Advancements in the Endovascular Management of Thoracic Aortic Pathologies

Abstract

Over recent years, an improved consensus has been established regarding diagnosis and management of type B aortic dissection (TBAD). Primary conservative medical treatment with antihypertensive agents in combination with close surveillance seems to be justified in TBAD, until complications such as aneurysmal expansion, rupture, or progression of the initial dissection occur. Several clinical and radiological predictors of aortic growth in uncomplicated TBAD patients have been identified and can be used to select patients at high-risk for aortic enlargement and rupture during follow-up. Those patients might benefit from closer surveillance or early endovascular intervention. Over recent decades, the management of thoracic aortic pathologies has evolved to include endovascular approaches next to conventional open aortic repair. Currently, thoracic endovascular aortic repair (TEVAR) is the preferred approach for patients presenting with complicated TBAD and other thoracic aortic pathologies. Advances in medical care have increased the number of patients surviving the acute phase of TBAD, forming a larger cohort presenting with chronic TBAD. A comparative analysis of open and endovascular approaches for chronic TBAD was performed. Large maximum aortic diameter (OR 1.1, p=0.001) and visceral aorta intervention (OR 3.5, p=0.026) independently predicted adverse early outcomes. Important predictors of late mortality included peripheral vascular disease (HR 2.5, p=0.021) and baseline creatinine (HR 1.7, p<0.001), but not treatment strategy (p=0.225). Conventional open aortic repair was associated with higher treatment efficacy, and TEVAR was an independent predictor of treatment failure (p=0.046), which warrants modification of current device design or endovascular approach before broad application of TEVAR for chronic TBAD. To study patients treated with TEVAR in depth, computational fluid dynamics (CFD) can give important information about aortic hemodynamics, and helps to understand patient-specific changes in aortic geometry after TEVAR. Based on the analysis of pulsatile aortic changes, defined as aortic radial expansion and elongation during the cardiac cycle, increased changes after TEVAR along the different aortic segments were observed. Overall, dynamic imaging modalities help improve the evaluation of pulsatile aortic changes, specifically pre-TEVAR for stent graft sizing, and post-TEVAR to detect potential complications during follow-up. A patient-specific approach should be adopted in which stent graft design is focused on individual anatomy and morphologic changes. The expanding bioengineer-medical collaboration and increasing experience with dynamic aortic evaluation is therefore encouraging. Additionally, endovascular aortic repair is continuously evolving. When TEVAR candidates have unfavorable iliac artery anatomy (small, tortuous, or calcified vessels), traditionally retroperitoneal iliac artery conduits have been considered as most appropriate route for stent graft delivery. More recently, the endoconduit approach has been introduced as alternative and can be performed using a standard femoral approach, avoiding the complications associated with a retroperitoneal approach. Currently, TEVAR is also used to treat rare thoracic aortic pathologies, such as aberrant subclavian arteries with associated Kommerell diverticulum. The evolution towards endovascular and hybrid approaches to treat this aortic anomaly did not appear to affect late outcomes, suggesting that choice of treatment should be based on patient-specific anatomy and associated comorbidities.