Evaluation of Blood Flow Energy Loss before and after Endovascular Aneurysm Repair Using Four-dimensional Flow MR...

To evaluate hemodynamic changes associated with aortic stiffness after endovascular aneurysm repair (EVAR) for abdominal aortic aneurysm using 4-dimensional flow MRI (4D Flow MRI), with a focus on blood flow energy loss (EL).

Thirty-five patients underwent 4D Flow MRI before and after EVAR. Flow velocity, volume, and reflux ratio were measured at the juxtarenal aorta, aneurysmal orifice, and distal iliac landing zone. EL was assessed at the neck and treatment segments, and its relationship with pulse wave velocity (PWV) was analyzed.

Post-EVAR velocity and volume increased across all segments, whereas reflux ratio decreased at the aneurysmal orifice. EL significantly increased at the neck (6.3 [4.0-9.7] vs 16.7 [5.4-29.9] mW, P < 0.001) and treatment segments (29.0 [21.8-45.2] vs 265.6 [182.7-443.6] mW, P < 0.001). Patients with increased PWV showed a greater EL rise at the neck (6.8 [4.2-11.5] vs 16.9 [7.9-30.4] mW, P = 0.001). When stratified by pre-EVAR brachial-ankle PWV, the high-risk group (≥ 1800 cm/s) had a higher post-/pre-EL ratio (6.7 [4.0-10.6] vs 10.4 [7.0-15.8], P = 0.018).

EVAR induces specific hemodynamic alterations. The post-operative rise in flow velocity, volume, and EL indicates increased aortic stiffness, suggesting elevated cardiac afterload in patients with advanced arterial stiffness.