What Is Cardiac Catheterization?

What to expect when undergoing this test

Cardiac catheterization (also referred to as cardiac cath or heart cath) is an invasive procedure used to evaluate and treat heart conditions. A thin, long, flexible tube is inserted, usually in the arm or groin, and is guided to the blood vessels of your heart.

Angiography is almost always done during the procedure, which involves injecting dye into your vessels so they can be visualized with imaging, typically an X-ray or an intravascular ultrasound.

Your healthcare provider may use this to help diagnose a concern, deliver medication, or repair heart defects and disease.

what to expect during a cardiac catheterization

Verywell / Emily Roberts

Purpose of Test

Cardiac catheterization allows your healthcare provider to access your coronary arteries for blockages and to assess heart muscle function and the structure and function of your heart valves. The catheterization procedure can also be used to deliver therapy for many cardiac conditions. 

A specialized type of cardiac catheterization, the electrophysiology study, is used to assess and treat various heart rhythm disturbances.

Diagnostic Uses

If you have signs of atherosclerosis or coronary artery disease (blockage in your heart vessels) such as fatigue, shortness of breath, or chest pain, you may need a cardiac catheterization.

Cardiac catheterization produces images that can identify the location and severity of blockages in the coronary arteries, show your overall heart function and the condition of individual cardiac chambers (cardiac ventriculography), and determine whether your heart valves are narrow, stiff, or leaky.

This test is also done preoperatively for planning cardiac procedures that involve treatment of narrow or blocked coronary arteries, such as coronary artery bypass surgery, angioplasty, and stenting.

A cardiac catheterization can also be used to take a sample of tissue if you have a possibility of an infection or inflammation of the heart, to measure oxygen levels for assessment of cardiac and pulmonary disease, or to determine the pressure in various areas of the heart (right heart catheterization).

Sometimes cardiac catheterization can be used as one of the diagnostic tests for heart valve disease, congestive heart failure, cardiomyopathy, or heart failure.

Therapeutic Uses

Often, cardiac catheterization is useful in the treatment of heart problems. As with diagnostic catheterization, imaging with angiography is used, which allows your healthcare providers to see your heart as the procedure is being performed.

Therapeutic catheterizations are used to relieve blockages in the coronary arteries with angioplasty (widening the arteries), to remove obstructive material (thrombectomy), and for stent placement (a tube that remains in place to keep the artery open).

The procedure can also treat heart valve conditions such as mitral stenosis and aortic stenosis (valvuloplasty) and heart rhythm irregularities (cardiac ablation), or to repair patent foramen ovale.

Sometimes a cardiac catheterization with an angioplasty is done urgently for the diagnosis and treatment of a heart attack to restore blood flow to a coronary artery, with the aim of preventing permanent heart damage.

Similar Tests

Depending on your condition, your healthcare provider may opt for:

  • Noninvasive angiogram: A noninvasive angiogram, such as a computed tomography-angiogram (CT-angiogram) or a magnetic resonance angiogram (MR-A), uses imaging to evaluate blood vessels in any area of the body, including the heart.
  • Carotid and aortic catheterization: A catheterization can access other arteries in the body, such as the carotid arteries in the neck, or the abdominal aorta. These procedures may be combined at the same time if widespread arterial disease is suspected.

Some forms of testing may be better suited to some patients than others. You and your healthcare provider can discuss which one(s) is right for you.


Certain heart problems, such as congenital heart defects, heart valve disease, and heart failure, may be detected by catheterization and angiography, but are better evaluated with cardiac echo, cardiac MRI, or cardiac CT; arrhythmias are best evaluated with an electrocardiogram (ECG or EKG), ambulatory monitoring, or an electrophysiology study.

Risks and Contraindications

Cardiac catheterization and angiography are relatively safe, but because they are invasive procedures involving the heart, several complications are possible. For this reason, a cardiac catheterization is performed only when the treatment is expected to be highly beneficial or when there is a strong likelihood that the information gained from the procedure will be of significant benefit.

Common complications of cardiac catheterization include minor bleeding at the site of catheter insertion, usually in the arm or the groin, temporary heart rhythm disturbances caused by the catheter irritating the heart muscle, and temporary changes in the blood pressure.

