Echocardiographic assessment of prosthetic valve endocarditis

Prosthetic valve endocarditis is still a very serious complication, carrying an incidence of death between 30 and 70% in some series. Therefore early and accurate diagnosis is crucial. Early (less than 60 days post surgery) endocarditis is usually a fulminant disease, where staphylococcal infection is most common. Late prosthetic endocarditis resembles more closely other forms of the disease. Conventional echocardiography is useful in the evaluation of prosthetic valve function, but it is very limited in the demonstration of infective lesions, primarily because of acoustic shadowing. Transoesophageal echocardiography (TE) enables high resolution imaging of the heart without chest wall interference, and viewing of the heart from the posterior (atrial, low pressure) side, where most of the vegetations are expected to be found in both mitral and tricuspid positions. It also enables better visualization of the left ventricular outflow tract, where aortic prosthetic vegetations tend to be present. Furthermore, transoesophageal echocardiography allows accurate diagnosis of some of the common complications of endocarditis: abscess/cavity formation; mycotic aneurysm; prosthetic valve dehiscence and regurgitation. In spite of these advantages, limitations should be recognized. Struts are commonly seen on transoesophageal echocardiography following surgery and should not be confused with vegetations. Similarly, normal prosthetic regurgitation should not be confused with paravalvar leakage. Nevertheless, transoesophageal echocardiography, when expertly used, changes the possibility for early and more accurate diagnosis of prosthetic valve endocarditis dramatically. Transoesophageal echocardiography should be included among the major criteria in the diagnosis and follow-up of prosthetic valve endocarditis.