Maintaining Your Health on Mackinac
Lifestyle Changes, Medications Help Coronary Artery Disease Patients
By Yvan Silva, M.D.

The heart is supplied by two arteries, the right and left coronary arteries, that arise in the root of the aorta, the large trunk that brings blood to the whole body. Coronary artery disease, similar to arterial disease elsewhere in the body, results from arteriosclerosis, the so-called "hardening" of the arterial system. This disease leads to narrowing of the arteries, as well as damage to the lining, which can also lead to clotting within the arteries. Narrowing and clotting are the major factors that lead to heart attacks. As blood flow to affected areas of the heart is reduced, depriving the heart muscle of sufficient oxygen, symptoms ensue - chest pain or pressure (angina) - especially during periods of physical exertion or stress, when areas of the heart muscle are threatened. If a coronary artery becomes totally clogged, acutely, by a blood clot, a heart attack can result. Survival is determined by the amount of muscle affected. In a massive heart attack, the pumping activity of the heart fails, leading to death.

In the 1970s, following the development of radiographic techniques enabling arteriography (injection of radio-opaque dye into the coronaries to delineate the degree of narrowing), surgical techniques were developed to supply sufficient blood to the heart. The first was coronary artery bypass graft surgery. Here the chest was opened, the heart exposed, and blood was routed by grafts from the aorta beyond the narrowed or blocked arterial areas to bring sufficient blood to maintain normal heart action. Blood vessels, segments of veins or arteries, were harvested from elsewhere in the body and sutured to provide these bypasses, the number depending on the number and location of the blockages. Synthetic tubular graft materials were also developed for this application.

We now live in the era of minimal surgery, with new and developing surgical techniques in various parts of the body. For coronary artery disease, minimal surgery was introduced in the late 1980s, initially with a method termed coronary angioplasty. In this technique, a tube is introduced into the coronary artery via a puncture in the femoral artery in the groin, under X-ray guidance. After localization of the narrowed segment, a tiny, deflated balloon at the tip of the tube is inflated in the narrowed area to stretch open the diseased segment of the artery and re-establish optimal blood flow. Balloon angioplasty rapidly became a very popular alternative to open heart surgery for bypass. It was successful in the short term, but over a period of six months or so, in about 30% to 40% of patients, the expanded areas would narrow again; restenosis would ensue.

This led to further innovation. Tiny, expandable mesh tube devices, or stents, were designed to be implanted into the narrowed coronary artery segments and prop open these clogged arteries. By the mid- 1990s, the Food and Drug Administration approved the use of stents, which are expanded into place by balloon angioplasty and left within the artery to keep it open and prevent restenosis. The first stents used were bare metal. After implantation, tissue healing in the narrowed segment helped keep them in place, smoothing over the metal. In the process, over a period of time, some 10% to 15% of these stents were affected by excessive tissue growth and restenosis ensued. Repeat angioplasty often became necessary.

This problem of restenosis has been addressed by the development and use of drug-releasing (drug-eluting) stents, coated with a drug that is released over a period of 30 days, designed to inhibit inflammation and unwanted scar tissue growth. Blood thinner drugs are used over longer periods of time with drug-eluting stents, and the need for repeat angioplasty has been considerably diminished.

Coronary artery stents are among the most commonly implanted devices and are used in about one million Americans every year. The current information available suggests that less than 5% of restenosis is possible. Most physicians agree that these techniques are more desirable compared with open heart coronary bypass graft surgery.

Deciding on which procedure is indicated depends on the degree of coronary artery disease - the location, severity, and number of blockages, as well as the overall health and the ability to withstand major open heart surgery.

Generally, the minimally invasive approach works well if the blockage is not long and fewer arteries are involved, there is no heart failure, and the main artery to the left side (ventricle) of the heart is not involved. The patient must be able to take antiplatelet drugs and aspirin.

There are major studies underway that suggest that angioplasty and stent placement may not be necessary in some patients who have chronic, regular, and predictable chest pain owing to partially-blocked arteries. Lifestyle changes and medications that relieve the angina reliably may be a choice. If there is a change in the pattern of chest pain, that is, when the angina becomes unstable, intervention may be indicated, and placement of a stent may be the treatment of choice.

Angioplasty does not require general anesthesia. A major incision is not required, and in the absence of other significant risk factors, the risk of major complications such as heart attack, stroke, or death is less than 2% to 3%. Recovery time is very short, and rehabilitation can begin soon. A daily dose of aspirin, usually for life, and a powerful anti-platelet drug are usually indicated for at least one year after implantation of a drugeluting stent, or about four to six weeks for bare metal stents. Platelets are cells that clump together in the initial phases of clot formation.

In summary, there are several factors to be considered in the management of blocked or narrowed coronary arteries. Lifestyle changes conducive to heart health and drugs, often combinations of aspirin, betablockers, calcium-channel blockers, and cholesterol-lowering drugs, and careful monitoring of progress may be chosen. Angioplasty with stent placement is minimally invasive and requires blood-thinning drugs, with their potential risks, in addition to other measures to manage heart health. Finally, bypass surgery is a factor when the degree of coronary artery disease is significant and not amenable to other methods.

Dr. Silva is a professor of surgery at Wayne State University and a resident of Woodbluff on Mackinac Island.