Methods for renal neuromodulation

Abstract

Methods and apparatus are provided for treating hypertension, e.g., via a pulsed electric field, via a stimulation electric field, via localized drug delivery, via high frequency ultrasound, via thermal techniques, etc. Such neuromodulation may effectuate irreversible electroporation or electrofusion, necrosis and/or inducement of apoptosis, alteration of gene expression, action potential attenuation or blockade, changes in cytokine up-regulation and other conditions in target neural fibers. In some embodiments, neuromodulation is applied to neural fibers that contribute to renal function. In some embodiments, such neuromodulation is performed in a bilateral fashion. Bilateral renal neuromodulation may provide enhanced therapeutic effect in some patients as compared to renal neuromodulation performed unilaterally, i.e., as compared to renal neuromodulation performed on neural tissue innervating a single kidney.

1 - 20 . (canceled) 
     
     
         21 . A method, comprising:
 positioning a drug delivery catheter within renal vasculature of a hypertensive human patient and adjacent to renal nerves innervating a kidney of the patient;   delivering a chemical agent via the drug delivery catheter to target tissue proximate the renal vasculature, wherein the chemical agent attenuates neural activity along the renal nerves; and   removing the drug delivery catheter from the patient after delivering the chemical agent to conclude the procedure.   
     
     
         22 . The method of  claim 21  wherein delivering the chemical agent to attenuate neural activity along the renal nerves results in a therapeutically beneficial reduction in blood pressure of the hypertensive patient. 
     
     
         23 . The method of  claim 21  wherein delivering a chemical agent comprises delivering alcohol. 
     
     
         24 . The method of  claim 21  wherein delivering a chemical agent comprises delivering phenol. 
     
     
         25 . The method of  claim 21  wherein delivering a chemical agent comprises delivering a neurotoxin. 
     
     
         26 . The method of  claim 21  wherein delivering a chemical agent comprises delivering botulinum toxin. 
     
     
         27 . The method of  claim 21  wherein positioning a drug delivery catheter within renal vasculature of a hypertensive human patient comprises positioning the drug delivery catheter within a renal artery of the patient. 
     
     
         28 . The method of  claim 21  wherein delivering a chemical agent via the drug delivery catheter to target tissue comprises delivering the chemical agent to tissue external to the renal artery of the patient and in contact with or adjacent to the renal nerves. 
     
     
         29 . The method of  claim 21  wherein positioning a drug delivery catheter within renal vasculature of the patient comprises intravascularly delivering the drug delivery catheter through an abdominal aorta to a renal artery of the patient. 
     
     
         30 . The method of  claim 21  wherein positioning a drug delivery catheter within renal vasculature of the patient comprises intravascularly delivering the drug delivery catheter to a renal artery of the patient via a guidewire. 
     
     
         31 . The method of  claim 21  wherein the drug delivery catheter comprises an expandable feature at a distal region of the catheter, and wherein the method further comprises:
 transforming the expandable feature from a low-profile delivery arrangement to an expanded treatment arrangement within a renal artery of the patient after positioning the catheter within the renal artery and before delivering the chemical agent. 
 
     
     
         32 . The method of  claim 21  wherein delivering the chemical agent to attenuate neural activity along the renal nerves comprises systemically reducing sympathetic tone in the patient. 
     
     
         33 . The method of  claim 21  wherein delivering the chemical agent to attenuate neural activity along the renal nerves comprises reducing afferent and/or efferent renal neural activity. 
     
     
         34 . The method of  claim 21  wherein delivering a chemical agent to attenuate or block neural signaling along the renal nerves comprises delivering the neuromodulatory agent to ablate the renal nerves. 
     
     
         35 . The method of  claim 21 , further comprising monitoring a parameter of the patient before and during delivery of the chemical agent. 
     
     
         36 . The method of  claim 35 , further comprising altering delivery of the chemical agent in response to the monitored parameter. 
     
     
         37 . The method of  claim 35 , further comprising adjusting a treatment parameter in response to the monitoring.