Differential Diagnosis for Sinus Bradycardia in a 46-year-old Man After a Fall

The patient's presentation with sinus bradycardia after a significant fall from scaffolding suggests a traumatic cause. The following differential diagnoses are considered:

• Single most likely diagnosis

  • Pericardial effusion on FAST: The presence of a pericardial effusion, as indicated by the Focused Assessment with Sonography for Trauma (FAST), is highly suggestive of cardiac tamponade, which can cause sinus bradycardia due to increased intrapericardial pressure compressing the heart and reducing cardiac output. The patient's hypotension (90/50 mm Hg) further supports this diagnosis.

• Other Likely diagnoses

  • Absence of breath sounds on the right: This finding could indicate a pneumothorax, which can cause hypoxia and lead to bradycardia. However, the patient's SaO₂ is 99%, making this less likely as the primary cause of bradycardia.
  • Gross deformity of the right thigh with ecchymosis: Significant trauma to the thigh could lead to hypovolemic shock, but the presence of bradycardia instead of the expected tachycardia makes this less likely as the primary cause.

• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)

  • Midline cervical spine step-off and inability to move legs: This suggests a cervical spine injury, which could lead to spinal shock. Spinal shock can cause bradycardia due to the loss of sympathetic tone. Although the patient is awake and alert, which might suggest against spinal cord injury as the primary cause of bradycardia, missing a cervical spine injury could have devastating consequences.
  • Cardiac tamponade (already mentioned but included here for emphasis): It's crucial not to miss cardiac tamponade, as it is life-threatening and requires immediate intervention.

• Rare diagnoses

  • Other rare cardiac conditions (e.g., myocardial contusion) could potentially cause bradycardia but are less likely given the information provided.
  • Hypothermia-induced bradycardia, though the patient's temperature is normal, making this unlikely.
  • Intracranial injury causing the Cushing's reflex (bradycardia, hypertension, and irregular breathing), though the patient's blood pressure is low, not high, and there's no mention of irregular breathing or other signs of increased intracranial pressure.