Which studies may be helpful in the diagnosis of infective endocarditis (IE)?

Updated: Jan 03, 2019
  • Author: John L Brusch, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
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Ventilation/perfusion scanning may be useful in right-sided endocarditis.

Electrocardiography may help detect the 10% of patients who develop a conduction delay during IE by documenting an increased P-R interval. Nonspecific changes are common. First-degree atrioventricular (AV) block and new interventricular conduction delays may signal septal involvement in aortic valve disease; both are poor prognostic signs.

Catheterization of the heart is rarely required for the diagnosis of IE or any of its complications, though it may be indicated to determine the degree of valvular damage. The findings from echocardiography correlate well with the findings from cardiac catheterization. The characteristic findings of IE are intravascular endocardial vegetations that contain microorganisms surrounded by fibrin and platelets.

Various radionuclide scans using, for example, gallium (Ga)-67–tagged white cells and indium (In)-111–tagged white cells, have proven to be of little use in diagnosing IE. Radionuclide scans of the spleen are useful to help rule out a splenic abscess, which is a cause of bacteremia that is refractory to antibiotic therapy.

A computed tomography (CT) scan of the head should be obtained in patients who exhibit central nervous system (CNS) symptoms or findings consistent with a mass effect (eg, macroabscess of the brain). [75, 76, 77] This imaging modality has proven most useful for localizing abscesses. With new advanced multislice techniques, CT can now also be used to identify valvular abnormalities and vegetations. [78]

An increasing amount of evidence supports the advantages of fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography (PET) scanning over electrocardiographically gated computed tomographic angiography (CTA) in certain circumstances. PET scanning may facilitate earlier diagnoses of infected intracardiac devices and prosthetic valves than do these other studies. [79]

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