The goal of coronary artery bypass surgery is to get more blood around narrowings and blockages in the coronary arteries. This will provide the heart with more oxygen and nutrients and decrease ischemia. Surgeons accomplish this by removing blood vessels from one part of the body and reattaching them to the heart, constructing new pathways for blood to get around the blockages in the native arteries. Successful completion and recovery from bypass surgery will relieve patients of their angina symptoms, decrease risk of a heart attack, decrease shortness of breath and congestive heart failure, decrease fatigue, and in some cases increase survival.
Coronary bypass surgery is performed under general anesthesia, so patients are completely asleep. After administration of the anesthetic the heart is exposed by dividing the sternum (breast bone). The blood vessels to be used for bypass; the saphenous vein, radial artery, internal thoracic artery are removed and prepared for use. Patients are then placed on the heart lung machine. The heart lung machine does the work of the heart and lungs while surgeons operate on the heart. The heart is stopped and surgeons attach the new blood vessels to arteries on the heart beyond the blockages using fine sutures. The other end of the grafts are attached to another vessel in the chest (aorta) or to the internal thoracic artery to provide a new source for blood flow into the heart. Once the bypasses are finished the heart is allowed to restart and patients are taken off the heart lung machine. Following closure of all incisions patients are take to intensive care unit for recovery.
Conduits (Blood vessels) for Coronary Artery Bypass Surgery
Internal Thoracic Artery (ITA): Also known as the internal mammary artery (IMA). These vessels are found on each side of the sternum. Most commonly the left ITA is used for bypassing the left anterior descending artery. Once dissected from the chest wall the left ITA (LITA or LIMA), is detached at its distal end to be used for bypass. The proximal end is left in its natural anatomic position.
Saphenous Vein: The saphenous vein is located in the leg. The vein is found superficially, under the skin. Because we have a second and larger vein deep in the leg musculature to provide for blood return to the heart, the saphenous vein can be utilized without many adverse affects. The veins are removed using either an open or endoscopic technique. In the open technique, a long or multiple incisions are made in the leg and the vein dissected out using direct visualization. In the endoscopic technique, a small incision is made near the knee, and a telescope and video visualization is used to dissect the vein. Endoscopic vein harvest results in more patient comfort with a lower risk of infection and less swelling in the extremity. The saphenous vein grafts once removed are attached proximally to the aorta and distally to the coronary artery.
Radial Artery: The radial artery is located in the forearm. It is the artery felt when a pulse is taken in the wrist. The radial artery is often attached to the left ITA or aorta proximally and distally to the coronary artery.
Coronary artery bypass can be performed with either venous or arterial conduits. However, over time saphenous vein grafts tend to develop the same type of atherosclerotic changes which are present in the native arteries. Because of this surgeons have turned to using arterial grafts for as many bypasses as possible. The left ITA is the most commonly used arterial graft. It is commonly used to bypass the left anterior descending artery. Use of an arterial graft for this specific bypass has been found to give the best long term result with patency rates approaching 95% at 10-15 years. The radial artery or right ITA can be used to bypass other arteries. Often they are attached to left ITA to make a T shaped graft (T-graft). This technique enables surgeons to perform a complete arterial revascularization of the heart. Extensive use of arterial revascularization has been associated with a decrease risk of further intervention as compared to vein grafts or percutaneous intervention. The greatest benefit is in younger patients. Surgeons for Albany Cardiothoracic Surgeons have extensive experience in using arterial grafts. Almost 99% of patients receive one arterial grafts and 40-50% receive more than one arterial graft.
Transmyocardial Laser Revascularization (TMR)
Transmyocardial laser revascularization is a procedure where a carbon dioxide laser is used to drill small channels into the heart muscle. With time these channels allow more blood to reach the heart muscle and can decrease angina. TMR is useful when the blood vessels are too small or badly diseased to be bypassed. It is often used in addition to bypass but can performed without bypass grafts. The best results with TMR are obtained when it used in patients with good heart muscle function, who are having angina, and don’t have blood vessels which can be bypassed.
Off Pump Bypass Surgery
Conventional surgery for coronary artery disease has utilized the heart lung machine (cardiopulmonary bypass). This has allowed surgeons to perform surgery on the heart in a still and bloodless field. Newer advances in surgical devices have allowed surgeons to perform surgery without the use of cardiopulmonary bypass (off pump or beating heart surgery). Although many advantages of off pump surgery have been proposed, large studies have not been shown it to be more advantageous.