Serious and less common complications include:

  • An allergic reaction to the dye: This can cause flushing, a rash, extreme shortness of breath, hypertension or hypotension, or heart rhythm irregularities and is treated as an emergency, usually with epinephrine.
  • Artery damage: This can occur in any artery between the location of catheter insertion all the way to the arteries in the heart, causing a defect called a pseudoaneurysm.
  • Perforation of the heart wall: This can cause a life-threatening condition, cardiac tamponade.
  • Sudden blockage of a coronary artery, which can lead to a heart attack.
  • Extensive bleeding.
  • Stroke.

In addition, cardiac catheterization and angiography involve exposure to radiation. As with any medical test using radiation, these tests may produce a tiny increase in the lifetime risk of developing cancer.

Cardiac catheterization for the treatment of coronary artery disease is less invasive than open-heart surgery. But complicated heart conditions often require open-heart surgery, which can allow your healthcare providers better access to your heart for extensive repairs. Complications and emergencies that result from a diagnostic or therapeutic catheterization and angiography may require emergency open-heart surgery.

Before the Test

If you are going to have a cardiac catheterization, you will first need some pre-testing to make sure you can tolerate the procedure and that your healthcare providers are well-prepared for complications.

  • You will need a blood count to screen for infection. A nonemergency cardiac catheterization is likely to be postponed until you recover from an infection.
  • You will need a PT/PTT, blood tests that assess your blood clotting factors. 
  • You will likely need to have an ECG to assess your heart rhythm and function, because a cardiac catheterization may be riskier if you have an arrhythmia or weak heart function.
  • You will likely have a chest X-ray to screen for major anatomical variations around your heart and lungs, which prepares your healthcare providers in case your procedure will be particularly challenging.

You may also be instructed to stop some of your medications, such as blood thinners and heart medications, a day or two before the test. Always alert your healthcare provider about any nonprescription medications you take as well.


If you are scheduled for a cardiac catheterization, you should be prepared to spend the rest of the day recovering after your exam is complete.

A diagnostic cardiac catheterization procedure can take between 30 minutes to over an hour, and a therapeutic catheterization can take several hours. For both, you will need to have an IV placed and you will receive an anesthetic.

You may or may not be awake during the procedure. It can take approximately an hour to fully wake up after anesthesia, even if you are not completely put to sleep, and most people feel groggy until after getting a full night's sleep.

Your healthcare provider may talk to you about the preliminary results after you recover from anesthesia, or you may need to come back at another time to discuss the results. If there is something concerning noted during a diagnostic test, you may need to have another test or a procedure, so ask your healthcare provider if you should be prepared to spend the whole day or even to stay overnight.

After a therapeutic procedure, you may need to spend a few hours in recovery, or even spend the night in the hospital.


A cardiac catheterization with an angiogram is performed in a special cardiac procedure suite. Sometimes, if there is a concern that the procedure may be complicated, it is performed in an operating room in case open heart surgery is needed.

With all catheterization procedures, there is a backup plan for a surgical emergency, in which case you would need to move from the cardiac procedure suite to the operating room. Some hospitals do not perform cardiac surgery. In this case, if emergency surgery is required, you will be transferred to another hospital.

What to Wear

You will need to wear a gown for the procedure, so you can wear whatever is comfortable to the test.

Food and Drink

You will need to abstain from food and drink after midnight before your test or for six to eight hours if your test is scheduled for late in the day.

Cost and Health Insurance

You may need health insurance preauthorization before your test, and the facility where it is being done will most likely take care of obtaining the approval. You may also need to pay a copay, and you can ask your health insurance provider or the facility about your fee responsibility in advance.

If you are paying for the procedure yourself, the cost can run in the high thousands for a diagnostic procedure and in the tens of thousands for a therapeutic procedure.

There is a huge range in cost, depending on the facility, the region of the country, and your specific diagnosis, so it is best to get an estimate in writing ahead of time instead of making any assumptions. In fact, for a nonemergency cardiac catheterization, it is not unusual to "shop around" if you are paying for it yourself.

What to Bring

You should bring your test order form (if you have one), your insurance card, a form of identification, and a method of payment. Because you will not be able to drive yourself home after the test, you should make sure you have someone to drive you home.

During the Test

Your cardiac catheterization will be performed by a healthcare provider, most likely a cardiologist. There will be nurses or technical assistants helping with the procedure as well.


After you fill out the sign-in forms, you will meet with a nurse or a technician, who will confirm that you have not eaten after midnight and may ask you whether you have any symptoms of chest pain, shortness of breath, dizziness, or vision changes.

You will be asked to change into a gown, and you will have an IV placed in your hand. You will meet with the healthcare provider who is going to perform the procedure, the rest of the team, and the healthcare provider, nurse, or other practitioners who will give you the anesthetic.

