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Difficulty: MediumOrdering Imaging Studies

A 62-year-old male is evaluated in the emergency department for sudden-onset, severe chest pain radiating to his interscapular area. He describes the pain as "tearing" in nature. His medical history is significant for poorly controlled hypertension and stage 4 chronic kidney disease. Vital signs reveal a blood pressure of 182/105 mmHg in the right arm and 144/88 mmHg in the left arm, and a heart rate of 102/min. Physical examination is notable for a new decrescendo diastolic murmur heard best at the right upper sternal border. Laboratory testing demonstrates a serum creatinine of 3.8 mg/dL. An electrocardiogram shows left ventricular hypertrophy with no acute ischemic changes, and a portable chest radiograph reveals widening of the mediastinum. Which of the following is the most appropriate next step in imaging to confirm the suspected diagnosis?

  1. A
    Computed tomography angiography of the chest and abdomen
  2. B
    Magnetic resonance angiography of the chest and abdomen
  3. C
    Transthoracic echocardiography
  4. Transesophageal echocardiographyAnswer
  5. E
    Non-contrast computed tomography of the chest

Answer

Transesophageal echocardiography is the preferred imaging modality to confirm aortic dissection in a patient with severe chronic kidney disease.
The clinical presentation of sudden, tearing chest pain, asymmetric blood pressures, a new decrescendo diastolic murmur, and a widened mediastinum is highly suspicious for an acute aortic dissection. Imaging is required to confirm the diagnosis and classify the dissection to guide management. While computed tomography angiography is typically the initial imaging modality of choice due to its speed and availability, this patient has stage 4 chronic kidney disease with a significantly elevated serum creatinine. The intravenous iodinated contrast required for this scan poses an unacceptably high risk for contrast-induced nephropathy. Transesophageal echocardiography is highly sensitive and specific for detecting aortic dissection (particularly in the ascending aorta), does not require intravenous contrast, and can be performed rapidly at the bedside. Therefore, it is the safest and most appropriate diagnostic test for this patient.

Step-by-Step Solution

1
Analyze the clinical presentation.
Sudden, tearing chest pain, asymmetric blood pressures, a new diastolic murmur, and a widened mediastinum strongly suggest an acute aortic dissection.
Identifying the primary differential diagnosis dictates the required diagnostic imaging workup.
2
Evaluate patient-specific comorbidities and contraindications.
The patient has stage 4 chronic kidney disease with a serum creatinine of 3.8 mg/dL.
Imaging choices must be modified based on the risk of adverse events, such as contrast-induced nephropathy.
3
Select the optimal imaging modality.
Transesophageal echocardiography is chosen because it is highly sensitive, avoids nephrotoxic contrast agents, and can be performed at the bedside.
It provides definitive diagnostic information without exacerbating the patient's underlying severe renal failure.

Key Concept

In patients with suspected acute aortic dissection who have severe renal impairment, transesophageal echocardiography is the preferred imaging modality over computed tomography angiography to avoid contrast-induced nephropathy.
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Ordering Imaging Studies

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