RF ablation system and method having automatic temperature control

An apparatus for delivering energy to biological tissue while maintaining the temperature of the biological tissue near a target temperature, said apparatus comprising:

• a catheter having a plurality of electrodes at its distal end, the distal end positionable so that the electrodes are located proximal the biological tissue;
• a plurality of temperature sensing devices, at least one temperature sensing device located on a select number of the electrodes, for providing a temperature signal indicative of the temperature at the interface between the electrode and the tissue;
• a generator operating under the control of a processor to apply power to each of the electrodes, the power having an associated phase angle and, within a time duration, a plurality of alternating on periods and off periods, one set of adjacent on and off periods defining a duty cycle;
• wherein the processor is adapted to:
• in response to each of the temperature signals, determine the temperature at the electrode/tissue interface;
• regulate the temperature of a plurality of temperature zones, each zone comprising at least one combination electrode/temperature sensing device, by controlling the power to at least one electrode in the zone;
• and
• regulate the power to a plurality of phase groups, each group comprising at least one electrode, by controlling the phase of the power to each electrode in the group such that during the on portion of a duty cycle the phase in one group is different then the phase in another group.

A method for delivering energy to biological tissue while maintaining the temperature of the biological tissue near a target temperature, said method comprising:

• positioning a plurality of electrodes proximal the biological tissue, at least one of the electrodes carrying a temperature sensing device for providing a temperature signal indicative of the temperature at the interface between the electrode and the tissue;
• providing power to each of the electrodes, the power having, within a time duration, a plurality of alternating on periods and off periods, one set of adjacent on and off periods defining a duty cycle;
• during the on period of each duty cycle, providing power with different phase angles to at least two of the electrodes;
• determining the temperature at the at least one electrode/tissue interface in response to the temperature signal;
• comparing the at least one electrode/tissue interface temperature to the target temperature;
• and
• adjusting the duty cycle of the power provided to the at least one electrode in response to the comparison.

A method for delivering energy to biological tissue while maintaining the temperature of the biological tissue near a target temperature, said method comprising:

• positioning a catheter having a plurality of electrodes at its distal end so that the electrodes are located proximal the biological tissue, a select number of the electrodes carrying at least one temperature sensing device, for providing a temperature signal indicative of the temperature at the interface between the electrode and the tissue;
• providing power having an associated phase and, within a time duration, a plurality of alternating on periods and off periods, one set of adjacent on and off periods defining a duty cycle;
• in response to the temperature signals, determining the temperature at the electrode/tissue interface;
• individually regulating the temperature of a plurality of temperature zones, each zone comprising at least one combination electrode/temperature sensing device, by controlling the power to at least one electrode in the zone;
• and
• regulating the power to a plurality of phase groups, each group comprising at least one electrode, by controlling the phase of the power to each electrode in the group such that during the on portion of a duty cycle the phase in one group is different then the phase in another group.