Systems, devices, and methods for ablation of endocardial tissue

A system for ablating tissue by irreversible electroporation, the system comprising:

• a catheter comprising:
• a catheter shaft defining a longitudinal axis and having a proximal end, a distal end opposite the proximal end, and a shaft lumen therethrough;
• an inner shaft disposed within the shaft lumen;
• a set of splines extending from the distal end of the catheter shaft, each spline of the set of splines including a plurality of first electrodes disposed thereon, wherein the first electrodes on each spline are jointly wired by a single insulated lead such that each of the first electrodes on each spline have a common polarity when an electrical signal is delivered thereto,
• wherein the inner shaft is movable within the shaft lumen along the longitudinal axis from a first inner shaft position defining a first configuration of the set of splines to a second inner shaft position defining a second configuration of the set of splines, and
• wherein in the first configuration each spline of the set of splines extends substantially parallel to the longitudinal axis, and
• wherein in the second configuration, the set of splines are arranged as a set of loops extending away from the catheter shaft and the inner shaft in a direction generally perpendicular to the longitudinal axis;
• and
• a signal generator operatively coupled to the plurality of first electrodes, wherein the signal generator is configured to deliver a pulse waveform to the plurality of first electrodes to selectively activate the first electrodes on adjacent first and second splines such that the first electrodes on the first spline have a first polarity and first electrodes on the second spline have a second polarity opposite the first polarity, wherein the pulse waveform is delivered between the first electrodes on the first and second splines, and wherein the first electrodes on the first and second splines have a potential difference of at least about 700V.