How does nitroglycerin help control angina during exercise?

Nitroglycerin primarily works by dilating peripheral arteries and veins, resulting in a decrease in systemic vascular resistance and venous return to the heart. This reduction in preload and afterload decreases the workload on the heart, which can be beneficial during episodes of angina, particularly those triggered by physical exertion. By reducing the amount of oxygen the heart requires, the drug alleviates the chest pain associated with angina.

The vasodilatory effects of nitroglycerin help to increase the coronary blood flow, improving oxygen delivery to the heart muscle, particularly in areas that may be ischemic during increased activity. Therefore, this mechanism not only helps control angina but also plays a significant role during exercise by preventing the onset of anginal symptoms.

While the other options may reflect some aspects of cardiovascular physiology, they do not specifically pertain to the primary action of nitroglycerin in managing angina during exercise.