BLOOD-FLOW VELOCITY IN THE RIGHT CORONARY-ARTERY - ASSESSMENT BEFORE AND AFTER ANGIOPLASTY

Objectives. This study attempted 1) to assess the utility of rest meas urements of intracoronary blood flow velocity for the physiologic asse ssment of coronary stenoses before and after right coronary artery ang ioplasty, and 2) to compare the phasic flow pattern in the right coron ary artery proper with the phasic flow pattern in its major branches t o the left ventricle. Background. Previous investigations have demonst rated that a reduction in distal blood flow velocity and a loss of dis tal diastolic predominant flow are characteristic of physiologically s ignificant stenoses and that these indexes normalize after successful coronary artery dilation. However, these studies mere predominantly pe rformed in the left coronary artery. The utility of monitoring rest ve locity variables during angioplasty of the right coronary artery has n ot been studied. Methods. We studied 20 patients undergoing angioplast y 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 proxima l vs. 20.2 +/- 11.1 cm/s distal, p = 0.20). The proximal/ distal veloc ity 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 t o detect a difference between proximal and distal average peak velocit y. There was no relation between percent diameter stenosis and proxima l/distal velocity ratios (r = 0.15, p = 0.55). Diastolic predominant h ow was not observed in the proximal or distal right coronary artery. H owever, after angioplasty, diastolic predominant flow was observed in the posterolateral and posterior descending coronary arteries. Conclus ions. Rest phasic Doppler flow velocity indexes are not useful for eva luating stenoses in the right coronary artery proper before or after a ngioplasty. In contrast to the right coronary artery proper, diastolic predominant flow is observed in the posterior descending and posterol ateral coronary arteries. The utility of measuring hyperemic Doppler f low velocity indexes, such as distal coronary flow reserve, for assess ing right coronary artery stenoses merits further investigation.