A method and apparatus for reducing restenosis of a stenotic region of a blood vessel after performing dilation angioplasty treatment is disclosed. The method includes radiating microwave energy from a microwave antenna (52) 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 (18) to permanently dilate the stenotic region. When radiation is applied during dilatation of the stenotic region, the dilatation balloon (18) 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 (70, 72) 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. Finally, the method also preferably includes perfusing blood in the vessel through the catheter (250) across the stenotic region during dilatation of the stenotic region to maintain circulation of blood through the blood vessel during the dilatation of the stenotic region.La présente invention concerne un procédé et une méthode permettant de réduire la resténose dune zone sténosée dun vaisseau sanguin suite à un traitement angioplastique de dilatation. Le procédé consiste à émettre une énergie micro-onde dune antenne à micro-ondes (52) pour tuer une couche de tissu médiane du vaisseau sanguin dans la zone sténosée. Le rayonnement est appliqué pendant ou après le gonflement du ballonnet de dilatation (18) pour permettre une dilatation permanente de la zone sténosée. Lors de lapplication du rayonnement pendant la dilatation de la zone sténosée, le ballonnet de dilatation (18) forme une obturation contre la surface de la paroi interne de la zone sténosée du vaisseau sanguin, de façon à empêcher le sang d
