Which procedure is commonly used to visualize blood vessels?

Angiography is a procedure specifically designed for visualizing blood vessels. It involves the use of contrast material and imaging techniques, such as X-rays, to highlight the blood vessels in the body. This allows healthcare providers to detect abnormalities, blockages, or other issues within the vascular system, aiding in diagnoses and treatment planning.

In contrast, the other procedures listed serve different purposes. Cardiopulmonary resuscitation is a lifesaving technique used during cardiac arrest or respiratory failure, focusing on maintaining blood flow and breathing rather than imaging. An electrocardiogram records the electrical activity of the heart, which helps assess heart rhythm and function, rather than providing imagery of blood vessels. Echocardiography utilizes ultrasound waves to create images of the heart's structure and function, focusing primarily on the heart itself rather than the blood vessels.

Thus, angiography is unequivocally the procedure that specializes in the visualization of blood vessels, making it the correct choice for this question.