Impact of Cardiac Cycle on Thoracic Aortic Geometry—Morphometric Analysis of Ecg Gated Computed Tomography

Abstract

Understanding morphological changes of ascending aorta, aortic 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. In this retrospective study, electrocardiogram-gated cardiac computed tomography from 116 patients who were evaluated for transcatheter 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 multiplanar views perpendicular to the semiautomatically created centerline on both systolic and diastolic phases. Mean age was 77±11years of our study cohort. Mean systolic and diastolic diameter were 31.6±0.42 and 30.1±4.4mm at the sinotubular junction (STJ), 35.6±4.8 and 34.8±4.7mm in the ascending aorta, 29.1±3.3 and 28.5±3.3mm in the aortic arch (distal left common carotid artery), and 26.7±5.4 and 25.8±5.4mm in the descending aorta. Mean diameter change was 1.5±0.9mm at the STJ, 0.8±0.9mm in the ascending aorta, 0.6±0.8mm in the aortic arch, and 0.9±1.2mm in the descending aorta. Mean arterial strain was 5.0±3.2% at the level of the STJ, 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. 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.