Final answer:
A β-adrenergic blocking agent is prescribed for angina to decrease heart rate and blood pressure, which reduces the heart's oxygen demand and helps prevent chest pain. β-blockers, such as metoprolol and propranolol, block receptors that adrenaline affects, thus improving cardiac function.
Step-by-step explanation:
The patient prescribed a β-adrenergic blocking agent for angina needs to take this medication to decrease the heart rate and blood pressure. These drugs, known as β-blockers, act by blocking the β-receptors, which adrenaline stimulates to increase heart rate and blood pressure. By blocking these receptors, β-blockers reduce the workload on the heart and consequently the heart's demand for oxygen, thus helping to prevent angina, which is chest pain due to reduced blood supply to the heart muscle.
β-blockers like metoprolol and propranolol are common examples that have revolutionized the treatment of cardiovascular diseases like hypertension and angina pectoris. These medications are able to improve cardiac function in a compromised system by allowing blood vessels to dilate and keeping the heart rate from rising unnecessarily.