through a hole in the circularly configured RF electrode. A circularly configured RF electrode can be placed in the renal artery ostium by inserting at least a portion of the distal end of the imaging catheter into the entrance of the renal artery so that the device is relative to the renal artery. Makes it possible to maintain its position in the aorta. When the device is so positioned, the wire frame can be expanded into the inner surface of the aorta, allowing the RF electrode to be positioned in the renal artery ostium and the RF electrode to perform its ablation function. Run. Further, as described below, the balloon can be placed through the imaging catheter in the proximal portion of the renal artery for improved positioning and stabilization of the aortic device.

  In some embodiments, the sheath surrounding the device has a longitudinal cutout to allow the imaging catheter / positioning device to protrude out of the wire frame and into the renal artery. This allows the device to be placed in the renal artery ostium, whether in the undeployed configuration where the wire frame is still folded within the sheath or while the sheath has not yet been removed from the wire frame. When the device is properly positioned, for example, by inserting at least a portion of the distal end of the imaging catheter into the entrance of the renal artery, the sheath is withdrawn and the wire frame is expanded. When the device is properly placed, this expansion of the frame will direct its outer surface to the inner edge of the aorta, allowing the RF electrode to be placed against the renal artery ostium.

  In another embodiment, the positioning mechanism comprises a balloon catheter, with an inflatable balloon at the distal end protruding through the imaging catheter and entering the entrance to the renal artery. The balloon catheter passes from the distal direction through the imaging catheter and the wire frame, passes through the hole of the circularly configured RF electrode, and is at least partially inserted into the entrance of the renal artery. The catheter sheath is then withdrawn and the balloon is inflated to allow the device to hold its position within the aorta relative to the renal artery. When the device is so positioned by an inflatable balloon, the device sheath is retracted, so that the RF electrode is in the renal artery heart so that the wire frame can expand to the inner surface of the aorta and perform the ablation function. It becomes possible to be placed at the gate.

  Means for measuring renal nerve afferent and efferent nerve activity before and after RF nerve ablation are also included in this design. Measuring renal nerve activity after surgery provides certainty that proper nerve ablation has been achieved. Renal nerve activity is measured by the same electrode mechanism required for energy delivery at the location of the renal artery ostium, but also along the renal artery positioning balloon.

  In addition to the functions described above, the device includes a mechanism that cools the aortic wall to limit the possibility of damaging the endothelial surface of the aorta even if ablation energy is effectively transmitted to the adventitia layer. .

  The present invention is also directed to a method of radiofrequency (RF) thermal ablation of tissue by use of one or more circular RF electrodes, wherein the one or more circular RF electrodes are within the sheath at the distal end of the catheter. Attached to one side of a cylindrically shaped wire frame or stent attached in a compressed configuration. In the first step of the invention, the catheter is deployed within the body at a relevant location, such as within the aorta at the location of the renal artery ostium. The catheter can be inserted into the body through a natural hole, stomach, or a surgically created opening made to insert the catheter, which can be inserted through a guide wire or general support structure or vision. This can be done easily by using a conversion device.

  In the next step, the device must be placed in the renal artery portal of the aorta. This placement can be done via a positioning mechanism as described herein. In one embodiment, an imaging catheter can extend out of the wire frame to help the user determine where the renal artery portal is. In an alternative, the balloon catheter can extend out of the wire frame and the balloon is inflated to place a circular RF element around the circumference of the renal artery ostium.

  In the next step of the present invention, when the catheter is placed in the relevant position, the wire frame is attached to the inner wall of the aorta at the desired branch artery ostium and attached to the wire frame or stent and the RF electrode. Expanded to position. In one embodiment, the RF electrode is placed around the opening of the renal artery so as to surround the renal artery ostium.

  In the next step of the present invention, RF energy is applied to an RF electrode attached to a wire frame or stent to effect a change in the target tissue. Heat is generated by supplying a suitable energy source to a device that includes at least one electrode that contacts body tissue via a wire frame or stent. Furthermore, stagnant or circulating coolant can be used to cool the inner surface of the vessel wall. This coolant function can protect or insulate the inner vessel wall surface during RF energy activation and heat transfer.

