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Anticoagulation after implantation of a bioprosthetic heart valve has been suggested during a high-risk period of 3 months following surgery. There is little information available concerning the risk of thromboembolism during this period if anticoagulation is not carried out. However, this is of interest since 60-80% of all bleeding complications due to anticoagulation occur during the first year of treatment. Between 1983 and 1993, 57 of our patients did not receive oral anticoagulation after implantation of a bioprothesis in the aortic position (49 Hancock, 7 Mitroflow and one Edwards stentless). All patients were investigated retrospectively. A risk for thromboembolic complications of 1.75% is calculated for the first six months following surgery, being 3.5 per 100 patients/year. There seems to be no advantage in standard anticoagulation (INR 2.5-4) with its risk of serious bleeding complications of about 4% during this period of treatment. Low-dose anticoagulation (INR 2.0-2.3), however, preferably in combination with prothrombin estimation by the patients, seems to offer a relatively safe treatment for these patients.

Between 1983 and 1922 70 patients of the author's institution underwent valve replacement for bacterial endocarditis of native valves. In 22 cases the source of infection could be identified. Among them the most frequent source of infection was dental manipulation (7 patients). The predominating causative microorganism was Streptococcus viridans followed by Staphylococcus aureus. Preoperative complications, the intraoperative finding of extensive destructions, and the histological finding of acute changes influenced significantly the occurrence of perioperative complications. 20 patients died (28.6% overall mortality), there were 9 perioperative deaths (perioperative survival 87.1%). The one-year survival was 73.8% the five-year survival 61.5%. Significant risk factors for the prognosis were preoperative complications, positive bacteriological result of the analyzed resected valves, perioperative complications, duration of the postoperative antibiotic treatment, and the postoperative NYHA functional class. Therefore one should intervene surgically before preoperative complications appear. Perioperative complications must by treated immediately, and an adequate postoperative antibiotic therapy must be guaranteed.

Nocardial sepsis occurred after aortic valve replacement in two patients. A septic suture aneurysm of the aortotomy was resected and the prosthesis exchanged in one of them. The other received conservative treatment for sternal osteomyelitis and local mediastinitis. Clinical cure was followed by relapse and death from cerebral infarction, and necropsy revealed a septic suture aneurysm of the aortotomy. Radical surgical revision seems to be necessary for lasting cure in such infections.