Transesophageal echocardiographic evaluation of St. Jude Medical and bioprosthetic valve endocarditis

Imaging techniques for diagnosis of infective endocarditis

Cardiac imaging, specifically echocardiography, has greatly enhanced the ability of clinicians to effectively diagnose and manage IE. Echocardiograms should generally be obtained in all patients suspected of having IE, both to establish the diagnosis and to identify complicated cardiac involvement that may warrant surgical intervention. Transesophageal imaging is more sensitive and specific than the transthoracic approach and currently represents the optimal approach to echocardiographic imaging. Manifestations of endocardial involvement include vegetations, abscesses, aneurysms, fistulae, leaflet perforations, and valvular dehiscence. The roles of other imaging modalities including CT, MRI, and nuclear imaging have yet to be fully established.

Imaging techniques for diagnosis of infective endocarditis

With the ability to structurally characterize cardiac manifestations, echocardiography is used for the diagnosis and management of infective endocarditis. In establishing the diagnosis according to the Duke criteria, the findings of endocardial involvement (vegetation, abscess, prosthetic valve dehiscence) or new valvular regurgitation represent "major" diagnostic criteria. As echocardiography cannot reliably differentiate noninfective from infective lesions, however, proper diagnosis lies in correlating echocardiography with clinical findings. The more invasive transesophageal approach provides substantially greater image resolution; this approach should be considered first in the evaluation of patients with higher prior probabilities of endocarditis and those with potential endocardial complications.

Transesophageal echocardiographic (TEE) evaluation of prosthetic valves

TEE overcomes many of the imaging constraints associated with transthoracic echocardiography for the assessment of valvular anatomy and function. Additional imaging artifacts and constraints associated with prosthetic valves are minimized or overcome with TEE. As such, TEE allows assessment of prosthetic valve anatomy and function and paraprosthetic anatomy, and serves as the diagnostic imaging modality of choice for patients with suspected prosthesis dysfunction or endocarditis.

Role of transthoracic and transesophageal echocardiography in diagnosis and management of infective endocarditis

Echocardiography has become a mainstay in the diagnosis of endocarditis. Vegetations were first visualized noninvasively beginning with M-mode echocardiography in the mid-1970s. The evolution of echocardiography, to include first two-dimensional imaging and then Doppler imaging in the 1980s, established echocardiography as the noninvasive test of choice to evaluate for the presence of vegetations as well as for their sequelae. Most recently, the addition of transesophageal echocardiography has expanded the role and yield of echocardiography in diagnosing endocarditis as well as in guiding management.

Echocardiographic assessment of vegetations in patients with infective endocarditis: prognostic implications

Today, echocardiography is the most important technique next to clinical findings and blood cultures in the diagnosis of infective endocarditis. The sensitivity of echocardiography, particularly the transesophageal approach, for detection of vegetations and endocarditis related valvular destructions is high. In addition, echocardiographic findings may have some prognostic implications. The size and mobility of vegetations stratifies endocarditis patients into a high risk group for arterial embolism. In particular, mobile vegetations attached to the mitral valve with a maximal diameter > 10 mm may be prone to embolic events. Furthermore, increase in size of vegetations during antimicrobial treatment may identify patients with no, or at least a prolonged, healing process. Also, a lack of increase in the echo density of vegetations under adequate antibiotic treatment may indicate a poor healing process and may necessitate more aggressive management. The demonstration of paravalvular abscesses by echocardiography, particularly by transesophageal echocardiography, identifies a subgroup of patients who will need urgent cardiac surgery before widespread tissue destruction has occurred.