PROSTHETIC VALVE ENDOCARDITIS - CURRENT P ROBLEMS

Prosthetic valve endocarditis is a rare complication of valve replacem ent 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, d iagnosed in the first year following valve replacement is observed in 0.7 to 3 % of cases: staphylococci are the predominant organism as con tamination usually occurs at operation. The prognosis is poor due to t he high incidence of complications and the mortality rate is about 60 to 70 %; late endocarditis: diagnosed after the second year, it is obs erved in 0.5 to 1 % of cases per year. Contamination is due to bactera emia and the commonest organisms are the streptococci. The mortality r ate is over 20 %. The diagnosis is particularly difficult in chronic f orms and those with negative blood cultures. Cardiac imaging in prosth etic valve endocarditis is mainly dependant on Doppler echocardiograph y especially using the transoesophageal approach which allows evaluati on of lesion such as abscesses, vegetations and perivalvular leaks, an d 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 a s soon as bacteriological specimens have been sent for culture. Surger y is essential in early forms but may be avoided in uncomplicated late forms. The timing of surgery (the objectives of which are to excise t he infected material, to repair destructive lesions and to implant a n ew valve) is a decisive factor in reducing the morbidity and mortality of this condition. Prophylactic measures have a particularly importan t role to play: they are based on pre- per- and postoperative guide li nes.