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The Speed of Sound

Ultrasound's Immediate Answers for Diagnosing Endocarditis

Butts, Christine MD

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doi: 10.1097/01.EEM.0000547202.09020.45
    ultrasound, endocarditis
    ultrasound, endocarditis:
    Image 1. Parasternal long axis view demonstrating mitral regurgitation (blue jet in left atrium). A video of this on our website (http://bit.ly/VideosSound) demonstrates mobile vegetation on the anterior leaflet.
    Figure
    Figure

    Making the diagnosis of endocarditis in the ED can be extremely difficult. Many cases present with vague symptoms (malaise, body aches, fever) and can seem like a benign viral syndrome. Certainly the Duke criteria (http://bit.ly/2nAphmA) are not very helpful for emergency physicians because blood culture results take days.

    The initial presentation in a lot of our high-risk patients, specifically those with a history of intravenous drug use, is our best opportunity to catch this condition. I often cannot reach patients after discharge when I receive notification of positive blood culture results, which I suspect is not uncommon for other EPs. Ultrasound of the heart and lungs can add concrete evidence to our clinical suspicion and help to convince our hospitalist colleagues that endocarditis is a likely cause of the patient's vague symptoms.

    Knowledge of basic views of the heart allows an assessment of most valves. The standard parasternal long axis view demonstrates the mitral and aortic valves (two of the three cusps). Mobile vegetations are often visible from this approach. (Image 1; video available at http://bit.ly/VideosSound.) From this view, tilting the transducer slightly so that its base (where the cord comes out) rises toward the patient's head will reveal the right ventricular inflow view. (Image 2; video available at http://bit.ly/VideosSound.) This view allows assessment of the tricuspid valve, which is often tough to see unless a quality apical view can be obtained, and that's not always easy, even in a cooperative patient! If a heart murmur is detected, the addition of color flow can demonstrate regurgitation, best seen in the apical four-chamber view. Small, nonmobile vegetations also may be tough to see with transthoracic echo, and regurgitation may be an important clue.

    After assessing the valves of the heart, consider taking a look at the lungs. Septic emboli, particularly when small or early in the course, are often difficult to identify on plain films, but can easily be seen with ultrasound. Using the low-frequency transducer (the cardiac transducer works well), each side of the chest should be examined superiorly and inferiorly. Breaking these sections down further into the anterior, axillary, and posterior aspects will help assess the entirety of both fields. Emboli appear similar to the consolidation seen in pneumonia with “hepatization,” in which the normally hazy gray appearance of the lung is replaced by dense, liver-like, tissue. An irregular border is common and signs of interstitial edema, such as “B lines,” may be seen at the periphery. If a patient has back, flank, or chest pain, consider that ground zero for looking for these signs.

    Figure
    Figure:
    Image 2. Right ventricular inflow view. Left ventricle (LV) seen to left with right atrium (RA), ventricle (RV), and tricuspid valve on the right. Watch of a video of this at http://bit.ly/VideosSound.
    Figure
    Figure:
    Image 3. Area of consolidation seen adjacent to the pleural border. Note the liver-like appearance (H) compared with the surrounding normal lung tissue (L) and the adjacent “B lines” (arrow).

    We are likely only seeing the beginning of an increase in the cases of endocarditis related to intravenous drug use. Putting our antennae higher by combining our clinical judgment with ultrasound can help catch these patients earlier in the course of their disease.

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