During a heart attack the cells that make up the muscle of the heart are subjected to a restricted blood supply, this is usually caused by a blood clot or a narrowing of the coronary arteries. If the blood supply is not restored quickly it will result in the death of the heart muscle, and to protect against this injury, blood clot prevention drugs, inflating balloons and artery bypass surgery are all used to restore blood flow as quickly as possible. Paradoxically, however, the very act of restoring such blood flow can also cause a significant amount of heart cells to die. In this lecture, Professor Yellon will discuss why this injury occurs, how simple techniques such as inflating a blood pressure cuff on the arm can protect the heart against such injury, and how developments in UCL’s laboratories are already benefiting patients at risk.