Detoxification on top of enhanced, diamine-extended glutaraldehyde fixation significantly reduces bioprosthetic root calcification in the sheep model.
OBJECTIVE
Increased concentrations of glutaraldehyde (GA), diamine-extension (DA) of crosslinks and subsequent extraction of excess GA all reduce bioprosthetic calcification in the subdermal rat model. The study aim was to demonstrate the combined effect of all three treatments in a circulatory sheep model.


METHODS
Two fixation treatments were used for GA detoxification (urazole in acetate buffer, 0.1 M; pH 4.5; 37 degrees C; 7 days): (i) conventional 0.2% GA fixation (4 degrees C; 7 days); and (ii) enhanced 3.0% GA fixation (4 degrees C; 2 days, followed by a DA interim step; 100 mM L-lysine; 37 degrees C; 2 days, followed by GA; 3.0%; 37 degrees C; 5 days). Entire porcine root prostheses were implanted in the distal aortic arch of young sheep for 12 weeks (n = 5 per group). Non-detoxified 0.2% GA-treated roots served as controls (n = 5). Calcium analysis was based on atomic absorption spectrophotometry; morphology was assessed using light and transmission electron microscopy.


RESULTS
Detoxification alone resulted in an 83% reduction of leaflet calcification (p = 0.086), but achieved only 23% (p = 0.145) and 12% (p = 0.362) mitigation of calcification in aortic wall and sinus tissue, respectively. When combined with DA-enhanced 3% GA fixation, detoxification led to a 95% reduction in leaflet calcification (p = 0.057), followed by 79% in sinus (p = 0.003) and 79% in aortic wall tissue (p = 0.0003). Morphologically, detoxification primarily affected leaflets and the subadventitial layer of aortic wall tissue, whereas enhanced fixation seemed to affect all structures.


CONCLUSIONS
It was shown in a circulatory sheep model that a combination of DA-enhanced fixation with an extraction process of excess GA leads to a distinct mitigation of leaflet and aortic wall calcification.
Trantina-Yates
Ameli E
AE
Department of Cardiothoracic Surgery, Cape Heart Centre, University of Cape Town, South Africa.
Human
Paul
P
Zilla
Peter
P
D000818:Animals; D001705:Bioprosthesis; D002114:Calcinosis / Q000473:pathology / Q000517:prevention & control*; D003432:Cross-Linking Reagents; D003959:Diamines / Q000494:pharmacology; D005976:Glutaral / Q000737:chemistry; D006350:Heart Valve Prosthesis / Q000009:adverse effects; D007150:Immunohistochemistry; D008422:Materials Testing; D023421:Models, Animal; D012756:Sheep; D016060:Sorption Detoxification; D013054:Spectrophotometry, Atomic; D016707:Tissue Fixation
D003432:Cross-Linking Reagents; D003959:Diamines; D005976:Glutaral