Which of the following classes of medications protects the ischemic myocardium by blocking catecholamines and sympathetic nerve stimulation?
A. Beta-adrenergic blockers
B. Calcium channel blockers
C. Narcotics
D. Nitrates
Correct Answer: A. Beta-adrenergic blockers
Beta-adrenergic blockers work by blocking beta receptors in the myocardium, reducing the response to catecholamines and sympathetic nerve stimulation. They protect the myocardium, helping to reduce the risk of another infarction by decreasing the workload of the heart and decreasing myocardial oxygen demand.
Option B: Calcium channel blockers reduce the workload of the heart by decreasing the heart rate.
Option C: Narcotics reduce myocardial oxygen demand, promote vasodilation, and decrease anxiety.
Option D: Nitrates reduce myocardial oxygen consumption by decreasing left ventricular end-diastolic pressure (preload) and systemic vascular resistance (afterload).