Sign of Subendocardial Ischemia on Echocardiography

Abstract

A 73-year-old man with a 10-year history of hypertension had unstable angina. Because ischemic heart disease was highly suspected, he underwent echocardiography. There was no asynergy in the parasternal short axis (Figure1) and long axis views; however, in the apex 2-chamber view, asynergy was noted (Figure 2). Contrast echocardiography, performed to identify and assess the ischemic region, showed an enhancing defect in the subendocardium of the inferior wall (Figure 3). Subsequent coronary angiography revealed 90% diffuse stenosis in the hypoplastic right coronary artery, 75% to 90% diffuse stenosis in the left anterior descending branch, and 90% stenosis in the circumflex branch. On the basis of these findings, coronary artery bypass grafting was indicated. During off-pump coronary artery bypass grafting, no abnormality was observed in the left ventricular surface grossly. Transmural myocardial infarction was excluded. He was discharged after an uneventful course, and the asynergy of the inferior wall was improved after the operation. We propose that noticeable asynergy in the apex view despite the absence of asynergy in the short axis at the same segment is a sign of subendocardial ischemia that has not been reported previously. The subendocardium is the area of the myocardium initially most vulnerable to ischemic damage. Because subendocardial ischemia is a forerunner of more serious complications, early detection of a subendocardial ischemic sign is important to improve the prognosis of patients with this disease. 1 The arrangement of the myocardial fibers within the ventricular wall is complicated. Dissection shows that they can be broadly divided into 3 layers, the so-called subepicardial, middle, and subendocardial fibers. 2 The subendocardial fibers, comprising preferentially arranged longitudinal fibers arising from the vortex at the apex, mainly contribute to longitudinal contraction. A part of the subendocardial layer supports the origins of the papillary muscles.