Abstract: A method and apparatus for reducing restenosis of a stenotic region of a blood vessel after performing a dilatation angioplasty treatment is disclosed. The method includes radiating microwave energy from a microwave antenna to kill a medial tissue layer of the blood vessel in the stenotic region. The radiation is applied during or after inflation of dilatation balloon to permanently dilate the stenotic region. When radiation is applied during dilatation of the stenotic region, the dilatation balloon forms a seal against the inner wall surface of the blood vessel to exclude blood in the vessel from contacting the stenotic region. The method preferably further includes cooling the blood circulating in the blood vessel about a shaft of the catheter with cooling fluid circulating within cooling lumens of the catheter and cooling an inner wall surface of the blood vessel in the stenotic region during the application of radiation to the medial cell layer.

Abstract: A method of applying microwave energy to cardiac tissue uses a catheter adapted for insertion into a cardiac chamber and which includes a microwave antenna, a cooling lumen structure, and an inflatable cooling balloon. Necrosing levels of microwave energy are delivered from the microwave antenna to diseased cardiac tissue spaced from the catheter. Tissues immediately surrounding the catheter are cooled and microwave energy emitted by the antenna is selectively absorbed by the cooling lumen structure surrounding the antenna. The cooling balloon of the catheter is positioned adjacent the antenna and partially surrounds the cooling lumen structure on one side of the catheter to provide additional cooling capability and additional microwave energy absorption on the side of the catheter opposite the diseased cardiac tissue to prevent unwanted heating of blood within the cardiac chamber.