Coronary microcirculation in the beating heart

Kajiya, Fumihiko; Yada, Toyotaka; Hiramatsu, Osamu; Ogasawara, Yasuo; Inai, Yousuke; Kajiya, Masahito

doi:10.1007/s11517-008-0335-x

Cited by 24 publications

(16 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Forward flow occurred during systole and diastole in subepicardial vessels (Fig. 5B), in agreement with Kajiya et al (28) and Toyota et al (68), although simulated data did not predict the early systolic retrograde flow evident in some (but not all) in vivo waveforms. Vascular volume varied over the cardiac cycle by 17% in the subendocardial arterial compartment but only 1.6% in the subepicardial arterial compartment, consistent with measured diameter variations of these vessels (68).…”

Section: Model Validationsupporting

confidence: 85%

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

View full text Add to dashboard Cite

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 ...

show abstract

Section: Model Validationsupporting

confidence: 85%

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

View full text Add to dashboard Cite

show abstract

“…However, they did not observe systolic blood filling and diastolic collapse. 23,24) In the present study, diastolic blood filling and systolic collapse were observed in AMs and VMs located in normokinetic-to-hypokinetic segments but were reversed in those located in akineticto-dyskinetic segments. Furthermore, AMs that did not collapse throughout one cardiac cycle were observed.…”

Section: Discussionsupporting

confidence: 48%

Cardioscopic Observation of Subendocardial Microvessels in Patients With Coronary Artery Disease

et al. 2011

View full text Add to dashboard Cite

SummaryCoronary microvessels play a direct and critical role in determining the extent and severity of myocardial ischemia and cardiac function. However, because direct observation has never been performed in vivo, the functional properties of the individual microvesssels in patients with coronary artery disease remain unknown.Subendocardial coronary microvessels were observed by cardioscopy in 149 successive patients with coronary artery disease (81 with stable angina and 68 with old myocardial infarction).Twenty-four arterial microvessels (AMs) and 27 venous microvessels (VMs) were observed in the left ventricular subendocardium. All 12 AMs and 13 of 14 VMs that were located in normokinetic-to-hypokinetic left ventricular wall segments were filled with blood during diastole and were collapsed during systole. In contrast, 8 of 12 AMs and 9 of 13 VMs that were located in akinetic-to-dyskinetic wall segments were filled with blood during systole and were collapsed during diastole. There were no significant correlations between the timing of blood filling and the severity of coronary stenosis and collateral development.In patients with coronary artery disease, the timing of blood filling of AMs and VMs was dependent on the regional left ventricular contractile state; during diastole when contraction was preserved and during systole when it was not. It remains to be elucidated whether and how blood filling is disturbed in other categories of heart disease. (Int Heart J 2011; 52: 274-279)

show abstract

“…During systole, the authors observed a dominant forward-travelling pushing wave in proximal coronary arteries that is reflected when reaching the microvascular bed in distal coronary arterioles, causing blood to move in the opposite direction. Coronary arteries are also known to have a significant capacitance to accommodate for blood supply [37]. Also, during ventricular contraction, the compressive forces on the small vessels lying in the myocardium increase while venous outflow is in its dominant phase.…”

Section: Discussionmentioning

confidence: 99%

“…In a study published by Kajiya et al [37], the authors focused on the phase opposition of velocity waveforms between coronary arteries and veins. They introduced the unstressed volume (UV), which refers to a capacitance accommodating for blood supply during diastole without significant increase in UV pressure to propel venous outflow.…”

Section: Discussionmentioning

confidence: 99%

In vivo characterization of rodent cyclic myocardial perfusion variation at rest and during adenosine-induced stress using cine-ASL cardiovascular magnetic resonance

Troalen

Capron

Bernard

et al. 2014

Journal of Cardiovascular Magnetic Resonance

View full text Add to dashboard Cite

BackgroundAssessment of cyclic myocardial blood flow (MBF) variations can be an interesting addition to the characterization of microvascular function and its alterations. To date, totally non-invasive in vivo methods with this capability are still lacking. As an original technique, a cine arterial spin labeling (ASL) cardiovascular magnetic resonance approach is demonstrated to be able to produce dynamic MBF maps across the cardiac cycle in rats.MethodHigh-resolution MBF maps in left ventricular myocardium were computed from steady-state perfusion-dependent gradient-echo cine images produced by the cine-ASL sequence. Cyclic changes of MBF over the entire cardiac cycle in seven normal rats were analyzed quantitatively every 6ms at rest and during adenosine-induced stress.ResultsThe study showed a significant MBF increase from end-systole (ES) to end-diastole (ED) in both physiological states. Mean MBF over the cardiac cycle within the group was 5.5 ± 0.6 mL g-1 min-1 at rest (MBFMin = 4.7 ± 0.8 at ES and MBFMax = 6.5 ± 0.6 mL g-1 min-1 at ED, P = 0.0007). Mean MBF during adenosine-induced stress was 12.8 ± 0.7mL g-1 min-1 (MBFMin = 11.7±1.0 at ES and MBFMax = 14.2 ± 0.7 mL g-1 min-1 at ED, P = 0.0007). MBF percentage relative variations were significantly different with 27.2 ± 9.3% at rest and 17.8 ± 7.1% during adenosine stress (P = 0.014). The dynamic analysis also showed a time shift of peak MBF within the cardiac cycle during stress.ConclusionThe cyclic change of myocardial perfusion was examined by mapping MBF with a steady-pulsed ASL approach. Dynamic MBF maps were obtained with high spatial and temporal resolution (6ms) demonstrating the feasibility of non-invasively mapping cyclic myocardial perfusion variation at rest and during adenosine stress. In a pathological context, detailed assessment of coronary responses to infused vasodilators may give valuable complementary information on microvascular functional defects in disease models.

show abstract

Coronary microcirculation in the beating heart

Cited by 24 publications

References 58 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

Cardioscopic Observation of Subendocardial Microvessels in Patients With Coronary Artery Disease

In vivo characterization of rodent cyclic myocardial perfusion variation at rest and during adenosine-induced stress using cine-ASL cardiovascular magnetic resonance

Contact Info

Product

Resources

About