Microwave catheter apparatuses, systems, and methods for renal neuromodulation

Abstract

Microwave catheter apparatuses, systems, and methods for achieving renal neuromodulation by intravascular access are disclosed herein. One aspect of the present application, for example, is directed to apparatuses, systems, and methods that incorporate a catheter treatment device comprising an elongated shaft. The elongated shaft is sized and configured to deliver a microwave transmission element to a renal artery via an intravascular path. Renal neuromodulation may be achieved via dielectric heating in the presence of microwave irradiation that modulates neural fibers that contribute to renal function or alters vascular structures that feed or perfuse the neural fibers.

1 . A catheter apparatus, comprising:
 an elongated shaft having a proximal portion, a distal portion, and a central lumen;   a therapeutic assembly at the distal portion of the elongated shaft, wherein the therapeutic assembly is configured for intravascular delivery to a renal artery of a human patient; and   a microwave transmitting element carried by the therapeutic assembly, wherein the microwave transmitting element is configured to radiate microwaves through a wall of the renal artery to modulate a renal nerve at a treatment site within the renal artery.   
     
     
         2 . The catheter apparatus of  claim 1  wherein the therapeutic assembly comprises a tubular inner conductor, an outer conductor, and an insulator separating at least a portion of the inner conductor and the outer conductor. 
     
     
         3 . The catheter apparatus of  claim 1 , further comprising a radiating element and a shield at least parially surrounding the radiating element, wherein the shield is configured to preferentially direct the radiated microwaves. 
     
     
         4 . The catheter apparatus of  claim 1 , further comprising a radiator positioned in the central lumen. 
     
     
         5 . The catheter apparatus of  claim 4  wherein:
 the therapeutic assembly comprises a tubular inner conductor, an outer conductor, and an insulator separating at least a portion of the inner conductor and the outer conductor, and 
 the radiator comprises protrusions configured to contact an inner wall of the inner conductor to electrically couple the radiator to the inner conductor. 
 
     
     
         6 . The catheter apparatus of  claim 4  wherein the radiator extends distally beyond a distal end of the elongated shaft. 
     
     
         7 . The catheter apparatus of  claim 1  wherein the central lumen comprises a coolant supply channel configured to deliver coolant in a vicinity of the microwave transmitting element. 
     
     
         8 . The catheter apparatus of  claim 7 , further comprising a temperature sensor coupled to the elongated shaft and configured to sense the temperature in a vicinity of the microwave transmitting element. 
     
     
         9 . The catheter apparatus of  claim 1 , further comprising a guide wire positioned in the central lumen, wherein the therapeutic assembly is configured to be delivered over the guidewire for placement within the renal artery. 
     
     
         10 . A method for treatment of a human patient via renal denervation, the method comprising:
 intravascularly positioning a catheter having a microwave transmitting element within a renal artery of the patient;   generating microwaves with a microwave generator positioned externally to the patient and transferring the microwaves through the catheter to the microwave transmitting element; and   radiating the microwaves from the microwave transmitting element through a wall of the renal artery to modulate neural function of a renal nerve of the patient.   
     
     
         11 . The method of  claim 10  wherein modulating neural function of the renal nerve comprises dielectrically heating the renal nerve. 
     
     
         12 . The method of  claim 11  wherein dielectrically heating the renal nerve comprises inducing necrosis in the renal nerve. 
     
     
         13 . The method of  claim 10  wherein intravascularly positioning a catheter having a microwave transmitting element within a renal artery of the patient comprises centering the microwave transmitting element within the renal artery. 
     
     
         14 . The method of  claim 13  wherein centering the microwave transmitting element within the renal artery comprises centering the microwave transmitting element within the artery without fully occluding blood flow through the renal artery. 
     
     
         15 . The method of  claim 10  wherein generating microwaves with a microwave generator comprises generating microwaves with a cavity magnetron. 
     
     
         16 . The method of  claim 10  wherein intravascularly positioning a catheter having a microwave transmitting element comprises positioning a catheter having a microwave antenna. 
     
     
         17 . The method of  claim 16  wherein intravascularly positioning a catheter having a microwave antenna comprises positioning a catheter having a coaxial antenna. 
     
     
         18 . The method of  claim 17  wherein transferring the microwaves through the catheter to the microwave transmitting element comprises transferring the microwaves through a coaxial cable to the coaxial antenna. 
     
     
         19 . The method of  claim 17  wherein the coaxial antenna includes a radiating element, and wherein radiating the microwaves from the microwave transmitting element comprises dynamically varying a length of the radiating element. 
     
     
         20 . The method of  claim 17  wherein the coaxial antenna includes a radiating element, and wherein radiating the microwaves from the microwave transmitting element further comprises shielding a portion of the radiating element of the coaxial antenna to preferentially direct the radiated microwaves. 
     
     
         21 . The method of  claim 10  wherein radiating the microwaves from the microwave transmitting element comprises preferentially directing the radiated microwaves. 
     
     
         22 . The method of  claim 10  wherein intravascularly positioning a catheter having a microwave transmitting element within the renal artery comprises advancing the catheter to the renal artery over a guide wire via an intravascular path. 
     
     
         23 . The method of  claim 10 , further comprising redirecting arterial blood flow within the renal artery of the patient while radiating the microwaves. 
     
     
         24 . The method of  claim 23  wherein redirecting arterial blood flow comprises increasing a velocity of the blood flow near a wall of the renal artery in order to enhance a rate of heat transfer between the wall and the blood flow. 
     
     
         25 . The method of  claim 10 , further comprising actively cooling the microwave transmitting element while radiating the microwaves. 
     
     
         26 . The method of  claim 25  wherein actively cooling the microwave transmitting element comprises circulating a coolant in a vicinity of the microwave transmitting element. 
     
     
         27 . The method of  claim 25 , further comprising monitoring a temperature of the microwave transmitting element while radiating the microwaves. 
     
     
         28 . The method of  claim 27 , further comprising altering the active cooling or the microwave radiation in response to the monitored temperature of the microwave transmitting element. 
     
     
         29 . The method of  claim 10 , further comprising monitoring a temperature of the microwave transmitting element.