Assessment by radionuclide ventriculography of postischemic regional left ventricular dysfunction in patients with healed myocardial infarction or angina pectoris

Abstract

Postischemic left ventricular (LV) dysfunction has been observed in experimental animal models after brief, complete coronary artery occlusion followed by reperfusion, but less relevant information is available for humans. The incidence and duration of postischemic LV dysfunction was examined by exercise radionuclide ventriculography in 50 patients with coronary artery disease. Cardiac imaging was performed at rest and was repeated during exercise and then immediately after and 5, 10, and 20 minutes after exercise. LV regional wall motion abnormalities were noted in 50 segments during exercise; they persisted in 30 of 50 segments after exercise, and remained apparent for 20 minutes in 11 segments. In contrast, in 33 segments, wall motion abnormalities were noted only after exercise and continued for 20 minutes in 13 of 33 segments. Exercise-related wall motion abnormalities were observed in 63 segments (76%) after exercise, and in 24 of 63 segments abnormalities continued for 20 minutes after exercise, although parameters of LV hemodynamic functions approached normal values after exercise. The mechanism of postexercise dysfunction is considered to involve acute myocardial stunning after a brief episode of myocardial ischemia, whereas regional wall motion abnormalities observed only after exercise seem to be related to increased levels of catecholamines or sympathetic overdrive, which mask less significant myocardial ischemia during exercise.