A nurse is caring for a client who has recently undergone cardiopulmonary arrest. The emergency response team has successfully restored a pulse but the client now has symptomatic bradycardia. The nurse anticipates the use of which of the following medications to help correct this arrhythmia?

Symptomatic bradycardia results from decreased sinoatrial node firing or atrioventricular conduction, leading to reduced cardiac output. Key features include vagal stimulation, reduced heart rate, hypotension, and impaired perfusion, requiring rapid pharmacologic intervention to restore adequate circulation and oxygen delivery. Rationale: A. Epinephrine stimulates alpha and beta receptors, increasing heart rate and contractility during cardiac arrest or severe hypotension. However, it is not first-line for symptomatic bradycardia, where vagal inhibition rather than direct adrenergic stimulation is the primary therapeutic target. B. Magnesium is used to treat torsades de pointes and correct electrolyte imbalances affecting ventricular arrhythmias. It does not address vagally mediated bradycardia or improve sinoatrial node firing, making it inappropriate for symptomatic slow heart rhythms. C. Sodium bicarbonate corrects metabolic acidosis and certain drug toxicities, improving acid-base balance. It has no direct chronotropic effect on heart rate or conduction pathways, so it is not effective in treating symptomatic bradycardia. D. Atropine is an anticholinergic that blocks vagal influence on the sinoatrial and atrioventricular nodes, increasing heart rate and improving conduction. It is the first-line medication for symptomatic bradycardia to enhance cardiac output and tissue perfusion.