The heart can be considered a pump and like any pump or engine it needs its own fuel supply. The heart pumps blood back itself through “fuel pipes” that run over the surface of the heart. These pipes are called the coronary arteries. If a coronary artery blocks and the fuel supply to the engine is restricted then the heart “chokes”. This usually causes chest pain or angina. If the interruption in blood supply is temporary then the heart recovers but if the obstruction is prolonged then a small part of the heart muscle dies and a heart attacks occurs.

The heart is in fact two separate pumps which work together. The right side of the heart pumps blood to the lungs and the left side of the heart pumps blood to the circulation around our bodies. The side of the heart has a thin walled "collecting chamber" called the atrium, which helps to fill the thick walled main pump, the ventricle. The heart wall is made of a special sort of muscle called the myocardium. The left and right sides of the heart are divided by a muscular wall called the septum.