The heart is a unique organ in our body. It pumps blood to all parts of body untiringly and continuously. Do you know how the heart gets its energy? Not from the blood in its cavities but from special blood vessels which penetrate into its muscles and are called coronary arteries. As it beats regularly it has to repair the wear and tear while in action! Another peculiarity is that coronary arteries are more prone to narrowing and blockage by atherosclerosis, a process of deposition of fatty material which gets, hardened gradually. The resulting occlusion impairs the blood supply to heart muscle, a condition called ischaemia (thirst amongst plenty!). When occlusion is complete ischaemic necrosis (cell death) results and a clinical entity called acute myocardial infarction (heart attack) occurs. A condition in-between these two is called 'intermediate syndrome'.



Depending on the extent of occlusion there may be chest pain on working and exertion (stable or exertional angina pectoris) which gets relieved on rest, or increasingly severe chest pain on minimal exertion (unstable angina) or prolonged chest pain with sweating and marked ECG changes (acute myocardial infarction). Occasionally, a person may be without chest pain and only on routine angiography, narrowing is detected. In rare cases sudden death may be the first (and last!) manifestation of the disease called coronary artery disease (CAD) or ischaemic heart disease (IHD).

In one form of angina pectoris (IHD) the patient experiences heaviness, pressure, tightness, or a squeezing type of pain in the chest lasting for a few minutes, and is relieved by nitroglycerin table placed under tongue. In the second form, the chest pain which is of an extremely severe squeezing or crushing type, often lasting for long periods, and associated with nausea, vomiting, giddiness, and sweating may be due to myocardial infarction. Although the pain in the chest and dificiency of oxygen supply are features common to both conditions, the pain in angina pectoris appears to be due to the narrowing or loss of elasticity in the coronary arteries, whereas in myocardial infarction, there is obstruction of the blood supply to segment of heart muscle, leading to necrosis. Due to these differences, the treatment of these two conditions varies considerably and will be discussed

separately.

A heart attack, characterized by a severe pain in the chest, is due to sudden cutting off of the oxygen supply to the heart muscle. Heart failure leads to impaired pumping capacity of the heart, which may or may not be related to lack of oxygen supply.

Causes of Coronary Artery Disease (Ischaemic Heart Disease): Atherosclerosis is the most common cause. It starts at an early age and progresses with age. For this reason the incidence of heart attacks is greater during the 50s or later years. There are various factors which may enhance the process of atherosclerosis, such as a fatty and high caloric diet, lack of physical activity, obesity, cigarette smoking and diabetes.

A study on Japanese immigrants in the US found that the incidence of heart attack among them was significantly higher than those living in Japan, indicating that the change in food habits - eating plenty of rich foods - was the main cause of higher incidence. A similar survey was done on Indians who had migrated to Singapore. It was found that the incidence was eight times more than those who stayed behind. The reasons were the same. It is, therefore, very necessary for patients of heart attack to exercise control over diet and eat food which is low in fat and calories. Cigarette smoking has also been linked to increase

incidence of heart attacks. Smoking should be forbidden for a heart patient unless it is feared that abstaining is likely to cause dangerous psychological disturbances. In such cases the patient is generally advised to cut down smoking as far as possible. The high cholesterol content in the blood can also lead to heart attack. There are two kinds of cholesterol: low density cholesterol (LDL-C) is bad, while high density cholesterol (HDL-C) is good. If the ratio of LDL vs HDL is higher than normal, the chances of a heart attack are more.