Hyperkalemia secondary to renal hypoperfusion in a dog with third-degree atrioventricular block

Objective: To demonstrate a critical role of artificial cardiac pacing to normalize severe bradyarrhythmia-induced hyperkalemia in a dog with third-degree atrioventricular (AV) block. Case Summary: A dog was presented for evaluation of severe hyperkalemia and bradyarrhythmia. ECG revealed third-degree AV block with heart rate of 10-20 min, which was lower than usual ventricular escape rate. The etiology of severe hyperkalemia was considered secondary to significantly decreased renal perfusion and potassium excretion as a result of poor cardiac output caused by the AV block. Since potassium disorders may lead to life-threatening conditions such as cardiopulmonary arrest, artificial cardiac pacing was immediately pursued. Within 1 hour, serum potassium concentration was normalized, which confirmed that severe hyperkalemia occurred primarily due to third-degree AV block. The dog was then treated with permanent pacemaker implantation. A recheck evaluation 3-month post pacemaker implantation showed normal serum potassium concentration and the dog was clinically healthy. New or Unique Information Provided: This report describes hyperkalemia secondary to significantly decreased cardiac output and renal hypoperfusion caused by third-degree AV block. The authors propose that artificial cardiac pacing must be considered as an emergency treatment for bradyarrhythmia-induced hyperkalemia, which ultimately restores cardiac output and renal perfusion and normalizes serum potassium concentration.