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Chirurgia 2011 October;24(5):263-6


language: English

Bioprosthetic valve modification for full retention of the native mitral valve

Paterson H. 1, 2, Seitz M. 1, Symes M. 1, See V. 3, Lu J. 3, Byth K. 4, Thomas L. 5

1 Department of Cardiothoracic Surgery, Westmead Hospital, Westmead, Australia; 2 Department of Surgery, University of Sydney, Sydney, Australia; 3 Department of Cardiology, Westmead Hospital, Westmead, Australia; 4 Westmead Millenium Institute, Westmead, Australia 5Department of Cardiology, Liverpool Hospital, Sydney, Australia


Aim. Preservation of the mitral valve anterior leaflet at the time of prosthetic valve insertion improves left ventricular function but may cause left ventricular outflow tract obstruction (LVOTO). The incidence and predictors of LVOTO following prosthetic mitral valve insertion have not been identified.
Methods. Twenty-two adult sheep underwent insertion of 44 mitral prostheses of various sizes, with complete retention of the native mitral valve. The high profile Mosaic stented porcine (Medtronic Inc), the low profile Biocor stented porcine (St Jude Medical Inc) and non-co mmercial rigid circular annular rings were used. Bioprosthetic distortion was performed with cinching sutures. The valves were inserted with the stent posts adjacent the co mmissures, (orthotopic position) or with a stent post adjacent to the mid point of the anterior leaflet (malrotated).
Results. LVOTO with associated systolic anterior motion of the retained native anterior mitral leaflet (SAM) was identified with 18 of the 44 prostheses. There were no independent predictors of LVOTO/SAM on multivariate statistical analysis. LVOTO/SAM was reduced or abolished by reducing the antero-posterior diameter of the prosthesis by external cinching.
Conclusion. We were able to successfully produce LVOTO/SAM in an ovine model. The LVOTO/SAM could be abolished by reducing the antero-posterior diameter of the prosthetic valve by external cinching. No independent predictors of LVOTO/SAM were identified in this study but that may be due to the large variety of prosthetic sizes and shapes used in the relatively small number of sheep.

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