The effect of synthetic patch repair of coarctation on regional deformation of the aortic wall

Abstract

Background: A long-term complication of synthetic patch repair of coarctation is true aneurysm formation. Aim: An in vitro study was undertaken to determine the effects of patch angioplasty on aortic geometry and strain adjacent to the patch. Methods: Segments of human descending thoracic aorta were subject to 10 pressure loading cycles (10-120 mm Hg; 1.36-16.32 kPa) before and after simulated coarctation repair with a synthetic patch. Local curvature and strain were estimated by fitting a geometric model to reconstructed three-dimensional surface marker points. Results: In the control aortas, when pressure increased from 11 ± 1.0 to 124 ± 4.0 mm Hg (1.5 ± 0.14 to 16.86 ± 0.54 kPa), average circumferential curvature decreased from 0.1543 ± 0.03 to 0.1065 ± 0.03 mm-1. The average major extension reached a maximum of 1.43 ± 0.08. After patch implantation, the average circumferential curvature was reduced relative to control at all pressures. Average major extensions were significantly greater than paired control values and reached a maximum of 1.55 ± 0.08 at 122 ± 4.0 mm Hg (16.59 ± 0.54 kPa). Substantial strain inhomogeneity was observed and major extensions were greatest immediately adjacent to the patch. Inference: Synthetic patch repair of coarctation of the aorta increases wall strain and produces significant regional gradients in strain. With control aortic material properties there may be a substantial increase in wall stress immediately adjacent to the aorta, which could lead to true aneurysm formation.