VALVE DISEASE: Prosthetic valve endocarditis

After 40 years of continuous improvements in the design and materials used for prosthetic heart valves, valve replacement surgery is now performed with low morbidity and mortality. These advantages have been hampered by a few but severe adverse effects; in particular, infections of the prosthetic material continue to be an extremely serious complication occurring with a relatively low but increasing frequency ranging from 0.1–2.3% per patient year.1-3 The prosthesis obviously predisposes to device related infections, especially those caused by novobiocin susceptible, coagulase negative staphylococci, which are able to adhere to a variety of surfaces4 and produce an antibiotic resistant biofilm.5 6 Prosthetic valve endocarditis (PVE) is an endovascular, microbial infection occurring on parts of a valve prosthesis or on reconstructed native heart valves.7 It is recommended to determine whether (a) a mechanical prosthesis, (b) a bioprosthetic xenograft, stented or unstented, (c) an allograft, (d) a homograft, or (e) a repaired native valve with or without implantation of an annular ring is involved.8 Although clinical relevance and therapeutic considerations may be similar, infections of devices or lines placed inside the heart but not connected to the endocardial structures should be classified as “polymer associated infections” rather than PVE. PVE should be classified as either being acquired perioperatively, and thus nosocomial (early PVE), or as community acquired (late PVE).8 Because of significant differences in microbiology of PVE observed within the first year of operation and later on, the time cut off point between early and late PVE should be regarded as one year.9 The risk for early PVE is higher (approximately 5%) in patients with replacement surgery during active infective endocarditis, especially if the causal organism is unknown or the antibiotic treatment is insufficient. The incidence of late PVE is lower for mechanical prostheses than …