The purpose of this study was to utilize dynamic computed tomographic angiography (CTA) on pre- and postoperative thoracic endovascular aneurysm repair (TEVAR) patients to characterize cardiac pulsatility-induced aortic motion on essential TEVAR proximal sealing zones and to study the influence of endograft placement. Six pre- and six postoperative dynamic CTA studies were obtained in six patients with thoracic aortic aneurysms (TAAs) undergoing TEVAR. Data were acquired using a retrospective electrocardiography-triggered dynamic CTA scan, with eight reconstructed phases over the cardiac cycle. Scans were acquired during a single breath hold. Multiplanar reconstructions were made perpendicular to the aorta at five surgically relevant anatomical thoracic landmarks: 1 cm proximal to the innominate trunk, 1 cm proximal and 1 cm distal to the left subclavian artery, and 1 cm proximal and 3 cm distal to the proximal end of the stent. After segmentation of the aortic lumen in the images, diameter change and area change over the cardiac cycle were measured. Diameter change was measured through the center of mass of the aortic lumen, and the average change over 180 axis is presented. We found significant distention of the thoracic aortic arch and descending thoracic aorta during the cardiac cycle before and after TEVAR. Distention ranged 3-12% in diameter and 2-20% in area. This distention was preserved after TEVAR. Patients with TAA experience aortic diameter and area changes during the cardiac cycle. The magnitude, and hence the clinical importance, of this aortic distention varies among patients. After stent-graft placement, aortic distention throughout the cardiac cycle is preserved. This may have major implications for correct sizing of the endograft as well as for stent-graft design and durability as the forces on the stents may be much larger after implantation than initially anticipated by stent manufacturers.