Abstract
This study aims to investigate the haemodynamic response induced by implantation of a double-branched endograft used in thoracic endovascular aortic repair (TEVAR) of the aortic arch. Anatomically realistic models were reconstructed from CT images obtained from patients who underwent TEVAR using the RelayPlus double-branched endograft implanted in the aortic arch. Two cases (Patient 1, Patient 2) were included here, both patients presented with type A aortic dissection before TEVAR. To examine the influence of inner tunnel branch diameters on localised flow patterns, three tunnel branch diameters were tested using the geometric model reconstructed for Patient 1. Pulsatile blood flow through the models was simulated by numerically solving the Navier–Stokes equations along with a transitional flow model. The physiological boundary conditions were imposed at the model inlet and outlets, while the wall was assumed to be rigid. Our simulation results showed that the double-branched endograft allowed for the sufficient perfusion of blood to the supra-aortic branches and restored flow patterns expected in normal aortas. The diameter of tunnel branches in the device plays a crucial role in the development of flow downstream of the branches and thus must be selected carefully based on the overall geometry of the vessel. Given the importance of wall shear stress in vascular remodelling and thrombus formation, longitudinal studies should be performed in the future in order to elucidate the role of tunnel branch diameters in long-term patency of the supra-aortic branches following TEVAR with the double-branched endograft.
Highlights
Pathologies in the aortic arch can arise due to a number of well documented causes: elevated blood pressure, trauma and congenital conditions, to name only a few
Two patients were included in this study and both presented with type A aortic dissection located in the arch region, underwent thoracic endovascular aortic repair (TEVAR) using the RelayPlus double-branched endografts of the same tunnel branch diameter and neither required any further revascularisation
In order to illustrate the dynamics of the pulsatile flow of blood through the vessels, instantaneous velocity streamlines are plotted and displayed at three distinct points in the cardiac cycle: peak systole, mid-systolic deceleration and mid-diastole, as shown in Figure 4 shows the instantaneous velocity streamlines for cases 1, 1A and 1B, which have tunnel branch diameters of 12 mm, 10 mm and 8 mm, respectively
Summary
Pathologies in the aortic arch can arise due to a number of well documented causes: elevated blood pressure, trauma and congenital conditions, to name only a few. As is the case with most vascular conditions, pathological changes affect flow through the region and can compromise perfusion to distal parts of the body. Common aortic arch diseases include aneurysms and aortic dissections (AD) [1]. Degenerative aneurysms in the arch are often asymptomatic and can go undetected. The increased use of diagnostic imaging has resulted in most aneurysms being detected and treated. If left untreated, this bulge in the wall can grow and eventually rupture with fatal consequences
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