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Difficulty: MediumOrdering Imaging Studies

A 72-year-old man is brought to the emergency department due to the sudden onset of severe, tearing anterior chest pain that radiates to his back. His medical history is significant for poorly controlled hypertension, hyperlipidemia, and stage 4 chronic kidney disease. His most recent baseline serum creatinine is 3.8 mg/dL. Upon arrival, his blood pressure is 185/105 mm Hg in the right arm and 145/85 mm Hg in the left arm. His heart rate is 112/min. Physical examination reveals a new diastolic decrescendo murmur at the right upper sternal border. An electrocardiogram shows sinus tachycardia and voltage criteria for left ventricular hypertrophy. A portable chest radiograph displays a widened mediastinum. Which of the following is the most appropriate next step in diagnostic imaging?

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

Answer

Transesophageal echocardiography
Transesophageal echocardiography is the most appropriate imaging study for this patient. He presents with classic signs of an acute aortic dissection (tearing chest pain, asymmetric blood pressures, widened mediastinum). While computed tomography angiography is typically the gold standard, this patient has stage 4 chronic kidney disease. Transesophageal echocardiography is highly sensitive and specific for diagnosing thoracic aortic dissection and can be performed rapidly at the bedside without the need for nephrotoxic contrast agents.

Step-by-Step Solution

1
Identify the primary suspected diagnosis based on the clinical presentation.
The patient has sudden-onset, severe, tearing chest pain radiating to the back, asymmetric blood pressures, a new diastolic murmur of aortic regurgitation, and a widened mediastinum, all highly indicative of an acute thoracic aortic dissection.
Recognizing the life-threatening condition dictates the urgency and type of diagnostic imaging required.
2
Determine the standard diagnostic imaging modalities for the suspected condition.
Computed tomography angiography (CTA), transesophageal echocardiography (TEE), and magnetic resonance angiography (MRA) are the definitive imaging studies for evaluating aortic dissection.
A highly sensitive and specific test is needed to clearly visualize the intimal flap and the extent of the dissection.
3
Evaluate patient-specific factors that present contraindications to standard imaging modalities.
The patient has stage 4 chronic kidney disease (baseline creatinine 3.8 mg/dL). This is a strong contraindication to iodinated contrast (used in CTA) due to contrast-induced nephropathy, and to gadolinium (used in MRA) due to nephrogenic systemic fibrosis.
Choosing an imaging modality must account for patient safety and significant comorbidities.
4
Select the optimal imaging study that provides a definitive diagnosis while avoiding contraindications.
Transesophageal echocardiography provides excellent visualization of the thoracic aorta without the need for intravenous contrast, making it the most appropriate choice.
TEE balances the need for high diagnostic accuracy with patient safety in the setting of severe renal impairment.

Key Concept

In patients with suspected acute thoracic aortic dissection who have severe renal impairment, transesophageal echocardiography is the preferred definitive imaging modality because it avoids the risks of contrast-induced nephropathy (associated with CTA) and nephrogenic systemic fibrosis (associated with MRA).
Estimated Time:1m 30s
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Ordering Imaging Studies

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