Susceptibility to Streptococcus viridans endocarditis in rabbits with intracardiac pacemaker electrodes or polyethylene tubing.

Abstract

Abstract The susceptibility to endocarditis of rabbits following intracardiac placement of solid cannulae (cardiac pacemaker electrodes) was compared to the susceptibility following placement of hollow polyethylene tubing of equal diameter. Aortic valvular and mural endothelial lesions produced by transvenous pacemaker electrodes 24 hours after intracardiac insertion in rabbits were similar to those produced by polyethylene tubing. Infective endocarditis was initiated by injecting Streptococcus viridans intravenously. The inoculum required to produce infective endocarditis in 50 per cent of rabbits with solid cannulae or hollow polyethylene tubing was about 10 5 colony forming units of S. viridans . The titers of streptococci in vegetations in rabbits in both groups were about the same. These studies indicate that solid intracardiac cannulae predispose rabbits to streptococcal endocarditis as much as hollow intracardiac cannulae.