Retrograde aortic endograft side-branch design is associated with delayed cervical branch filling: A fluid mechanics scaling analysis.

Although perioperative stroke is a recognized risk in thoracic endovascular aortic arch repair, the long-term impact of altered cervical flow resulting from different device configurations is underappreciated. We compared angiographic data from two aortic stents, with anatomical (in-line) and nonanatomical (retrograde inner branch) configurations, and demonstrated a persistent filling delay in the retrograde inner branch device. Using computational fluid dynamic modeling, we demonstrated that parameters such as turbulence, vorticity, and Q-criterion are elevated in an idealized retrograde inner branch geometry. By way of a fluid mechanic scaling analysis, we show that the retrograde inner branch configuration results in a larger Dean number, thereby explaining our observed angiographic and computational modeling results. Our work should prompt further investigation regarding the long-term impact of branch configuration and altered cervical blood flow. Clinical Relevance: Thoracic endovascular aortic arch repair is growing in prevalence. Perioperative stroke risk remains a major risk factor. A less studied phenomenon is the impact of differing branch configurations on long-term hemodynamics. This work compared angiographic data from two devices with differing branch flow configurations: antegrade vs retrograde. A persistent cervical branch filling was noted in the retrograde branch device. We applied fluid mechanic scaling analysis and validated with computational modeling to show that the retrograde branch configuration is promoting of disturbed flow. This work should promote further clinical investigation regarding long-term impact of branch configuration.