Products of myocardial ischemia and electrical instability of the heart.

Products of ischemic metabolism can make a major contribution to electrical instability of the heart. In particular, enhanced extracellular potassium slows conduction, thereby predisposing to reentrant circuits, especially when levels of cyclic adenosine monophosphate (AMP) increase in the early ischemic period. Other products (lactate, lipid metabolites) alter the duration of the action potential. Accumulated calcium may induce inward diastolic currents.