What happens during cardiac catheterization?

Cardiac catheterization is a procedure used to show on a computer monitor diseases that affect the heart, the cardiac valves or the coronary arteries. A cardiac is a thin, flexible plastic tube that is moved through a blood vessel until it reaches the heart. X-ray monitoring is used to guide the . There are two main types of cardiac catheterization:

  • Right heart catheterization (venous or flow-directed ): The is inserted through a vein in the groin region or at the elbow and then advanced to the right ventricle and the pulmonary artery. Flow-directed catheters have a small inflatable balloon at the tip, allowing them to be carried by the flow of blood. The is used to measure the pressure levels in the right ventricle and the pulmonary artery. A contrast medium is injected through the so that the right chamber, the circulation of blood and the function of the cardiac valves can be examined.
  • Left heart catheterization (arterial ): This is advanced through an artery in your groin region, elbow or wrist and into the heart’s left ventricle. After a contrast medium has been injected it’s possible to examine the left ventricle, the aorta, the circulation of blood and the performance of the cardiac valves.
Illustration: Right and left heart catheterization, depicting the catheter reaching the heart with respective entry points

Right and left heart catheterization

Coronary angiography is also possible with the commonly used left-heart catheterization procedure. Contrast medium is injected into the coronary arteries to find possible constrictions. Treatment can also be performed during the examination: If narrowed arteries are found, they can be pushed open using a balloon affixed to the tip of the . The can also be used to implant a metal tissue support (stent) to keep the blood vessel open.

Illustration: Cardiac catheter with balloon and stent

Cardiac catheter with balloon and stent

It’s possible to take tissue samples during both of these procedures. Doctors can also check possible causes of arrhythmia. Specialized catheters may be used to measure how much blood the heart pumps in one minute. This can help doctors find out whether the heart is performing poorly.

When is cardiac catheterization used?

Cardiac catheterization is especially well-suited for the following situations:

  • Symptoms such as chest pain or tightness and shortness of breath, or after a . Left heart catheterization can help to determine the location and severity of a possible narrowed coronary artery and expand a constricted or blocked blood vessel.
  • Suspected degenerative changes or dysfunction affecting the cardiac valves.
  • Before heart surgery: If heart valve or surgery is planned, the heart muscle tissue and the coronary arteries are checked for any abnormal changes using cardiac catheterization.
  • For biopsies: Heart muscle tissue can be taken using a in case of myocarditis (heart muscle ).

What kind of preparation needs to be done?

Before starting the doctor first needs to know about any other medical problems you may have, such as diabetes, infections, bleeding disorders or allergies. It’s also important to let the doctors know what medication you use (like anticoagulants, beta blockers or antidiabetics). A number of tests need to be completed before the procedure can be started:

  • ECG
  • Blood pressure reading
  • Blood testing: This serves to find out your blood count, and determine other parameters describing blood clotting ability and kidney and thyroid function. The latter is useful if a contrast medium containing iodine is injected.

Further examinations may be done, depending on what the doctors are looking for, possibly including a lung x-ray or an ultrasound of the heart (echocardiography).

What does the examination involve?

The procedure is done in a catheterization laboratory (sometimes called a “cath lab”). Often the lab is in a hospital, but catheterization can also be done in an outpatient setting at a specialist clinic. You’re not allowed to eat anything for about six hours before the examination. The area of skin right at the insertion site in your groin region or on your arm may need to be shaved right before the procedure. You’ll also be given a local anesthetic. A sedative is also available on request.

The doctor punctures a blood vessel and then inserts the to move it up to your heart. While this is done, the situation is monitored on a computer screen. Usually you don’t feel anything because the inside walls of the blood vessels aren’t sensitive to pain.

An x-ray contrast medium is injected through the into the chambers of the heart and the coronary arteries to make them visible on the computer screen. This may feel warm for a short time. You may also feel temporary heart pain if one of the narrowed arteries is pushed open. This usually goes away as soon as the expansion is completed.

You can watch pictures of your own heart on the screen during the examination. It usually lasts about 30 minutes, but may also take much longer, depending on what the doctors find and whether further measurements, expansion of the blood vessels or stent implantation are needed.

A pressure bandage is applied to the insertion site afterwards to prevent bleeding. Doctors will ask you to stay at the hospital another five hours for your own safety. You’ll need to continue to stay in a lying position for about four hours if the was inserted in the groin region. And an additional two days of monitoring is usually required if a narrowed artery was detected and treated.

It’s always important to rest at home for the first few days and avoid lifting heavy objects.

What risks does cardiac catheterization involve?

Cardiac catheterization is classified as a minimally invasive procedure, because no larger incisions are needed to reach the heart. It’s considered to be a safe examination method: only about 1 out of 100 examinations results in complications. But it still involves the heart, and if complications arise, they may be serious. Because of this, your doctor must talk to you about the risks, possible consequences and alternative methods for examining your heart one day or more in advance of the procedure, unless it’s an emergency. You then sign a patient consent form once you’ve been informed of the risks.

The risks include:

  • Bleeding and bruising at the insertion site,
  • Allergic reaction to the contrast medium (ranging from itchy skin, swelling, or shortness of breath to circulatory shock),
  • Usually temporary arrhythmia,
  • Blood vessel and nerve damage,
  • Acute or stroke.
The risk of complications increases in people who already have severe cardiac disease or other related conditions.

Bundesärztekammer, Kassenärztliche Bundesvereinigung, AWMF. Nationale Versorgungsleitlinie Chronische KHK (S3, Langfassung). February 2016 (AWMF-Leitlinien; Volume nvl - 004).

Deutsche Gesellschaft für Kardiologie (DKG). Leitlinie Diagnostische Herzkatheteruntersuchung. Clin Res Cardiol 2008; 97: 475-512.

Erdmann E, Klinische Kardiologie. Berlin: Springer; 2011.

Institut für angewandte Qualitätsförderung und Forschung im Gesundheitswesen (AQUA). Qualitätsreport 2013: Ergebnisse der Qualitätssicherung zur Koronarangiographie und Perkutane Koronarintervention (PCI): 61ff. August 2014.

Stierle U, Hartmann, F. Klinikleitfaden Kardiologie. München: Elsevier; 2014.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

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Updated on March 9, 2016
Next planned update: 2022


Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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