Early Degeneration of Aortic Bioprosthetic Valves Chemical interactions, prevention and treatment

Abstract

Bioprosthetic heart valves ensure a better quality of life compared to mechanical valves but are prone to degeneration with leaflet calcification and tearing. Valvular leaflets mineralization process is initiated within interstitial cells devitalized by glutaraldehyde with formation of calcium phosphate hydroxyapatite crystals. The aim of the current paper is to analyse early bioprosthetic valve degeneration occurring in three patients that needed bioprosthetic valve explantation and reimplantation of a mechanical valve. The three patients, aged 29, 64 and 78 years presented early degeneration of the implanted valve at 30, 36 and 52 months after the intervention in the context of unavoidable risk factors like young age, chronic kidney disease and small stented valve. Computed tomography examination demonstrated calcifications of the bioprosthetic valve and histological examination confirmed the findings by identifying tissue degeneration with calcification in all cases. Early bioprosthetic valve degeneration is a serious issue in cardiovascular surgery and a major cause of valve failure requiring reintervention. Several methods could be used to delay degeneration like systemic therapy with general anti-calcification agents, the use of locally delivered drugs or tissue pretreatment with special substances (ethanol, nonionic detergents, tridecyl alcohol ethoxylate). No optimal decellularization method for all types of tissues has been yet discovered. In conclusion, early bioprosthetic valve degeneration is a reality that should be taken into account in high risk patients. Current tissue pretreatment with glutaraldehyde is not perfect as it accelerates degeneration with formation of hydroxyapatite calcifications. New methods are needed to achieve efficient decellularization while preserving the functional characteristics of the transplanted tissue.