Use of aortic valve allografts from hepatitis B surface antigen-positive donors.

Over a 28-month period, 31 patients undergoing aortic valve replacement received valve allografts from hepatitis B surface antigen-positive, hepatitis B e antigen-negative donors. At the time of operation, 22 recipients were immune to hepatitis B infection; 19 had antibodies to hepatitis B surface antigen, and 3 were hepatitis B surface antigen positive. Nine patients were regarded as being susceptible to hepatitis B; 7 lacked hepatitis B markers, and records of serological status could not be found for the other 2. Four of the susceptible patients received hepatitis B immunoglobulin postoperatively, and 1 of them also received one 10-micrograms dose of hepatitis B vaccine. The 9 susceptible patients underwent hepatitis B serological studies a mean of 17 months (range, 4 to 31 months) postoperatively. In only 1 patient, tested 29 months after operation, had antibodies to hepatitis B surface, hepatitis B core, and hepatitis B e antigens developed. He had not experienced a clinical episode of hepatitis, and results of liver function tests were normal. He had not received prophylaxis. Because hepatitis B virus may be transmitted by hepatitis B surface antigen-positive, hepatitis B e antigen-negative valves, prophylaxis should be given whenever they are used and follow-up serological studies undertaken.

Morphology of heart valves preserved by liquid nitrogen freezing.

As a preliminary to establishing a frozen valve bank for replacement surgery, the possible effects of the proposed freezing and thawing procedure on tissue structure were assessed in 16 human pulmonary valves removed from cadavers at necropsy and nine dog valves obtained fresh. The valves were frozen and stored in liquid nitrogen for intervals ranging from 23 to 380 days. Blocks of tissue cut from the central area of one leaflet, and including some adjacent arterial wall and ventricular myocardium, were obtained both before freezing and after thawing and examined by a large specimen resin embedding technique for light and electron microscopy, with histochemical staining for matrix material. Control and thawed tissue from all valves appeared similar, indicating good preservation irrespective of storage time. Fine structural alterations in the cellular elements correlated with the total interval of autolysis (from death to freezing) rather than the cause of death or other variables and were not uniform in any of the specimens.

Disinfection of human heart valve allografts with antibiotics in low concentration.

Antibiotic disinfection of allograft heart valves is now an established procedure. A new low-concentration, broad-spectrum mixture of antibiotics was formulated and used successfully to disinfect 58 of 60 human aortic and pulmonary valves after 48 h exposure at 4 degrees C. The antibiotics included were cefoxitin 240 mcg/ml, lincomycin 120 mcg/ml, polymyxin B 100 mcg/ml, vancomycin 50 mcg/ml and amphotericin B 25 mcg/ml. Microorganisms isolated from experimental tissue and from clinical valves before treatment were tested for sensitivity to these antibiotics and were found to be sensitive to one or more. One isolate of Pseudomonas spp. showed decreased sensitivity to polymyxin B, and was found to have a minimum bactericidal concentration of 70 mcg/ml. Results indicated this antibiotic mixture had superior antibacterial efficiency to that in routine clinical use for the past 13 yr.