Background: Thoracic endovascular repair (TEVAR) stiffens the elastomechanical properties of
the aorta from the moment of deployment. Chronically, the stent-wall interaction can
lead (cardio)-vascular ramifications that stem from stent-induced biomechanical events.
The present experimental study aims to investigate the early biomechanical impact
of TEVAR against the aortic wall.
Method: Human cadaver thoracic aortas (n = 10) were exposed to pulsatile perfusion for 8 hours under physiological pressure
and volume conditions within a mock circulation loop. The pressure, diameter and compliance
variations of the aortas were measured with pressure sensors and a video-extensometer
was tracking the cyclic circumferential stretch of the aorta at the proximal landing
zone of the stent graft. The compliance variations were visualized and compared by
plotting hysteresis loops. After perfusion, biaxial tension tests were conducted to
investigate strength and stiffness profiles, respectively, on stented and nonstented
samples. Further investigations of possible damage and local alterations caused by
the stent or the implantation process were assessed with histological analysis.
Results: In our experiments, there was a significant loss in aortic elasticity (> 25%) indicating
global aortic stiffening and compliance mismatch as visualized in the hysteresis loops.
Additionally there was a slight increase in systolic blood pressure, revealing reduced
energy storage capacities of the stiffer stented aorta. Post-perfusion mechanical
analysis reveals tissue stiffening in the stented area compared with the nonstented.
That implies elastin loss reflected into the shorter elastic phase of the stress-stretch
relationship. Global loss of distensibility and local tissue stiffening occurred already
in the first hours post implantation.
Conclusion: For the first time early stiffening after TEVAR has been artificially created and
studied. The loss of cyclic distensibility is shown in the hysteresis loops and highlights
the compliance mismatch between the stent-graft and aortic wall. The knowledge gained
might give a better insight into the etiology of device related problems and provide
knowledge on how to refine next-generation stent-grafts meeting a more natural compliance
and therefore reducing complications.