Acute LPA angulation is associated with adverse haemodynamic performance. This should be particularly addressed during the reconstruction of pulmonary artery in the repair of tetralogy of Fallot.

Objectives The left subclavian artery during thoracic endovascular aortic repair could be reconstructed by in situ fenestration. This study aims to evaluate the effects of thoracic endovascular aortic repair with in situ fenestration thoracic endovascular aortic repair on the hemodynamics. Methods A male patient suffering from aortic dissection is treated by in situ fenestration thoracic endovascular aortic repair and the fenestration stent implanted in the left subclavian artery is partially protruding in the aortic arch for the stability. Two-phase non-Newtonian blood model is applied and three-element Windkessel model is implemented to reproduce physiological pressure waves. Simulations are carried out in three postoperative models to analyze different in situ fenestration thoracic endovascular aortic repair strategies; Case A: the protrusion length of fenestration stent is 23.2 mm representing the clinical postthoracic endovascular aortic repair aorta; Case B: the protrusion length is reduced by half simulating the improved surgery; Case C: the protruding portion is removed to simulate the ideal fenestration. Results In Case A, a pressure difference is found on the fenestration stent surface and a blood acceleration phenomenon around the stent is observed. Only 2.36% of the inlet blood flow is assigned to the left subclavian artery. In the improved surgery, the blood supply to the left subclavian artery is elevated to 4.01%. As for the ideal fenestration, a further improvement is observed (6.14%). Moreover, the aortic arch surface exposed to low time-averaged wall shear stress expands significantly when the protrusion length is shortened. Conclusions Overall, we conclude that appropriately shortening the protrusion length of the stent-graft may improve the efficacy of in situ fenestration thoracic endovascular aortic repair from the perspective of hemodynamics.

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