Effect of glucose-insulin-potassium infusion on the human conduction system

Abstract

His bundle electrograms were performed in 21 patients with organic heart disease. Recordings were made at various rates utilizing right atrial pacing. A mixture containing 50 g of glucose, 10 mEq of potassium and 20 units of insulin was given intravenously over 10 minutes to 10 subjects. The P-A, A-H, H-Q and H-S intervals were determined before and immediately after the glucose-insulin-potassium infusion. A significant prolongation in the A-H interval occurred with negligible effects on the P-A, H-Q and H-S intervals. At the atrial pacing rate of 100/min, the average A-H interval increased from the control value of 140 msec to 151 msec after the infusion ( P < 0.05); at the pacing rate of 140/min, the A-H interval increased from 145 to 165 msec ( P < 0.05). The identical study was performed in three additional patients who received an infusion of 50 g of glucose and 20 units of insulin. No significant change was observed in the conduction system. In eight patients a solution of 2.6 mEq of potassium in 65 cc of 5 percent glucose and water was infused over an 8 minute period. A significant prolongation of the A-H interval was observed. At the atrial pacing rate of 100/min, the average A-H interval increased from the control value of 122 to 133 msec after the glucose and potassium infusion ( P < 0.05), whereas at the pacing rate of 140/min, the A-H interval increased from 165 to 188 msec ( P < 0.05). These findings demonstrate that the potassium in a glucose-potassium-insulin infusion may cause impaired conduction through the atrioventricular node.