Role of magnesium ion in the initiation of ventricular fibrillation produced by acute coronary occlusion.

The incidence of ventricular fibrillation following acute coronary occlusion in dogs was reduced by perfusing the ischemic area of the rrryocardium with Locke-Ringer's solution and solutions of magnesium ion in physiological saline. In contrast, normal serum concentrations of magnesium in 5 per cent dextrose appeared to induce ventricular fibrillation in these circumstances. The results suggest that changes in the concentration of magnesium and sodium ion in extracellular fluid may initiate ventricular fibrillation in the ischemic heart.