Cardiac catheterization is a diagnostic procedure for evaluating certain problems with the heart and its blood supply. The procedure involves the placement of a long, thin tube (called a catheter) into the heart to measure pressures, inject dye, and take x-ray pictures. This procedure normally takes two to three hours. Cardiac catheterization provides information about The blood flow through the heart and coronary arteries (blood vessels that supply blood to the heart muscle) or other major blood vessels that carry blood to and from the heart;. Pressure within the heart chambers; The detailed structure of various parts of the heart and vascular (blood vessel) system; and the heart's pumping ability.