What is the cause of unconsciousness in a patient with Mobitz type II (second-degree) atrioventricular (AV) heart block: hypoglycemia, hypothermia, or beta blocker (beta-adrenergic blocking agent) overdose?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: February 15, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

Differential Diagnosis for Unconscious Patient with Mobitz Type 2 Heart Block

Single Most Likely Diagnosis

  • Hypoglycemia: This is a common and reversible cause of altered mental status, and it can also precipitate or worsen heart block in susceptible individuals, such as those with pre-existing Mobitz type 2 heart block. The body's stress response to hypoglycemia can exacerbate cardiac issues.

Other Likely Diagnoses

  • Beta Blocker Overdose: Beta blockers can worsen or precipitate heart block, including Mobitz type 2, by slowing the heart rate and reducing the contractility of the heart. An overdose could lead to severe bradycardia and hypotension, resulting in reduced consciousness.
  • Hypothermia: Hypothermia can cause altered mental status and can also affect the heart, leading to bradycardia and potentially worsening pre-existing heart block. It's a plausible cause given the outdoor setting.

Do Not Miss Diagnoses

  • Myocardial Infarction (MI): Although less likely given the context, an MI could precipitate a Mobitz type 2 heart block, especially if the block is new onset. Missing an MI could be fatal, making it a critical diagnosis not to overlook.
  • Cardiac Tamponade: This is a life-threatening condition that could cause hypotension and altered mental status. While less common, it's a diagnosis that must be considered due to its high mortality rate if not promptly treated.
  • Stroke: A stroke could cause altered mental status and, in rare cases, could be associated with cardiac abnormalities, including heart block, due to autonomic nervous system dysfunction.

Rare Diagnoses

  • Hyperkalemia: This electrolyte imbalance can cause cardiac arrhythmias, including heart block. However, it's less directly linked to altered mental status unless severe and causing significant cardiac dysfunction.
  • Toxicity from Other Medications: Certain medications, such as calcium channel blockers or other anti-arrhythmic drugs, could potentially worsen heart block or cause altered mental status, but these would be less common causes compared to the others listed.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.