Protection of Critical Structures During Radiofrequency Ablation of Adjacent Myocardial Tissue Using Catheter Tips Partially Insulated With Thermally Conductive Material

METHODS Open-irrigated, 4and 8-mm RF ablation catheter tips were insulated partially by coating one-half of their surfaces with a layer of vinyl, silicone, vinyl–silicone, polyurethane, or a composite of aluminum oxide/boron nitride (AOBN). These coated catheters or corresponding noninsulated catheters were positioned with 10 g of force on viable bovine myocardial tissue during RF application in an ex vivo setup. Tip temperatures, power, and lesion volumes were compared. The most effective coating, AOBN, was modified further by adding fenestrations to aid in passive cooling. PIFA catheters with fenestrated AOBN coating were then tested in an in vivo porcine model to target myocardial tissue adjacent to the AV node and the phrenic nerve.