  According to one embodiment, ablation is performed specifically for ablation of aortic nerve activity leading to the kidney.

  Other features and advantages of the present invention will become apparent from the following detailed description and drawings. However, since various changes and modifications within the principles and scope of the invention will become apparent to those skilled in the art from this detailed description, the detailed description and specific examples, while indicating the preferred embodiment of the invention, It should be understood that this is only given by way of illustration.

  Embodiments of the present invention will be more fully understood and identified from the following detailed description in conjunction with the drawings, which are not to scale. In the drawings, the same reference numerals indicate corresponding similar or similar elements.

1 is a diagram illustrating a first embodiment of a device for delivering high frequency energy to the renal artery ostium. FIG. 1 is a cross-sectional exploded perspective view of a first embodiment of an apparatus for delivering high frequency energy to a body cavity wall. FIG. FIG. 2 is a further cross-sectional view of a first embodiment of a device for delivering radio frequency energy to a wall of a body cavity. FIG. 3 is a further cross-sectional view of a first embodiment of a device for delivering high frequency energy to a body cavity wall. 1 is a perspective view of a sheath used in a first embodiment of a device for delivering high frequency energy to a body cavity wall. FIG.

  As used herein, “proximal” refers to the portion of the device that is closer to the operator, while “distal” refers to the portion of the device that is further away from the operator.

  As used herein, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly indicates otherwise. For example, the term “a wire” includes one or more wires and can be considered equivalent to the term “at least one wire”.

  The term “subject” or “patient” refers, in one example, to mammals, including humans, in need of treatment for a condition or sequelae or susceptible condition. Subjects or patients can include dogs, cats, pigs, cows, sheep, goats, horses, rats and mice, and humans.

  FIG. 1 is a diagram of one embodiment of an apparatus 1 for delivering high frequency energy to a wall of a body cavity. In one embodiment, high frequency energy is delivered to the walls of the renal artery or aorta. In one embodiment of the device, the high frequency energy is delivered using a non-conductive catheter.

  In one embodiment, the device 1 comprises a generally tubular catheter (not shown) having a proximal opening and a distal opening, i.e., a long thin tubular device, preferably constructed from a non-conductive material. The catheter may be any type of catheter known to those skilled in the art having a proximal end for manipulation by the operator and a distal end for manipulation within the patient. The distal end and the proximal end preferably form one continuous body. In the preferred embodiment, the catheter is non-conductive. As described in more detail below, the catheter is used as a delivery system to deliver a device that includes a radio frequency electrode to the desired site for nerve ablation.

  In one embodiment, as is known in the art, a guide wire 11, such as having a thickness of 0.035 inches, is first used in a natural hole, stomach, or catheter. Can be inserted into the patient's vasculature and advanced to the desired location, for example through the groin, through a surgically formed opening made to insert the device.

  The catheter is then inserted into the patient and passed over the guide wire to the desired location. In a preferred embodiment, the device 1 is used in a patient's vasculature using, for example, a rapid exchange (RX) or over-the-wire wire (OTW) delivery system. It is advanced to the desired position. Radiographic contrast media may be injected at the beginning of the surgery, for example through an imaging catheter port, to aid in the operation of the device.

  In one example, the device 1 comprises a wire frame or stent 3 that supports one or more electrodes 8 that can conduct RF energy and contact body tissue. In one embodiment, the one or more electrodes 8 have a generally circular structure on one side of the wire frame 3. When two or more electrodes 8 are used, the circular electrodes 8 are arranged concentrically. The wire frame 3 is expanded to contact the inner surface of the aorta at the joint of the renal arteries so that the circular electrode 8 is located around the renal artery ostium.

  In one embodiment, the wire frame or stent 3 is generally cylindrical so that when placed in the aorta, its outer surface is supported on the inner surface of the aorta. In one embodiment, as shown in FIG. 1, the structure of the wire frame or stent 3 has two or more elongated supports 5 that are connected to two or more circular rings 7. Connected. In one example, the structure of the wire frame or stent 3 has 2-4 elongated supports 5, although more or fewer elongated supports 5 may be used if desired. In one embodiment, the structure of the wire frame or stent 3 has 2 to 4 circular rings 7 arranged substantially orthogonal to the elongated support 5, although more or fewer circular rings 7 are required. May be used according to The elongated support 5 is connected to the circular ring 7 by any method, for example by welding. FIG. 2 shows these elongated supports 5 and circular ring 7 in an exploded configuration.

