Tissue ablation catheter with passive conductive elements to shape electric fields

A tissue ablation catheter with passive conductive elements to shape electric fields, comprising:

• a tubular element comprising:
• a distal end configured to be placed proximal to a tissue to be ablated;
• a proximal end opposite said distal end;
• an inner surface surrounding a lumen;
• an outer surface;
• and,
• an electrical insulator between said inner surface and said outer surface;
• one or more inner electrodes within said lumen, each offset away from said distal end in a proximal direction towards said proximal end;
• one or more outer electrodes coupled to said outer surface;
• a controller coupled to said one or more inner electrodes and to said one or more outer electrodes and configured to:
• set voltages of said one or more inner electrodes and voltages of said one or more outer electrodes to generate an electric field outside said tubular element that induces ablation of said tissue to be ablated by electroporation;
• and,
• one or more passive conductive elements coupled to said tubular element, wherein:
• each passive conductive element of said one or more passive conductive elements is not coupled to said controller;
• and each passive conductive element comprises a conductive material, wherein charges within said conductive material move to modify said electric field.