Medical devices for renal nerve ablation

Abstract

Medical devices and methods for making and using the same are disclosed. An example medical device may include a medical device for renal nerve ablation. The medical device may include an elongate shaft having a distal region. An expandable member may be coupled to the distal region. A plurality of electrodes may be coupled to the expandable member and a single conductive member may be coupled to each electrode. Where one of the plurality of electrodes is active, the remaining electrodes may be inactive and act as ground or return electrodes. The electrode of the plurality of electrodes that is active may change over time.

What is claimed is: 
     
         1 . A method for ablating tissue in a body of a patient within a treatment duration, the method comprising:
 advancing a medical device into the body of the patient adjacent to the tissue, the device comprising an elongate shaft having a distal region, three or more electrodes coupled to the distal region, a conductive member connected to each of the electrodes, and a controller connected to each of the conductive members;   activating each of the electrodes a single electrode at a time during the treatment duration for selected time periods, by the controller supplying power through the conductive member connected to the single electrode during the selected time periods, while automatically maintaining the remaining electrodes during the selected time periods as unpowered so as to act as ground electrodes.   
     
     
         2 . The method of  claim 1 , wherein the treatment duration corresponds to a total pre-determined time. 
     
     
         3 . The method of  claim 1 , wherein the treatment duration corresponds to a set temperature or impedance value of the tissue. 
     
     
         4 . The method of  claim 1 , wherein the selected time periods for the electrodes are a set time that is pre-determined prior to the treatment duration or a time that is variable during the treatment duration. 
     
     
         5 . The method of  claim 1 , wherein the selected time periods for each one of the electrodes within the treatment duration are uniform for that one electrode. 
     
     
         6 . The method of  claim 5 , wherein the selected time periods across each of the electrodes within the treatment duration are uniform for all the electrodes. 
     
     
         7 . The method of  claim 1 , wherein the cumulative sum of the selected time periods for each one of the electrodes within the treatment duration is a predetermined percentage of a total time of the treatment duration. 
     
     
         8 . The method of  claim 7 , wherein the percentages across each of the electrodes within the treatment duration are uniform for all the electrodes. 
     
     
         9 . A method for ablating tissue in a body of a patient within a treatment duration, the method comprising:
 advancing a medical device into the body of the patient adjacent to the tissue to be ablated, the device comprising an elongate shaft having a distal region, an expandable balloon coupled to the distal region, at least three electrodes coupled to the expandable balloon, and a conductive trace for each of the electrodes that is capable of supplying power to the electrode to which the conductive trace is connected independent of the conductive traces for the other electrodes;   expanding the balloon to place the electrodes in contact with the tissue;   activating the electrodes one electrode at a time during the treatment duration for selected time periods, by supplying power through the conductive trace connected to the one electrode and automatically maintaining the remaining electrodes as unpowered so as to act as ground electrodes.   
     
     
         10 . The method of  claim 9 , wherein the selected time periods for the electrodes are a set time that is pre-determined prior to the treatment duration or a time that is variable during the treatment duration. 
     
     
         11 . The method of  claim 9 , wherein the selected time periods for each one of the electrodes within the treatment duration are uniform for that one electrode. 
     
     
         12 . The method of  claim 9 , wherein the cumulative sum of the selected time periods for each one of the electrodes within the treatment duration is a predetermined percentage of a total time of the treatment duration. 
     
     
         13 . The method of  claim 9 , wherein expanding the balloon places the electrodes in direct or indirect contract with the tissue. 
     
     
         14 . The method of  claim 9 , wherein the tissue is nerve tissue adjacent to a position along a renal artery, and the balloon is advanced with the medical device within the renal artery to the position and expanded. 
     
     
         15 . A method for ablating tissue in a body of a patient within a treatment duration, the method comprising:
 advancing a medical device into the body of the patient adjacent to the tissue to be ablated, the device comprising an elongate shaft having a distal region, at least three electrodes coupled to the distal region, and a controller configured to independently supply power to the electrodes;   activating a first one of the electrodes during the treatment duration for first selected time periods, while automatically maintaining the other of the electrodes as inactive to act as ground electrodes;   activating a second one of the electrodes during the treatment duration for second selected time periods, while automatically maintaining the other of the electrodes as inactive to act as ground electrodes; and   activating a third one of the electrodes during the treatment duration for third selected time periods, while automatically maintaining the other of the electrodes as inactive to act as ground electrodes.   
     
     
         16 . The method of  claim 15 , wherein the treatment duration corresponds to a set temperature or impedance value of tissue. 
     
     
         17 . The method of  claim 15 , wherein the selected time periods for the electrodes are a set time that is pre-determined prior to the treatment duration or a time that is variable during the treatment duration. 
     
     
         18 . The method of  claim 15 , wherein the selected time periods for each one of the electrodes within the treatment duration are uniform for that one electrode. 
     
     
         19 . The method of  claim 15 , wherein the cumulative sum of the selected time periods for each one of the electrodes within the treatment duration is a predetermined percentage of a total time of the treatment duration. 
     
     
         20 . The method of  claim 19 , wherein the percentages across each of the electrodes within the treatment duration are uniform for all the electrodes.