  In one embodiment, the wire frame 3 is formed from a material that is flexible and has shape memory, such as Nitinol. As shown in FIG. 1, the natural shape 3 of the wire frame is an expanded, generally cylindrical configuration. In particular, the elongated support 5 has a straight configuration in the natural state, and the transverse ring 7 has a circular structure in the natural state. However, the elongated support 5 and the circular ring 7 of the wire frame 3 are formed from a material that is sufficiently flexible and elastic, and when an external force is applied, the elongated support 5 and the circular ring 7 are folded. It can be bent and deformed to other shapes such as configurations. The material of the wire frame 3 has sufficient shape memory so that the elongated support 5 and circular ring 7 of the wire frame 3 return to their natural shape when the external force is released.

  The wire frame or stent 3 can be selectively transferred between an undeployed position and a deployed position. In the undeployed position, the wire frame 3 is accommodated in an unexpanded or folded configuration. The folded wire frame 3 can be placed or enclosed in the sheath 10 at the end of the catheter in its undeployed position.

  In one embodiment, the guide wire 11 can first be inserted into the patient's vasculature through a natural hole, eg, through the groin, and advanced to the desired location. A cap 13 (see FIG. 3) at the distal end of the guide wire 11 facilitates entry through the skin, and the cap and guide wire are later separated from the sheath 10 for subsequent deployment of the ablation element. May be. A catheter comprising a sheath 10 is advanced longitudinally through a blood vessel, for example, over a guide wire 11 to a relevant location in a body cavity, such as within the aorta, and a desired inner circumference within the blood vessel, such as the renal artery ostia of the aorta Put into position.

  The sheath 10 is then withdrawn, thereby removing the constraint that keeps the wire frame 3 in its folded configuration. Withdrawing the sheath 10 exposes the wire frame 3 or stent member 3, allowing the wire frame 3 to expand spontaneously to its natural cylindrical configuration, i.e., the deployed position, to the lumen wall. Fits.

  The wire frame or stent 3 is also movable between a deployed expanded position and a non-deployed folded position. After ablation is complete, and when it is desirable to remove the catheter from the patient, the wire frame 3 can be folded back to its undeployed position to retract back into the catheter sheath 10. It is desirable.

  The wire frame 3 comprises at least one electrode 8 capable of conducting RF energy and in contact with body tissue. As an example, there is one circular electrode 8. In another embodiment, there are two or more circular electrodes 8. A single catheter system includes multiple RF electrodes to ensure more complete nerve ablation.

  As shown in FIG. 1, the RF electrode 8 is attached to the wire frame 3 as a means of delivering RF energy to the body cavity and sensing temperature and neural activity. In one embodiment, the electrode 8 is arranged outside one side of the wire frame 3. In another embodiment, the electrode 8 is attached to two elongated supports 5 on one side of the wire frame 3. The purpose of placing the electrode 8 on one side of the wire frame 3 is expanded when the wire frame 3 hits the inside of the aorta in the aorta and the electrode 8 is on one particular side of the aorta, for example, the renal artery ostium. For example, it is to be located on the side that branches to the renal artery for more effective ablation of the renal nerve.

  In one embodiment, the elongated support 5 to which the RF electrode 8 is attached is adapted to transfer RF energy from the RF control unit to the RF electrode 8. In this embodiment, these two elongate supports 5 contain connections from an RF control unit and RF electrodes attached for temperature control and ablation energy.

  When the wire frame 3 is changed to its deployed position by withdrawing the sheath, the electrodes 8 located on the wire frame are in direct contact with the lumen wall. If the wire frame 3 is properly positioned before the sheath 10 is withdrawn, the electrode 8 contacts the lumen wall at the desired location, eg, the renal artery ostium. By supplying an appropriate RF energy source to the instrument, heat is generated to the electrode 8 and specifically ablation is performed for ablation of neural activity such as neural activity leading to the kidney.

