Everything you need to know about heart attacks

The actively contracting heart muscle needs a constant supply of oxygen and nutrients to function. They are delivered by blood vessels known as coronary arteries. Over the course of one’s lifetime, the inner lining of these arteries, normally smooth, can slowly become clogged with clumps of fats, cholesterol, and other materials called atherosclerotic plaques. This is also known as hardening or narrowing of the arteries. The inner walls of the coronary arteries become narrow slowly because of buildup of these plaques or can suddenly occlude by a rupture of a plaque and the formation of a blood clot, a process called coronary thrombosis or heart attack.

As a result, the supply of blood going to the heart muscle is choked off (myocardial ischaemia). Chest pain (angina pectoris) occurs when the oxygen demand of the heart muscle exceeds the oxygen supply because of the narrowed or occluded coronary arteries. When the supply of oxygen continues to be inadequate, heart muscle cells can begin to die, causing a heart attack (myocardial infarction). This may occur without symptoms (silent heart attack), especially in people with diabetes.

In addition, the lack of blood to the heart can lead to serious disorders of the heart rhythm, known as arrhythmias or dysrhythmias, and can cause sudden death. The heart is especially vulnerable to this rhythm disorder within 24 hours of a heart attack. More commonly, the death of the heart muscles can lead to congestive heart failure, a condition when the body starts to retain water and the other parts of the body are not well supplied with oxygen due to a failing heart.

(Dr. Charles Chan is a senior consultant cardiologist at Gleneagles Medical Centre of Singapore. He shed light on one of the leading causes of death in the region in his talk "Everything You Want to Know About Heart Attack," which he delivered at the recent Reader’s Digest Forum.)