Background: Potassium, as an extracellular ion, plays an important role in the electrophysiologic function of the myocardium and any change in extracellular concentration of this ion might have a marked impression upon myocyte electrophysiologic gain. High serum potassium levels are thought to impair pulse conduction in Purkinje fibers and ventricles more than that in the Atrioventricular (AV) node. Therefore, although complete AV block can occur, it is a rare initial presentation.
Case Report: We describe a 62-year-old man with a history of diabetes mellitus, ischemic heart disease and previous Coronary Artery Bypass Graft (CABG), who came to our emergency department due to generalized weakness starting 2 days before admission. The patient also had decreased force in lower limbs, exacerbating from the morning, and was finally diagnosed as a hyperkalemia-induced Complete Heart Block (CHB). It should also be noted that the patient responded dramatically to the administration of 10 mL of 10% calcium gluconate along with external pacing until potassium level correction became effective.
Conclusion: In spite of the fact that Hyperkalemia can be associated with frequent Electrocardiogram (ECG) abnormality, advanced heart blocks (second- and third-degree AV blocks) are usually found only in patients with pre-existing heart failure, conduction abnormalities, or other cardiac diseases. Institution of effective treatment rapidly and forgiveness of traditional non-effective, time consumptive and sometimes risking full-adjustment modalities, such as sodium bicarbonate infusion or exchange resins that prevent their use in the emergent phase, can help minimize patient morbidity and mortality.