  In a preferred embodiment, the device 1 has a positioning element or mechanism for positioning and securing the device in a desired location in a blood vessel, for example in the aorta. Such a mechanism is necessary in order for the electrodes to be able to move in the correct position, ie around the arterial ostium. Otherwise, if the device is not properly placed, the electrode 8 can ablate tissue that is not intended to be damaged, causing irreversible damage. In embodiments where the RF electrode 8 is circular, the positioning mechanism should properly center the electrode around the arterial ostium, ie, the circumference of the opening to the renal artery.

  In one embodiment, as shown in FIG. 3, the positioning element or mechanism allows the user to see exactly where the renal arterial ostia is and to view the device 1, specifically the RF electrode 8, by visual means. Including an imaging catheter 15 that allows proper positioning. In one embodiment, the imaging catheter 15 includes a proximal end that is external to the patient and manipulated by the user along with the manipulation end of the device 1, and also includes a distal end located within the wire frame 3 of the device 1. . The distal end 15 of the imaging catheter extends from the proximal direction into the wire frame 3 and exits the wire frame 3 in a direction perpendicular to the longitudinal direction of the wire frame 3. In one embodiment, as shown in FIG. 3, the distal end 15 of the imaging catheter exits the wire frame 3 through the central hole 9 of the circularly configured RF electrode 8.

  In another example, as shown in FIG. 4, the positioning element or mechanism includes a catheter with an inflatable balloon 16 at the distal end that projects into the entrance to the renal artery. Like the imaging catheter, the inflatable positioning balloon 16 passes through the imaging catheter 15 and the wire frame 3 from the distal direction, and passes through the hole 9 of the RF electrode 8 configured in a circular shape. In one embodiment, the balloon catheter is external to the patient with the operating end of the device 1 and comprises a proximal end that is manipulated by the user and also includes a distal end located within the wire frame 3 of the device 1. . The distal end of the balloon catheter 16 extends from the proximal direction into the wire frame 3 and exits from the wire frame 3 in a direction perpendicular to the longitudinal direction of the wire frame 3. In one embodiment, as shown in FIG. 3, the distal end of the balloon catheter 16 exits the wire frame 3 through the central hole 9 of the RF electrode 8 configured in a circle.

  An inflatable positioning balloon 16 is located at the distal end of the balloon catheter. The balloon catheter 16 may be inserted at least partially at the entrance of the renal artery. The catheter sheath 10 is then withdrawn and the balloon 16 is exposed at its end. The balloon is then inflated against the inner wall of the renal artery, allowing the device 1 to be held in that position within the aorta relative to the renal artery. The diameter of the balloon 16 when expanded will depend on the inner diameter of the branch artery where placement is desired. In general, a balloon 16 having an expanded diameter of about 4-5 mm is sufficient. When the device is so positioned by the inflatable balloon 16, the wire frame can be expanded to the inner surface of the aorta, such as by retracting the device sheath, and the RF electrode 8 is positioned against the renal artery ostium. So that it can perform its ablation function.

  In other embodiments, both the imaging catheter 15 and the balloon catheter 16 can include an outer sheath 10 that is inserted into the wire frame 3 using a guide wire 11, through which the imaging device is passed. And a balloon device can be inserted. For example, the imaging catheter 15 is inserted and used and then removed, and the sheath remains in the patient and extends through the wire frame 3 and enters the renal artery portal. Balloon 16 can be advanced through the sheath (eg, over guide wire 11) and enter the renal artery portal to secure the device therein. Radiographic contrast agents injected at the beginning of the surgery can aid in the operation of the device.

  In these embodiments, the positioning element or mechanism operates to position the circularly configured RF electrode 8 around the opening to the renal artery ostium, specifically the opening to the branch renal artery of the ostium. . This is achieved by insertion of the distal end 15 of the imaging catheter or the balloon catheter 16, and the distal end 15 of the imaging catheter or the balloon catheter 16 passes through the central hole 9 of the RF electrode 8 configured in a circular shape. Passing out of the device's wire frame 3, at least a portion enters the renal artery entrance to serve as a fixture for the device 1 in the aorta, by inflation of the balloon 16 exposed alone or from within. When the distal end 15 of the imaging catheter or the balloon 16 exposed from the distal end of the balloon catheter 16 is so positioned, the device 1 retains its position within the aorta relative to the renal artery. The wire frame 3 can be expanded to abut the inner surface of the aorta. When the wire frame 3 is expanded against the inner surface of the aorta, the RF electrode 8 can be centered around the opening to the renal artery, i.e. around the circumference of the renal artery ostium, so that the RF electrode 8 is Their ablation function can be performed.

