The present invention is directed to a procedure and a special balloon used in balloon angioplasty and stent installation in percutaneous transluminal coronary angioplasty (PTCA), which employs a heart catheter with a balloon at its distal end. After being inflated, the balloon is in doughnut shape with a hole in the center; its length is made to fit the length of the stent to be inflated. During an angioplasty procedure, the balloon is pushed forward into the stenosis and inflated with a device to dilate the blockage. The doughnut_shaped balloon provides a pass way for blood to flow through the coronary artery vessel, which does not cause angina akin to a heart attack resulted from traditional tube_shaped balloons used in the PTCA procedure that completely block blood flow after being fully inflated during balloon angioplasty and stent installation.