In Silico Modelling of Aortic Strain and Strain Rate in Aortic Coarctation Treated with Stent Angioplasty with Comparison to Clinical Cohorts

Objective

Treatment of aortic coarctation has seen a shift from traditional surgical repair to the use of aortic stents. The aim of this study was to assess the impact upon hemodynamics and arterial strain when aortic coarctation is treated with a stent using an experimental coarctation model, and to confirm any findings in a clinical cohort using MRI.

Methods

An experimental patient model included a silicone arterial tree, and ventricular stroke profile was derived from patient MRI data. Pressure, flow and aortic strain was measured before and after stent placement in the model. A clinical study comprised of strain measurements using MRI in two patient cohorts; those treated with a stent, and those treated with surgical repair.

Results

Before stent placement, peak strain decreased as the pulse propagated away from the aortic valve. After stent placement however, peak strain was amplified as it approached the stent, despite peak systolic pressure having dropped by 20 mmHg. Introduction of the stent caused an almost three fold increase in aortic strain rate to 150%.s ^− 1. Echoing these results the stented patient group's strain increased from 28% +/- 14% in the ascending aorta to 43% +/- 24% (p < 0.05) pre-coarctation. This was not seen in those with surgical repair of coarctation, (ascending aorta 40% +/- 22% compared to the pre-coarctation aorta strain 38% +/- 20%, p = 0.81).

Conclusions

Despite a reduced systolic pressure gradient through a stented coarctation, dramatic increases in strain and strain rate could attribute subsequent pathologies in the aorta proximally.