Using patient-specific computational fluid dynamics to assess intraprosthetic thrombus formation risk and guide relining after endovascular aneurysm repair.

A patient-specific computational fluid dynamics (CFD) analysis was performed to explore hemodynamic contributors of recurrent intraprosthetic thrombus and limb thrombosis in a patient after endovascular aneurysm repair (EVAR) and to investigate the potential of CFD to guide revision strategies. Key hemodynamic parameters, Time-averaged wall shear stress (TAWSS) and residence time (RT), were assessed showing a region with depressed TAWSS (below 0.1 Pa) at the site of intraprosthetic thrombus and a quasi-infinite RT of entrapped particles in that area. Next, CFD simulations tested a virtual limb-relining configuration, with geometric modifications resulting in improved TAWSS and RT. After mimicking the CFD-based relining with the implantation of an endograft a postprocedural analysis was performed. The postoperative results were in line with the prediction model and showed a 544% reduction in low area of TAWSS (<0.1 Pa) and a normalization of RT to 5 seconds. A contrast-enhanced computed tomography 1 year after stent placement showed a patent endograft without any signs of recurrent mural thrombus. Therefore, CFD may provide valuable insights into the hemodynamic mechanisms underlying endograft thrombosis and may support personalized planning of relining strategies to reduce recurrent thromboembolic risk. The second most common complication after endovascular aneurysm repair is thrombosis in one of the iliac stent graft limbs or distal thromboembolic events, which can cause acute limb ischemia. In some patients, these events persist even after a successful relining of the iliac stent graft with normal flow profiles on ultrasound. This report describes how computational fluid dynamics can identify flow pattern abnormalities and high residence time in a patient with recurring thromboembolic events after endovascular aneurysm repair placement, coinciding with the location of thrombus formation. Moreover, relining strategies can be virtually assessed in the patient's computer model to select a strategy that is expected to normalize the increased residence time.