Mapping sympathetic nerve distribution for renal ablation and catheters for same

Abstract

This invention provides methods for mapping and ablating renal nerves to treat disease caused by systemic renal nerve hyperactivity, e.g. hypertension, heart failure, renal failure and diabetes. Also provided are catheters for performing the mapping and ablating functions.

What is claimed is: 
     
         1 . A method of mapping renal nerves for ablative procedures to treat disease caused by systemic renal nerve hyperactivity, comprising the steps of:
 a) introducing catheters that perform stimulatory and ablative processes into renal artery;   b) measuring indicia of disease before site-specific electrical stimulation to obtain baseline measurements;   c) introducing electrical current through the catheter in a site-specific manner to portions of the renal artery lumen in order to stimulate underlying renal nerves;   d) optionally moving the catheter tip of the catheters according to a specified protocol in order to make contact with desired portions of the renal artery lumen;   e) measuring indicia of disease after each site-specific electrical stimulation and recording changes over baseline; and   f) correlating changes in disease indicia with the portions of the renal artery lumen which were stimulated to produce said changes, thereby mapping specific locations of renal nerves underlying the renal artery lumen.   
     
     
         2 . The method of  claim 1 , wherein the catheters that perform stimulatory and ablative processes are ablative catheters currently in use to treat cardiac arrhythmias. 
     
     
         3 . The method of  claim 1 , wherein the indicia of disease measured comprise indicia of hypertension, indicia of diabetes, or indicia of congestive heart failure. 
     
     
         4 . The method of  claim 3 , wherein the indicia of hypertension are selected from the group consisting of systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, muscular sympathetic activity, and urine output. 
     
     
         5 . The method of  claim 1 , wherein the optional protocol for moving the catheter tip comprises moving the stimulatory or ablative section of the catheter tip from the half of the renal artery closer to the interior of the kidney to the half of the renal artery closer to the aorta and applying one or more electrical stimulation to each of the two halves. 
     
     
         6 . The method of  claim 1 , wherein the optional protocol for moving the catheter tip comprises turning the stimulatory or ablative section of the catheter tip within the renal artery in the following sequence:
 (a) turning from the anterior wall to the posterior wall of the artery;   (b) turning from the posterior wall to the superior wall of the artery; and   (c) turning from the superior wall to the inferior wall of the artery,   wherein each turn is 90° or less.   
     
     
         7 . The method of  claim 6 , wherein one or more electrical stimulations are applied after each turning of the catheter tip within the renal artery. 
     
     
         8 . The method of  claim 1 , wherein the electrical stimulation applied falls within the following parameters:
 (a) voltage of between 2 to 30 volts;   (b) resistance of between 100 to 1000 ohms;   (c) current of between 5 to 40 milliamperes;   (d) applied between 0.1 to 20 milliseconds.   
     
     
         9 . A method of ablating renal nerves to treat disease caused by systemic renal nerve hyperactivity, comprising the steps of:
 a) applying the mapping method of  claim 1  to map renal nerves; and   (b) applying radiofrequency energy through the catheter to site-specific portions of the renal artery lumen to ablate the mapped renal nerves.   
     
     
         10 . A method for mapping and ablating renal nerves to treat disease caused by systemic renal nerve hyperactivity, comprising the steps of:
 (a) introducing a catheter into the renal architecture at a desired location where it remains stationary;   (b) keeping the catheter stationary while electrical current is introduced through individual electrodes of the catheter and while indicia of disease are measured to perform renal nerve mapping according to the method of  claim 1 ; and   (c) keeping the catheter stationary while radiofrequency energy is introduced through individual electrodes of the catheter to ablate the mapped renal nerves.   
     
     
         11 . A catheter for performing the mapping functions of  claim 1  wherein the catheter comprises catheter tip possessing electrodes that lie proximal to the arterial lumen, and wherein the electrodes can deliver both a direct and alternating current as well as radiofrequency energy. 
     
     
         12 . The catheter of  claim 11 , wherein the electrodes perform both stimulatory and ablative functions. 
     
     
         13 . The catheter of  claim 11 , wherein the electrodes may be activated independently of one another or in any combination. 
     
     
         14 . The catheter of  claim 11 , wherein the entire catheter is between 1.0 to 1.5 m in length, wherein the catheter tip is between 2.0 and 6.0 cm in length, wherein the catheter tip has a diameter of from 2.0 mm to 10.0 mm. 
     
     
         15 . The catheter of  claim 11 , wherein the shape of the catheter tip is either a single helix or a double helix, wherein the coil of the helix is either round or flat in shape and the electrodes are spaced along the length of the coil, wherein said electrodes may be round in shape if the coil is round or flat in shape if the coil is flat in shape. 
     
     
         16 . The catheter of  claim 15 , wherein the electrodes are evenly spaced along the length of the helix or helices 90° or 120° from each other. 
     
     
         17 . The catheter of  claim 11 , wherein the catheter tip comprises a balloon around which is wrapped a helical coil or an umbrella component, wherein spaced along the length of the helical coil or the umbrella component are electrodes. 
     
     
         18 . The catheter of  claim 17 , wherein the umbrella component is either open-ended or close-ended.