Tissue modification systems and methods and signal generators for use therewith

A tissue treatment system that is configured to deliver a predetermined target current to patient tissue during a treatment procedure, wherein the predetermined target current comprises a default target current specified prior to beginning the treatment procedure or is specified by a clinician using a user interface of the tissue treatment system prior to beginning the treatment procedure, the tissue treatment system comprising:

• a pair of electrodes including an active electrode and a return electrode;
• a plurality of capacitors;
• a power supply configured to charge the plurality of capacitors;
• a waveform shaping circuit coupled between the plurality of capacitors and the pair of electrodes;
• a current sense circuit configured to measure a current that is delivered to the patient tissue via the active electrode while a low voltage (LV) tissue impedance measurement signal is delivered to the patient tissue;
• and
• a controller configured to
• cause a first subset of the plurality of capacitors to be coupled to the waveform shaping circuit during a first period of time during which the LV tissue impedance measurement signal is to be delivered to patient tissue via the pair of electrodes;
• cause a second subset of the plurality of capacitors to be coupled to the waveform shaping circuit during a second period of time during which a high voltage (HV) tissue treatment signal is to be delivered to the patient tissue via the pair of electrodes;
• produce an estimate of an impedance of the patient tissue based on a voltage of the LV tissue impedance measurement signal that is delivered to the patient tissue and based on the current measured by the current sense circuit;
• and
• adjust a voltage of the HV tissue treatment signal during the treatment procedure, based on the estimate of the impedance of the patient tissue and one or more updates thereto, so that when the HV tissue treatment signal is delivered to the patient tissue during the treatment procedure the patient tissue is treated with a current that is approximately equal to the predetermined target current that was specified prior to beginning the treatment procedure;
• wherein
• the voltage of the HV tissue treatment signal is at least five times greater than the voltage of the LV tissue impedance measurement signal;
• the first subset of the plurality of capacitors includes at least one of the plurality of capacitors;
• and
• the second subset of the plurality of capacitors includes at least one of the plurality of capacitors and differs from the first subset of the plurality of capacitors.

A method for delivering a predetermined target current to patient tissue during a treatment procedure, wherein the predetermined target current comprises a default target current specified prior to beginning the treatment procedure or is specified by a clinician using a user interface prior to beginning the treatment procedure, the method comprising:

• (a) producing a low voltage (LV) tissue impedance measurement signal and delivering the LV tissue impedance measurement signal to patient tissue via an active electrode and a return electrode;
• (b) measuring a current that is delivered to the patient tissue via the active electrode while the LV tissue impedance measurement signal is delivered to the patient tissue;
• (c) producing an estimate of an impedance of the patient tissue based on a voltage of the LV tissue impedance measurement signal that is delivered to the patient tissue and based on the current that is measured;
• and
• (d) producing a high voltage (HV) tissue treatment signal and delivering the HV tissue treatment signal via the active and return electrodes, wherein a voltage of the HV tissue treatment signal is at least five times greater than the voltage of the LV tissue impedance measurement signal, and wherein the producing the HV tissue treatment signal includes adjusting the voltage of the HV tissue treatment signal during the treatment procedure based on the estimate of the impedance of the patient tissue and one or more updates thereto so that when the HV tissue treatment signal is delivered to the patient tissue during the treatment procedure the patient tissue is treated with a current that is approximately equal to the predetermined target current that was specified prior to beginning the treatment procedure.

A tissue treatment system that is configured to deliver a predetermined target current to patient tissue during a treatment procedure, wherein the predetermined target current comprises a default target current specified prior to beginning the treatment procedure or is specified by a clinician using a user interface of the tissue treatment system prior to beginning the treatment procedure, the tissue treatment system comprising:

• one or more voltage signal generators;
• a current sense circuit configured to measure a current that is delivered to the patient tissue via an active electrode while one of the one or more voltage signal generators is delivering a voltage signal to the patient tissue;
• and
• a controller configured to
• produce an estimate of an impedance of the patient tissue based on the current measured by the current sense circuit;
• and adjust a voltage of the voltage signal produced during the treatment procedure using one of the one or more voltage signal generators, based on the estimate of the impedance of the patient tissue, so that during the treatment procedure the patient tissue is treated with a current that is approximately equal to the predetermined target current that was specified prior to beginning the treatment procedure.