Influence of magnesium ion on human ventricular defibrillation after aortocoronary bypass surgery.
The administration of magnesium ion (Mg++) has been reported to defibrillate the ventricles and to decrease the incidence of arrhythmias after cardiopulmonary bypass. In a prospective study of 76 randomly selected patients undergoing coronary artery bypass grafting, patients received either no Mg++, 0.25 mEq/kg of Mg++ during cardiopulmonary bypass with the aorta clamped, or 0.375 mEq/kg of Mg++ before cardiopulmonary bypass. Spontaneous resumption of a cardiac rhythm or spontaneous defibrillation during reperfusion was not significantly affected by Mg++ administration. However, the number of shocks to initial and to sustained defibrillation and the energy required for the last direct-current shock was greatest in patients who received Mg++ before bypass and in those whose plasma Mg++ was greater than 2.26 mg/dl. Thus, the administration of Mg++ may have adverse effects on the heart if intraoperative plasma Mg++ exceeds 2.26 mg/dl.
D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass; D004554:Electric Countershock; D006324:Heart Arrest, Induced / Q000379:methods; D006801:Humans; D007432:Intraoperative Period; D008274:Magnesium / Q000097:blood / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects*; D010477:Perfusion; D014693:Ventricular Fibrillation / Q000517:prevention & control*
D008274:Magnesium