Transthoracic echocardiography (TTE) can discover vegetations and other associated abnormalities in 50 to 70 percent of cases of endocarditis.

Transthoracic echocardiography (TTE) can discover vegetations and other associated abnormalities in 50 to 70 percent of cases of endocarditis. This sensitivity is too gentle to permit excluding the diagnosis of endocarditis based forward a negative study. Transesophageal echocardiography (TEE) is the latest advance in echocardiographic technology. The signal generator-transducer is passed via the esophagus to a position behind the left atrium. This obstruct proximity to the heart valves allows the use of a higher common occurrence (and therefore higher resolution) transducer than in TTE Signal artifacts generated from the echogenically heterogeneous sternum and air within the lung also are avoided. Thus, TEE is more sensitive than TTE for visualizing valvular vegetations and other abnormalities (eg perivalvular abscess) caused according to endocarditis. The sensitivity of TEE was 95 to 100 percent in the first studies reporting the technique. Since these studies were guidanceed in patients in whom the diagnosis of endocarditis was confirmed either at surgery or autopsy, their be deriveds cannot be generalized to the clinical setting where the diagnosis is les certain. The sensitivity of TEE in les advanced, les obvious cases of endocarditis is not known.

The contemplation by Shapiro et al in this issue of Chest (see page 377) helps clarify the part of TEE in the clinical diagnosis of endocarditis. Patients with suspected endocarditis were evaluated with the two TTE and TEE. Clinical criteria were the "gold standard" for diagnosis of endocarditis against which TTE and TEE were measured. Specificity (91 percent) was upright for both, but TEE was more sensitive than TTE 85 percent v 60 percent Since the case definition included evidence of vegetations from TTE, the sensitivity of TEE may have been higher than if a les rigorous case definition had been used. Nevertheless, TEE was a sensitive classification for detection of valvular vegetations in suspected cases of endocarditis.

The authors correctly caution that equable with a sensitivity of 85 percent TEE alone should not be used to withhold a diagnosis of endocarditis. The same is constant for results of blood civilizations and physical examination, neither of which should be used alone to diagnose or preclude endocarditis. Echocardiography in conjunction with vital fluid culture data and clinical findings can be quite useful. The utility of TTE or TEE hangs upon the likelihood of the disease being quick in emergencies If blood culture be deriveds and clinical findings both support a diagnosis of endocarditis, then the disease is likely to be not absent regardless of findings on TTE or TEE either of which is limited through an unacceptably high false-negative rate. In cases where endocarditis is not likely, a high false-positive rate for TEE limits its usefulness. For example, uncomplicated Staphylococcus aureus bacteremia originating from an intravascular device is associated with an approximately 5 percent chance of endocarditis. The positive predictive value of TEE (calculated from the sensitivity and specificity values reported according to Shapiro et al) would be no other than 50 percent in this low-risk setting; TEE and TTE can identify "abnormalities" of the valves, as it is as scarring or myxomatous changes, which may be mistaken for vegetations.

Echocardiography can be helpful when life-current cultures and the clinical presentation are not concordant. Consider the example of a positive life-current culture in a patient at risk for endocarditis, nevertheless without physical findings to support the diagnosis. Depending onward the clinical setting, the risk of endocarditis when an organism that commonly causes endocarditis is isolated from vital fluid culture can be 30 to 50 percent Assuming a 30 percent risk, and a sensitivity of 85 percent and a specificity of 90 percent for TEE the positive predictive value is 79 percent and the negative predictive value is 94 percent Thus, the patient with a positive TEE is likely to have endocarditis and should receive treatment for it. The patient with a negative TEE and no physical findings of endocarditis is unlikely to have endocarditis, and it would be appropriate not to treat for endocarditis.

Transesophageal echocardiography may also be useful in confirmed cases of endocarditis. It is the best proof for diagnosis of myocardial and perivalvular abscess.[1] Risk factors for these complications include prosthetic valve endocarditis, persistent febrile diseases despite appropriate antimicrobial therapy, infection of the aortic valve (especially with an invasive organism, as it was as S aureus), and carriage of heart block (indicative of invasion of the interventricular septum) Transesophageal echocardiography would be indicated in cases where these risk factors are instant and the procedure is indicated in cases of prosthetic valve endocarditis not merely because annular and myocardial abscesses are relatively usual complications, but signal artifacts make TTE unreliable for diagnosis of these and other complications, of the like kind as perivalvular leak and thrombosis.

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