Definition of Flow Parameters in Proximal Nonstenotic Coronary Arteries Using Transesophageal Doppler Echocardiography

Transesophageal echocardiography (TEE) enables the visualization of proximal coronary arteries. We investigated the feasibility of coronary flow evaluation using TEE, as well as to define flow parameters found in normal proximal coronary arteries. The subgroups of patients with normal proximal segments of coronary arteries were selected from the cohort of 210 patients undergoing routine coronary angiography. The left main coronary artery (LMCA), proximal segment of left anterior descending coronary artery (LAD), left circumflex artery (LCx), and right coronary artery (RCA) were analyzed separately in 147, 64, 53, and 70 patients, respectively. Proximal coronary arteries were evaluated in the transverse plane using a 5-MHz TEE probe, and the flow in normal arteries was registered using pulsed-wave Doppler. The registration of flow with pulsed-wave Doppler was feasible in 88% of studies for the LMCA, 85% for the LAD, 58% for the LCx, and 65% for the RCA. Normal flow was laminar with distinct phasic character (diastolic predominance). Mean +/- SD values of peak coronary flow velocity were (systole/diastole) for the LMCA, 36 +/- 11/71 +/- 19 cm/sec; the LAD, 31 +/- 9/67 +/- 19 cm/sec; the LCx, 36 +/- 13/75 +/- 24 cm/sec; and the RCA, 25 +/- 8/39 +/- 12 cm/sec. Peak diastolic coronary flow velocity was most significantly correlated with heart rate. Doppler evaluation of proximal coronary flow is feasible using TEE in the majority of patients. The knowledge of normal flow values, which is different for the left and the right coronary artery, provides the background for proper interpretation of flow in diseased coronary arteries.