Review articleImaging techniques for diagnosis of infective endocarditis
Section snippets
Echocardiography in the diagnosis and management of IE
Earlier diagnostic criteria for endocarditis did not usually include echocardiography [1]. However, the more recent Duke criteria do incorporate the results echocardiography [2]. In the original paper defining the Duke criteria, the sensitivity of clinical criteria was 80% for diagnosis of pathologically confirmed cases among 405 retrospectively reviewed cases of suspected IE, compared to 51% for the older von Reyn criteria [1]. Many subsequent retrospective and prospective studies among
Echocardiographic technique: transthoracic or transesophageal approach?
To best appreciate the value of echocardiography in the management of endocarditis, as well as to be able to make the proper choice of modality, it is important to understand the fundamentals of the technique. Diagnostic echocardiography employs high frequency sound waves, on the order of 3 to 7 million cycles per second, which are reflected by body tissues and processed by a transducer to create characteristic images. In transthoracic echocardiography (TTE), the transducer is placed on the
Vegetations
The primary objective of cardiac imaging in suspected endocarditis is to identify, localize, and characterize valvular vegetations—the pathologic hallmark of infected endocardium. Among subjects in a tertiary care hospital with “definite” IE according to Duke criteria, vegetations were detected by echocardiography in 67% of cases [23].
Echocardiographic description of vegetations
With two-dimensional imaging in which the cardiac structures are observed throughout the cardiac cycle, vegetations are defined as irregularly shaped, discrete
Cost effectiveness
Although echocardiography has been shown to be more effective than simple clinical criteria in diagnosing and managing endocarditis, it is moderately expensive. Some have argued that in uncomplicated cases of bacteremia (patients without underlying cardiac abnormalities who defervesce promptly), echocardiograms do not need to be performed to look for endocardial involvement because the findings will not alter treatment. Clinicians who hold this view argue that antibiotics will be given in
Chest radiography
Most information provided by chest radiographs in IE is nonspecific, but radiographs should be done routinely in any comprehensive work-up of the disease. Cardiomegaly may indicate cardiac failure or pericardial involvement. Prosthetic valves may be revealed in patients who are unable to recall or recount their medical history. Enlarged vessels provide evidence of pulmonary congestion. If the patient is a febrile injecting drug user, nodular infiltrates are highly suggestive of tricuspid
Conclusion
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
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