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Blood flow velocity in the right coronary artery: assessment before and after angioplasty
L I Heller1, K H Silver, B J Villegas
1Coronary Blood Flow Research Laboratory, University of Massachusetts Medical Center, Worcester 01655.
Insights
Rest Doppler flow velocity measurements are not useful for assessing right coronary artery stenoses. Diastolic predominant flow was observed in branches after angioplasty, suggesting further investigation into hyperemic Doppler flow velocity indexes.
Area of Science:
- Cardiology
- Vascular Physiology
- Interventional Cardiology
Background:
- Previous studies on coronary artery stenoses focused on the left coronary artery.
- Resting blood flow velocity and diastolic flow patterns are known indicators of significant stenoses and normalize after successful dilation.
- The utility of resting velocity measurements in the right coronary artery (RCA) remained unstudied.
Purpose of the Study:
- To assess the utility of resting intracoronary blood flow velocity measurements for evaluating right coronary artery (RCA) stenoses before and after angioplasty.
- To compare phasic flow patterns in the RCA proper with its major branches.
Main Methods:
- A Doppler angioplasty guide wire was used to study 20 patients undergoing right coronary artery (RCA) angioplasty.
- Measurements included rest average peak velocity and proximal/distal velocity ratios.
- Phasic flow patterns were analyzed in the RCA and its branches.
Main Results:
- Rest average peak velocity did not decrease distal to significant RCA stenoses (23.3 cm/s proximal vs. 20.2 cm/s distal).
- The proximal/distal velocity ratio did not significantly change after angioplasty (1.4 +/- 0.9).
- Diastolic predominant flow was absent in the RCA proper but present in posterolateral and posterior descending arteries post-angioplasty.
Conclusions:
- Resting Doppler flow velocity indexes are not effective for evaluating RCA stenoses.
- Diastolic predominant flow is characteristic of RCA branches, not the RCA proper.
- Further research into hyperemic Doppler flow velocity indexes, like distal coronary flow reserve, is warranted for RCA stenosis assessment.
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.
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