A client is admitted for observation following complaints of intermittent chest pain while mowing the grass. The pain persisted for an hour following the activity. All cardiac labs, electrocardiogram, and radiologic studies were normal and the client was provided nitroglycerin for a new diagnosis of angina pectoris. Discharge education includes information that angina is most often attributable to what cause?

A. Coronary arteriosclerosis: The narrowing and hardening of the coronary arteries restrict the flow of oxygenated blood to the myocardium. When physical activity increases the heart's oxygen demand, the restricted vessels cannot provide adequate supply, resulting in ischemic pain known as angina. This is the primary underlying cause of most cases of chronic stable angina. B. Decreased workload of the heart: A reduction in cardiac workload would actually decrease the likelihood of experiencing angina. Angina is triggered when the workload exceeds the available oxygen supply, such as during physical exertion or stress. Management of angina focuses on reducing this workload through rest and medications like beta-blockers. C. Atrial septal defect: This congenital heart defect involves an opening in the wall between the atria, which primarily causes shunting of blood. While it can lead to long-term complications like pulmonary hypertension, it is not the most common cause of typical angina pectoris in adults. Angina is almost always a result of obstructive coronary artery disease. D. Infarction of the myocardium: Myocardial infarction refers to actual tissue death due to a complete and prolonged lack of blood flow. Angina is a warning sign of ischemia without cell death, which is why the client's cardiac labs and EKG remained normal. Infarction represents a permanent injury, whereas angina is a transient episode of oxygen mismatch.