Coronary artery disease is our number-one killer in the United States. It claims more lives than all forms of cancer combined, and it affects women more than men. To understand how we treat coronary artery disease, I'd like to first explain the condition.

The coronary arteries emerge from the aorta, the major artery that continues out of the heart and feeds oxygen-rich blood to the rest of the body. The right and left coronary arteries are responsible for feeding blood to the heart muscle itself, ensuring the heart's ability to pump.

	Ultrasound revealing artery disease.

In most patients, both arteries are located so as to deliver uninterrupted flow to all four chambers of the heart. (Some patients have congenital anomalies that locate the arteries between other major structures in the heart, where they can be compressed and cause sudden cardiac death. CT angiograms can now find these anomalies noninvasively, which helps reduce the risk of cardiac arrest for patients who have them.) Given normal anatomy, the blood flow from the coronary arteries increases with exercise to deliver as much as four to six times the normal resting levels. Cholesterol buildup or arterial sclerosis can narrow the arterial opening. The buildup of material may directly obstruct flow, while the artery itself may malfunction due to an unhealthy arterial lining, prohibiting the artery from dilating appropriately. Initially the buildup may weaken the wall causing expansion locally without a decrease in blood flow.