[Correlation between malfunction of a bioprosthesis and deformation of a valve stent. Comparison of three different vale models].
BACKGROUND
Stent deformation seems to be effective in the long term performances of bioprostheses.


METHODS
The Inward Banding Angle (IBA) of three different models of bioprostheses explanted during the period 1991-1992 at our Division of Cardiac Surgery in 45 different patients (26 males; 9 females; mean age 59.71 +/- 10.74, range 26-75) has been measured. Explanted valves were as follow: Hancock, (H = 13); Carpentier-Edwards (C = 14) e Xenomedica (X = 18). Primary tissue failure was the most common cause of re-operation (n = 30; 66.7%) but also endocarditis (n = 6; 13.3%) and paraprothetic leak (n = 10; 22.2%). A semi-quantitative score (0-4) was used to assess calcifications (1.51 +/- 1.56); tears (0.41 +/- 0.98); vegetation's (0.51 +/- 0.99) and fibrosis (2.7 +/- 1.27). The mean follow-up was 7.77 +/- 3.79 years (range 1.5 +/- 16 years). The mean IBA evaluated after explantation was 3.34 +/- 2.29 degrees.


RESULTS
Statistical analysis showed a significance in term of IBA in the Hancock group vs Carpentier (P < 0.02); a less duration in the Xenomedica group vs H and C (p < 0.001) and an increased susceptibility to vegetation's and fibrosis in the Xvs C (p < 0.01) and H (p < 0.05) respectively. A suggestive correlation between IBA and time and between IBA and diameter was found but no statistical significance was observed.


CONCLUSIONS
In conclusions, it is suggested that all materials tends to deform during time and a possible explanation of stent deformation can be the different material used in the stent fabrication. Moreover, mechanical stress and compression around the ring can be another mechanism of creep.
Actis Dato
G M
GM
Divisione di Cardiochirurgia, Università degli Studi, Torino.
Caimmi
P
P
Di Rosa
E
E
Deorsola
L
L
Aidala
E
E
Punta
G
G
Poletti
G
G
Di Summa
M
M
D000328:Adult; D000368:Aged; D001705:Bioprosthesis; D005260:Female; D006349:Heart Valve Diseases / Q000601:surgery*; D006350:Heart Valve Prosthesis / Q000145:classification; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000601:surgery; D011475:Prosthesis Failure; D015607:Stents
Correlazione tra malfunzionamento di protesi biologiche e deformazione dello stent valvolare. Confronto tra diversi modelli di valvola.