Flow dynamics and endovascular repair of the aorta

Abstract

Thoracic endovascular aortic repair (TEVAR) is by now firmly established as the first line of treatment for most types of thoracic aortic disease. There are differences in the mechanical properties of commercially available stent grafts used for TEVAR, but all are stiff in comparison to the dynamic environment of the native thoracic aorta. This compliance mismatch between the endovascular device and the native aorta leads to an increase in pulse wave velocity, a measure of arterial stiffness. It also causes an increase in radial strain in the proximal, non-stented aorta. These negative effects on aortic flow dynamics could lead to complications and even mortality in the long term. Dynamic imaging techniques, such as ECG-gated CTA and 4D-flow MRI, can visualize aortic flow dynamics in the preoperative and postoperative phase, which can offer valuable diagnostic and prognostic information, and can help to prevent complications after TEVAR. Even with static imaging, certain anatomic characteristics can be identified that are associated with adverse flow dynamics, especially in the aortic arch. TEVAR might be at a high risk of failure in these patients. In order to expand the indications of endovascular repair to more complex patients, branched stent graft technology is promising, but still needs improvements.