Endocarditis echocardiography and ultrasound

Echocardiography may be diagnostic of endocarditis. Echocardiography allows detection of microbial vegetations and the degree of valvular dysfunction. Findings on transthoracic and transesophageal echocardiogram diagnostic of endocarditis include vegetations, valvular regurgitation, pseudoaneurysms, paravalvular abscess, and fistulas. The role of electrocardiography has been addressed in clinical practice guidelines from theAmerican Heart Association, with endorsement by the Infectious Diseases Society of America, have been updated in 2015.

The goals of echocardiography in the patient with endocarditis include the following:^[1][2][3]

1. Determine the presence, location and size of vegetations
2. Assess the damage to the valve apparatus and determine the magnitude of regurgitation, perforation or leak
3. To assess the dimensions and function of the ventricle(s)
4. To identify any abscess formation
5. To determine the need for surgical intervention

• Irregular echogenic mass attached to valve leaflet
• The attachment of the vegetation is on the upstream side of the valve leaflet
• There is chaotic independent movement of the mass relative to the valve
• The minimum size of a vegetation that is identifiable on transthoracic echocardiography is 3 mm and by transoesophageal echocardiography route is 2 mm.
• With treatment and time, the vegetation shrinks and can become fibrosed or calcified. It may not disappear completely.
• Large vegetations occur with fungal endocarditis or Staphylococcus aureus endocarditis.
• The hemodynamic effects are mostly due to valvular regurgitation as a result of valve destruction.

The valve and the surrounding anatomy should be carefully inspected for the following complications:

• Fistula
• Perforation
• Prosthetic dehiscence
• Aneurysm
• Vegetations
• Valve ulcers or erosions
• Rupture of chordaes
• Endocardial jet lesions
• Flail leaflets or cusps
• Abscess formation (annular and ring)

• In general, transthoracic echocardiography (TTE) is often adequate for the diagnosis of infective endocarditis in cases where cardiac structures-of-interest are well visualized.
• The transthoracic echocardiogram has a sensitivity and specificity of approximately 65% and 95% if the echocardiographer believes there is ‘probable’ or ‘almost certain’ evidence of endocarditis.^[4][5]

Specific situations where transesophageal echocardiography (TEE) is preferred over TTE include:

• The presence of a prosthetic valve
• Poor transthoracic views
• Continuing sepsis despite adequate antibiotic therapy
• New PR prolongation
• No signs of endocarditis on transthoracic echocardiography, but high clinical suspicion
• Suspected periannular complications
• Children with complex congenital cardiac lesions
• Patients with S. Aureus caused bacteremia and pre-existing valvular abnormalities that make TTE interpretation more difficult (e.g. calcific aortic stenosis).

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• 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.

• 2008 Focused Update Incorporated Into the ACC/AHA 2006 Guidelines for the Management of Patients With Valvular Heart Disease ^[7]

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