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

Background: A long-term complication of synthetic patch repair of coarctati on is true aneurysm formation. Aim: An in vitro study was undertaken to det ermine the effects of patch angioplasty on aortic geometry and strain adjac ent to the patch. Methods: Segments of human descending thoracic aorta were subject to 10 pre ssure loading cycles (10-120 mm Hg; 1.36-16.32 kPa) before and after simula ted coarctation repair with a synthetic patch. Local curvature and strain w ere estimated by fitting a geometric model to reconstructed three-dimension al 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 circumferen tial curvature decreased from 0.1543 +/- 0.03 to 0.1065 +/- 0.03 mm(-1). Th e average major extension reached a maximum of 1.43 +/- 0.08. After patch i mplantation, the average circumferential curvature was reduced relative to control at all pressures. Average major extensions were significantly great er 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 o bserved and major extensions were greatest immediately adjacent to the patc h. Inference: Synthetic patch repair of coarctation of the aorta increases wal l strain and produces significant regional gradients in strain. With contro l aortic material properties there may be a substantial increase in wall st ress immediately adjacent to the aorta, which could lead to true aneurysm f ormation.