Methods for renal neuromodulation

Abstract

Methods and apparatus are provided for renal neuromodulation using a pulsed electric field to effectuate electroporation or electrofusion. It is expected that renal neuromodulation (e.g., denervation) may, among other things, reduce expansion of an acute myocardial infarction, reduce or prevent the onset of morphological changes that are affiliated with congestive heart failure, and/or be efficacious in the treatment of end stage renal disease. Embodiments of the present invention are configured for percutaneous intravascular delivery of pulsed electric fields to achieve such neuromodulation.

1 - 23 . (canceled) 
     
     
         24 . A method for performing renal neuromodulation, the method comprising:
 applying a stimulation signal to tissue of a human patient;   monitoring a physiologic response to the stimulation signal via electrical impedance tomography to determine the presence of renal nerves proximate a renal blood vessel of the patient; and   inhibiting neural activity along the renal nerves in a minimally invasive manner,   wherein inhibiting neural activity along the renal nerves comprises delivering an energy field to the renal nerves via an intravascularly positioned catheter.   
     
     
         25 . The method of  claim 24 , further comprising identifying one or more optimal locations for delivering the energy field based on the monitored physiologic response. 
     
     
         26 . The method of  claim 24  wherein applying a stimulation signal and monitoring a physiologic response comprises:
 applying a first stimulation signal and monitoring a first physiologic response prior to delivering the energy field; and 
 applying a second stimulation signal and monitoring a second physiologic response after delivering the energy field. 
 
     
     
         27 . The method of  claim 26 , further comprising comparing the first physiologic response and the second physiologic response to determine an extent of renal neuromodulation. 
     
     
         28 . The method of  claim 24  wherein the stimulation signal is a first stimulation signal, and wherein the method further comprises applying a second stimulation signal to the tissue and monitoring the absence of a physiologic response following inhibiting neural activity along the renal nerves to determine treatment efficacy. 
     
     
         29 . The method of  claim 24  wherein applying a stimulation signal comprises stimulating afferent renal nerve fibers of the patient. 
     
     
         30 . The method of  claim 24  wherein applying a stimulation signal comprises stimulating efferent renal nerve fibers of the patient. 
     
     
         31 . The method of  claim 24  wherein applying a stimulation signal comprises intravascularly delivering the stimulation signal. 
     
     
         32 . The method of  claim 24  wherein applying a stimulation signal comprises delivering the stimulation signal via the catheter before delivering the energy field to the renal nerves via the catheter. 
     
     
         33 . The method of  claim 24  wherein applying a stimulation signal comprises applying a stimulation electric field to the tissue. 
     
     
         34 . The method of  claim 24  wherein delivering an energy field comprises delivering radio frequency (RF) energy to the renal nerves via one or more electrodes carried by the catheter. 
     
     
         35 . The method of  claim 24  wherein delivering an energy field comprises delivering ultrasound energy to the renal nerves. 
     
     
         36 . The method of  claim 24  wherein delivering an energy field comprises delivering electrical energy to the renal nerves. 
     
     
         37 . The method of  claim 24  wherein delivering an energy field to the renal nerves comprises ablating the renal nerves via the energy field. 
     
     
         38 . The method of  claim 24  wherein delivering an energy field to the renal nerves comprises partially ablating the renal nerves via the energy field. 
     
     
         39 . The method of  claim 24  wherein delivering an energy field comprises delivering at least partially denervating a kidney of the patient. 
     
     
         40 . The method of  claim 24 , further comprising monitoring at least one of renin, sodium, renal blood flow, and blood pressure in response to the stimulation signal. 
     
     
         41 . A method for identifying locations for renal neuromodulation treatment via electrical impedance tomography, the method comprising:
 delivering stimulation electrical signals to target tissue proximate a renal artery of a human patient;   monitoring a physiologic response to the stimulation electrical signals to identify the location of renal nerves proximate a renal blood vessel of the patient; and   delivering a denervating electric field to the identified renal nerves via an intravascularly positioned catheter, wherein the electric field at least partially ablates the renal nerves.   
     
     
         42 . The method of  claim 41  wherein the stimulation electrical signals are first stimulation electrical signals, and wherein the method further comprises applying second stimulation electrical signals to the target tissue and monitoring for a physiologic response after delivering the denervating electric field to at least partially ablate the renal nerves to determine treatment efficacy. 
     
     
         43 . The method of  claim 41  wherein the intravascularly positioned catheter comprises a distal helical section and a plurality of electrodes arranged thereon, and wherein the method further comprises:
 transforming the catheter from a low-profile delivery configuration to a treatment configuration to place the electrodes into apposition with an inner wall of the renal artery, and 
 wherein delivering a denervating electric field to the identified renal nerves comprises delivering radio frequency (RF) energy via the electrodes to at least partially ablate the renal nerves. 
 
     
     
         44 . The method of  claim 41  wherein the intravascularly positioned catheter comprises a distal section having a plurality of electrodes, and wherein the electrodes at the distal section of the catheter are used both to apply the stimulation electrical signals and to deliver the denervating electric field. 
     
     
         45 . The method of  claim 41 , further comprising monitoring a parameter of the catheter, the renal nerves, and/or tissue adjacent the renal nerves within the patient before and during delivery of the denervating electric field. 
     
     
         46 . The method of  claim 45  wherein monitoring a parameter comprises monitoring impedance, temperature, and/or power, and wherein the method further comprises altering delivery of the denervating electric field in response to the monitored parameter.