Translate the following two sentences Patients with severe cases of CAD may be candidates for angioplasty, surgical dilatation of the blocked vessel by means of a catheter, technically called percutaneous transluminal coronary angioplasty (PTCA). In this procedure, known as a coronary artery bypass graft (CABG) 冠状动脉旁路移植术 , another vessel or a piece of another vessel, usually the saphenous vein of the leg or the left internal mammary artery, is used to carry blood from the aorta to a point past the obstruction in a coronary vessel.