The heart, although one of the most important organs in the body, is simply a muscular pump. It pumps blood containing oxygen and other essential nutrients throughout the body and delivers waste products to the kidneys and lungs. For the heart pump to function normally it requires its own blood supply (through the three coronary arteries) and a regular and reliable heart beat (through its own electrical circuitry). Problems with the heart muscle, its blood supply through the coronary arteries and with its electrical regulation cause symptoms such as breathlessness, chest pain, palpitations, dizzy spells and blackouts.