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Waterworth, Pamela M., Lockey, Eunice, Berry, E. M., and Pearce, Helen M. (1974).Thorax, 29, 432-436. A critical investigation into the antibiotic sterilization of heart valve homografts. Sterility tests of homograft heart valves sterilized by antibiotics were found to be invalidated by carry-over of the antibiotics. A method was devised to test the efficacy of different antibiotic mixtures using membrane filters. Fifty-five organisms, including 13 species, were tested, and sterility was achieved with only 35.

We have analysed the bacteraemias occurring before discharge from hospital in patients subjected to open-heart surgery. The overall incidence was 2·7%. The predominant organisms at first were staphylococci and streptococci, but in the later years of the study almost all positive blood cultures were due to Gram-negative bacilli. Short-term prophylactic antibiotics were used throughout. Eleven of the 12 Gram-positive bacteraemias occurred after the period of antibiotic prophylaxis; eight of the patients had endocarditis and a further three had serious wound infections. Most of the 32 Gram-negative bacillaemias occurred while antibiotics were being given. Some were transient phenomena in well patients; others were associated with terminal states. Infection was a major cause of death in four patients, however, and two patients had endocarditis. Serratia, providence, hafnia, and citrobacter were all identified as well as the more usual escherichia, klebsiella, and pseudomonas. We discuss the possible origins and management of these bacteraemias.

Ten cases of serum hepatitis occurring after open-heart surgery at the National Heart Hospital, London are reported. The incidence seemed to be rising and was at least 2% before antigen-screened blood became available. Investigation of 135 patients for the presence of Australia antigen and antibody showed that five (3·7%) had responses to exposure to the infective agent. All were and remained clinically well, but such patients may constitute a source of infection. Since tested blood has been used no hepatitis cases have been recognized.

The present study was undertaken to find an antibiotic mixture which would rapidly and completely sterilize a heavily contaminated allograft heart valve without reducing its viability. Two different antibiotic combinations were used; formula A was used for 66 valves and formula B for 60 valves. Viability of the valves was assessed by autoradiography and tissue culture, and was found to be similar in both formulae. Formula B proved more effective; all valves were sterile after 24 hours9 exposure to the antibiotics and remained so thereafter. The period of viability was greatly extended when a nutrient medium was used to store the valves.

No-one would debate the need to correct a very low or a very high plasma potassium or a profound metabolic acidosis. Many problems in heart surgery are iatrogenic, however, and many can be prevented. The aim of this talk is to show how laboratory tests can be used to foresee and forestall problems and thus make cardiac surgery safer.

The well-prepared and properly inserted homograft has many advantages and like the people who make prosthetic valves, those in the homograft field are constantly trying to improve their product. The author will deal here only with the antibiotic method of sterilisation and to a large extent her presentation is self-critical.

In order to examine the relation between cardiac state and the capacity to excrete a water load, 10 normal subjects and 61 patients with heart disease were studied during water diuresis. Under these conditions, urine flow approximates to the rate of delivery of filtrate, and therefore of sodium, from the proximal tubule of the kidney to the loop of Henle, while free water clearance is a function of distal sodium reabsorption. In 12 patients with complete heart block, ventricular pacing was associated with increased urine flow and free water clearance. Oral propranolol in 3 normal subjects and in 9 patients with intact atrial septa caused a reduction, and oral practolol in 4 normal subjects and 8 patients caused no change. In 6 patients with atrial septal defect, propranolol was without effect. Maximum urine flow correlated with left ventricular end-diastolic pressure but not mean left atrial pressure in 16 patients with chronic rheumatic heart disease. In 7 patients with ischaemic heart disease, maximum urine flow was higher than in those with chronic rheumatic heart disease and similar increase in left ventricular end-diastolic pressure. These results reflect a close relation between proximal tubular sodium reabsorption and cardiac state, and suggest that inappropriate sodium reabsorption at this site may contribute to fluid retention in heart disease.

Two hundred and thirty-two patients subjected to open-heart surgery have been analysed regarding early post-operative jaundice. The overall incidence of jaundice was 13%, being 55% where the mitral valve and 5% where the aortic valve was predominantly involved. Only one out of 59 patients in whom a congenital lesion was repaired became jaundiced. Hyperbilirubinaemia without jaundice was common. The biochemical pattern of the jaundice was singularly constant, the most striking feature being the rise in serum bilirubin level. The highest value occurred between the second and tenth post-operative days. At total levels less than about 4 mg./100 ml. the unconjugated fraction usually equalled or exceeded the conjugated. The alkaline phosphatase was normal in the first post-operative week but was sometimes slightly raised in the second, when the bilirubin levels were usually falling. The S.G.P.T. was normal or very slightly raised. Bilirubinuria was present. Centrilobular congestion with no evidence of extrahepatic biliary obstruction was found at post-mortem examination, and liver biopsy in three very severely jaundiced patients revealed only intrahepatic cholestasis. Pre-operative evidence of liver dysfunction was found in 13 patients who subsequently became jaundiced. Twelve had lesions predominantly affecting the mitral valve. Haemolysis, heart failure, and infection probably all played a part, and the effect of operation per se on liver function has been discussed. Drugs and viral hepatitis do not seem implicated in our patients. Maintenance of lower venous pressures in the post-operative period and the use of less blood reduced both the incidence and severity of jaundice.

Four new cases of Candida endocarditis after heart surgery are described and predisposing factors are discussed. Details are given of the one patient diagnosed in life and treated successfully with amphotericin B.