Devices for thermally-induced renal neuromodulation

Abstract

Methods and system are provided for thermally-induced renal neuromodulation. Thermally-induced renal neuromodulation may be achieved via direct and/or via indirect application of thermal energy to heat or cool neural fibers that contribute to renal function, or of vascular structures that feed or perfuse the neural fibers. In some embodiments, parameters of the neural fibers, of non-target tissue, or of the thermal energy delivery element, may be monitored via one or more sensors for controlling the thermally-induced neuromodulation. In some embodiments, protective elements may be provided to reduce a degree of thermal damage induced in the non-target tissues. In some embodiments, thermally-induced renal neuromodulation is achieved via delivery of a pulsed thermal therapy.

1 . A field generator, comprising:
 a processor configured to:   increase energy delivery, from the field generator to an energy delivery element of a catheter intravascularly positioned at a target site within a renal blood vessel of a patient, to a first power level;   determine that a temperature is greater or equal to a threshold temperature; and   decrease the energy delivery, from the field generator to the energy delivery element, to a second power level when the temperature is greater than or equal to the threshold temperature.   
     
     
         2 . The field generator of  claim 1 , wherein the energy delivery element is an electrode and the temperature is an electrode temperature. 
     
     
         3 . The field generator of  claim 1 , further comprising a temperature sensor that is configured to measure the temperature at the target site. 
     
     
         4 . The field generator of  claim 1 , wherein the processor is configured to maintain the energy delivery at the first power level over a period of time. 
     
     
         5 . The field generator of  claim 1 , wherein to decrease the energy delivery to the second power level the processor is configured to stop the energy delivery. 
     
     
         6 . The field generator of  claim 1 , wherein the processor is configured to:
 monitor the temperature and impedance; and   decrease the energy delivery, from the field generator to the electrode, to a second power level when the temperature is greater than or equal to the threshold temperature and the impedance exceeds a predetermined impedance.   
     
     
         7 . A field generator, comprising:
 a processor configured to:   increase energy delivery, from the field generator to an energy delivery element of a catheter intravascularly positioned at a target site within a renal blood vessel of a patient, to a first power level;   determine that a temperature is greater or equal to a predetermined temperature; and   decrease the energy delivery, from the field generator to the energy delivery element, to a second power level based on the determination.   
     
     
         8 . The field generator of  claim 7 , wherein the processor is configured to monitor the temperature and impedance. 
     
     
         9 . The field generator of  claim 8 , wherein to decrease the energy delivery to the second power level is further based on the impedance. 
     
     
         10 . The field generator of  claim 9 , wherein the processor is configured to decrease the energy delivery, from the field generator to the electrode, to the second power level when the temperature is greater than or equal to the threshold temperature and the impedance exceeds a predetermined impedance. 
     
     
         11 . The field generator of  claim 7 , wherein the processor is configured to maintain the energy delivery at the first power level over a period of time. 
     
     
         12 . The field generator of  claim 7 , wherein the energy delivery element is an electrode and the temperature of the energy delivery element is an electrode temperature. 
     
     
         13 . The field generator of  claim 7 , further comprising a temperature sensor that is configured to measure the temperature. 
     
     
         14 . A method, comprising:
 intravascularly positioning a catheter having an energy delivery element at a target site within a renal blood vessel of a patient;   increasing, by a processor of a field generator, energy delivery to the energy delivery element to a first power level;   determining, by the processor, that a temperature of the energy delivery element is greater or equal to a threshold temperature; and   decreasing, by the processor, the energy delivery, from the field generator to the energy delivery element, to a second power level when the temperature is greater than or equal to the threshold temperature.   
     
     
         15 . The method of  claim 14 , further comprising monitoring the temperature and impedance of the energy delivery element. 
     
     
         16 . The method of  claim 15 , wherein decreasing the energy delivery to the second power level is further based on the impedance. 
     
     
         17 . The method of  claim 14 , further comprising monitoring the temperature continuously. 
     
     
         18 . The method of  claim 14 , wherein the energy delivery element is an electrode and the temperature of the energy delivery element is an electrode temperature. 
     
     
         19 . The method of  claim 14 , further comprising measuring the temperature of the energy delivery element. 
     
     
         20 . The method of  claim 14 , further comprising:
 maintaining the energy delivery at the first power level over a period of time.