An experimental model of the Ross operation: Development of resorbable reinforcements for pulmonary autografts

Objectives To circumvent the issue of pulmonary autograft (PA) dilation after the Ross procedure, surgical reinforcement strategies have been suggested in clinical or anecdotal series. However, no preclinical large-animal model of the Ross procedure is available, which is needed to enable full comprehension of the pathologic mechanisms and the effectiveness of reinforcement techniques during growth. Our aim was to develop a large-animal model of the Ross operation, to reproduce the clinical scenario in which this procedure might be applied, and allow for development and testing of various devices and techniques to improve PA performance. In addition, we aimed to test the effectiveness of a bioresorbable mesh for PA reinforcement. Methods An experimental model of transposition of the pulmonary trunk as an autograft in the aortic position has been developed and performed under cardiopulmonary bypass in 20 growing lambs, aged 3 months. The experimental design included: a control group that underwent PA transposition; a group in which the PA was reinforced with an external, synthetic, nonresorbable, polypropylene grid; and a group that received various combinations of resorbable meshes. Animals were followed up during growth for 6 months by angiography and echocardiography and eventually killed for pathologic analysis. Results All animals survived the procedure with no complications. The model was easy and reproducible. Resorbable meshes prevented PA dilation and preserved its progressive growth process, aiding histologic remodelling. Conclusions We developed an easy and reproducible model of the Ross procedure, allowing for a reliable simulation of the clinical scenario. Resorbable PA reinforcement may represent an interesting option in this context.