Abstract: While performing cardiopulmonary bypass, the aorta is cross-clamped and the beating heart is stopped by introducing of an ATP-dependent potassium channel opening agent. The infusion into the coronary circulation shortens the cardiac action potential thereby arresting the heart muscle at a hyperpolarized membrane potential. This maintains the heart in a state of minimal metabolic requirement, thereby preserving transmembrane ionic gradients, intercellular energy stores and cellular integrity. Cardiac arrest is reversed simply by flushing the heart by the coronary circulation upon removal of the aortic cross-clamp. This use is also germane to organ preservation during transport for transplantation. For example, the donor heart is arrested using an ATP-dependent potassium channel opening agent, it is then removed and transported to the recipient and transplanted. Cardiac arrest is reversed by reperfusing the orthotropic graft.