Systems and methods for radiofrequency ablation with phase sensitive power detection

Claim 1

A system for ablating tissue at an ablation site using radiofrequency energy comprising a source of radiofrequency energy, an electrode electrically connected to the source for emitting radiofrequency energy at the ablation site, current monitoring means for measuring radiofrequency current delivered to the electrode and generating a measured radiofrequency current signal, voltage monitoring means for measuring radiofrequency voltage at the electrode and generating a measured radiofrequency voltage signal, means for multiplying the measured current signal by the measured voltage signal and deriving a phase sensitive power signal that represents real power (P Real ) transmitted to the electrode, means for deriving a root mean squared current signal based upon the measured radiofrequency current signal, means for deriving a root mean squared voltage signal based upon the measured radiofrequency voltage signal, means for multiplying the root mean squared current signal by the root mean squared voltage signal and deriving a root mean squared power signal that represents the apparent power (P Apparent ) transmitted to the electrode, means for generating a deviation signal that indicates a phase shift (φ) between P Real and P Apparent , where: φ=cos.sup.-1, and first control means for performing a function based upon the phase shift deviation signal, and second control means for performing a function based upon the phase sensitive power signal.

Claim 2

A system for ablating tissue at an ablation site using radiofrequency energy comprising a source of radiofrequency energy, an electrode electrically connected to the source for emitting radiofrequency energy at the ablation site, current monitoring means for measuring radiofrequency current delivered to the electrode and generating a measured radiofrequency current signal, voltage monitoring means for measuring radiofrequency voltage at the electrode and generating a measured radiofrequency voltage signal, means for multiplying the measured current signal by the measured voltage signal and deriving a phase sensitive power signal that represents real power (P Real ) transmitted to the electrode, means for deriving a root mean squared current signal based upon the measured radiofrequency current signal, means for deriving a root mean squared voltage signal based upon the measured radiofrequency voltage signal, means for multiplying the root mean squared current signal by the root mean squared voltage signal and deriving a root mean squared power signal that represents the apparent power (P Apparent ) transmitted to the electrode, means for generating a deviation signal that indicates a phase shift (φ) between P Real and P Apparent , where: φ=cos.sup.-1, and first control means for performing a function based upon the phase shift deviation signal, and second control means for performing a function based upon the phase sensitive power signal.