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A Novel Biomimetic Synthetic Expandable Pulmonary Valve In A Chronic Growing Ovine Model
Sophie C Hofferberth1, John P. Carney2, Jill T. Schappa Faustich2, Mossab Saeed1, Richard W. Bianco2, Elazer R. Edelman3, Pedro J. del Nido1.
1Department of Cardiac Surgery, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA, 2Experimental Surgical Services, University of Minnesota, Minneapolis, MN, USA, 3Biomedical Engineering Center, Institute for Medical Engineering & Science, Massachusetts Institute of Technology, Cambridge, MA, USA.

OBJECTIVE: Congenital pulmonary valve disease has life-limiting consequences that often warrant early valve replacement. Yet, a growth-accommodating prosthetic valve remains elusive. Today, pediatric patients face repeated high-risk open-heart operations to replace outgrown valves. This study evaluated the safety and feasibility of a novel biomimetic synthetic expandable surgical pulmonary valve (Autus Size-Adjustable Valve; Autus Valve) in a 20-week growing ovine model.
METHODS: The Autus Valve was implanted at 12.7 mm internal diameter (ID) in the native pulmonary valve position of six juvenile sheep (mean weight: 23.4 +/- 2.4 kg). All animals underwent minimally invasive transcatheter balloon dilation to expand the valve at three pre-defined timepoints (30, 60, and 90 days post-valve implantation, Figure 1) and then survived to 140 days (20 weeks). Device function was evaluated by serial transthoracic echocardiography and intracardiac catheterization pre and post each balloon dilation procedure.
RESULTS: The Autus Valve was successfully implanted in all six animals, and all survived to term. All study animals displayed expected growth profiles, gaining >80% in body weight. In each animal the Autus Valve was serially balloon dilated up to 20 mm ID, without complications. The valve exhibited preserved leaflet mobility and coaptation in all six animals, with unidirectional pulmonary blood flow maintained at all expansion diameters. At term, the peak transvalvular gradient was 12 +/- 10 mmHg, with no regurgitation. In all animals, necropsy and histopathology demonstrated healthy right ventricular myocardium, no inflammatory infiltrate, no clinically significant thrombus on the device or device-related distal thrombo-emboli, and no leaflet mineralization. There was no damage to the native pulmonary artery wall integrity due to device expansion.
CONCLUSIONS: The Autus size-adjustable surgical pulmonary valve can be safely and effectively balloon-expanded post-implantation to accommodate growth, offering new alternatives to pediatric patients with valve disease.

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