Differential Diagnosis for Bradycardia

Given the negative workup for aortic dissection, pulmonary embolism (PE), and acute coronary syndrome (ACS), the following differential diagnoses for bradycardia can be considered:

• Single Most Likely Diagnosis
  • Hypervagotonia or vasovagal syncope: This condition is characterized by an excessive vagal tone leading to bradycardia and possible syncope. It's a common cause of bradycardia in the absence of other cardiac or pulmonary issues.
• Other Likely Diagnoses
  • Medication-induced bradycardia: Various medications, including beta-blockers, calcium channel blockers, and certain antidepressants, can cause bradycardia as a side effect.
  • Hypothyroidism: Untreated or severe hypothyroidism can lead to bradycardia due to the decreased metabolic rate affecting the heart.
  • Electrolyte imbalance: Abnormal levels of potassium, magnesium, or calcium can affect heart rhythm, leading to bradycardia.
• Do Not Miss Diagnoses
  • Cardiac conduction abnormalities (e.g., AV block): These conditions can lead to bradycardia and may require pacemaker implantation.
  • Hypothermia: Accidental or environmental hypothermia can cause bradycardia, and it's crucial to identify and treat promptly.
  • Severe intracranial hypertension: Increased intracranial pressure can lead to the Cushing's reflex, which includes bradycardia, hypertension, and irregular breathing.
• Rare Diagnoses
  • Neuromuscular disorders (e.g., myasthenia gravis, muscular dystrophy): Certain neuromuscular conditions can affect the autonomic nervous system, leading to bradycardia.
  • Infiltrative cardiac diseases (e.g., amyloidosis, sarcoidosis): These rare conditions can infiltrate the heart, affecting its electrical conduction system and leading to bradycardia.
  • Autoimmune disorders (e.g., systemic lupus erythematosus): Some autoimmune diseases can cause bradycardia due to their effects on the heart or autonomic nervous system.