Impact of Cardiac Cycle on Thoracic Aortic Geometry – Morphometric Analysis of ECG Gated Computed Tomography

Abstract Objective Understanding morphological changes of ascending, arch and descending aorta with cardiac and respiratory motion is critical for planning of endovascular repair of thoracic aorta. The aim of this study was to determine the impact of the cardiac cycle on thoracic aortic geometry Methods In this retrospective study, electrocardiogram-gated cardiac computed tomography from 116 patients who were evaluated for trans-catheter aortic valve replacement were reviewed. A protocol for measurements of maximal diameters and lengths of the thoracic aorta and supra-aortic vessels was established. Measurements were made in multi-planar views perpendicular to the semi-automatically created centerline on both systolic and diastolic phases. Results Mean age was 77±11 years of our study cohort. Mean systolic and diastolic diameter were 31.6±0.42 and 30.1±4.4 mm at the sinotubular junction, 35.6±4.8 and 34.8±4.7 mm in the ascending aorta, 29.1±3.3 and 28.5±3.3 mm in the aortic arch (distal left common carotid artery), and 26.7±5.4 and 25.8±5.4 mm in the descending aorta respectively. Mean diameter change was 1.5±0.9 mm at the STJ, 0.8±0.9 mm in the ascending aorta, 0.6±0.8 mm in the aortic arch, and 0.9±1.2 mm in the descending aorta. Mean arterial strain was 5.0±3.2% at the level of the sinotubular junction, 2.4±2.7% in the ascending aorta, 2.0±2.9% in the aortic arch, and 3.9±5.7% in the descending aorta. Conclusions Our results demonstrated that small but significant circumferential and longitudinal strain was present at every aortic level. These findings may have implications for endovascular thoracic aortic repair and may provide reference values for future comparison.