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Expandable Polyurethane Stent Valve, implanted by catheter
Miguel A. Maluf1, Mariana G. Massei2.
1Universidade Federal de São Paulo, São Paulo, Brazil, 2Universidade Federal de São Paulo, São paulo, Brazil.

OBJECTIVE: A expandable Polyurethane stent valve®, (EPSV), with a special design for pediatric patients, may be an option for biological prostheses, whose calcification or mismatch, in child's development, shorten their durability.
METHODS:Methods: An expandable chrome - cobalt stent, was applied polyurethane, for the formation of three leaflets, without sewing, it was sumitted to: I- Physical test of samples of PU crimped and non-crimped was performed and scanner for surface for mechanical properties. II- Hydrodynamic test. Using a pulsatile flow, to register: valvular area, pressure gradient and valve regurgitation. III- Experimental: Ten sheep were submitted to implantation of EPSV by catheter, in pulmonary position. Expansion diameter: 22mm (7 cases) and 18mm (3 cases).
RESULTS: Results: I- Physical tests: PU showed to be a thermoplastic structure, resistant to crimping and elongation. II- Hydrodynamic test showed low gradients and absent or trivial regurgitation of the prosthesis. III- Experimental test: Eight (80%) surviving sheep were submitted to 3D echocardiographic study, showed: satisfactory hemodynamic performance, with low transvalvular gradient (M = 6.60 mmHg), absent or trivial valvular regurgitation, absent leak and free of calcification.Three sheep (18 mm valve stent), were submitted to expansion of the prosthesis to 22 mm, with success. Eight prostheses were explanted with 6 to 21 months of follow-up; all prostheses were intact.Two sheep survive after 24 months of follow-up.
CONCLUSIONS:
Conclusions: EPSV can be implanted in pulmonar position in growing children, during conventional surgery and expanding for peripheral vessels approach.


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