[Ultrasonography in the diagnosis of bacterial endocarditis: value and limits]

This cooperative study recensed 148 patients who had infective endocarditis (IE) with anatomopathological correlations. The infection was on native valves in 89 cases and prosthetic valves in 59 cases. Transoesophageal echocardiography diagnosed vegetations on native valves with a sensitivity, specificity, positive predictive and negative predictive values of 89%, 87%, 88% and 90% respectively, whereas for transthoracic echocardiography the results were 68%, 83%, 81% and 72% respectively. With respect to prosthetic valve vegetations, transoesophageal echocardiography had a sensitivity, specificity, positive predictive and negative predictive values of 67%, 84%, 48% and 92% respectively compared with 56%, 84%, 44% and 83% respectively for transthoracic echocardiography. These results underline the difficulties in differentiating degeneration and endocarditis of bioprostheses. Transoesophageal echocardiography diagnosed aneurysm formation and valvular perforation with a sensitivity, specificity, positive and negative predictive values of 61%, 93%, 91% and 72% respectively compared with 35%, 96%, 98% and 58% respectively for transthoracic echocardiography. The false negative results of transoesophageal echocardiography were usually observed in lesions of the posterior leaflet or commissures. In this series, the 6 aortic cusp perforations were undiagnosed by both transthoracic and transoesophageal echocardiography. With respect to aortic ring abscess, the sensitivity, specificity, positive and negative predictive values of transoesophageal echocardiography were 89%, 100%, 100% and 93% respectively, compared with 27%, 100%, 100% and 62% for transthoracic echocardiography. The false negative results of transoesophageal echocardiography were observed in cases of anterior abscesses or of calcific aortic valves. These results demonstrate the superiority of transesophageal over transthoracic echocardiography in the diagnosis of infective endocarditis and its complications. However, the limitations of the method should be recognized in the situations described.