Intracoronary flow velocity measurements in adjacent stenotic and normal coronary arteries during incremental intravenous dobutamine stress and intracoronary adenosine injection

To investigate the concomitant coronary flow and hemodynamic changes induced by dobutamine and adenosine in the catheterization laboratory, we studied stenotic and adjacent normal coronary arteries in 20 patients using paired Doppler Flowires. Coronary flow velocity and hemodynamics were measured sequentially after intracoronary (ic) adenosine, during incremental iv dobutamine infusion, and after the addition of ic adenosine during sustained peak dobutamine stress (adenosine on dobutamine). Distal to stenotic arteries, average peak velocity (APV) increased significantly (from 11 ± 5 to 16 ± 7 cm/sec, P < 0.001) at an intermediate dose of dobutamine (20 μg/kg/min, Dobutamine20) but did not change further thereafter to peak dobutamine stress (17 ± 7 cm/sec), despite the significant further increase in rate-pressure product (RPP). Peak stress APV did not change with adenosine on dobutamine (to 18 ± 7 cm/sec). In normal arteries, APV increased at Dobutamine20 (from 20 ± 7.5 to 30 ± 12 cm/sec, P < 0.01) and further at peak dobutamine stress (to 42 ± 10 cm/sec, P < 0.0001) always exceeding the concomitant significant increases in RPP. Peak stress APV increased further with adenosine on dobutamine (to 53 ± 13 cm/sec, P < 0.001). Our data demonstrate that at peak dobutamine stress there is supply/demand mismatch only in stenotic arteries where coronary flow reserve is exhausted at an intermediate dobutamine dose. Furthermore, adenosine on dobutamine potentiates coronary flow heterogeneity between stenotic and normal adjacent arteries.