Cardiac catheterization (also called cardiac cath or heart cath) is a procedure that allows your Doctor to see how well your blood vessels supply your heart.

During the test, they will insert a long, narrow tube called catheter into a blood vessel in your arm or leg and guide it to the heart with the aid of a special X-Ray machine. 

Doctors use contrast dye that they inject into your blood vessel through the catheter to create X-Ray videos of your valves, coronary arteries and heart chambers.