What is coronary artery disease?

Like any pump the heart needs energy to do its job of pumping blood around the body. The heart receives its energy through 3 coronary arteries which lie around it. These arteries supply the oxygen and glucose that the heart needs to pump. If these arteries become narrowed the heart muscle beyond the area of narrowing becomes starved of blood and oxygen when the heart works harder this causes impairment of the heart function and chest pain. This pain is called Angina

Narrowing of the coronary arteries is like a pipe being “furred up” and it is caused by atheroma (atherosclerosis). This is comprised of fatty deposits (plaques) which develop on the inner lining of the arteries. These plaques are made up of cholesterol, vascular smooth muscle cells and inflammatory cells.

	Artery narrowed by cholesterol containg atheroma.  Note how the tube which the blood flows through has been   narrowed and restricted.

Risk factors for atheroma include smoking, high blood pressure, high cholesterol levels and diabetes

Incidence and mortality:

The British Heart Foundation estimates that there are 1.5 million men in the UK with coronary heart disease (who either have angina or have had a heart attack) and 1.15 million women. There has been a marked reduction in cardiovascular deaths over the last ten years — the male death rate has fallen from 393 per 100,000 in 1990 to 226 per 100,000 in 2000, and female deaths from 145 per 100,000 to 78 per 100,000.

Coronary heart disease can manifest itself in several ways.

Angina:

Narrowed coronary arteries may not cause problems at rest, but if the heart works harder than normal during exercise, the coronary arteries may be unable to keep up with the increased demand for oxygen, leading to pain in the chest (angina). This usually feels like a heaviness or tightness in the centre of the chest, which may spread to the arms, neck, jaw, back or stomach. It is also often associated with shortness of breath. Symptoms generally resolve when the demand for oxygen is reduced by resting and the pain resolves.

Unstable angina:

Because atheroma disrupts the smooth lining of the arteries, cracks and breaks can occur. If this happens blood platelets may stick to the surface and form blood clots. These clots may narrow the leading to a sudden deterioration in blood flow and pain in the chest occurring at rest without provocation (unstable angina). This is a sign of critical disease and it usually requires urgent medical attention or the artery will block completely causing a heart attack.

Heart attack:

Also known as myocardial infarction (MI). When atheromatous plaques crack and blood platelets form blood clots the artery may block completely. Unless these clots are removed the area of heart muscle beyond the blockage will die as a result of oxygen deprivation. This is a heart attack. In a heart attack the pain can be similar to angina but is usually more severe and does not go away with rest or administration of GTN. It may also be accompanied by sweating, light headedness, nausea or shortness of breath.

	Once the surface of the vessel is damaged, platelet clot accumulates restricting flow.  This may resolve or worsen
	Platelets may accumulate so that blood flow is limited by the clot and this causes starvation of oxygen death of muscle and a heart attack.

Diagnosis:

The first step is to take a history of the symptom of chest pain. Pain caused by narrowed coronary arteries causes characteristic symptoms in many patients and a clear history and an electrocardiogram (ECG) may be all that is necessary to make a diagnosis.
An electrocardiogram (ECG). Every time the heart beats it causes natural electrical changes which can be picked up by electrodes placed at various points around the body. The tracing records the heart rate and rhythm and whether the muscle is conducting electricity normally. It will also pick up signs of damaged muscle or muscle that is short of oxygen.
When the ECG is normal at rest, an exercise ECG may be helpful. Exercising on a treadmill increases the work of the heart and may reveal angina. If treadmill exercise produces pain and typical changes in the ECG, it confirms the diagnosis of angina.

Next >                                     Back to top of Page