Coronary flow velocity dynamics in normal and diseased arteries.

Distal coronary flow velocity measurements were previously limited to open heart or experimental procedures. Unlike previous Doppler catheter techniques, a Doppler angioplasty flow wire permits flow velocity measurements in both the proximal and distal segments of normal and diseased coronary arteries. In order to determine the potential clinical application of the Doppler flow wire, we performed baseline and hyperemia flow velocity measurements in proximal and distal segments of 20 angiographically normal arteries (right coronary = 8; left circumflex = 7; left anterior descending = 5) and 29 significantly stenosed arteries. All 3 normal coronary arteries had a diastolic-predominant pattern in both proximal and distal segments; the right coronary artery showed significantly less diastolic predominance. The coronary vasodilator reserve was similar in all three normal coronary arteries, and in the proximal and distal arterial segments. Abnormal arteries had significantly lower coronary vasodilator reserve (normal vs abnormal, 2.3 +/- 0.8/1.6 +/- 0.7; p < 0.02). Normal arteries had preservation of velocity parameters in the distal segments; abnormal arteries had a significant decrease in distal velocity parameters. The proximal-to-distal velocity ratio was thus significantly higher in abnormal arteries (2.4 +/- 0.7 vs 1.1 +/- 0.2; p < 0.001). The coronary vasodilator reserve in proximal and distal arteries--in addition to the proximal to distal velocity ratio--may provide functional and hemodynamic data complementary to coronary angiography in the assessment of coronary artery stenosis.