Pioneered in the 1960's by Dr. Rene Favaloro, then of the Cleveland Clinic, coronary bypass surgery for the relief of angina pectoris became a readily accepted form of therapy in the mid-1970's, and today is routinely and safely performed in cardiovascular centers and many community hospitals around the world.
Many scientific studies, both randomized and non-randomized, have clearly shown that the benefits of bypass surgery become most apparent in the sickest and highest risk patients. Bypass surgery reduces mortality rates in patients with critical blockages of the Left Main coronary artery and also in patients with blockages in two or three of the major coronary arteries when underlying heart damage is already present. Bypass surgery has also been shown to reduce the pain of angina pectoris better and more reliably than standard anti-anginal medications.
Generalizations about the success rate of bypass surgery can only be used as guides to the recommendation for treatment in any one individual. Case by case decision making requires an intimate knowledge of an individual patients specific heart status including the precise character of the patients coronary arteries, the strength of the heart itself, separate but co-existing heart valve malfunction, and co-morbid illnesses (lung disease, diabetes mellitus, hypertension, stroke, kidney disease, etc.).
Operative mortality rates (defined as the risk of death within the first 30 days after surgery) may be highly variable, both from operating institution to institution, from surgical team to surgical team, and especially between varying subgroups of patients. Average quoted mortality rates of between 1% to 3.5% are common, but can be misleading to an individual or his/her family. At any one institution, mortality rates are typically worse for patients with underlying prior heart muscle damage (a prior heart attack), advanced age, prior, long-standing and poorly controlled hypertension, and/or diabetes mellitus. In most studies, female surgical bypass mortality rates are higher than those found in men.
It is important to understand that bypass surgery does not in any way alter the natural history of atherosclerosis ("hardening of the arteries"). Once an individual has been identified as having severe coronary artery blockages, and once bypass surgery has been successfully performed, it is mandatory that the individual, with the help of his/her physician, aggressively attacks the recognized risk factors of this insidious disease.
Eventually however, this disease may progress. If a vein bypass has remained open in its first 4-12 months, it will probably remain open for the next 5-7 years. After that time vein bypasses may start to degenerate and develop narrowings. By 10-12 years, as many as 50%-60% of vein bypasses will have closed and half of the still patent vein grafts will have evidence of severe atherosclerotic narrowing.
Not all bypasses are performed using saphenous (leg) veins. When feasible, most heart surgeons today will attempt to utilize the internal mammary artery, and artery located along either inside edge of the breastbone, for one or several bypasses. This vessel has the benefit of being nearly the same size as a coronary artery and has a much better long term patency rate (nearly 90% patent at 10 years) than a vein bypass.
A variety of new and promising surgical techniques are presently undergoing investigation and evolution. Whereas traditional bypass surgery requires stopping the heart's pumping action and placing the patient on a heart-lung bypass apparatus, new technology is being refined that allows the heart surgeon to attach a bypass to a blocked artery while the heart is still beating, thus avoiding the rigors imposed on the body by the heart-lung pump. Still other developing techniques are allowing the heart surgeon to perform several bypasses through a smaller chest incision, which may further shorten the patient's post-operative hospital length-of-stay.
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