Impact of Thoracic Endovascular Repair on Pulsatile Aortic Strain in Acute Type B Aortic Dissection: Preliminary Results

Background: The impact of thoracic endovascular aortic repair (TEVAR) on pulsatile aortic strain remains undetermined in patients with Type B aortic dissection (TBAD). Therefore, we quantified pulsatile aortic strain in TBAD patients and control subjects. Methods: We retrospectively analyzed two TBAD patients from our database with cardiac-gated computed tomography angiography imaging available before and after TEVAR and two control subjects (67- and 76-year-old males). Patient 1 (54-year-old female) presented with acute TBAD, and Patient 2 (55-year-old male) had Marfan syndrome and ruptured acute TBAD. Custom-developed software was used to compute aortic length, diameter, and area during the cardiac cycle. Pulsatile strain was calculated as systolic increments of length and circumference divided by corresponding diastolic values. Results: Before TEVAR, pulsatile longitudinal strain of the thoracic aorta was lower in TBAD patients (1.4-1.7%) than in control subjects (2.1-4.5%). After TEVAR, pulsatile longitudinal strain increased proximal to the stent-graft by 65% in the arch of Patient 1 and by 70% in the ascending aorta of Patient 2. Pulsatile circumferential strain was elevated in false lumen patency (4.4-6.2%) compared with thrombosed false lumen (1.4-2.1%) or control subjects (0.9-3.3%). Following TEVAR, circumferential measurements within stented segments were deemed unreliable due to artifacts. Conclusions: TEVAR led to a considerable increase of pulsatile longitudinal strain proximal to the stent-grafts, and TBAD was associated with longitudinally stiffer aortas, which may be part of the pathophysiology of TEVAR-related complications such as retrograde dissection and aneurysmal dilatation. These preliminary data call for larger prospective studies.