Detection of coronary blood flow associated with left main coronary artery stenosis by transesophageal Doppler color flow echocardiography. Demonstration of disordered blood flow in a coronary artery may be helpful in anticipating the presence of stenosis. To examine the possibility of disordered coronary blood flow associated with left main coronary stenosis, left main coronary flow was visualized by transesophageal Doppler color flow echocardiography in 52 patients undergoing coronary angiography. Twenty patients had significant left main coronary stenosis (Group 1) and 32 patients did not (Group 2). Adequate two-dimensional echocardiographic images of the left main coronary artery were obtained in 17 patients in Group 1 and 30 patients in Group 2. Sixteen patients in Group 1, including five patients in whom the stenosis could not clearly be defined by two-dimensional echocardiography, exhibited the aliased reddish-yellowish elements producing the mosaic pattern at the stenotic or poststenotic segments, or both. In contrast, nonaliased bluish jets, suggesting laminar flow away from the transducer, were seen in echocardiograms from 27 patients in Group 2. This group included four patients with stenosis-like images on two-dimensional echocardiography. The aliased mosaic pattern was found in only three patients in Group 2 (p less than 0.01). Thus, sensitivity to detect the stenosis was improved when Doppler color flow imaging was applied. Flow velocity was significantly higher at the site of stenosis in patients in Group 1 (116 +/- 28 cm/s, n = 10, mean +/- SD) than in Group 2 (29 +/- 12 cm/s, n = 21, p less than 0.01), suggesting that the augmentation of flow velocity with or without turbulence due to the stenosis contributed to the appearance of the mosaic flow images. 