Final answer:
Stable angina symptoms typically lessen with rest or nitroglycerin, which dilates coronary arteries to improve blood flow. Unstable angina, presenting with pain at rest or lasting over 15 minutes, is serious and may indicate an impending heart attack.
Step-by-step explanation:
Symptoms of stable angina typically lessen with rest or the administration of nitroglycerin. Stable angina is characterized by chest pain or discomfort that is triggered by exertion, such as brisk walking or running. This type of angina indicates that the heart muscle is not receiving enough oxygen due to partial blockage of the coronary arteries. Nitroglycerin works to dilate coronary arteries and improve blood flow, thereby relieving symptoms quickly. However, if angina symptoms occur at rest, last more than 15 minutes, or are new, it may indicate unstable angina, which is a more serious condition and could signal an imminent heart attack, requiring urgent medical attention.