Method and device for thermal ablation having improved heat transfer

Abstract

A thermal ablation catheter includes an elongate body member having a heating element disposed over a predetermined length of its distal end or within an axial lumen. The heating element is suspended away from an exterior surface of the elongate member to form a circulation region thereunder. Alternatively, the heating element is distributed over some or all of the axial lumen. Thermally conductive fluid can be introduced through the lumen in the elongate member and into the circulation region to effect heat transfer. The catheter is used to introduce the thermally conductive medium to a hollow body organ where the heating element raises the temperature of the medium sufficiently to induce injury to the lining of the organ. Optionally, an expandable cage in the catheter or on an associated introducer sheath may be used in combination with a thermal ablation catheter. The expandable cage helps center the heating element on the catheter within the body organ and prevents direct contact between the heating element and the wall of the organ. When disposed on the catheter, the cage can be useful to position a flow directing element attached to the flow delivery lumen of the catheter. Heat transfer and temperature uniformity can be enhanced by inducing an oscillatory flow of the heat transfer medium through the catheter while heat is being applied.