Computed Tomography-based Patient-specific Biomechanical and Fluid Dynamic Study of Anomalous Coronary Arteries with Origin from the Opposite Sinus and Intramural Course.

Background: The anomalous coronary arteries originating from the opposite sinus of Valsalva (ACAOS) constitutes one of the most clinically relevant coronary artery anomalies in adults. Exact pathophysiology and the impact of intramural (IM) course segment stenting in ACAOS with IM course (ACAOS-IM) has not been clarified. We aimed to elucidate the pathophysiology and impact of stenting applying biomechanical and computational fluid dynamics to computed tomography (CT) in patient-specific coronary vessel reconstruction.

Methods: We separated coronary artery (left or L-, right or R-) ACAOS-IM into segments (proximal, mid and distal), based on coronary angiography and coronary CT angiography features, in a series of patients at Rovigo General Hospital, Italy, between 1 January 2003 and 1 January 2018. Blood pressure gradient across the coronary circulation, calculated blood flow, vorticity magnitude, wall shear stress (WSS) and IM segment deformation were analysed by simulating exercise, before and after virtual stent implantation.

Results: In 21 symptomatic patients (13 males, mean age 46.1 ± 8.1 years, L-ACAOS-IM in 9 and R-ACAOS-IM in 12 patients), computational fluid dynamic analysis in both L- and R-ACAOS demonstrated higher basal WSS values in the IM course (9.5 ± 0.2 and 8.6 ± 0.2 Pa for R- and L-ACAOS, respectively), than in the rest of the vessels. These values decreased after stenting. Vorticity magnitude significantly decreased after stenting as well, compared with baseline. Biomechanical deformation analysis revealed not only compression, but also a twisting of the IM segment with a mean distal pressure drop of 32% and 35% in R- and L-ACAOS, respectively, which was corrected by stent implantation.

Conclusions: In both L- and R-ACAOS subtypes, the IM segment appeared to be phasically compressed and deformed with a degree of twisting that causes resting and exercise cross-sectional deformation and a drop in distal pressure. Stenting of the IM segment results in normalisation of the flow profile, correction of the IM segment deformation and reverses the drop in pressure, for both variants of ACAOS.