OBJECTIVES: Reinforcements for the pulmonary autograft (PA) in the Ross operation have been introduced to avoid the drawback of conduit
expansion and failure. With the aid of an in silico simulation, the biomechanical boundaries applied to a healthy PA during the operation
were studied to tailor the best implant technique to prevent reoperation.
METHODS: Follow-up echocardiograms of 66 Ross procedures were reviewed. Changes in the dimensions and geometry of reinforced
and non-reinforced PAs were evaluated. Miniroot and subcoronary implantation techniques were used in this series. Mechanical stress
tests were performed on 36 human pulmonary and aortic roots explanted from donor hearts. Finite element analysis was applied to obtain
high-fidelity simulation under static and dynamic conditions of the biomechanical properties and applied stresses on the PA root and leaflet
and the similar components of the native aorta.
RESULTS: The non-reinforced group showed increases in the percentages of the mean diameter that were significantly higher than those
in the reinforced group at the level of the Valsalva sinuses (3.9%) and the annulus (12.1%). The mechanical simulation confirmed geometrical
and dimensional changes detected by clinical imaging and demonstrated the non-linear biomechanical behaviour of the PA anastomosed
to the aorta, a stiffer behaviour of the aortic root in relation to the PA and similar qualitative and quantitative behaviours of leaflets
of the 2 tissues. The annulus was the most significant constraint to dilation and affected the distribution of stress and strain within the entire
complex, with particular strain on the sutured regions. The PA was able to evenly absorb mechanical stresses but was less adaptable to
circumferential stresses, potentially explaining its known dilatation tendency over time.
CONCLUSIONS: The absence of reinforcement leads to a more marked increase in the diameter of the PA. Preservation of the native geometry
of the PA root is crucial; the miniroot technique with external reinforcement is the most suitable strategy in this context
