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Which diameter and angle rule provides optimal flow patterns in a coronary bifurcation?

ABSTRACT: The branching angle and diameter ratio in epicardial coronary artery bifurcations are two important determinants of atherogenesis. Murray's cubed diameter law and bifurcation angle have been assumed to yield optimal flows through a bifurcation. In contrast, we have recently shown a 7/3 diameter law (HK diameter model), based on minimum energy hypothesis in an entire tree structure. Here, we derive a bifurcation angle rule corresponding to the HK diameter model and critically evaluate the streamline flow through HK and Murray-type bifurcations. The bifurcations from coronary casts were found to obey the HK diameter model and angle rule much more than Murray's model. A finite element model was used to investigate flow patterns for coronary artery bifurcations of various types. The inlet velocity and pressure boundary conditions were measured by ComboWire. Y-bifurcation of Murray type decreased wall shear stress-WSS (10%-40%) and created an increased oscillatory shear index-OSI in atherosclerosis-prone regions as compared with HK-type bifurcations. The HK-type bifurcations were found to have more optimal flow patterns (i.e., higher WSS and lower OSI) than Murray-type bifurcations which have been traditionally believed to be optimized. This study has implications for changes in bifurcation angles and diameters in percutaneous coronary intervention.

SUBMITTER: Huo Y

PROVIDER: S-EPMC4913552 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature

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Which diameter and angle rule provides optimal flow patterns in a coronary bifurcation?

Huo Yunlong Y Finet Gérard G Lefevre Thierry T Louvard Yves Y Moussa Issam I Kassab Ghassan S GS

Journal of biomechanics 20120225 7

The branching angle and diameter ratio in epicardial coronary artery bifurcations are two important determinants of atherogenesis. Murray's cubed diameter law and bifurcation angle have been assumed to yield optimal flows through a bifurcation. In contrast, we have recently shown a 7/3 diameter law (HK diameter model), based on minimum energy hypothesis in an entire tree structure. Here, we derive a bifurcation angle rule corresponding to the HK diameter model and critically evaluate the streaml ...[more]

PMID: 22365499

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Project description:This work investigates the effect of arterial bifurcation angulation on atherosclerosis development through in-silico simulations of coupled cell dynamics. The computational model presented here combines cellular pathways, fluid dynamics, and physiologically-realistic vessel geometries as observed in the human vasculature. The coupled cells model includes endothelial cells (ECs) and smooth muscle cells (SMCs) with ion dynamics, hetero and homotypic coupling, as well as electro-diffusive coupling. Three arterial bifurcation surface models were used in the coupled cells simulations. All three simulations showed propagating waves of Ca2+ in both the SMC and EC layers, following the introduction of a luminal agonist, in this case ATP. Immediately following the introduction of ATP concentration Ca2+ waves propagate from the area of high ATP toward the areas of low ATP concentration, forming complex patterns where waves interact with eachother, collide and fade. These dynamic phenomena are repeated with a series of waves of slower velocity. The underlying motivation of this research was to examine the macro-scale phenomena, given that the characteristic length scales of atherosclerotic plaques are much larger than a single cell. The micro-scale dynamics were modeled on macro-scale arterial bifurcation surfaces containing over one million cells. The results of the simulations presented here suggest that susceptibility to atherosclerosis development depends on the bifurcation angulation. In conjunction with findings reported in the literature, the simulation results demonstrate that arterial bifurcations containing wider angles have a more prominent influence on the coupled cells pathways associated with the development of atherosclerosis, by means of disturbed flow and lower SMC Ca2+ concentrations. The discussion of the results considers the findings of this research within the context of the potential link between information transport through frequency encoding of Ca2+ wave dynamics and development of atheroprone conditions.

Project description:Background and objectiveThe modified double-stent and provisional stenting strategies have been widely used in patients with coronary bifurcation lesions, but what is the optimization has not been clearly defined. This meta-analysis is to elucidate the benefits from modified double-stent and provisional stenting strategies in patients with coronary bifurcation lesions.MethodsElectronic databases were searched to identify studies comparing the modified double-stent and provisional stenting strategies in patients with coronary bifurcation lesions. The clinical outcomes were divided into early (≤6 months) and late (>6 months) events according to the follow-up duration. The early endpoints included cardiac death, myocardial infarction, target lesion revascularization or target vessel revascularization, and major adverse cardiac events (MACE), and the late endpoints also include stent thrombosis in addition to the early endpoints index. The angiographic endpoint was in-stent restenosis. Data were analyzed by the statistical software RevMan (version 5.3).ResultsA total of 6 studies involving 1683 patients with coronary bifurcation lesions were included in this meta-analysis, which found that the modified double-stent strategy was associated with a lower risk of cardiac death (odds ratio [OR] = 0.29, 95% confidence intervals [CI] 0.11-0.78, P = .01), myocardial infarction (OR = 0.41, 95% CI 0.21-0.82, P = .01), target lesion revascularization or target vessel revascularization (OR = 0.31, 95% CI 0.15-0.63, P = .001), and MACE (OR = 0.41, 95% CI 0.22-0.74, P = .003) compared with provisional stenting in the early follow-up endpoint events, while the risk of cardiac death and stent thrombosis were similar between both strategies (OR = 0.59, 95% CI 0.31-1.10, P = .09; and OR = 0.62, 95% CI 0.34-1.15, P = .13; respectively) in the late follow-up endpoint events. There were significant differences between both strategies in myocardial infarction (OR = 0.42, 95% CI 0.24-0.75, P = .003), MACE (OR = 0.44, 95% CI 0.31-0.62, P < .00001), and target lesion revascularization or target vessel revascularization (OR 0.35, 95% CI 0.25-0.49, P < .00001) between both strategies in the late follow-up endpoint events. The risk of in-stent restenosis favored the modified double-stent strategy (OR 0.29, 95% CI 0.20-0.43, P < .00001).ConclusionThe modified double-stent strategy is associated with excellent clinical and angiographic outcomes except for the occurrence of cardiac death and stent thrombosis late-term outcome compared with provisional stenting strategy in patients with coronary bifurcation lesions. These findings suggest that the modified double-stent strategy can be recommended as an optimization in patients with coronary bifurcation lesions.

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Which diameter and angle rule provides optimal flow patterns in a coronary bifurcation?

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Which diameter and angle rule provides optimal flow patterns in a coronary bifurcation?

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