  In this embodiment, whether the imaging catheter 15 or the balloon catheter 16, the distal end of the positioning mechanism can be used as a fastener to act as a fixture even before the wire frame 3 is expanded. Note that at least a portion is inserted into the inlet. However, in an embodiment made of shape memory material so that the wire frame 3 expands spontaneously when released from the constraint of keeping it in the folded position, the wire frame 3 is retracted by the sheath 10 covering the entire device. It cannot be expanded until it is done or withdrawn. Accordingly, the device 1 is positioned at the renal artery ostium, either during the undeployed configuration in which the wire frame 3 is folded within the sheath 10 or while the sheath 10 has not yet been withdrawn from the wire frame 3. The positioning mechanism must be in a manner that protrudes out of the wire frame 3 and the device 1 and extends into the entrance of the renal artery.

  Thus, in some embodiments, as shown in FIG. 5, the sheath 10 enclosing the device has a longitudinal notch 20 extending from its distal most edge. While the sheath 10 is still in position around the wire frame 3 and keeps the wire frame in the folded and undeployed position, this notch 20 is passed by the positioning device through the imaging catheter 15 or It should be wide enough to allow the balloon catheter 16 to be placed within the renal artery entrance.

  In this embodiment, as shown in the cross-sectional view in FIG. 3, the wire frame 3 is within the sheath 10, but the imaging catheter 15 or balloon catheter 16 can be manipulated, which is the wire frame. 3 but just behind the circularly configured RF electrode 8. When it is desired that the imaging catheter 15 or balloon catheter 16 serve as a positioning mechanism to position the device in the aorta, the sheath rotates about its longitudinal axis so that the notch 20 is , Directed to the central hole 9 of the RF electrode 8 configured in a circle. This exposes the central hole 9 of the circularly configured RF electrode 8 and the imaging catheter 15 or balloon catheter 16 is pushed through the central hole 9 of the circularly configured RF electrode 8 and enters the entrance of the renal artery. It becomes possible.

  If the positioning mechanism includes an imaging catheter 15, the device 1 will be properly positioned in the aorta when the imaging catheter 15 is positioned at least in part within the entrance of the renal artery. If the positioning mechanism includes a balloon catheter 16, the device 1 will retract the balloon catheter 16 and expand the balloon 16 even when the balloon catheter 16 is positioned at least partially within the renal artery entrance. Until it is placed in the aorta. When the balloon 16 is expanded within the renal artery entrance, the balloon catheter 16 and the protruding device of the balloon catheter 16 are securely held.

  When the device 1 is properly positioned, the sheath 10 is withdrawn or retracted, eg, by at least partially inserting the distal end 15 of the imaging catheter into the entrance of the renal artery, and the wire frame 3 And the attached RF electrode (s) 8 are exposed, allowing the wire frame 3 to be expanded. Then, when the device is properly positioned, the outer surface of the wire frame 3 is supported by the inner edge of the aorta by expansion of the wire frame 3. Since the imaging / positioning catheter 15 passes through the central hole 9 of the circularly configured RF electrode 8 and enters the entrance of the renal artery, the expansion of the wire cage 3 causes the RF electrode 8 to be directly connected to the renal artery ostium. Put it in place.

  At its proximal end, the catheter includes at least one port. This port is for connection to a radio frequency (RF) source and can be coupled to a radio frequency (RF) energy source such as RF in the range of 300-500 kilohertz. Electrode 8 is electrically coupled to the RF energy source through this port. The catheter can also be connected to a control unit to sense and measure other factors such as temperature, conductivity, pressure, impedance, and nerve energy, and other variables.

