Blood flow dynamic improvement with aneurysm repair detected by a patient-specific model of multiple aortic aneurysms

Abstract

Aortic aneurysms may cause the turbulence of blood flow and result in the energy loss of the blood flow, while grafting of the dilated aorta may ameliorate these hemodynamic disturbances, contributing to the alleviation of the energy efficiency of blood flow delivery. However, evaluating of the energy efficiency of blood flow in an aortic aneurysm has been technically difficult to estimate and not comprehensively understood yet. We devised a multiscale computational biomechanical model, introducing novel flow indices, to investigate a single male patient with multiple aortic aneurysms. Preoperative levels of wall shear stress and oscillatory shear index (OSI) were elevated but declined after staged grafting procedures: OSI decreased from 0.280 to 0.257 (first operation) and 0.221 (second operation). Graftings may strategically counter the loss of efficient blood delivery to improve hemodynamics of the aorta. The energy efficiency of blood flow also improved postoperatively. Novel indices of pulsatile pressure index (PPI) and pulsatile energy loss index (PELI) were evaluated to characterize and quantify energy loss of pulsatile blood flow. Mean PPI decreased from 0.445 to 0.423 (first operation) and 0.359 (second operation), respectively; while the preoperative PELI of 0.986 dropped to 0.820 and 0.831. Graftings contributed not only to ameliorate wall shear stress or oscillatory shear index but also to improve efficient blood flow. This patient-specific modeling will help in analyzing the mechanism of aortic aneurysm formation and may play an important role in quantifying the energy efficiency or loss in blood delivery.

Validation of numerical simulation methods in aortic arch using 4D Flow MRI

“…Computational fluid dynamics (CFD) are considered a gold standard method of blood flow visualization and are often used for analyzing blood flow in cases of aortic disease to evaluate the wall shear stress (WSS) [1–3] or in cases of congenital heart disease to evaluate the flow energy loss (EL) [4, 5]. Compared to in vivo measurements, including echocardiography or phase contrast MRI, CFD has various advantages.…”

Improvement of Severe Heart Failure after Endovascular Stent Grafting for Thoracic Aortic Aneurysm

“…The mechanism of hemodynamic parameter improvement after aortic aneurysm repair is unknown; however, Sughimoto, et al 12) suggested a new perspective on blood flow dynamic improvement with aneurysm repair by introducing the concept of energy loss through altered blood flow with an aortic aneurysm. Flow turbulence reduces the efficiency of blood delivery around the dilated aortic lesion, causing local viscous energy loss and enhancing the systemic circulation afterload.…”

Multi-scale modeling of hemodynamics in the cardiovascular system

“…(14) and (15) are derived from fluid dynamic equations for a single vessel, they can be used to describe blood flow through many vessels. In practice, when 0D modeling methods are applied to the cardiovascular system, the system is often first divided into a set of compartments according to its anatomical configuration, with each compartment corresponding to a certain vascular portion, such as the arterial portion, the microvascular portion and the venous portion, and so on [32,33].…”

“…3D modeling with rigid walls Three-dimensional rigid wall models, where blood flow is determined by assuming that the vascular wall is rigid and that any wall motion does not affect the flow, are often used to obtain details of the pressure and velocity fields as well as wall shear stresses in specific arterial regions of particular physiological or pathological interest such as bifurcations, aortic arch, abdominal aorta, or cerebral aneurysms [15]. Assuming a rigid wall largely simplifies the numerical approach and reduces computational effort, but is justifiable only in the cases where the wall motion is relatively small.…”