Insertion of a narrow flexible tube, or catheter, through a blood vessel into the heart to withdraw blood samples, measure pressures, and inject contrast medium for imaging purposes is called Cardiac catheterization. Cardiac catheterization is a procedure to examine how well the heart is working. A thin, hollow tube called a catheter is inserted into a large blood vessel that leads to the heart. It is normally performed if one has a disease of the heart muscles, valves, or coronary arteries. During this procedure, the pressure and blood flow in the heart can be measure and therefore a problem or a disease can be diagnosed; or the efficiency at which the heart is working.