Electrolyte Alterations in Acute Myocardial Ischemic Injury

The electrolyte shifts occurring in myocardial cells irreversibly injured by ischemia were compared in two groups of dogs; one given 40 minutes of transient ischemia followed by 20, 50, 80, and 200 minutes of restored coronary arterial flow and the other 30, 60, 90, 130, and 240 minutes of permanent ischemia. Each interval of restored arterial flow in the transient ischemia group was associated with marked changes in the electrolyte content of the injured myocardium. Sodium, chloride, and water were increased and potassium and phosphorus were decreased. These changes occurred much more quickly in dogs exposed to transient ischemia than in dogs with comparable periods of permanent ischemia. These data indicate that objective chemical evidence of the death of myocardial cells develops slowly in areas of permanent ischemia primarily because of the reduced flow of blood through the ischemic injured tissue.