Catheter with deformation sensing

A system for ablating cardiac tissue through irreversible electroporation, the system comprising:

• a catheter for ablating cardiac tissue through irreversible electroporation, the catheter comprising:
• an outer shaft having a proximal end and an opposite distal end;
• an electrode assembly extending distally from the distal end of the outer shaft, the electrode assembly defining a distally located central hub portion and a plurality of splines each including a distal end portion extending from the central hub portion, a proximal end portion attached to and constrained by the outer shaft, and an intermediate portion disposed between the distal end portion and the proximal end portion, each of the plurality of splines also including an outwardly facing portion and an inwardly facing portion, the electrode assembly comprising:
• an outwardly facing flexible circuit disposed on the outwardly facing portions and having a flex circuit hub and a plurality of outwardly facing flex circuit branches extending proximally from the flex circuit hub, the outwardly facing flexible circuit further including an outwardly facing ablation electrode including an ablation electrode hub portion located on the flex circuit hub and a plurality of outwardly facing radial segments integrally formed with the ablation electrode hub portion, each of the outwardly facing radial segments extending proximally along a portion of a respective one of the outwardly facing flex circuit branches and terminating in a proximal end;
• and
• an inwardly facing flexible circuit disposed on the inwardly facing portions of the plurality of splines and having a plurality of inwardly facing flex circuit branches, the inwardly facing flexible circuit including an inwardly facing strain gauge disposed on the inwardly facing and intermediate portions of the plurality of splines;
• a graphical display;
• and
• a controller coupled to the graphical display and the catheter, the controller configured to:
• determine an impedance from a four-terminal configuration, wherein a current is injected to a current carrying pair of the plurality of electrodes and a volage is measured across a sensing pair of electrodes comprising a plurality of sensing electrodes;
• determine a force applied to the plurality of splines from sensor strain signals received from the inwardly facing strain gauge;
• and
• facilitate a visualization of a representation of the electrode assembly indicating which of the plurality of splines and electrodes are in contact with tissue and the state of the electrode assembly under deformation.

A method for ablating cardiac tissue through irreversible electroporation including a catheter having an electrode assembly extending distally from the distal end of the outer shaft, the electrode assembly defining a distally located central hub portion and a plurality of splines each including a distal end portion extending from the central hub portion, a proximal end portion attached to and constrained by the outer shaft, and an intermediate portion disposed between the distal end portion and the proximal end portion, each of the plurality of splines also including an outwardly facing portion and an inwardly facing portion, the electrode assembly comprising an outwardly facing flexible circuit disposed on the outwardly facing portions and having a flex circuit hub and a plurality of outwardly facing flex circuit branches extending proximally from the flex circuit hub, the outwardly facing flexible circuit further including an outwardly facing ablation electrode including an ablation electrode hub portion located on the flex circuit hub and a plurality of outwardly facing radial segments integrally formed with the ablation electrode hub portion, each of the outwardly facing radial segments extending proximally along a portion of a respective one of the outwardly facing flex circuit branches and terminating in a proximal end, and an inwardly facing flexible circuit disposed on the inwardly facing portions of the plurality of splines and having a plurality of inwardly facing flex circuit branches, the inwardly facing flexible circuit including an inwardly facing strain gauge disposed on the inwardly facing and intermediate portions of the plurality of splines, the method comprising:

• determining an impedance from a four-terminal configuration, wherein a current is injected to a current carrying pair of the plurality of electrodes and a volage is measured across a sensing pair of electrodes comprising a plurality of sensing electrodes;
• determining a force applied to the plurality of splines from sensor strain signals received from the inwardly facing strain gauge;
• and
• facilitating a visualization of a representation of the electrode assembly indicating which of the plurality of splines and electrodes are in contact with tissue and the state of the electrode assembly under deformation.