Cardiac catheterization (also called coronary angiogram) is an invasive procedure that allows a patient’s cardiologist to see how well his/her vessels supply blood to the heart. During the procedure, a catheter (a long, hollow tube) is threaded into the patient’s heart through a blood vessel in his/her leg, dye is injected into the coronary arteries, and x-ray pictures are taken. The pictures identify narrowings and blockages in the heart, and allow the cardiologist to determine the best treatment for the patient’s heart disease. Catheterization is also important for evaluating the heart’s pumping function as well as certain heart valve problems.