Echocardiography in the study of myocardial ischemia in man: the clinical model of Prinzmetal's angina.

Standard echocardiography was employed to study the clinical model of myocardial ischemia with ST-segment elevation, well known as Prinzmetal's angina. Ultrasonic monitoring was performed during the appearance of ST-segment elevation, from onset of pain, during an ergonovine maleate test, hemodynamic monitoring, radioisotopic studies and, occasionally, during routine examinations, when spontaneous episodes occurred. Reliability of findings was supported by two important conditions: each patient acted as his own control, since recording was carried out from basal state to basal state, throughout ischemia, or from ischemia to basal state; behaviour of ischemic walls was compared with that of non-ischemic ones. Echocardiographic findings in acute myocardial ischemia were similar both in spontaneous and in induced episodes and were mainly characterized by: decrease in contractility indices of the ischemic segment, such as wall motion and percent systolic thickening; increase in left ventricular end-systolic and end-diastolic diameter, with a decrease in percent fractional shortening; distorted shape of ventricular cavity, transiently deformed as in a "functional" aneurysm; a sharp demarcation between ischemic and non-ischemic adjacent segment, "step sign", was present only in severe cases. Taking ST-segment elevation as a reference the time sequence of events was studied, correlating mechanical, electric and clinical markers of ischemia. At least three different echocardiographic phases were identified in the evolution of ischemic attacks: Pre-electrocardiographic phase, when mechanical impairment is detected by ultrasounds in the absence of both ST-segment changes and pain; Electrocardiographic phase, when echocardiographic signs of ischemia co-exist with obvious electrocardiographic sign