THREE-DIMENSIONAL PRINTING OF CUSTOM SEMIFLEXIBLE AORTIC ROOT MODELS FOR OPERATIVE PLANNING AND SURGICAL PROCTORING OF PERCEVAL VALVE IMPLANTATION

Abstract

<h3>BACKGROUND</h3> The Perceval Valve (LivaNova, London, United Kingdom) is a rapid-deployment aortic bioprosthesis with a stentless self-expanding design conducive to minimally-invasive approaches. Uptake of this valve may be limited by sizing-related nuances and its unique implantation technique. Three-dimensional modeling and printing of custom patient-specific models can be used for surgical teaching and preoperative planning. Herein, we describe our method for 3D-printing aortic roots using a semi-flexible material and demonstrate their utility for sizing and surgical planning before Perceval Valve Implantation. <h3>METHODS AND RESULTS</h3> Semiflexible models of aortic roots were virtually modelled and 3D-printed from DICOM files containing contrast-enhanced ECG-gated CTA images of the thoracic aorta obtained in patients awaiting surgical aortic valve replacement via right anterior minithoracotomy. Segmentation of the aortic root, annulus and the left ventricular outflow tract was performed using a free, open source, multi-platform software package (http://slicer.org). In Slicer, a three-dimensional shell was generated around the luminogram model and then hollowed out, replicating the interior of the aortic root. After converting the aortic surfaces to standard tessellation language (STL), the models were printed using Thermoplastic Polyurethane (NinjaFlex, NinjaTek, PA,USA) in a direct drive extruder desktop 3D printer (Printrbot Simple Metal, Printrbot, USA). Preliminary model validation was performed in a prospective and blinded manner. Surgeons sized two de-identified aortic roots prior to the patient's operation. Implantation was then performed in the operating room without knowledge of the model sizing. The same size selected in the model corresponded to the size implanted in the operating room. The root models correctly predicted the size of the implanted valve. They also demonstrated the consequences of incorrect sizing (Image). Undersizing resulted in poor leaflet coaptation. Oversizing resulted in pinwheeling or buckling of the Perceval valve, both oversizing-related complications. A prototype holder was developed for simulation of the implantation procedure, including guiding suture placement, traction-countertraction of the sutures and balloon expansion. <h3>CONCLUSION</h3> Custom 3D-printed semiflexible aortic roots allowed for simulation of intraoperative sizing and can reproduce surgically relevant signs of inappropriate sizing, including oversizing (pinwheeling and buckling) and undersizing (suboptimal coaptation). This model will be of use for preoperative planning, sizing and surgical proctoring for the Perceval valve. Custom modeling may accelerate the learning curve associated with this valve and improve uptake for use in minimally invasive aortic valve surgery, combined cases, and patients with small roots.