Dr Chris answers a query from John in Glasgow about heart attacks. What is a Heart Attack? A heart attack is the sudden death of part of the heart muscle. This is usually caused by the blockage of vital blood supply to the heart by a clot of blood, ot thrombosis, in one of the coronary ateries. This is known as a `coronary thrombosis', often shortened to `a coronary'! The heart muscle is called the myocardium and the resultant death of this tissue following a coronary thrombosis is medically termed a `myocardial infarction'. Doctors in fact use either of these terms to describe a heart attack. Would you believe it? The heart pumps 1 gallon of blood every minute. That's equivalent to 8 tons of blood a day! Your heart started beating 7 months before you were born and will continue to do so without rest until the day you die!