[Accurate diagnosis of temporary myocardial ischemia by noninvasive regional wall motion analysis].

Abstract

Exercise ECG testing is the most popular method clinically detecting temporary myocardial ischemia, but both false-positive and false-negative results are reported. Detection of regional myocardial dysfunction during exercise using radionuclide angiocardiography or echocardiography has recently been developed to detect temporary myocardial ischemia in patients with coronary artery disease. In patients having chest pain and ECG changes during exercise, most of whom have coronary stenosis arteriographically, exercise radionuclide angiocardiography revealed an increased number of abnormal regional motion walls, an aggravation of asynergy by point scoring system, and a decrease of left ventricular ejection fraction (EF). In most of patients without coronary stenosis, on the other hand, no asynergy with increase of EF was observed. For detecting temporary myocardial ischemia, abnormal exercise radionuclide angiocardiography seemed rather sensitive than exercise 201-T1 myocardial imaging abnormality. During exercise, the regional wall motion abnormality was detected earlier by echocardiography than by electrical abnormality. In the cases, in which ST segment elevated during exercise, EF measured by radionuclide angiocardiography decreased remarkably, suggesting severe myocardial ischemia. In many of those, however, T waves were negative at rest and became positive during exercise, and EF increased, suggesting the other mechanism than myocardial ischemia. The success rate of exercise radionuclide angiocardiography was high. This method was useful not only in localizing abnormal wall motion but in obtaining reliable EF, though it is such an expensive device that it can be set only in the limited institutions. A major difficulty with standard M-mode echocardiography is in its "ice-pick" view, which may be compensated by 2-dimensional technique. Echocardiography can be used to detect the time course of the influence of myocardial ischemia. For evaluating temporary myocardial ischemia, examinations of regional wall motion abnormality is useful, because of high specificity, high sensitivity, localizing and grading the ischemia, and new interpretation of the findings of other examinations such as exercise ECG.