How does diltiazem help relieve angina?

Diltiazem is effective in relieving angina primarily by blocking calcium channels, which causes the dilation of both coronary and peripheral arteries. When calcium channels are blocked, there is a reduction in the intracellular calcium that is essential for muscle contraction. This leads to relaxation of the vascular smooth muscle, resulting in vasodilation. The dilation of the coronary arteries enhances blood flow to the heart muscle, which can alleviate the oxygen demand during episodes of angina.

Moreover, the decrease in vascular resistance due to this dilation lowers the workload on the heart, further reducing oxygen consumption. This dual effect helps in managing angina symptoms, particularly during exertion or stressful situations when the heart demands more oxygen.

In contrast, the other choices do not accurately depict the mechanism of action for diltiazem in the context of angina relief. For instance, increasing heart rate and contractility would actually increase myocardial oxygen demand, potentially worsening angina. Preventing blood clot formation is more aligned with the action of antiplatelet agents rather than diltiazem, while increasing aerobic metabolism does not relate directly to the pharmacological effects of calcium channel blockers in treating angina.