  The catheter can also be connected to a second port for connecting to an air source. This port is used when the port is required for balloon inflation and deflation, as in one embodiment when the balloon 16 is used in a positioning mechanism. This port may be pneumatically coupled to a pump or other device for inflating or deflating the balloon. This same port can also be used to circulate coolant into the interior of the balloon to cool the balloon during RF energy activation.

  In one embodiment, the RF electrode 8 operates to provide high frequency energy to heat the desired location during a nerve ablation procedure. The electrode 8 can be composed of any suitable conductive material as is known in the art. Examples include stainless steel and platinum alloys.

  The RF electrode 8 can operate in bipolar mode or unipolar mode using a ground pad electrode. In the unipolar mode of delivering RF energy, a single electrode is used in combination with an indifferent electrode patch applied to the body to make other electrical contacts and complete the electrical circuit. Bipolar operation is possible when two or more electrodes are used, such as two concentric electrodes. Electrode 8 can be attached to an electrode delivery member such as wire frame 3 by using soldering or welding methods well known to those skilled in the art.

  In embodiments where the one or more RF electrodes 8 are circular, the diameter of the circular RF electrode 8 is determined by the width of the arterial branch of the aorta where denervation is desired. If the diameter of the RF electrode 8 is smaller than the diameter of the arterial branch of the aorta where denervation is desired, the RF electrode 8 will not actually touch the tissue and no ablation will occur. For example, when denervation is desired for a renal artery that is approximately 6-7 mm in diameter at the aortic ostium, the diameter of the circular RF electrode 8 is at least sufficient to properly ablate at the renal artery ostium. The distance must be 7 mm.

  If the device comprises two circularly configured RF electrodes 8 arranged concentrically, the spacing between the two RF electrodes 8 determines the depth of tissue at which ablation is achieved. The farther the electrode 8 is, the deeper the tissue denervation that is achieved. For denervation of the renal arteries, the spread between the electrodes 8 of about 2-6 mm provides sufficient depth to penetrate the tissue to achieve the desired level of ablation, thereby providing denervation. . For example, in one embodiment, if the inner RF electrode 8 has a diameter of about 10 mm, the outer RF electrode 8 has a diameter of about 12-17 mm.

  In embodiments where the imaging catheter protrudes from the wire frame 3 in a circularly configured RF electrode, the diameter of the RF electrode 8 can be calculated with reference to the imaging catheter 15. For example, in the case of an imaging catheter 15 having a distal end diameter of about 2 mm, the RF electrode 8 surrounding the imaging catheter 15 can be centered at 5 mm and 10 mm, respectively, from the central position of the imaging catheter 15.

  Each electrode 8 can be arranged to treat tissue by delivering radio frequency (RF) energy. The frequency of the high frequency energy delivered to the electrode is about 5 kilohertz (kHz) to about 1 GHz. In particular embodiments, the frequency of the RF energy is about 10 kHz to about 1000 MHz, specifically about 10 kHz to about 10 MHz, more specifically about 50 kHz to about 1 MHz, and even more specifically about 300 kHz to about 500 kHz. It can be.

  In the preferred embodiment, the electrodes 8 can operate separately or in combination with each other as a series of electrodes arranged in an array. Treatment is directed to a single region of the blood vessel or several different regions by selective electrode movement.

  The electrode selection and control switch can include elements arranged to select and activate individual electrodes.

  The RF power supply may have multiple channels that send modulated power separately to each electrode. This reduces selective heating, i.e., more energy is sent to areas with high electrical conductivity and less heating around electrodes placed in tissues with low electrical conductivity. If the level of tissue hydration in the tissue or the rate of transfusion is uniform, a single channel RF power source may be used to provide power to cause relatively uniform damage.

  The RF energy sent to the tissue through the electrode 8 generates heat in the tissue by absorption of the RF energy by the tissue and ohmic heating due to the electrical resistance of the tissue. This heating can damage the affected cells and is sufficient to cause cell death, a phenomenon also known as cell necrosis. To simplify the remaining discussion of this application, cell damage will include all cell effects including cell death up to cell necrosis resulting from the delivery of energy from the electrode. Cell damage can be realized as a relatively simple medical procedure using local anesthesia. In one example, cell damage proceeds to a depth of about 1-5 mm from the surface of the mucosal layer of the sphincter or adjacent anatomy.

