Noninvasive estimation of coronary flow reserve by transthoracic Doppler echocardiography with a high-frequency transducer.

Recent technological advances in transthoracic Doppler echocardiography (TTDE) provide visualization of the coronary blood flow signal and noninvasive analysis of coronary flow reserve with a high frequency transducer. Coronary flow velocity and coronary flow reserve measured by TTDE were compared with those measured by a Doppler guide wire. Values of mean coronary flow velocity and coronary flow reserve measured by TTDE were closely correlated with values measured by the invasive Doppler guide wire (r = 0.97, y = 0.94x + 0.40; r = 0.94, y = 0.95x + 0.21, respectively). This noninvasive technique was applied to patients who underwent coronary angiography to evaluate coronary artery disease. There was a significant difference in coronary flow reserve measured by TTDE between patients with and without significant left anterior descending coronary artery stenosis (% diameter stenosis > 70%) (1.5 +/- 0.2 vs 2.6 +/- 0.4, p < 0.001). Coronary flow reserve < 2.0 obtained by TTDE had a high sensitivity (92%) and a high specificity (86%) for the presence of significant left anterior descending coronary artery stenosis. TTDE with a high-frequency transducer can be applied to noninvasive estimation of coronary flow reserve in the clinical setting, and is useful in noninvasive diagnosis of significant coronary stenosis in patients with coronary artery disease.