How Transmyocardial Revascularization Surgery Is Done (3D Animation) Transmyocardial revascularization (TMR) is a surgical procedure used to treat severe angina when coronary arteries cannot be treated with bypass or stents. During the operation, the surgeon exposes the heart through a chest incision. A specialized laser device is used to create small channels directly into the heart muscle (myocardium). These channels are believed to improve blood flow to oxygen-starved areas of the heart and m