Cardiac catheterization (KATH-eh-ter-ih-ZA-shun) is a medical procedure used to diagnose and treat some heart conditions.

A long, thin, flexible tube called a catheter is put into a blood vessel in your arm, groin (upper thigh), or neck and threaded to your heart. Through the catheter, your doctor can do diagnostic tests and treatments on your heart.

For example, your doctor may put a special type of dye in the catheter. The dye will flow through your bloodstream to your heart. Then, your doctor will take x-ray pictures of your heart. The dye will make your coronary (heart) arteries visible on the pictures. This test is called coronary angiography (an-jee-OG-rah-fee).

The dye can show whether a waxy substance called plaque (plak) has built up inside your coronary arteries. Plaque can narrow or block the arteries and restrict blood flow to your heart.

The buildup of plaque in the coronary arteries is called coronary heart disease (CHD) or coronary artery disease.

Doctors also can use ultrasound during cardiac catheterization to see blockages in the coronary arteries. Ultrasound uses sound waves to create detailed pictures of the heart’s blood vessels.

Doctors may take samples of blood and heart muscle during cardiac catheterization or do minor heart surgery.

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.