Quantifying the effect of IMPEDE-FX packing rate and volume on pressure-normalized principal wall strain in an idealized 3D-printed aneurysm model

Background

This study aimed to quantify the nonbiologic effects of Shape Memory IMPEDE-FX embolization plug deployment rate and packing volume on pressure-normalized wall strain ($\overline{{\epsilon }_{\rho +}}$/PP) of an idealized 3D-printed abdominal aortic aneurysm model.

Methods

An endograft was deployed into an abdominal aortic aneurysm model and connected to an industry-validated hemodynamic simulator. Plugs were deployed into the excluded sac to packing volumes of 100%, 200%, 300%, and 400% under two conditions: (1) sequential and (2) immediate deployment. Axial ultrasound images were taken for each packing volume. Frame-to-frame displacements of the aneurysm wall were measured with ultrasound elastography over one cardiac cycle and normalized to the circuit's pulse pressure to calculate the mean principal strain ($\overline{{\epsilon }_{\rho +}}$/PP).

Results

In the 100% packing condition, $\overline{{\epsilon }_{\rho +}}$/PP was +113% above baseline at 15 minutes. After sequential deployment to 400%, the $\overline{{\epsilon }_{\rho +}}$/PP trended down to +43% above baseline. Immediate packing was associated with a greater $\overline{{\epsilon }_{\rho +}}$/PP reduction than sequential packing. When packed immediately to 400%, the $\overline{{\epsilon }_{\rho +}}$/PP was −6.7% below baseline.

Conclusions

These modeling data suggest that an immediate deployment strategy and higher plug packing volumes are associated with lower $\overline{{\epsilon }_{\rho +}}$/PP, which has been associated with decreased sac growth rates.

Clinical Relevance

The present findings suggest that rapid, high-volume filling of IMPEDE-FX embolization plugs results in a reduction in wall $\overline{{\epsilon }_{\rho +}}$/PP, independent of thrombus formation. Fully expanded embolization plugs in aggregate limit pulsatile aortic sac displacement likely contribute to a greater reduction in overall wall strain compared with low packing volumes. These findings may inform clinical application for this device, supporting a rapid and high-volume deployment strategy for greater reduction in $\overline{{\epsilon }_{\rho +}}$/PP status post endovascular aneurysm repair.