A left cardiac catheterization (also known as a left heart catheterization) is a specialized test done under X-ray, that shows the blood flow through the coronary arteries. The coronary arteries are responsible for supplying oxygenated blood to your heart. During the procedure, your doctor inserts a catheter into the wrist (radial artery) or groin (femoral artery) and advances it through the artery leading up into your coronary artery in the heart. Your doctor then injects a special fluid called contrast media, or contrast dye, through the catheter into your heart’s blood stream.

The contrast dye allows the x-ray to show real time moving images of the blood flow through the coronary arteries. The doctor uses these images to identify the precise location of any blockages in your arteries and the extent of plaque buildup. Based on the findings of this test, your doctor is able to determine if further treatment such as coronary angioplasty, coronary stents, or open-heart surgery is needed to fix the lack of blood supply.