Medtronic, Inc.

Sara A Frantz

Steven J Fraasch

Mark T Stewart

Gonzalo Martinez

Brian T Howard

Lars M Mattison

Kevin D Gollon

Bryce W Bunkers

Methods and apparatus for monitoring and actively reducing leakage currents flowing on patient applied parts used in ablation therapy. In an example, a signal-processing circuit connected between a toroidal-coil sensor and a sleeve-capacitor coupler, both AC-coupled to the catheter cable, applies a Fourier transform and an energy minimization algorithm to the output of the toroidal-coil sensor to determine amplitudes and phases for frequency components of the signal applied to the sleeve-capacitor coupler. A corresponding current coupled through the sleeve-capacitor coupler into the catheter cable counteracts the leakage current to force the total non-therapy electrical current flowing on the patient applied parts to a level that is lower than a fixed threshold value, e.g., selected in accordance with an applicable standard.

Methods and apparatus for reducing leakage currents in cryo, radio-frequency, and pulsed-field ablation systems

A method and pulsed field ablation (PFA) system configured to provide variable impedance paths for delivery of electric fields to patient tissue using a PFA catheter are disclosed. According to one aspect, a method includes determining a current for each of a plurality of circuit paths, each circuit path including two electrodes. Each current may be determined based at least in part on: a desired voltage between the two electrodes; a tissue impedance between the two electrodes; and a parasitic impedance associated with the circuit path. The method also includes determining at least one of an excitation voltage and an input resistance for each circuit path of the plurality of circuit paths based at least in part on the determined current for the circuit path, parasitic impedances associated with the circuit path and a tissue impedance between the two electrodes in the circuit path.

Variable impedance paths for delivery of electric fields

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Mounds View, MN, United States of America

Sara A Frantz