Mapping and ablation method for the treatment of ventricular tachycardia

A method of using a catheter comprising a substrate, comprising the acts of:

• (a) introducing the substrate into a ventricle of the heart, the substrate comprising a distal end;
• (b) configuring the substrate in a first configuration wherein the distal end of the substrate forms a proboscis extending from the substrate;
• (c) with the substrate in the first configuration and the proboscis cannulating a blood vessel connected to the heart, ablating a first lesion on a wall of the ventricle, the first lesion at least partially encircling a first region of the wall that includes an ostium of the blood vessel;
• (d) configuring the substrate in a second configuration wherein the substrate is inverted such that an annular surface of the substrate extends beyond the distal end;
• (e) with the substrate in the second configuration, ablating a second lesion on the wall of the ventricle, the second lesion encircling a second region of the wall that does not include any blood vessel ostia.