Transesophageal doppler echocardiography evaluation of coronary blood flow velocity in baseline conditions and during dipyridamole-induced coronary vasodilation

Abstract

Transesophageal echocardiography allows the evaluation of proximal coronary artery anatomy and coronary blood flow velocity (CBFV). To assess the potential of transesophageal echocardiography in evaluating CBFV and its variations induced by coronary-active drugs, we studied 15 patients by high-quality pulsed wave Doppler recordings of CBFV. In these patients, transesophageal Doppler evaluation of CBFV was performed before, 2 minutes after cessation of dipyridamole infusion (0.56 mg/kg in 4 minutes), and 2 minutes after aminophylline infusion (240 mg injected 4 minutes after cessation of dipyridamole infusion). The following CBFV parameters were evaluated at each of the three steps of the study protocol: maximal and mean diastolic velocities and maximal and mean systolic velocities. Furthermore, the following indexes of coronary flow reserve were evaluated: the ratio between maximal diastolic velocity recorded after and before dipyridamole administration and the ratio between mean diastolic velocity recorded after and before dipyridamole administration. Nine of the 15 patients had a normal left anterior descending coronary artery (group A), whereas the remaining six had significant (≥75%) stenosis (group B). In group A patients, all CBFV parameters increased significantly during dipyridamole infusion and returned to near baseline values after aminophylline infusion. In group B patients, on the other hand, none of the CBFV parameters increased after dipyridamole infusion. Dipyridamole/baseline maximal diastolic velocity and mean diastolic velocity ratios were, respectively, 3.22±0.96 and 3.04±0.88 in group A and 1.46±0.45 (p<0.01 versus group A) and 1.48±0.49 (p<0.01 versus group A) in group B patients. We conclude that transesophageal Doppler echocardiography evaluation of CBFV is feasible and makes possible the evaluation of the changes induced by coronary-active drugs. This new approach has potential in assessing coronary blood flow reserve.