Wall stresses of early remodeled pulmonary autografts.

Abstract

OBJECTIVE\nThe Ross procedure is an excellent option for children or young adults who need aortic valve replacement because it can restore survival to that of the normal aged-matched population. However, autograft remodeling can lead to aneurysmal formation and reoperation, and the biomechanics of this process is unknown.\xa0This study investigated postoperative autograft remodeling after the Ross procedure by examining patient-specific autograft wall stresses.\n\n\nMETHODS\nPatients who have undergone the Ross procedure who had intraoperative pulmonary root and aortic specimens collected were recruited. Patient-specific models (n\xa0=\xa016) were developed using patient-specific material property and their corresponding geometry from cine magnetic resonance imaging at 1-year follow-up. Autograft\xa0±\xa0Dacron for aneurysm repair and ascending aortic geometries were reconstructed to develop patient-specific finite element models, which incorporated material properties and wall thickness experimentally measured from biaxial stretching. A multiplicative approach was used to account for prestress geometry from in\xa0vivo magnetic resonance imaging. Pressure loading to systemic pressure (120/80) was performed using LS-DYNA software (LSTC Inc, Livermore, Calif).\n\n\nRESULTS\nAt systole, first principal stresses were 809\xa0kPa (25%-75% interquartile range, 691-1219\xa0kPa), 567\xa0kPa (485-675\xa0kPa), 637\xa0kPa (555-755\xa0kPa), and 382\xa0kPa (334-413\xa0kPa) at the autograft sinotubular junction, sinuses, annulus, and ascending aorta, respectively. Second principal stresses were 360\xa0kPa (310-426\xa0kPa), 355\xa0kPa (320-394\xa0kPa), 272\xa0kPa (252-319\xa0kPa), and 184\xa0kPa (147-222\xa0kPa) at the autograft sinotubular junction, sinuses, annulus, and ascending aorta, respectively. Mean autograft diameters were 29.9\xa0±\xa02.7\xa0mm, 38.3\xa0±\xa05.3\xa0mm, and 26.6\xa0±\xa04.0\xa0mm at the sinotubular junction, sinuses, and annulus, respectively.\n\n\nCONCLUSIONS\nPeak first principal stresses were mainly located at the sinotubular junction, particularly when Dacron reinforcement was used. Patient-specific simulations lay the foundation for predicting autograft dilatation in the future after understanding biomechanical behavior during long-term follow-up.