Post-EVAR aortic neck elongation: is a real phenomenon or a conformational change during the cardiac cycle?

Stent-graft migration is a late-term complication of endovascular abdominal aortic aneurysm repair (EVAR). A recent published study suggests that stent graft migration could be explained only by aortic neck elongation, mimicking the appearance of distal stent graft migration. Several studies about the use of dynamic CT Angiography (CTA) in the evaluation of aortic conformation changes during the cardiac cycle demonstrate that axial aortic pulsatility exists. No studies have been carried out to evaluate if a longitudinal aortic pulsatility also exists, that could justify the aortic neck elongation previously reported.

To assess variations in length of proximal neck and infrarenal abdominal aorta in patients selected to undergo EVAR; to assess if longitudinal aortic pulsatility could modify EVAR planning.

40 patients with Abdominal Aortic Aneurysm (AAA) underwent both static and dynamic ECG-gated 64-CTA (0.625 mm-slice-collimation; 1.25 mm-reconstruction increment). Manual measurements of aortic neck length and infrarenal abdominal aorta were performed on modified coronal images to determine dynamic conformational changes.

Significant longitudinal pulsatility was demonstrated within aneurysm neck (19.1 ± 8.6%) and infrarenal abdominal aorta (6.6 ± 1.6%). When compared to dynamic measurements, the endograft previously selected according to static images in terms of fixation, would be potentially changed in 6/40 patients (15%) whereas 4/40 (10%) patients were not eligible for EVAR.

Dynamic ECG-gated CTA may provide information regarding longitudinal pulsatile motion that could change the EVAR planning based on static imaging. Reported post-EVAR elongation of infrarenal aortic neck could be an unreal phenomenon only due to a conformational change during cardiac cycle.