Blood flow velocity in the right coronary artery: Assessment before and after angioplasty

Objectives. This study attempted 1) to assess the utility of rest measurements of intracoronary blood flow velocity for the physiologic assessment of coronary stenoses before and after right coronary artery angioplasty, and 2) to compare the phasic flow pattern in the right coronary artery proper with the phasic flow pattern in its major branches to the left ventricle. Background. Previous investigations have demonstrated that a reduction in distal blood flow velocity and a loss of distal diastolic predominant flow are characteristic of physiologically significant stenoses and that these indexes normalize after successful coronary artery dilation. However, these studies were predominantly performed in the left coronary artery. The utility of monitoring rest velocity variables during angioplasty of the right coronary artery has not been studied. Methods. We studied 20 patients undergoing angioplasty of the right coronary artery with use of a Doppler angioplasty guide wire. Results. Values were expressed as the mean value ± 1 SD. The rest average peak velocity did not decrease distal to angiographically significant right coronary artery stenoses (23.3 ± 9.4 cm/s proximal vs. 20.2 ± 11.1 cm/s distal, p = 0.20). The proximal/ distal velocity ratio was 1.4 ± 0.9 before angioplasty and did not significantly decrease after angioplasty (p = 0.58). This study had a 99.4% power to detect a difference between proximal and distal average peak velocity. There was no relation between percent diameter stenosis and proximal/distal velocity ratios (r = 0.15, p = 0.55). Diastolic predominant flow was not observed in the proximal or distal right coronary artery. However, after angioplasty, diastolic predominant flow was observed in the posterolateral and posterior descending coronary arteries. Conclusions. Rest phasic Doppler flow velocity indexes are not useful for evaluating stenoses in the right coronary artery proper before or after angioplasty. In contrast to the right coronary artery proper, diastolic predominant flow is observed in the posterior descending and posterolateral coronary arteries. The utility of measuring hyperemic Doppler flow velocity indexes, such as distal coronary flow reserve, for assessing right coronary artery stenoses merits further investigation.