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Zorluk: OrtaDiagnostic Workup and Test Sequencing

A 52-year-old man is admitted to the hospital with a two-week history of low-grade fever, fatigue, and generalized joint pain. He has a past medical history of a bicuspid aortic valve. He reports undergoing a root canal procedure four weeks ago without taking prophylactic antibiotics. On examination, his temperature is 38.3°C (100.9°F), pulse is 96/min, and blood pressure is 128/76 mmHg. Cardiovascular examination reveals a new grade 3/6 decrescendo diastolic murmur heard best at the right second intercostal space. Physical exam also shows small, non-tender erythematous macules on his palms. Initial laboratory studies show a mild normocytic anemia and an elevated C-reactive protein. Three sets of blood cultures obtained at admission are growing *Streptococcus mutans*. A transthoracic echocardiogram is performed and demonstrates a thickened bicuspid aortic valve but does not visualize any definite valvular vegetations or abscesses. The patient remains hemodynamically stable. Which of the following is the most appropriate next step in the diagnostic workup?

  1. A
    Cardiac magnetic resonance imaging
  2. B
    Repeat transthoracic echocardiography in one week
  3. C
    18F-fluorodeoxyglucose positron emission tomography
  4. Transesophageal echocardiographyCevap
  5. E
    Cardiac catheterization with coronary angiography

Cevap

Transesophageal echocardiography
The patient presents with a classic clinical picture of native valve infective endocarditis, supported by positive blood cultures for *Streptococcus mutans*, a new diastolic murmur, and Janeway lesions. Although transthoracic echocardiography (TTE) is the most appropriate initial imaging test, its sensitivity for detecting vegetations is relatively low (50-60%), and visualization can be further obscured by a thickened bicuspid aortic valve. When initial TTE is negative or non-diagnostic in a patient with a high pre-test probability of endocarditis, the standard diagnostic sequence requires proceeding to transesophageal echocardiography (TEE). TEE offers superior spatial resolution and a sensitivity of greater than 90% for detecting valvular vegetations and perivalvular abscesses.

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1
Evaluate the patient's pre-test probability for infective endocarditis based on history and physical exam.
The patient meets criteria for a high clinical suspicion of endocarditis (positive blood cultures for a typical organism, new regurgitant murmur, and Janeway lesions on the palms).
Establishing the clinical suspicion dictates the required sensitivity of subsequent diagnostic imaging.
2
Review the results of the initial diagnostic workup.
The initial transthoracic echocardiogram (TTE) is non-diagnostic, showing a thickened bicuspid valve but no definitive vegetations.
While TTE is the recommended initial imaging modality for all suspected endocarditis cases, it can yield false negatives, particularly in patients with abnormal native valves (e.g., bicuspid valve).
3
Determine the next indicated imaging modality when TTE is non-diagnostic in a high-probability patient.
Transesophageal echocardiography (TEE) should be ordered.
TEE has superior spatial resolution and sensitivity (>90%) for visualizing valvular vegetations and root abscesses compared to TTE.

Anahtar Kavram

The appropriate diagnostic sequencing for suspected infective endocarditis involves performing transesophageal echocardiography (TEE) when an initial transthoracic echocardiogram (TTE) is negative or non-diagnostic but the clinical suspicion for the disease remains high.
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Diagnostic Workup and Test Sequencing

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