A balloon dilatation catheter having heating elements raise the temperature of the working surface of the balloon while the balloon is being inflated during an angioplasty procedure. In one embodiment, the balloon is provided with a thin electrically conductive layer in heat transfer relationship therewith preferably on the interior surface of the balloon. Electrical power at radio frequencies is preferred and a coaxial cable is employed to deliver such power to a conductive layer for heating the balloon. In another embodiment, the ballon itself is formed of electrically conductive material. A perfusion lumen may be provided through the balloon with one or more proximal inlet ports and one or more distal discharge ports in fluid communication with the lumen to allow blood to pass through the balloon when it is inflated during angioplasty procedures. This faciltiates the flow of oxygenated blood distally of the catheter when the balloon is inflated thus allowing for extended balloon inflations, e.g., up to 30 minutes or more. The catheter assembly may also be employed to treat myocardial infarction by dilating thrombotic occlusions.