BACTEREMIA AND THROMBUS ACCUMULATION ON PROSTHETIC HEART VALVES IN DOG

A consecutive series of 134 mitral valve replacement experiments in dogs is reported in which survival rate is related to the presence or absence of postoperative bacteremia. Of 89 animals surviving the operation (24 hours), only 21% lived for longer than 1 month if bacteremia was demonstrated postoperatively; whereas, of the animals in which no bacteria could be cultured from peripheral blood samples, 94% lived for more than 1 month. The dogs with bacteremia most frequently died from pulmonary edema secondary to massive thrombus accumulation around the valve or to septic dehiscence of the valve. It is suggested that the bacteremia may arise because of autocontamination of the portal blood from the dog's intestine. The long-term survival rate was improved from 21% to 93% in the last 14 dogs by antibiotic therapy based upon this hypothesis. The successful regimen consisted of preoperative oral neomycin-polymyxin and an elemental diet combined with postoperative cephaloridine for broad-spectrum antibiotic coverage. Valves examined after 1 month to 1 year in animals free of bacteremia showed minimal thrombus accumulation despite the fact that anticoagulants were not used. This technique makes it unnecessary to resort to the calf as the experimental animal for evaluation of prosthetic heart valves. © 1969.