Coronary Angiography (CAG)

Coronary Angiography is a test that uses dye and special x rays to show the insides of your coronary arteries. The coronary arteries supply oxygen-rich blood to your heart.

A waxy substance called plaque can build up inside the coronary arteries. The buildup of plaque in the coronary arteries is called coronary heart disease.

Over time, plaque can harden or rupture (break open). Hardened plaque narrows the coronary arteries and reduces the flow of oxygen-rich blood to the heart. This can cause chest pain or discomfort called angina.

If the plaque ruptures, a blood clot can form on its surface. A large blood clot can mostly or completely block blood flow through a coronary artery. This is the most common cause of a heart attack. Over time, ruptured plaque also hardens and narrows the coronary arteries.


During coronary angiography, special dye is released into the bloodstream. The dye makes the coronary arteries visible on x-ray pictures. This helps doctors see blockages in the arteries.

A procedure called cardiac catheterization is used to get the dye into the coronary arteries.

For this procedure, a thin, flexible tube called a catheter is put into a blood vessel in your arm, groin (upper thigh), or neck. The tube is threaded into your coronary arteries, and the dye is released into your bloodstream. X-ray pictures are taken while the dye is flowing through the coronary arteries.

Cardiologists (heart specialists) usually do cardiac catheterization in a hospital. You’re awake during the procedure, and it causes little or no pain. However, you may feel some soreness in the blood vessel where the catheter was inserted.

Cardiac catheterization rarely causes serious complications.

Before the Procedure

Before having coronary angiography, talk with your doctor about:

How the test is done and how to prepare for it
Any medicines you’re taking, and whether you should stop taking them before the test
Whether you have diseases or conditions that may require taking extra steps during or after the test to avoid complications. Examples of such conditions include diabetes and kidney disease.
Your doctor will tell you exactly which procedures will be done. For example, your doctor may recommend coronary angioplasty if the angiography shows a blocked artery.

You will have a chance to ask questions about the procedures. Also, you’ll be asked to provide written informed consent to have the procedures.

It’s not safe to drive after having cardiac catheterization, which is part of coronary angiography. You’ll need to have someone drive you home after the procedure.

During the procedure

During coronary angiography, you’re kept on your back and awake. This allows you to follow your doctor’s instructions during the test. You’ll be given medicine to help you relax. The medicine might make you sleepy.

Your doctor will numb the area on the arm, groin (upper thigh), or neck where the catheter will enter your blood vessel. Then, he or she will use a needle to make a small hole in the blood vessel. The catheter will be inserted in the hole.

Next, your doctor will thread the catheter through the vessel and into the coronary arteries. Special x-ray movies are taken of the catheter as it’s moved into the heart. The movies help your doctor see where to place the tip of the catheter.

Once the catheter is properly placed, your doctor will inject a special type of dye into the tube. The dye will flow through your coronary arteries, making them visible on an x ray. This x ray is called an angiogram.

If the angiogram reveals blocked arteries, your doctor may use percutaneous coronary intervention (PCI), commonly known as coronary angioplasty to restore blood flow to your heart.

After your doctor completes the procedure(s), he or she will remove the catheter from your body. The opening left in the blood vessel will then be closed up and bandaged.

A small sandbag or other type of weight might be placed on the bandage to apply pressure.

After the procedure

After coronary angiography, you’ll be moved to a special care area in the hospital. You’ll be carefully watched for several hours or overnight. During this time, you’ll need to limit your movement to avoid bleeding from the site where the catheter was inserted. While you recover in the special care area, nurses will check your heart rate and blood pressure regularly. They’ll also watch for any bleeding at the catheter insertion site. You may develop a small bruise on your arm, groin (upper thigh), or neck at the catheter insertion site. That area may feel sore or tender for about a week. Let your doctor know if you develop problems such as: A constant or large amount of blood at the catheter insertion site that can’t be stopped with a small bandage Unusual pain, swelling, redness, or other signs of infection at or near the catheter insertion site Your doctor will tell you whether you should avoid certain activities, such as heavy lifting, for a short time after the test.