Objectives: Residual regurgitation is common after congenital surgery for right ventricular outflow tract malformation. It is accepted as there is no competent valve solution in a growing child. We investigated a new surgical technique of trileaflet semilunar valve reconstruction (also called AVaTAR procedure) possessing the potential of remaining sufficient and allowing for some growth with the child. In this proof-of-concept study, our aim was to evaluate if it is achievable as a functional semilunar valve reconstruction in vitro.
Methods: Explanted pulmonary trunks from porcine hearts were evaluated in a pulsatile flow-loop model.
Figure: Illustration of the heart simulator: (A) atrial chamber; (B) ventricular chamber; (C) compliance chamber; (D) mechanical valve; (E) recirculation tube; (F) piston pump; (G1) arterial trunk holder, ventricular side; and (G2) arterial trunk holder, arterial side.
First, the native pulmonary trunk was investigated, after which the native leaflets were explanted. Then, the trileaflet semilunar valve reconstruction (AVaTAR procedure) was performed and investigated. All valves were initially investigated at a flow output of 4 l/min and subsequently at 7 l/min. The characterization was based on hydrodynamic pressure and echocardiographic measurements.
Results: Eight pulmonary trunks were evaluated.
All valves were competent on colour Doppler. There was no difference in mean pulmonary systolic artery pressure gradient at 4 l/min (P = 0.32) and at 7 l/min (P = 0.20).
Figure: Grouped bars chart with mean and standard deviation at 4 and 7 l/min: (A) mean systolic pulmonary artery gradient and (B) mean diastolic pulmonary artery gradient.
Coaptation length was increased in the neo-valve at 4 l/min (P < 0.001, P < 0.001, P = 0.008) and at 7 l/min (P < 0.001, P = 0.006, P = 0.006). All leaflets in the neo-valve billowed below the annular plane at both flow outputs. These two features are key to allow for accommodation to the patient ́s growth.
Figure: Box plots and whiskers with median and upper/lower interquartile range 1.5 depicting (A) coaptation in all 3 echocardiographic views and (B) billow for each leaflet in all 3 echocardiographic views the native valve and neo-valve at 4 and 7 l/min, respectively.
A windmill shape, the third key feature of the ability to accommodate to child ́s growth, was observed in all neo-valves.
Figure: Echocardiographic images of the native and the neo-valve in (A) short- axis view and a (B) long-axis view.
Conclusions: Trileaflet semilunar valve reconstruction (AVaTAR procedure) results in a neo-valve that is sufficient and non-stenotic. This valve showed an increased coaptation length, a windmill shape and a billow below the annular plane, which are speculated to decrease with the growth of the patient, while keeping the neo-valve sufficient during this time.
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