Noninvasive visualization of the left main coronary artery by cross-sectional echocardiography.

Real time cross-sectional echocardiographic studies of the left main coronary artery (LMCA) were performed in 15 normal patients, 15 patients with angiographically proven coronary artery disease but normal left main coronary segments, three patients with greater than 75% obstruction of the left main coronary artery, and one patient with a larger aneurysm of the left main coronary artery. In normal subjects the LMCA evaginates from in inferolateral wall of the aorta. The artery appears as two dominant parallel linear echoes separated by a clear space representing the lumen of the vessel. The LMCA courses beneath the right ventricular outflow tract and can generally be followed to its expected point of bifurcation. Confirmation that this structure was in fact the LMCA was obtained by injection of cardiogreen dye directly into the LMCA in two cases and by visualization of dye in this structure following aortic flush in one case. In the three cases with obstructive lesions of the LMCA, there was an area of inward bending of the parallel vessel wall echoes resulting in varying degrees of narrowing of the arterial lumen. In the case with the aneurysmal dilatation of the LMCA, an echo-free circular bulge in the distal portion of the LMCA was recorded. This study demonstrates the fesibility of recording the left main coronary artery using the cross-sectional echocardiographic technique.