Electrosurgical medical device with power modulation

Abstract

An electrosurgical ablation device provides pulse width modulated DC power to a heating segment in a catheter for use in providing treatment. In some embodiments the DC power to be modulated is sourced from an AC/DC power converter coupled to a source of AC power. In some embodiments the DC power to be modulated is sourced from a battery. In some embodiments the device switchably selects for modulation DC power sourced from either the AC/DC power converter or the battery, for example based on availability of power from the AC/DC power converter.

1 - 19 . (canceled) 
     
     
         20 . A medical system comprising:
 a heating element configured to ablate tissue;   a power converter configured to convert a high direct current (DC) power to a low DC power lower than the high DC power;   a pulse width modulator configured to modulate the second DC power and deliver DC power pulses to the heating element; and   a pulse width modulation (PWM) driver configured to provide signals that control the pulse width modulator to turn on and off power to generate the DC power pulses.   
     
     
         21 . The medical system of  claim 20 , further comprising a catheter including a heating segment comprising the heating element. 
     
     
         22 . The medical system of  claim 20 , wherein the DC power pulses comprise a minimum duty cycle greater than 0% and a maximum duty cycle less than 100%. 
     
     
         23 . The medical system of  claim 22 , wherein the PWM driver is configured to control the pulse width modulator to decrease a duty cycle of the DC power pulses in response to a sensed temperature from a temperature sensor being greater than a desired temperature plus a first offset value, and wherein the PWM driver is configured to control the pulse width modulator to increase the duty cycle of the DC power pulses in response to the sensed temperature from the temperature sensor being less than the desired temperature minus a second offset value. 
     
     
         24 . The medical system of  claim 20 , further comprising an AC/DC power converter and a battery. 
     
     
         25 . The medical system of  claim 24 , further comprising a switch configured to switchably provide power from either the AC/DC converter or the battery to the pulse width modulator. 
     
     
         26 . The medical system of  claim 25 , wherein the AC/DC converter and the battery are coupled in parallel to the switch. 
     
     
         27 . The medical system of  claim 25 , wherein the power converter is coupled between the AC/DC power converter and the switch. 
     
     
         28 . The medical system of  claim 20 , wherein the heating element is a resistive coil. 
     
     
         29 . The medical system of  claim 20 , wherein the heating element is constructed of at least one of nickel chromium, a nickel iron alloy, copper, stainless steel, titanium, or zirconium. 
     
     
         30 . The medical system of  claim 20 , wherein the heating element is constructed of a material from which temperature is indirectly measured as a function of impedance, and wherein the medical system comprises a temperature sensor configured to measure the temperature as the function of the impedance of the heating element. 
     
     
         31 . The medical system of  claim 20 , further comprising plastic cover within which the heating element is housed. 
     
     
         32 . A method comprising:
 converting, by a power converter of a medical system, a high direct current (DC) power to a low DC power lower than the high DC power;   modulating, by a pulse width modulator of the medical system, the low DC power;   delivering, by the pulse width modulator, DC power pulses to a heating element; and   providing, by a pulse width modulation (PWM) driver of the medical system, signals controlling the pulse width modulator to turn on and off power to generate the DC power pulses.   
     
     
         33 . The method of  claim 32 , wherein the medical system comprises a catheter including a heating segment comprising the heating element. 
     
     
         34 . The method of  claim 32 , wherein the DC power pulses comprise a minimum duty cycle greater than 0% and a maximum duty cycle less than 100%. 
     
     
         35 . The method of  claim 34 , further comprising:
 controlling, by the PWM driver, the pulse width modulator to decrease a duty cycle of the DC power pulses in response to a sensed temperature from a temperature sensor being greater than a desired temperature plus a first offset value; and   controlling, by the PWM driver, the pulse width modulator to increase the duty cycle of the DC power pulses in response to the sensed temperature from the temperature sensor being less than the desired temperature minus a second offset value.   
     
     
         36 . The method of  claim 32 , further comprising switchably providing, by a switch, power from either an AC/DC converter or a battery to the pulse width modulator, wherein the AC/DC converter and the battery are coupled in parallel to the switch. 
     
     
         37 . The method of  claim 32 , further comprising switchably providing, by a switch, power from either an AC/DC converter or a battery to the pulse width modulator, wherein the power converter is coupled between the AC/DC power converter and the switch. 
     
     
         38 . The method of  claim 32 , wherein the heating element is constructed of a material from which temperature is indirectly measured as a function of impedance, and wherein the method further comprises measuring, by a temperature sensor, the temperature as the function of the impedance of the heating element. 
     
     
         39 . A medical system comprising:
 a heating element configured to ablate tissue;   an AC/DC power converter;   a battery;   a power converter configured to convert a high direct current (DC) power to a low DC power lower than the high DC power;   a pulse width modulator configured to modulate the second DC power and deliver DC power pulses to the heating element;   a switch configured to switchably provide power from either the AC/DC converter or the battery to the pulse width modulator; and   a pulse width modulation (PWM) driver configured to provide signals that control the pulse width modulator to turn on and off power to generate the DC power pulses, wherein the PWM driver is configured to control the pulse width modulator to decrease a duty cycle of the DC power pulses in response to a sensed temperature from a temperature sensor being greater than a desired temperature plus a first offset value, and wherein the PWM driver is configured to control the pulse width modulator to increase the duty cycle of the DC power pulses in response to the sensed temperature from the temperature sensor being less than the desired temperature minus a second offset value.