Effect of cold isotonic glucose infusion on A-V nodal conduction.

His bundle electrograms were performed in eight patients with organic heart disease. Recordings were made at various rates utilizing right atrial pacing. A solution of 100 cc of iced cold 5% glucose and water was infused through a cardiac catheter placed at the level of the tricuspid valve. The P-A, A-H, H-Q and H-S intervals were determined before and immediately after the cold water infusion. A significant prolongation of 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 116 to 125 msec after the infusion (P less than 0.02); at the pacing rate of 140/min, the A-H interval increased from 147 to 158 msec (P less than 0.01). This represents an impairment in conduction through the atrioventricular node.