[Prosthetic valve endocarditis: current problems].

Abstract

Prosthetic valve endocarditis is a rare complication of valve replacement surgery but carries a grim prognosis. The physiopathology of this condition allows identification of two clinically distinct forms based on their bacteriological profiles and outcome: early endocarditis, diagnosed in the first year following valve replacement is observed in 0.7 to 3% of cases: staphylococci are the predominant organism as contamination usually occurs at operation. The prognosis is poor due to the high incidence of complications and the mortality rate is about 60 to 70%; late endocarditis: diagnosed after the second year, it is observed in 0.5 to 1% of cases per year. Contamination is due to bacteraemia and the commonest organisms are the streptococci. The mortality rate is over 20%. The diagnosis is particularly difficult in chronic forms and those with negative blood cultures. Cardiac imaging in prosthetic valve endocarditis is mainly dependent on Doppler echocardiography especially using the transoesophageal approach which allows evaluation of lesion such as abscesses, vegetations and perivalvular leaks, and enables planning of treatment. Management is medico-surgical. Apart from symptomatic treatment of complications, antibiotic therapy using synergistic drugs at bactericidal dosages intravenously is essential as soon as bacteriological specimens have been sent for culture. Surgery is essential in early forms but may be avoided in uncomplicated late forms. The timing of surgery (the objectives of which are to excise the infected material, to repair destructive lesions and to implant a new valve) is a decisive factor in reducing the morbidity and mortality of this condition. Prophylactic measures have a particularly important role to play: they are based on pre- per- and postoperative guide lines.