Two-dimensional echocardiography evaluates the effect of myocardial ischemia on left ventricular wall motion, but a direct measure of coronary flow by this method is still lacking. The aim of the present study is to evaluate the efficacy of new, high-resolution ultrasound equipment designed to image by color Doppler transthoracic echocardiography the epicardial and intramural coronary vessels. We have studied 33 consecutive patients in apical projections, to detect by color Doppler > or = 1 segments of the middle-distal tract of the left anterior descending coronary artery. In 25 of 33 patients (76%), the middle-distal tract of the left anterior descending coronary artery was imaged by color Doppler. In 15 of 33 patients (46%), the periapical tract of the left anterior descending was imaged along with its perforating branches. In 2 of 4 patients who had coronary artery bypass grafting, the anastomosis between the left internal mammary artery and the left anterior descending coronary artery was imaged. Once the coronary artery was imaged, pulsed Doppler was used to measure coronary blood flow velocity at rest. Peak and mean flow velocity, as well as the deceleration time (msec) and deceleration rate (cm/sec2), were measured on the diastolic phase of the Doppler tracing. In all 25 patients, it was possible to measure by pulsed Doppler the coronary flow velocity pattern characterized by a typical prevalent diastolic component. Peak diastolic flow velocity was 50 +/- 17 cm/sec and mean diastolic flow velocity was 37 +/- 12 cm/sec. The deceleration time was 916.2 +/- 429.1 msec and the deceleration rate was 86.3 +/- 69.3 cm/sec2. The Doppler pattern of the grafted mammary artery was different from the native mammary flow. This new noninvasive imaging technique of the coronary arteries promises to expand the field of diagnostic and experimental echocardiography and brings new insight into the pathophysiology of ischemic heart disease.