The answer is, the indication for magnesium in cardiac arrest is Pulseless ventricular tachycardia. Pulselessness with a tachyarrhythmia happens because the ventricles, due to improper electrical activity, are not moving blood out of the heart and, therefore, there is no cardiac output. In the event of cardiac arrest, where the rhythm is a pulseless ventricular tachycardia, magnesium can be considered. The effects of magnesium can be due to several mechanisms, including improved potassium transport through myocardial potassium channels and shortening of the action potential duration.
