Think of your heart as a powerful muscle that needs its own supply of fuel and oxygen. This fuel is delivered through pipes, called coronary arteries, that wrap around the outside of your heart. Sometimes, these pipes can get narrow or clogged due to fatty buildup (called plaque).

A coronary angiogram (pronounced an-gee-o-gram) is like a plumbing inspection for your heart. It’s a special X-ray movie that lets the doctor see exactly what’s happening inside these pipes.

• It shows if your arteries are open and healthy.
• It shows if they are narrowed.
• It shows exactly where a blockage might be.

To see the arteries, the doctor needs to put a special dye inside them that shows up on X-rays. Here is how they do it:

1. The Entry Point: The doctor numbs a small area of skin, usually in your wrist or your groin (upper thigh). You will be awake, but you will be given medication to help you feel very relaxed and sleepy.
2. The Tiny Tube: The doctor gently inserts a small, flexible tube called a catheter into the blood vessel. This tube is very long and thin—about as thin as a strand of spaghetti.
3. The Journey: Because blood vessels form a highway throughout your body, the doctor can gently guide this tube up through the vessel to your heart. You will not feel it moving inside you.
4. The X-Ray Movie: Once the tube is in place at the opening of your coronary arteries, the doctor injects the special dye through the tube. When the dye flows into your arteries, it makes them light up on the X-ray screen. The doctor watches this “movie” in real-time to see if the dye flows freely or if it gets stuck at a narrowed spot.

• The Numbing Shot: You will feel a small pinch and a little burn when the doctor numbs the skin.
• The Catheter: You will not feel the tube moving through your body. The inside of your blood vessels does not have pain sensors.
• The Dye: This is the strangest part for most people. When the doctor injects the dye, you might feel a warm, flushing sensation that spreads through your body. It can feel like you’ve wet yourself for a second (don’t worry, you haven’t!). This feeling lasts for only 10–20 seconds.
• You: You may be asked to take a deep breath or hold your breath briefly. You can tell the doctor or nurse how you are feeling at any time.

The doctor uses this test to make a diagnosis. It answers the question: “Do you have a blocked artery causing your chest pain or other symptoms?” The results help the doctor decide the best treatment for you, which could be medication, a stent (a small mesh tube to prop the artery open), or bypass surgery.