与三叶主动脉瓣相比,二叶主动脉瓣与更高的血管壁和湍流切应力水平相关。

Bicuspid aortic valves are associated with increased wall and turbulence shear stress levels compared to trileaflet aortic valves.

作者信息

Saikrishnan Neelakantan, Mirabella Lucia, Yoganathan Ajit P

机构信息

Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA.

出版信息

Biomech Model Mechanobiol. 2015 Jun;14(3):577-88. doi: 10.1007/s10237-014-0623-3. Epub 2014 Sep 28.

Abstract

Congenital bicuspid aortic valves (BAVs) are associated with accelerated disease progression, such as leaflet calcification and ascending aorta dilatation. Although common underlying genetic factors have been implicated in accelerated disease in BAV patients, several studies have suggested that altered hemodynamics also play a role in this disease process. The present study compares turbulence and wall shear stress (WSS) measurements between various BAV and trileaflet aortic valve (TAV) models to provide information for mechanobiological models of BAV disease. BAV and TAV models were constructed from excised porcine aortic valves to simulate parametric variations in BAV stenosis, hemodynamics and geometry. Particle image velocimetry experiments were conducted at physiological pressure conditions to characterize velocity fields in the ascending aorta. The velocity fields were post-processed to calculate turbulence, viscous and wall shear stresses in the ascending aorta. Stenosed BAV models showed the presence of eccentric systolic jets, causing increased WSS. Lower cardiac output resulted in a narrower jet, lower turbulence and lower viscous shear stress (VSS). The specific severe stenosis BAV model studied here showed reduced WSS due to reduction in non-fused leaflet mobility. Dilation of the aorta did not affect any turbulence or VSS, but reduced the WSS. In comparison with BAVs, TAVs have similar VSS values, but much smaller WSS and turbulence levels. These increased turbulence  and WSS levels in BAVs may play a key role in amplifying the biological responses of the ascending aorta wall and valvular leaflets, and support the hemodynamic underpinnings of BAV disease processes.

摘要

先天性二叶式主动脉瓣(BAV)与疾病进展加速有关,如瓣叶钙化和升主动脉扩张。尽管常见的潜在遗传因素被认为与BAV患者的疾病加速有关,但多项研究表明,血流动力学改变在这一疾病过程中也起作用。本研究比较了各种BAV和三叶式主动脉瓣(TAV)模型之间的湍流和壁面剪应力(WSS)测量结果,为BAV疾病的机械生物学模型提供信息。BAV和TAV模型由切除的猪主动脉瓣构建而成,以模拟BAV狭窄、血流动力学和几何形状的参数变化。在生理压力条件下进行粒子图像测速实验,以表征升主动脉中的速度场。对速度场进行后处理,以计算升主动脉中的湍流、粘性和壁面剪应力。狭窄的BAV模型显示存在偏心收缩期射流,导致WSS增加。较低的心输出量导致射流变窄、湍流降低和粘性剪应力(VSS)降低。此处研究的特定严重狭窄BAV模型由于未融合瓣叶活动度降低而显示WSS降低。主动脉扩张不影响任何湍流或VSS,但会降低WSS。与BAV相比,TAV的VSS值相似,但WSS和湍流水平要小得多。BAV中这些增加的湍流和WSS水平可能在放大升主动脉壁和瓣膜叶的生物学反应中起关键作用,并支持BAV疾病过程的血流动力学基础。

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