Mechanical determinants of myocardial perfusion

Spaan, Jos A. E.

doi:10.1007/bf00789439

Cited by 58 publications

(37 citation statements)

References 75 publications

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“…The first is cavity-induced extracellular pressure (CEP), which arises from transmission of ventricular cavity pressure into the heart muscle. Solid mechanics theory predicts CEP will be equal to cavity pressure in the subendocardium, with an approximately linear decline to pericardial pressure in the subepicardium (63); this has been confirmed by computational and in vivo studies (23,57). The second mechanism is shortening-induced intracellular pressure (SIP).…”

Section: D Model Of Conduit Coronary Arteries Most Sheepmentioning

confidence: 83%

Scalability and in vivo validation of a multiscale numerical model of the left coronary circulation

Mynard

Penny

Smolich

2014

American Journal of Physiology-Heart and Circulatory Physiology

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Mynard JP, Penny DJ, Smolich JJ. Scalability and in vivo validation of a multiscale numerical model of the left coronary circulation. Am J Physiol Heart Circ Physiol 306: H517-H528, 2014. First published December 20, 2013 doi:10.1152/ajpheart.00603.2013.-Multiscale modeling is a promising tool for the study of coronary hemodynamics. A key strength of this approach is that it accounts for microvascular properties and extravascular forces that differ regionally and transmurally, as well as wave propagation effects in the conduit arteries. However, little validation of such models has been reported and no models of the newborn coronary circulation have been described. We therefore validated a multiscale model of the left coronary circulation using high-fidelity data from nine adult sheep and nine newborn lambs and investigated whether wave propagation effects are more prominent in adults, whose body size (and hence wave transit distance) is greater. The model consisted of a one-dimensional (1D) network of the major conduit arteries and a lumped parameter model of microvascular beds. Intramyocardial pressure was considered to arise via contraction-related myocyte thickening and transmission of ventricular cavity pressure into the heart wall. 1D network geometry from published human anatomical data was scaled using myocardial weights, while subject-specific aortic pressure/flow and ventricular pressure formed model inputs. Total vascular resistance was determined iteratively from measured mean circumflex coronary flow (CxQ), but no fitting of phasic aspects of the waveform was performed. Excellent agreement was obtained between simulated and measured CxQ waveforms in most cases. Detailed flow waveform analysis did not clearly reveal a greater prominence of wave propagation effects in adults compared with newborns. This multiscale model is likely to be useful for investigating wave phenomena and phasic aspects of coronary flow in adults and during development. coronary arteries; wave propagation; allometric scaling; computer model; hemodynamics; newborn MATHEMATICAL MODELING, in concert with experimental studies, has played an important role in building our current understanding of coronary hemodynamics, providing insights into the role of intramyocardial pressure, large microvascular compliance, and transmural differences of vascular impedance and flow patterns (4, 9 -12, 18, 64, 67, 70). Many models of the coronary circulation have been of the lumped parameter [or zero-dimensional (0D)] type, where the resistive and capacitive properties of all coronary vessels are combined into a small number of elements. For example, the main conduit coronary arteries lying on the epicardium (or traversing the ventricular septum) have generally been represented by a single compliance (10, 12, 64) or windkessel compartment (4, 9, 18).One limitation of an exclusively 0D modeling approach is that wave propagation effects are neglected. That these effects play a role in shaping the coronary arterial flow waveform was first suggested ...

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Section: D Model Of Conduit Coronary Arteries Most Sheepmentioning

confidence: 83%

Scalability and in vivo validation of a multiscale numerical model of the left coronary circulation

Mynard

Penny

Smolich

2014

American Journal of Physiology-Heart and Circulatory Physiology

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“…Although such mechanisms provide adequate explanation, it is possible that alternative or additional interpretations may exist. 24 Our study is cross-sectional and therefore cannot give data on the development or regression of LVH and its consequences on wave intensity. Therefore, our implicit assumption that LVH is the cause of the abnormalities seen in the subjects with LVH is always subject to challenge.…”

Section: Study Limitationsmentioning

confidence: 92%

Evidence of a Dominant Backward-Propagating “Suction” Wave Responsible for Diastolic Coronary Filling in Humans, Attenuated in Left Ventricular Hypertrophy

et al. 2006

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Background-Coronary blood flow peaks in diastole when aortic blood pressure has fallen. Current models fail to completely explain this phenomenon. We present a new approach-using wave intensity analysis-to explain this phenomenon in normal subjects and to evaluate the effects of left ventricular hypertrophy (LVH). Method and Results-We measured simultaneous pressure and Doppler velocity with intracoronary wires in the left main stem, left anterior descending, and circumflex arteries of 20 subjects after a normal coronary arteriogram. Wave intensity analysis was used to identify and quantify individual pressure and velocity waves within the coronary artery circulation.A consistent pattern of 6 predominating waves was identified. Ninety-four percent of wave energy, accelerating blood forward along the coronary artery, came from 2 waves: first a pushing wave caused by left ventricular ejection-the dominant forward-traveling pushing wave; and later a suction wave caused by relief of myocardial microcirculatory compression-the dominant backward-traveling suction wave. The dominant backward-traveling suction wave (18.2Ϯ13.7ϫ10 3 W m Ϫ2 s

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“…While such mechanisms provide an adequate explanation, it is possible that alternative or additional interpretations may exist (23).…”

Section: Study Limitationsmentioning

confidence: 99%

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

Hadjiloizou

Davies²,

Malik³

et al. 2008

American Journal of Physiology-Heart and Circulatory Physiology

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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...

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Mechanical determinants of myocardial perfusion

Cited by 58 publications

References 75 publications

Scalability and in vivo validation of a multiscale numerical model of the left coronary circulation

Scalability and in vivo validation of a multiscale numerical model of the left coronary circulation

Evidence of a Dominant Backward-Propagating “Suction” Wave Responsible for Diastolic Coronary Filling in Humans, Attenuated in Left Ventricular Hypertrophy

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

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