Customized Expandable Polyurethane Stent Valve

M. Angel. Maluf
São Paulo Federal University, São Paulo, Sao Paulo

Purpose: Introducing a new concept of heart prosthesis: Expandable Polyurethane Stent Valve, tested and approved, following FDA guidelines: Two models for implantation in the pulmonary valve:
- Pediatric: for patients younger than 7 years old, by conventional surgery
- Adult: for patients older than 8 years, by catheter.

Methods: A new Expandable Polyurethane Stent Valve, implanted, in pulmonary position by surgery ( < 7-year-old) catheter, pulmonary position, for Pediatric and adult patients has been developed and approved in Biocompatibility, Physical, Hydrodynamic, Fatigue, Experimental, and Ultrastructure Study of explanted sheep prostheses after 24 months of follow-up, analysis, following ISO 5840-3, 2015 1
Method. In a group of 43 adult patients, in the late follow-up of surgical correction of Tetralogy of Fallot, with late follow-up, at São Paulo Federal University, with an indication for TPVR, they were classified into 6 groups according to the anatomical aspects of the pulmonary artery, analyzed by CT Angiography:
Tipe.1: Pulmonary valve insufficiency (PVI) (7 pat.)
Tipe.2: PVI + pulmonary trunk stenosis (8 pat.)
Tipe.3: PVI + pulmonary trunk aneurysmal dilation (15 pat.)
Tipe.4: PVI + PT + RPA + LPA – stenosis (6 pat.)
Tipe.5: Pulmonary prosthesis dysfunction (5 pat.)
Tipe.6: RV-PA Conduit disfunction (4 pat.)

Results: Through post-processing images by CT Angiography, it was possible to enlarge them to their natural size, followed by 3D printing, in elastic and transparent plastic mass, keeping the interior of the hollow cardiac cavities.
Custom prosthesis manufacturing: 3 transverse diameters (TD) are measured: TD1: At the level of the Pulmonary Ring; TD2: In the middle third of the TP and TD3: At the level of the origin of the pulmonary arteries. Also, a longitudinal measure( LM), allows for knowing the length of the prosthesis: The distance between the Pulmonary ring and the origin of the pulmonary arteries.
Patients older than 8 years are treated with interventional hemodynamic procedures: G1: TPVR procedure. G2, G3, and G6: Double Sent Valve Technique, is performed. After implanting in the same surgical procedure, a cylindrical stent is first implanted to correct the lesions in the pulmonary trunk and then the valve stent is implanted inside the cylindrical stent. In G4, as well as in patients under 8 years of age, valve stent implantation is performed by surgical approach; the correction of defects is made with synthetic material, such as a Polytetrafluoroethylene prosthesis, followed by implantation of a cylindrical stent. G5: Valve in valve procedure.

Conclusion: This new concept of heart prosthesis, with pediatric and adult models and with the double stent technique, allows the correction of virtually all congenital or residual diseases of the pulmonary artery.
The manufacture in the laboratory, with synthetic material, formation of leaflets without suture, hydrodynamic and fatigue tests, showing resistance of the material, expansion programmed with a balloon and free of mineralization, during the late follow-up of the experimental implant, make this a prosthesis ideal for pediatric use.
The customization of this prosthesis also allows for treating pulmonary insufficiency and correcting residual pulmonary artery defects.

Identify the source of the funding for this research project: Startup: Synthetic Heart Technology - São Paulo - Brazil.