  In some embodiments, as shown in FIG. 2, the catheter may be interposed between each RF electrode 8 and the wire frame 3 to protect the wire frame 3 from direct effects of RF energy, for example. A thermal barrier pad 19 is provided. The thermal pad 19 can also avoid potential damage to the body of the subject's blood, while ablation energy is effectively transferred to the blood vessel surface and the blood passes through the wire frame.

  Also included in this design is a means of measuring renal nerve afferent activity before and after RF nerve ablation. By measuring renal nerve activity after surgery, it can be confirmed that proper nerve ablation has been achieved. Renal nerve activity is measured by the same mechanism required for energy delivery and electrodes on a positioning balloon placed in the renal artery.

  Neural activity can be measured by one of two means. Proximal renal nerve stimulation is performed by transmitting electrical stimulation to a catheter placed in the proximal portion of the renal artery. The effect is measured from the portion of the catheter located within the more distal portion of the renal artery. The amount of downstream electrical activity and the time delay of electrical activity from the proximal electrode to the distal electrode gives a measure of the remaining neural activity after nerve ablation. A second means of measuring renal nerve activity is to measure the surrounding electrical stimulation before and after nerve ablation in a more distal site within the renal artery.

  In another embodiment, the RF electrode 8 operates to provide high frequency energy for both heating and temperature sensing. Thus, in this embodiment, the RF element can be used for heating during ablation surgery and can also be used for sensing neural activity before and after ablation.

  Each electrode 8 can be coupled to at least one sensor or control unit capable of measuring factors such as temperature, conductivity, pressure, impedance and other variables. For example, the device may have a thermistor that measures the temperature in the lumen, and the thermistor receives temperature information from the thermistor and measures the wattage, frequency, duration of energy delivery, or total energy delivered to the electrode. It may be a component of a system controlled by a coordinating microprocessor.

  The catheter may be coupled to a visualization device such as a fiber optic device, fluoroscope, anoscope, laparoscope, endoscope. In one embodiment, the device coupled to the visualization device is controlled from a position outside the body, such as by a device in the cab or an external device for manipulating the inserted catheter.

  In another example, the catheter may be configured with markers that help the operator know the desired placement, such as radiopaque markers, etching, or microgrooves. Thus, the catheter can be configured to enhance imaging capabilities by techniques such as ultrasound, CAT scan, or MRI. In addition, an x-ray contrast agent may be injected through the injection port and through the hollow interior of the catheter, thereby allowing localization by fluoroscopy or angiography.

  The present invention also includes a method for ablating renal artery nerve function in the aorta using the above-described devices described herein. This method is performed by a system including a catheter and a control assembly. Although this method is described as a series of methods, the steps of the method can be performed in combination or in parallel and separate elements, whether pipelined asynchronously or otherwise. Except as otherwise noted, the method is not required to be performed in the same order as the enumeration of steps according to the present description.

  At flow point a, the electrical energy port is coupled to an electrical energy source. The patient is placed on the treatment table at an appropriate location for insertion of the catheter.

  In step b, the visualization port is coupled to a suitable visualization device such as a fluoroscope, endoscope, display screen, or other visualization device. The visualization device is selected based on the judgment of medical personnel.

  In step c, the therapeutic energy port is coupled to an RF energy source.

  In step d, the aspiration and inflation device is coupled to the irrigation and aspiration control port so that the catheter balloon can be inflated later.

  At step e, the distal most end of the treatment balloon is lubricated and introduced into the patient. In the preferred embodiment, the balloon is fully deflated during insertion. The catheter can be inserted through the outer surface and into the body cavity, and the insertion can be percutaneous, can be through a surgical arteriotomy, or can be during a surgical incision. .

  In step f, a catheter comprising a wire frame and a positioning device, ie an imaging catheter or a balloon catheter, is passed through the blood vessel until the wire frame is completely located within the blood vessel to be treated. An introducer needle sheath or guide tube can also be used to facilitate insertion.

  In step g, the position of the catheter is confirmed using a visualization device coupled to the visualization port. This instrument can be continuously monitored by medical professionals throughout the surgery.

