As featured in the Daily Local News

June 18, 2007

Alan D. Troy, MD, FACC, FSCAI

The heart pumps blood to the entire body. To do so, the heart receives fuel and oxygen from the flow of blood through its own circulation, called the coronary arteries. Of the blood it pumps, the heart takes five percent for itself through the coronary circulation.

The coronary arteries are susceptible to cholesterol plaque formation, which can narrow the artery and obstruct blood flow. Smoking, high blood pressure, advanced age, diabetes, diet, high cholesterol and genetics play major roles in the development of plaques. These causes of plaque are called “risk factors” for coronary and vascular (blood vessel) disease.

When physical activity demands greater cardiac output of blood to the body’s muscles, a coronary narrowing can prevent the necessary increase in the coronary blood flow to that artery’s particular region of the heart. For this reason, a person can experience chest discomfort (angina pectoris). Generally, stable angina pectoris is a condition that can often be managed with medications that improve circulation, minimize cardiac work, and limit cholesterol plaque progression.

A coronary arterial plaque can release its contents due to the same risk factors that cause plaque formation. When this occurs, a clot (thrombus) can form atop the plaque. The result can be complete or near occlusion of the artery, resulting in chest discomfort that does not easily subside. A near-total occlusion often manifests as “unstable angina” or as a very small injury (sometimes called a “mild” heart attack) to the heart. When the occlusion is complete and fairly abrupt a “major heart attack” -- with major damage — is a potential consequence, and the pain is much worse. Such heart attacks show on an EKG.

When medications fail to relieve stable angina or the vessels involved affect a large portion of the heart, the coronary artery narrowing should be addressed with a mechanical solution (“revascularization”) to improve the flow of blood. Stent placement, positioning a sleeve-like metallic scaffold to expand the arterial narrowing, is another option. Performing bypass surgery can create a passage around the narrowing. Using these techniques, chest symptoms are promptly relieved and the dangers of death and heart attack can be reduced.

With unstable angina or heart attack, the situation is more immediately life-threatening, and urgent revascularization can reduce damage to the heart and improve survival. The less damaged the heart, the better the long-term survival.

Generally, bypass surgery serves well in situations of multiple, severe narrowings, narrowing of the “left main” — a big, major artery — and when valvular abnormalities require repair. Severe narrowing of multiple coronary arteries in diabetics is a situation that is often best treated with bypass surgery.

Coronary stenting has become popular for less complex cases because of reduced recovery time and, in some cases, reduced procedural risk.

May 30, 2007