A Case of Reversible Atrioventricular Block Potentially Associated with Atenolol-Induced Hyperkalemia

Abstract

Potassium is an extracellular ion that plays an important role in the electrophysiological function of the heart. Any change in the extracellular concentration of potassium can have a marked impression upon cardiac electrophysiology. Underlying kidney disease, certain medical conditions, dietary indiscretions, and medications can precipitate hyperkalemia. Drug-induced hyperkalemia is one of the most important causes of increased serum potassium in everyday clinical practice. Hyperkalemia can lead to various lifethreatening dysrhythmias and if left untreated, it will ultimately cause ventricular arrhythmias and asystole. This case report describes an end-stage renal disease (ESRD) patient taking atenolol who presented with hyperkalemia and type II second degree atrioventricular (AV) block. He presented with hyperkalemia when atenolol was introduced and normalized when atenolol was discontinued. The heart block completely resolved after treatment of hyperkalemia.

Profound Hyperkalemia and Anemia in a Dialysis Patient With a Gastrointestinal Bleed

“…In patients with hyperkalemia, the resting membrane potential is less negative and closer to the threshold for an action potential to cause muscle contraction. Initially, this can cause excitation, but, over time, the increase in inactivated sodium channels leads to decreased excitability as well as slowing of electrical impulses, leading to severe weakness or even paralysis of skeletal muscles [ 2 , 3 ].…”

“…The latter changes are due to prolonged depolarization and slowed conduction/longer action potential through the myocardium. Other conductance abnormalities that can be seen include atrioventricular nodal blocks, apparent bundle branch blocks due to intraventricular conduction delay, sinoventricular rhythms due to ventricular activity without atrial activity, and ventricular fibrillation after nodal conduction ceases and junctional rhythms appear [ 2 , 3 ].…”