Dynamic Changes in the Aorta During the Cardiac Cycle Analyzed by ECG-Gated Computed Tomography

BACKGROUND: To characterize the difference in aortic dimensions during the cardiac cycle with electrocardiogram (ECG)-gated computed tomography angiography (CTA) and to determine whether other parameters in comparison to diameter could potentially provide a more accurate size reference for stent selection at the aortic arch and the proximal thoracic descending aorta. METHODS: The CTA imaging of 90 patients during the cardiac cycle was reviewed. Three anatomic locations were selected for analysis (level A: 1 cm proximal to the innominate artery; level B: 1 cm distal to the left common carotid artery; and level C: 1 cm distal to the left subclavian artery). We measured the maximum diameter, the minimum diameter, the lumen area, the lumen perimeter, and the diameter derived from the lumen area, and the changes of each parameter at each level during the cardiac cycle were compared. RESULTS: The mean age was 60.9 ± 12.4 years (range, 16–78 years). There was a significant difference in the aortic dimensions during the cardiac cycle (p < 0.001). The diameter derived from the lumen area at all three levels was changed least over time when compared to the area, perimeter, and the maximum aortic diameter (all p < 0.01). CONCLUSION: The aortic dimensional differences during the cardiac cycle are significant. The aortic diameter derived from the lumen area over other parameters may provide a better evaluation for selecting the size of the stent at the aortic arch and the proximal thoracic descending aorta. A prospective study comparing these different measurement parameters regarding the outcomes is still needed to evaluate the clinical implications.