Influence of glucose, insulin, and potassium on vulnerability to ventricular fibrillation in the canine heart.

Abstract

SUMMARY We studied the influence of glucose (G), insulin (I) and potassium (K + ) on vulnerability to ventricular fibrillation (VF) of the nonischemic canine myocardium. Vulnerability was assessed by determining VF and repetitive extrasystole (RE) thresholds with a single stimulus applied to the right ventricular endocardium during the vulnerable period. Electrical testing of the heart was performed before and after 1 and 2 hours of infusing G (10 mg/kg per min) and I (0.025 U/kg per min) with and without K + . Infusion of glucose, insulin, and potassium (GIK) in 11 dogs significantly increased both VF (22%) and RE (33%) thresholds within the 1st hour and only the VF threshold (64%) in the 2nd hour. No significant changes in serum K + concentration occurred. Spontaneous termination of VF was observed in six dogs during GIK infusion. Glucose and insulin infusion increased both VF and RE thresholds within the 1st (17% and 19%) and 2nd hours (43% and 43%). This occurred despite substantial reductions in serum K + concentration. Lowering serum K + by hemodialysis in six dogs decreased both VF and RE thresholds within the 1st (33% and 32%) and 2nd hours (35% and 14%). Restoration of the serum K + concentration by KC1 infusion while maintaining dialysis returned the thresholds to control values. In six dogs, insulin infusion during low K + dialysis increased the VF and RE thresholds despite a further reduction in serum K + concentration. We concluded that insulin exerts a protective effect against vulnerability to VF in the normal canine heart. This salutary action is most marked when the drug's hypokalemic effect is prevented by concomitant K + infusion.

Part 12: Cardiac Arrest in Special Situations

“…211 However, the management of hypokalemia in the setting of cardiotoxicity, specifically torsades de pointes, is largely based on historical case reports that report slow infusion of potassium over hours. 212 The effect of bolus administration of potassium for cardiac arrest suspected to be secondary to hypokalemia is unknown and ill advised (Class III, LOE C).…”

Arrhythmia susceptibility and myocardial composition in diabetes. Influence of physical conditioning.

“…In a diabetic rat model, (52), an increased availability of glucose to the cell may have contributed to the raised vulnerability threshold (53) after epinephrine in the conditioned state.…”

Part 8: Advanced Life Support

“…734 Several clinical studies report an association between hypokalemia and the development of VF (LOE 5), 724,[735][736][737] and an animal study reported that hypokalemia lowers the VF threshold (LOE 5). 738 In an animal model of cardiac arrest, it was reported that hyperkalemic animals had a higher rate of survival (LOE 5). 739 …”