Synergistic Bradycardia from Beta Blockers, Hyperkalemia, and Renal Failure

Bradycardia is a common vital sign encountered in the emergency department. These patients are often hemodynamically stable and require no emergent intervention. On occasion, bradycardia can cause hemodynamic instability, and there are established treatment pathways involving atropine, ionotropic and vasopressive infusions, and eventual mechanical pacing, if necessary. However, these pathways fail to account for the many and varied causes of bradycardia and their treatment.

A 24-year-old man presented to our emergency department with syncope caused by symptomatic bradycardia. This was caused by a largely unrecognized synergistic bradycardia resulting from renal failure, AV nodal blocker use, and hyperkalemia. Our patient's worsening renal failure caused accumulation of both potassium and beta blocker, which resulted in bradycardia and hypotension, in turn worsening renal failure secondary to poor renal perfusion and potentiating his hyperkalemia and beta blocker toxicity. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: There is a growing number of cases that suggest this is an underrecognized synergistic and potentially lethal mechanism of hemodynamically unstable bradycardia and the treatment falls outside of typical algorithms for handling bradycardia. Understanding the multiple causes of these patients' hemodynamically unstable bradycardia allows for maximal medical management and can prevent unnecessary invasive management for these patients.