Background: The evaluation of the coronary flow velocity and coronary flow reserve (CFR) can provide important information on the functional significance of stenoses and of abnormalities of the coronary microcirculation. To date, the potential of echo-Doppler in the noninvasive evaluation of the coronary flow has been mainly reported for small groups of patients with stenoses of the left anterior descending coronary artery (LAD), eventually treated with percutaneous coronary angioplasty. The great majority of publications report the use of echo-Doppler together with contrast enhancement for an optimal visualization of the LAD. The aim of our study was to evaluate the feasibility of echo-Doppler examination of the LAD with a high-frequency probe and without the use of contrast enhancement.
Methods: We studied, in basal conditions, a group of 116 consecutive patients with a wide range of cardiovascular diseases. CFR was evaluated during infusion of adenosine in a subgroup of patients with a recent coronary artery bypass graft and left ventricular dysfunction (ejection fraction < 40%).
Results: The LAD was visualized in 105 out of 116 patients (90%), with no difference between the various cardiac pathologies. The mean diameter of the LAD was 1.8 +/- 0.4 mm. The peak systolic flow velocity was 16.3 +/- 6 cm/s and the peak diastolic flow velocity 28.5 +/- 10 cm/s. The mean CFR was 1.9 +/- 0.8.
Conclusions: The coronary flow of the LAD can be evaluated at transthoracic Doppler echocardiography without contrast enhancement in a wide range of cardiac pathologies. The noninvasive evaluation of the CFR with transthoracic echo-Doppler should be borne in mind during the clinical and instrumental work-up of cardiac patients.