Poster T18 - PHAST Valves: “Plug-and-play Hydrodynamic Apparatus for Simplified Testing of Valves" for in vitro bioprosthetic heart valve experimentation

Introduction: Bovine pericardial (BP) bioprosthetic heart valves (BHV) are the most common aortic valve replacement. The desirability and increased use of tissue-based valves coupled with longer survival of patients receiving valve replacements has led to a growth in BHV research. Validation of the hydrodynamic effects of various leaflet modifications to improve durability is limited by availability of costly clinical grade BHV models. We developed a reproducible, low-cost “plug-and-play" style bovine pericardial BHV model system.

Materials and

Methods: BP was obtained from an animal tissue supplier, glutaraldehyde fixed in flat sheets, and leaflets cut using a template produced using literature derived annulus based relative measurements. A frame for leaflet mounting was fabricated from a steel wire using a custom designed linear stamp, then wrapped around a 25mm stock and crimped (Figure 1a). BP leaflets were then sutured in a simple running fashion to the wireform (Figure 1b), requiring 30 minutes per valve. A two piece pulse duplicator interfacing (PDI) wireform-leaflet holder was designed from the shape of the wire and 3D printed (Figure 1c). Wire mounted leaftlet constructs are slid into place and held by the compression of the two PDI parts in the z-axis (Figure 1c). This apparatus covers all areas of potential leak or regurgitation that are not through the valve orifice, and the wire-leaflet construct is easily exchanged. Videography, echocardiography, and hydrodynamic data were collected in a pulse duplicator to evaluate the performance of the valve.

Results, Conclusions, and Discussions: A template was made for leaflet shape and the remainder of parts were all fabricated from CAD models and commercially available 3D printers, thereby making this model highly reproducible with minimal intermodel variability. The fabricated PHAST valve has an initial cost $351.03 for the first replicate (if external/contract 3D printing services are utilized), with a marginal cost of $17.77 for each subsequent testing replicate. Pulse duplicator testing demonstrated an effective orifice area (EOA) of 2.67 +/- 0.01cm2 (commercial 2.47cm2, Edwards PERIMOUNT Magna), mean transvalvular pressure gradient of 7.7 +/- 0.1mmHg (commercial 10.1mmHg), a regurgitant fraction (RF) of 13.4 +/- 0.1% (commercial 8.6%), with videography (Figure 1d) and 3D echocardiography (Figure 1e) confirming satisfactory valve leaflet motion.

BP based BHV models can be rapidly and reliably produced in a protocolized fashion with hydrodynamic properties that meet ISO-5840 specifications and are comparable to those of commercial valves for the purposes of research. This model is cost effective and fabrication does not require surgical training, making it a useful template for BHV investigators from various disciplines. The design is simplified significantly from other models in the literature for BHV research and allows for high replicate numbers with rapid fabrication and testing. The PHAST Valve is compatible with multiple pulse duplicator systems that are utilized for various testing purposes, including high precision hydrodynamic assessment and high quality 3D echocardiography, which offers the potential for comprehensive valve assessment in the in vitro experimental setting.

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