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What Is Cardiac Catheterization?

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.




Who Needs Cardiac Catheterization?

Doctors may recommend cardiac catheterization for various reasons. The most common reason is to evaluate chest pain.

Chest pain might be a symptom of coronary heart disease (CHD). Cardiac catheterization can show whether plaque is narrowing or blocking your coronary arteries.

Doctors also can treat CHD during cardiac catheterization using a procedure called angioplasty (AN-jee-oh-plas-tee).

During angioplasty, a catheter with a balloon at its tip is threaded to the blocked coronary artery. Once in place, the balloon is inflated, pushing the plaque against the artery wall. This creates a wider path for blood to flow to the heart.

Sometimes a stent is placed in the artery during angioplasty. A stent is a small mesh tube that supports the inner artery wall.

Most people who have heart attacks have narrow or blocked coronary arteries. Thus, cardiac catheterization might be used as an emergency procedure to treat a heart attack. When used with angioplasty, the procedure allows your doctor to open up blocked arteries and prevent further heart damage.

Cardiac catheterization also can help your doctor figure out the best treatment plan for you if: 

  • You recently recovered from a heart attack, but are having chest pain
  • You had a heart attack that caused major heart damage
  • You had an EKG (electrocardiogram), stress test, or other test with results that suggested heart disease

Cardiac catheterization also might be used if your doctor thinks you have a heart defect or if you're about to have heart surgery. The procedure shows the overall shape of your heart and the four large spaces (heart chambers) inside it. This inside view of the heart will show certain heart defects and help your doctor plan your heart surgery.

Sometimes doctors use cardiac catheterization to see how well the heart valves work. Valves control blood flow in your heart. They open and shut to allow blood to flow between your heart chambers and into your arteries.

Your doctor can use cardiac catheterization to measure blood flow and oxygen levels in different parts of your heart. He or she also can check how well a man-made heart valve is working and how well your heart is pumping blood.

If your doctor thinks you have a heart infection or tumor, he or she may take samples of your heart muscle through the catheter. With the help of cardiac catheterization, doctors can even do minor heart surgery, such as repair certain heart defects.




What To Expect Before Cardiac Catheterization

Before having cardiac catheterization, discuss with your doctor:

  • How to prepare for the procedure
  • Any medicines you're taking, and whether you should stop taking them before the procedure
  • Whether you have any conditions (such as diabetes or kidney disease) that may require taking extra steps during or after the procedure to avoid problems

Your doctor will let you know whether you need to arrange for a ride home after the procedure.




What To Expect During Cardiac Catheterization

Cardiac catheterization is done in a hospital. During the procedure, you'll be kept on your back and awake. This allows you to follow your doctor's instructions during the procedure. You'll be given medicine to help you relax, which 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, a needle will be used to make a small hole in the blood vessel. Your doctor will put a tapered tube called a sheath through the hole.

Next, your doctor will put a thin, flexible guide wire through the sheath and into your blood vessel. He or she will thread the wire through your blood vessel to your heart.

Your doctor will use the guide wire to correctly place the catheter. He or she will put the catheter through the sheath and slide it over the guide wire and into the coronary arteries.

Special x-ray movies will be taken of the guide wire and the catheter as they're moved into the heart. The movies will help your doctor see where to put the tip of the catheter.

When the catheter reaches the right spot, your doctor will use it to do tests or treatments on your heart. For example, your doctor may do angioplasty and stenting.

The animation below shows the process of cardiac catheterization. Click the "start" button to play the animation. Written and spoken explanations are provided with each frame. Use the buttons in the lower right corner to pause, restart, or replay the animation, or use the scroll bar below the buttons to move through the frames.

The animation shows the step-by-step process your doctor will follow to do cardiac catheterization.

During the procedure, 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.

Coronary angiography can show how well the heart's lower chambers, called the ventricles (VEN-trih-kuls), are pumping blood.

When the catheter is inside your heart, your doctor may use it to take blood and tissue samples or do minor heart surgery.

To get a more detailed view of a blocked coronary artery, your doctor may do intracoronary ultrasound. For this test, your doctor will thread a tiny ultrasound device through the catheter and into the artery. This device gives off sound waves that bounce off the artery wall (and its blockage). The sound waves create a picture of the inside of the artery.

