The characterization of normal coronary blood flow dynamics should provide crucial guidelines for the accurate functional assessment of diseased coronary artery. However, the regional characteristics of coronary blood flow dynamics in normal human coronary artery have not been fully evaluated.

We performed proximal and distal segment velocity measurement of angiographically normal left anterior descending(LAD) and right coronary artery(RCA) in 25 patients(14 males, 12 females, age 50±10 yesre) with atypical chest pain. Spectral flow velocity parameters including average peak velocity(APV), average diastolic peak velocity(ADPV), average systolic peak velocity(ASPV), and diastolic-to-systolic velocity ratio(DSVR) were measured using 0.014 inch 15MHz Doppler wire at baseline and intracoronary adenosine-induced maximal hyperemic state. Coronary flow reserve(CFR) was calculated from the ratio of hyperemia to baseline APV.

Comparison between LAD with RCA. LAD showed significantly higher APV than RCA at baseline(proximal ; 18±6cm/s vs 14±4cm/s, p<.005, and distal ; 17±6 cm/s vs 12±4cm/s, p<.005. LAD showed significantly higher ADPV and lower ASPV than RCA, therefore significantly higher DSVR than RCA> CFR was significantly lower in LAD than in RCA(proximal ; 301±0.9 vs 3.8±1.0 , p<3001, and distal ; 3.1±0.7 vs 3.6±0.8, p<.05). Comparison between proximal with distal segment. There was significant reduction in APV and ASPV from proximal to distal segment in RCA, but not in LAD. There was significant increase in DSVR from proximal to distal segment in RCA, but not in LAD. There was no difference in CFR between proximal and distal segment in both coronary arteries.

We measured coronary blood flow velocities in angiographically normal coronary artery to characterized normal coronary blood flow dynamics and provide the reference values for the assessment of coronary artery disease. Significant regional differences of coronary blood flow velocities should be considered when we assess the diseased coronary artery.