The Heart muscle or Myocardium is supplied by a number of medium sized arteries that take oxygen-bearing blood to the working muscle. These vessels are known as the Coronary Arteries. Various abnormalities may cause narrowing of the vessels sufficient to reduce the blood flow to the point at which, symptoms develop. Referred to as coronary artery diseases, these abnormal conditions then give rise to Ischemic Heart Disease.

There are two basic types.

• In one type, the blood flow may be reduced to a level at which the oxygen demands of the working muscle exceed the available supply. The set of symptoms that most commonly arise in this situation is called angina.
• In the other type, the blood flow may be practically entirely blocked off by a clot or Thrombus forming in the vessel. In this case, the segment of the myocardium, which is supplied by this particular vessel, dies from lack of blood supply. The consequence is more serious and often catastrophic. This is an Acute Myocardial Infarction, and is generally what is meant by the term “Heart Attack”.