OBJECTIVE: Thoracic endovascular aortic repair (TEVAR) can change the morphology of the flow lumen in aortic dissections, which may affect aortic hemodynamics and function. This study characterizes how helical morphology of the true lumen in type B aortic dissections is altered by TEVAR.METHODS: Patients with type B aortic dissection who underwent computed tomography angiography pre- and post-TEVAR were retrospectively reviewed. Images were used to construct 3D stereolithographic (STL) surface models of the true lumen and whole aorta using custom software. STL models were segmented and co-registered to determine helical morphology of the true lumen with respect to the whole aorta. The true lumen region covered by the endograft was defined based on fiducial markers pre- and post-TEVAR. Helical angle, average helical twist, peak helical twist, and cross-sectional eccentricity, area, and circumference were quantified in this region for pre- and post-TEVAR geometries.RESULTS: Sixteen patients (61.3±8.0 years, 12.5% female) were treated successfully for type B dissection (five acute and eleven chronic) with TEVAR and scans pre- and post-TEVAR were retrospectively obtained (follow-up interval 52±91 days). From pre- to post-TEVAR, true lumen helical angle (-70.0±71.1 to -64.9±75.4 deg, p=0.782), average helical twist (-4.1±4.0 to -3.7±3.8 deg/cm, p=0.674) and peak helical twist (-13.2±15.2 to -15.4±14.2 deg/cm, p=0.629) did not change. However, true lumen helical radius (1.4±0.5 to 1.0±0.6 cm, p<0.05) and eccentricity (0.9±0.1 to 0.7±0.1, p<0.05) decreased, and cross-sectional area (3.0±1.1 to 5.0±2.0 cm2, p<0.05) and circumference (7.1±1.0 to 8.0±1.4 cm, p<0.05) increased significantly from pre- to post-TEVAR. The distinct bimodal distribution of chiral and achiral native dissections disappeared post-TEVAR, and subgroup analyses showed that the true lumen circumference of acute dissections increased with TEVAR, while it did not for chronic dissections.CONCLUSIONS: The unchanged helical angle and average and peak helical twists as a result of TEVAR suggest that angular positions of the true lumen are constrained and that the endografts were helically conformable in the angular direction. The decrease of helical radius indicated a straightening of the "corkscrew" shape of the true lumen, and in combination with more circular and expanded lumen cross-sections, TEVAR produced luminal morphology that theoretically allows for lower flow resistance through the endografted portion. The impact of TEVAR on dissection flow lumen morphology and the interaction between endografts and aortic tissue can provide insight for improving device design, implantation technique, and long-term clinical outcomes.
View details for DOI 10.1016/j.jvs.2021.04.029
View details for PubMedID 33940073