Differences in cardiac microcirculatory wave patterns between the proximal left mainstem and proximal right coronary artery

Abstract

Hadjiloizou N, Davies JE, Malik IS, Aguado-Sierra J, Willson K, Foale RA, Parker KH, Hughes AD, Francis DP, Mayet J. Differences in cardiac microcirculatory wave patterns between the proximal left mainstem and proximal right coronary artery. Am J Physiol Heart Circ Physiol 295: H1198 -H1205, 2008. First published July 18, 2008 doi:10.1152/ajpheart.00510.2008.-Despite having almost identical origins and similar perfusion pressures, the flow-velocity waveforms in the left and right coronary arteries are strikingly different. We hypothesized that pressure differences originating from the distal (microcirculatory) bed would account for the differences in the flow-velocity waveform. We used wave intensity analysis to separate and quantify proximaland distal-originating pressures to study the differences in velocity waveforms. In 20 subjects with unobstructed coronary arteries, sensor-tipped intra-arterial wires were used to measure simultaneous pressure and Doppler velocity in the proximal left main stem (LMS) and proximal right coronary artery (RCA). Proximal-and distal-originating waves were separated using wave intensity analysis, and differences in waves were examined in relation to structural and anatomic differences between the two arteries. Diastolic flow velocity was lower in the RCA than in the LMS (35.1 Ϯ 21.4 vs. 56.4 Ϯ 32.5 cm/s, P Ͻ 0.002), and, consequently, the diastolic-to-systolic ratio of peak flow velocity in the RCA was significantly less than in the LMS (1.00 Ϯ 0.32 vs. 1.79 Ϯ 0.48, P Ͻ 0.001). This was due to a lower distal-originating suction wave (8.2 Ϯ 6.6 ϫ 10 3 vs. 16.0 Ϯ 12.2 ϫ 10 3 W ⅐ m Ϫ2 ⅐ s Ϫ1 , P Ͻ 0.01). The suction wave in the LMS correlated positively with left ventricular pressure (r ϭ 0.6, P Ͻ 0.01) and in the RCA with estimated right ventricular systolic pressure (r ϭ 0.7, P ϭ 0.05) but not with the respective diameter in these arteries. In contrast to the LMS, where coronary flow velocity was predominantly diastolic, in the proximal RCA coronary flow velocity was similar in systole and diastole. This difference was due to a smaller distal-originating suction wave in the RCA, which can be explained by differences in elastance and pressure generated between right and left ventricles. coronary artery hemodynamics; coronary blood flow; wave intensity analysis; coronary velocity THE CORONARY ARTERIES have a unique flow velocity profile in that most blood flow occurs in diastole (11) rather than in systole, as in other systemic arteries (14). The contractile function of the heart enables it to pump blood to other organs of the body, but, in doing so, it paradoxically impedes its own blood supply. Previous studies have investigated the basis for the unique flow velocity profile, some by analyzing the flow-velocity profile in normal (16) or diseased left coronary arteries (15) and others by using invasive animal models (5, 24).The right coronary artery (RCA) has a flow-velocity pattern that is less diastolic dominant than that of the left coronary arteries (7) and has different proxi...

Advances in Coronary Physiology

“…Wave intensity demonstrates that the forces propagating from the proximal vessel (the aorta) conflict with those travelling from the distal end (the microcirculation) (Figure 4). 40,41 Competing interaction between the waves occurs throughout systole and the largest microcirculatory wave occurs at the beginning of diastole to explain why coronary flow is predominantly diastolic. During diastole the waves are quiescent, 42 and during this wave-free period, microcirculatory resistance is at its lowest and most stable compared with the rest of the cardiac cycle.…”

Baseline Instantaneous Wave-Free Ratio as a Pressure-Only Estimation of Underlying Coronary Flow Reserve

“…Pressure and flow data acquired simultaneously were aligned as previously described. 20 The diastolic iFR window was identified using fully automated algorithms acting over ECG-gated, time-aligned pressure traces, as described previously. 15 Quantitative coronary angiography was performed off-line in appropriate consoles.…”

Arterial Pulse Wave Dynamics After Percutaneous Aortic Valve Replacement

“…It is likely that similar altered physiology would be identified in younger subjects with aortic stenosis, even in the presence of moderate coronary artery disease. Currently, most of the work in the field assessing wave travel in coronary arteries has concentrated on unobstructed vessels, 18,21 so further studies are needed to confirm and quantify the degree of coronary stenosis necessary to cause significant impediment of wave travel. Additionally, from our findings, we can only make interferences about temporal changes in coronary physiological reserve with worsening aortic stenosis.…”