Second degree type II and complete atrioventricular block due to hyperkalemia

Area of Science:

• Cardiology
• Electrophysiology
• Internal Medicine

Background:

• Atrioventricular (AV) block is a condition characterized by impaired electrical conduction between the atria and ventricles.
• Progressive bilateral bundle branch disease can lead to high-degree AV block.
• Hyperkalemia, or elevated serum potassium, is a known factor that can affect cardiac conduction.

Observation:

• An 83-year-old female presented with complete AV block and severe bradycardia (20/min).
• Initial electrocardiogram showed right bundle branch block and type II second-degree AV block.
• Admission potassium level was critically high at 7.8 meq/L.

Findings:

• Rapid normalization of potassium to 4.9 meq/L resulted in the complete resolution of AV block.
• The patient remained normokalemic for 19 months with no recurrence of AV block, though right bundle branch block persisted.
• A later readmission revealed recurrent complete AV block and bradycardia despite normal potassium levels, suggesting underlying conduction system disease.

Implications:

• This case highlights that severe hyperkalemia can transiently induce complete AV block, presenting as progressive bilateral bundle branch disease.
• The findings suggest that such hyperkalemia-induced AV block may occur in patients with pre-existing, extensive intrinsic disease of the cardiac conduction system.
• Understanding this association is crucial for accurate diagnosis and management of bradyarrhythmias, especially in patients with electrolyte abnormalities.