What does a cardiac angiogram visualize?

A cardiac angiogram is a medical imaging technique specifically designed to visualize the blood vessels of the heart, particularly the coronary arteries. This procedure involves the injection of a contrast dye into the coronary arteries through a catheter, allowing for detailed images to be captured. The objective is to identify any blockages, narrowing, or abnormalities in the coronary vessels that could affect blood flow to the heart muscle.

While other options pertain to different aspects of cardiac function, they do not accurately reflect what a cardiac angiogram specifically assesses. For instance, monitoring the electrical activity of the heart relates to procedures like an electrocardiogram (ECG), whereas assessing heart valve function would require echocardiography. Evaluating chamber sizes is generally done through imaging techniques like echocardiograms or cardiac MRI, which are not focused on the coronary vessels themselves. Thus, the role of a cardiac angiogram is uniquely valuable for visualizing the coronary vessels, affirming the correctness of that answer.