RESUMEN
Acute stressor states are associated with a homeostatic activation of the hypothalamic-pituitary-adrenal axis. A hyperadrenergic state follows and leads to a dyshomeostasis of several intra- and extracellular cations, including K, Mg, and Ca. Prolongation of myocardial repolarization and corrected QT interval (QTc) of the ECG are useful biomarkers of hypokalemia and/or hypomagnesemia and should be monitored to address the adequacy of cation replacement. A dyshomeostasis of several trace elements, including Zn and Se, are also found in critically-ill patients to compromise metalloenzyme-based antioxidant defenses. Collectively, dyshomeostasis of these electrolytes and trace elements have deleterious consequences on the myocardium: atrial and ventricular arrhythmias; induction of oxidative stress with reduced antioxidant defenses; and adverse myocardial remodeling, including cardiomyocytes lost to necrosis and replaced by fibrous tissue. To minimize such consequences during hyperadrenergic states, systematic surveillance of electrolytes and trace elements, together with QTc, are warranted. Plasma K and Mg should be maintained at > or =4.0 mEq/L and > or =2.0 mg/dL, respectively (the 4 and 2 rule).