Effects of moderate hyperkalemia on the sinus node. Evaluation in anesthetized dogs

From clinical experience that sinus node dysfunction was observed on the day of hemodialysis and that the arrhythmias were corrected immediately after initiation of hemodialytic therapy, the effect of moderate hyperkalemia on sinus node function was experimentally evaluated. When the serum potassium level was elevated to 5.78 +/- 0.96 mEq/L, sinus node recovery time evaluated by the overdrive suppression test was significantly prolonged (p less than 0.05). Atrial refractory periods also increased (p less than 0.01 or p less than 0.02). Atrial repetitive response was observed in some dogs after the induction of moderate hyperkalemia by premature stimuli. Although the study was performed in anesthetized dogs, moderate hyperkalemia might depress sinus node function in awake humans.