  At step h, the positioning mechanism is positioned such that the positioning mechanism protrudes through the circular electrode into the renal artery or the ostium of another artery.

  In step i, the irrigation and aspiration control port is manipulated to inflate the balloon of the positioning mechanism to stabilize the catheter tip in its position within the lumen.

  At step j, the device sheath is retracted, causing the wire frame to return to the expanded configuration so that the wire frame fits within the vessel interior.

  In step k, an electrode is selected using an electrode selection and control switch. In the preferred embodiment, all electrodes are deployed at once. In another preferred embodiment, the electrodes can be selected individually. This step can be repeated at any time before step j.

  In step l, the therapeutic energy port is manipulated to release energy from the electrode. The duration and frequency of energy are determined by medical personnel. This release of energy causes a circular pattern of damage to the renal artery ostium.

  In step m, the sheath is advanced along the wire frame to cause the wire frame to return to the folded state.

  In step n, the irrigation and aspiration control ports are operated to deflate the positioner balloon.

  In step o, the positioning device, balloon catheter or imaging catheter is withdrawn from the renal artery portal into the device.

  Once ablation is complete, the wire frame, balloon and imaging / positioning catheter are withdrawn to the sheath and the device can be used to position another location within the patient, eg, the contralateral (or accessory) renal artery, These steps can be repeated for each ablation site.

  In step p, the catheter is withdrawn from the patient.

  Although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to the exact embodiments, and various changes and modifications can be made to the invention as defined in the appended claims. It will be understood that this may be done by a person skilled in the art without departing from the scope or principle of the present invention.

Claims (18)

A wire frame,
A neuroablation device comprising: at least one radio frequency (RF) electrode having a circular structure disposed on an outer surface of the wire frame.   The nerve ablation device of claim 1, further comprising a rapid delivery (RX) wire system.   The nerve ablation device according to claim 1, further comprising a sheath retractable about the wire frame.   The nerve ablation device according to claim 3, wherein the wire frame is made of a shape memory material.   The nerve ablation device according to claim 4, wherein the wire frame is deformable by applying an external force, and returns to a predetermined configuration when the external force is released.   The nerve ablation device of claim 1, further comprising a positioning catheter extending within the wire frame.   The nerve ablation device according to claim 6, wherein a distal end of the positioning catheter is movable out of the wire frame.   The nerve ablation device of claim 7, wherein the distal end of the positioning catheter is movable out of the wire frame through the center of the circular structure RF electrode.   The nerve ablation device according to claim 7, wherein the positioning catheter comprises an expandable balloon.   Further comprising two ports along the proximal end of the positioning catheter, one of the two ports being a balloon inflation port and the other port connecting to RF energy, temperature and neural sensing control unit The nerve ablation apparatus according to claim 9, wherein the nerve ablation apparatus is a control unit.   The nerve ablation device according to claim 1, which has a quick exchange structure.   The nerve ablation device according to claim 1, wherein the RF member is arranged as a circular hole having a diameter of 1.5 mm along the length of the balloon catheter.   The nerve ablation device according to claim 1, comprising two circularly configured RF members, wherein the RF members are arranged concentrically. A method of performing nerve ablation at the arterial ostium of the aorta in a subject in need of ablation,
Inserting a catheter into the aorta comprising a wire frame and at least one radio frequency (RF) electrode having a circular structure disposed on an outer surface of the wire frame;
Positioning the wire frame such that the electrode is positioned around the arterial ostium of the aorta;
Delivering a high frequency energy at a specified location within a renal artery wall.   The method of performing nerve ablation according to claim 13, wherein the wire frame delivers RF energy while sensing temperature and nerve activity.   14. The method for performing nerve ablation according to claim 13, wherein positioning the wire frame comprises inflating a balloon catheter within the artery.   14. The method for performing nerve ablation according to claim 13, further comprising measuring renal nerve afferent activity before and after nerve ablation.   Renal nerve ablation reduces hypertension, improves renal function, increases renal plasma flow, decreases muscle sympathetic nerve activity, improves cardiac baroreflex, decreases ventricular weight in the subject The method for performing nerve ablation according to claim 13.

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