Method and system for radiofrequency ablation of tissue

A system for radiofrequency ablation of cardiac tissue, said system comprising:

• a catheter having a proximal end, a distal end, an electrode near said distal end, and a temperature sensor near said distal end, said electrode being coupled to an electrode connection wire extending to said proximal end, and said temperature sensor being coupled to a temperature sensor connection wire extending to said proximal end;
• and
• a radiofrequency power generator connected to said proximal end of the catheter, said generator including:
• (a) a power source including a digital RF signal generator for providing a digitized sinusoidal RF signal, a multiplying DAC having a digital input, coupled to receive said digitized RF signal, a reference voltage input for receiving a power output signal having a variable magnitude, and an analog output for delivering, via an amplifier, radiofrequency power to the electrode, based on the magnitude of the power output signal;
• (b) means, coupled to said power source, for measuring radiofrequency power delivered from the power source to the electrode to produce an actual power signal;
• (c) an analog temperature controller which receives a temperature set point signal and an actual temperature signal from the temperature sensor and based on a difference therebetween produces a power set point signal;
• (d) an analog power controller coupled the means for measuring radiofrequency power and to the analog temperature controller where the analog power controller receives the power set point signal and the actual power signal and based on a difference therebetween varies the magnitude the power output signal;
• (e) control means, coupled to said analog temperature controller, for providing said temperature set point signal;
• and
• (f) means for connecting said power source to said electrode connection wire and for connecting said temperature controller to said temperature sensor connection wire.

A system for radiofrequency ablation of tissue, said system comprising:

• a catheter having a proximal end, a distal end, an electrode near said distal end, and a temperature sensor near said distal end, said electrode being coupled to an electrode connection wire extending to said proximal end, and said temperature sensor being coupled to a temperature sensor connection wire extending to said proximal end;
• and
• a radiofrequency power generator connectable to the proximal end of the catheter, said generator including:
• (a) power supply means for delivering radiofrequency power to the electrode based on a power output signal;
• (b) means for controlling temperature at the temperature sensor, said means being connected to receive an actual temperature signal from the sensor and to modulate the power output signal to have an amplitude proportional to the difference between said actual temperature signal and a temperature set point;
• and
• (c) a battery connected to said power supply means and said means for controlling as the sole source of power for said radiofrequency power generator to reduce or eliminate spurious ground differential currents;
• (d) means for connecting said power supply means to said electrode connection wire and for connecting said temperature control means to said temperature sensor connection wire.

A system for radiofrequency ablation, said system comprising:

• a catheter having a proximal end, a distal end, an electrode near the distal end, a thermocouple near the distal end for measuring temperature near the distal end, and a verification circuit near the proximal end for testing the electrical continuity of the thermocouple, said electrode being coupled to an electrode connection wire extending to the proximal end;
• a radiofrequency power generator connectable to the proximal end of the catheter;
• means, coupled to said thermocouple, for providing a high/low temperature warning when the temperature near the distal end is outside a selected range;
• a current source for supplying a current to the verification circuit when the electrical continuity of the of the thermocouple is to be tested;
• means for sensing current flow through the verification circuit;
• means for connecting the radiofrequency power generator to the electrode connector wire and for connecting the current source to the verification circuit;
• and
• means for disabling the radiofrequency power generator when the current flow through the verification circuit is outside a selected range.

A system for radiofrequency ablation of tissue, said system comprising:

• a catheter having a proximal end, a distal end, an electrode near said distal end, and a temperature sensor near said distal end, said electrode being coupled to an electrode connection wire extending to said proximal end, and said temperature sensor being coupled to a temperature sensor connection wire extending to said proximal end;
• and
• a radiofrequency power generator connectable to the proximal end of the catheter, said generator including:
• (a) a power source which delivers radiofrequency power to the electrode based on a power output signal and provides an actual power signal indicating the magnitude of the radiofrequency power delivered;
• (b) means for controlling temperature at the temperature sensor, said means being connected to receive an actual temperature signal from the sensor, said actual power signal, and to modulate the power output signal based on a said actual power signal and a control signal having a magnitude indicating the difference between said actual temperature signal and a temperature set point;
• (c) means for connecting said power source to said electrode connection wire and for connecting said temperature control means to said temperature sensor connection wire;
• and
• (d) means for providing an alternative control signal having a magnitude indicating a selected power level;
• (e) means, coupled to said means for providing said alternative control signal and to receive said actual power signal, for limiting the radiofrequency power delivered to said electrode according to the magnitude of said alternative control signal and said actual power signal and irrespective of said actual temperature signal or said temperature set point.