If the angiogram or intracoronary ultrasound shows blockages in the coronary arteries, your doctor may use angioplasty to treat the blocked arteries.

After your doctor does all of the needed tests or treatments, he or she will pull back the catheter and take it out along with the sheath. The opening left in the blood vessel will be closed up and bandaged.

A small weight might be put on top of the bandage for a few hours to apply more pressure. This will help prevent major bleeding from the site.




What To Expect After Cardiac Catheterization

After cardiac catheterization, you will be moved to a special care area. You will rest there for several hours or overnight. During that time, you'll have to limit your movement to avoid bleeding from the site where the catheter was inserted.

While you recover in this area, nurses will check your heart rate and blood pressure regularly. They also will check for bleeding from the catheter insertion site.

A small bruise might form at the catheter insertion site, and the area may feel sore or tender for about a week. Let your doctor know if you have problems such as:

  • A constant or large amount of bleeding at the insertion site that can't be stopped with a small bandage
  • Unusual pain, swelling, redness, or other signs of infection at or near the insertion site

Talk to your doctor about whether you should avoid certain activities, such as heavy lifting, for a short time after the procedure.




What Are the Risks of Cardiac Catheterization?

Cardiac catheterization is a common medical procedure. It rarely causes serious problems. However, complications can include:

  • Bleeding, infection, and pain at the catheter insertion site.
  • Damage to blood vessels. Rarely, the catheter may scrape or poke a hole in a blood vessel as it's threaded to the heart.
  • An allergic reaction to the dye that's used during coronary angiography.

Other, less common complications include:

  • Arrhythmias (irregular heartbeats). These irregular heartbeats often go away on their own. However, your doctor may recommend treatment if they persist.
  • Kidney damage caused by the dye used during coronary angiography.
  • Blood clots that can trigger a stroke, heart attack, or other serious problems.
  • Low blood pressure.
  • A buildup of blood or fluid in the sac that surrounds the heart. This fluid can prevent the heart from beating properly.

As with any procedure involving the heart, complications sometimes can be fatal. However, this is rare with cardiac catheterization.

The risks of cardiac catheterization are higher in people who are older and in those who have certain diseases or conditions (such as chronic kidney disease and diabetes).




Clinical Trials

The National Heart, Lung, and Blood Institute (NHLBI) is strongly committed to supporting research aimed at preventing and treating heart, lung, and blood diseases and conditions and sleep disorders.

NHLBI-supported research has led to many advances in medical knowledge and care. For example, this research has helped look for better ways to diagnose and treat heart problems using methods such as cardiac catheterization.

The NHLBI continues to support research on cardiac catheterization. For example, a current study compares two strategies for managing patients who have stable ischemic heart disease.

One strategy involves using cardiac catheterization to treat all patients, while the other uses the procedure for only certain patients. The goal of this research is to find out whether the first strategy reduces the number of patient deaths, heart attacks, and hospital stays compared with the second strategy.

Much of the NHLBI's research depends on the willingness of volunteers to take part in clinical trials. Clinical trials test new ways to prevent, diagnose, or treat various diseases and conditions.

For example, new treatments for a disease or condition (such as medicines, medical devices, surgeries, or procedures) are tested in volunteers who have the illness. Testing shows whether a treatment is safe and effective in humans before it is made available for widespread use.

By taking part in a clinical trial, you can gain access to new treatments before they're widely available. You also will have the support of a team of health care providers, who will likely monitor your health closely. Even if you don't directly benefit from the results of a clinical trial, the information gathered can help others and add to scientific knowledge.

If you volunteer for a clinical trial, the research will be explained to you in detail. You'll learn about treatments and tests you may receive, and the benefits and risks they may pose. You'll also be given a chance to ask questions about the research. This process is called informed consent.

If you agree to take part in the trial, you'll be asked to sign an informed consent form. This form is not a contract. You have the right to withdraw from a study at any time, for any reason. Also, you have the right to learn about new risks or findings that emerge during the trial.

For more information about clinical trials related to cardiac catheterization, talk with your doctor. You also can visit the following Web sites to learn more about clinical research and to search for clinical trials:

For more information about clinical trials for children, visit the NHLBI's Children and Clinical Studies Web page.




Links to Other Information About Cardiac Catheterization

NHLBI Resources

Non-NHLBI Resources

Clinical Trials

 
January 30, 2012 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.