Allograft heart valve sterilization: A six-year in-depth analysis of a twenty-five–year experience with low-dose antibiotics

Abstract

At the Prince Charles Hospital, from a 25-year experience with allograft heart valves (1969 to 1994), a 6-year analysis from March 1988 to August 1994 of the contamination rates and efficiency of a short-duration, low-dose antibiotic sterilization protocol was made. This analysis covered 642 collections and 680 aortic and pulmonary valve implants. Tissue samples obtained at collection, valve trimming, postantibiotic incubation, and implant provided the raw data. At collection, valves retrieved in open mortuaries produced the highest contamination rate of 54%. Minimal exposure to antibiotics during transport and trimming reduced the contamination rate to 11% (p < 0.05). This was similar to the contamination rate at trimming for valves collected in the "sterile" operating room from multiorgan donors (12%). Antibiotic incubation at 37 degrees C for 6 hours reduced the contamination rate to 4% (p < 0.05). Only valves that showed no contamination at cryopreservation were implanted. However, at implant, resected tissue from valves that had been incubated in antibiotics showed a contamination rate of 3%, presumably from the theater environment, compared with 15% (p < 0.05) for tissue from valves that had not been incubated. A residual antibiotic effect appears present at the time of implant in valves that have been incubated in antibiotics and may assist in the reduction of and resistance to infection in the immediate postoperative period. This is supported by the low incidence of endocarditis in the first 3 postoperative months. The simple and effective protocol of collection within 24 hours of death combined with low-dose antibiotic sterilization is sufficient to produce pathogen-free valves in the majority of cases (> 95%).

Determination of Residual Antibiotics in Cryopreserved Heart Valve Allografts

“…The clinical use of heart valve and vascular allografts has been markedly limited by their availability [3]. Therefore, the retrieval of the allograft source material from the NHBDs was envisaged as one of the possibilities for increasing the yield of cardiovascular allografts.…”

“…Different protocols (with varying combinations of antibiotics, duration of incubation, and temperature conditions) were adopted in different Tissue Establishments [3,4,5,19,20], with relatively good success in the eradication of contaminant germs. However, some antibiotics, being part of the decontamination cocktail, may have led to premature allograft deterioration, necessitating reoperation within a few years and thereby potentially endangering the patient's life.…”

“…Exposure to low concentrations of different antibiotics during the 20-48 h before cryopreservation reduces the contamination rate to about 5-10% [2,3]. Different Tissue Establishments worldwide, responsible for cardiovascular allograft decontamination, have adopted different cocktails of antibiotics, under different temperature conditions and for varying duration [4][5][6].…”

Fresh Homografts Obtained through a National Organ-Sharing Programme for Repair of Congenital Heart Disease

“…Despite the fact that they were harvested under sterile conditions and used within a relatively short time, the use of antibiotics, particularly amphotericin B, renders them practically non-viable. 9,10 The importance of viability in homograft durability is not well defined. Experience with homovital aortic valves and aortic root replacement in adults has demonstrated a freedom from structural degeneration of 98% and 89% at 10 years, which is higher when compared with valves that were either cryopreserved or stored at 4°C.…”

Análise das atividades dos oito anos iniciais do Banco de Valvas Cardíacas Humanas do Hospital de Caridade da Irmandade da Santa Casa de Misericórdia de Curitiba

“…The harvesting procedures are made in environments that range from surgical centers with ideal conditions of antisepsis to contaminated morgues [16]. These variables significantly influence not only the rate of contamination but also the types of germs involved [17]. The success of decontamination, that uses a culture medium with low concentrations of antibiotic, is related to a low level of contamination and sterilized harvesting techniques [18].…”