Throughout the Test

After local anesthesia is given, a catheter is inserted in one of the blood vessels in your groin, arm, wrist, or neck. The catheter is inserted either through a small incision or with a needle-stick. Once in the artery, the catheter is advanced to the heart using X-ray guidance.

During the procedure, catheters are typically maneuvered to various locations within the heart, and the pressures within the chambers of the heart are measured. Measuring these intracardiac pressures can be helpful in diagnosing certain kinds of heart disease.

For instance, heart valve disease can be detected by measuring pressure differences between cardiac chambers. As an example, in mitral stenosis the left atrial pressure is higher than the left ventricular pressure when the mitral valve is open, indicating that the valve is not opening completely and that a partial obstruction to blood flow is present when it should not be.

Blood samples can be taken through the catheter from different locations in the heart to measure the amount of oxygen in the blood. You may be asked to hold your breath for a few seconds, as this can change oxygen concentration and help your healthcare providers visualize your heart from different angles.

Oxygen levels on the right side of the heart should be relatively low, while oxygen levels on the left side of the heart, which receives blood from the lungs, are higher. Unusual variations in blood oxygen in the various cardiac chambers can signal abnormal blood flow within the heart, often caused by congenital heart defects such as an atrial septal defect.

Dye is injected through the catheter while a series of rapid X-ray images are recorded, which produce videos of the blood flowing through the cardiac chambers or coronary arteries.

Once the procedure is completed, the catheter is removed. Bleeding is controlled by placing pressure on the catheter insertion site, which will need to continue for 30 to 60 minutes.


At this point, you will probably move to a post-surgical recovery suite. As the anesthetic wears off, your nurse will check your blood pressure, pulse, oxygen level, and possibly perform an ECG.

Your medical team will want to make sure you urinate at least once after the procedure because you have been abstaining from food and drink, which can make you dehydrated. If you need more fluid, your team will likely provide you with liquids to drink and/or IV fluid and wait for you to urinate before allowing you to leave.

Once you are fully alert and can walk without assistance, and it is confirmed that someone will drive you home, you will be discharged. You will be given instructions to check on your catheter puncture site and extra bandages in case they need to be replaced.

After the Test

At home, you should take it easy, try to get some rest, and eat something light. By the morning, you should feel fully recovered and can resume your normal activities.

Managing Side Effects

If you remain a bit tired on the day of the procedure, you should take a nap or relax. If there is minor bleeding that soaks one or two bandages on the day of the test without overflowing, then it is fine to change the bandages.

But if you experience continuous bleeding, swelling, or oozing from the puncture site, call your healthcare provider. If you have chest pain, shortness of breath, lightheadedness, or syncope (loss of consciousness), you should seek emergency help right away.

Interpreting Results

The test results are generally descriptive and detailed. The report will note how well each of the coronary arteries was visualized and provide a characterization of their shape, whether there is calcification or narrowing, and the exact extent and location of narrowing.

Often, a description of the heart chambers and valves, anatomical defects, or aspects of heart function may be included in the report as well.

When the procedure is done for therapeutic reasons, you can expect the report to specify the findings, as well as to describe how the procedure was done, and to report on any complications, unexpected challenges, and whether the procedure achieved what it was meant to achieve.


After a cardiac catheterization, you may need some follow-up tests after a few days or weeks, including ECG to check your heart function after the procedure, or cardiac echo, depending on whether there are still concerns that were not answered based on the catheterization. You may also need to have some medication adjustments after the procedure.

In general, a cardiac catheterization would not be routinely repeated, and you will need to have another one only if your healthcare provider thinks you have had a significant change in the blood vessels of your heart that requires intervention.

A Word From Verywell

The medical treatments available for heart disease are generally very successful and safe. If you need to have a cardiac catheterization with angioplasty or if you need to have heart surgery, you should know that most people recover quite well.

If you need a cardiac catheterization, this is generally the most invasive portion of an extensive cardiac evaluation that includes ECG, blood tests, X-rays, and possibly echocardiogram or pulmonary function tests.

Sometimes the workup can take time, and you may not get a diagnosis right away. While it can be frustrating to have to wait to know what is affecting you, try to take comfort in knowing that this test puts you one step closer to an answer.

14 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Richard N. Fogoros, MD
Richard N. Fogoros, MD, is a retired professor of medicine and board-certified in internal medicine, clinical cardiology, and clinical electrophysiology.