Abstract 16230: Pulmonary Autograft Wall Stresses One Year After Ross Operation

Abstract

Introduction: The Ross procedure is an excellent option for children and young adults who need aortic valve replacement as this surgery can restore patient survival to that of a normal sex and aged-matched population. However, some patients experience aneurysmal formation during autograft remodeling and require reoperation. As the underlying biomechanics of autograft remodeling are unknown, we investigated patient-specific wall stresses in pulmonary autografts one year post-operatively to better understand systemic pressure-driven early autograft wall stresses. Methods: Ross patients (n=16) who underwent intraoperative collection of pulmonary root/aortic specimen, and subsequent one-year MRI follow-up were recruited. Patient-specific material properties from their tissue were experimentally determined and incorporated into autograft ± Dacron and ascending aorta finite element models. A multiplicative approach was used to account for pre-stress geometry from in-vivo MRI. Physiologic pressure loading was simulated with LS-DYNA software. Results: At systemic systole, first principal stresses were 567kPa (25-75% IQR, 485-675kPa), 809kPa (691-1219kPa), and 382kPa (334-413kPa) at autograft sinuses, sinotubular junction (STJ), and ascending aorta, respectively. Second principal stresses were 355kPa (320-394kPa), 360kPa (310-426kPa), and 184kPa (147-222kPa) at autograft sinuses, STJ, and ascending aorta, respectively. Mean autograft diameters were 38.3±5.3mm, 29.9±2.7mm, and 26.6±4.0mm at sinuses, STJ, and annulus, respectively. Conclusions: First principal stresses were mainly located at STJ, particularly when Dacron reinforcement was applied to constrain STJ dilatation. However, at one-year after the Ross operation, autograft dilatation was not seen despite elevated autograft wall stresses compared to their internal controls, the lower wall stresses in corresponding native distal ascending aorta. In this group of patients, higher risk of dilatation is expected in the sinuses and STJ if not constrained by Dacron than the corresponding ascending aorta. Future follow-up will elucidate the biomechanics of long-term autograft remodeling to develop predictive models for autograft dilatation.