Cardiac catheters: shapes, procedures, risks

A cardiac catheter examination is used to diagnose and often also to treat diseases of the coronary arteries, the heart valves and the heart muscle, as well as arrhythmias

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Heart catheter - briefly explained

During a cardiac catheter examination, a very thin, long plastic tube, the catheter, is inserted directly into or onto the heart via the vessels and an X-ray contrast medium is injected. This examination can make the heart chambers and the coronary arteries visible on an X-ray screen. It can provide information on:

  • the pumping function of the heart chambers
  • the pressure in the ventricles and atria
  • Severity of existing heart valve defects
  • existing constrictions of the coronary arteries

The cardiac catheter can also be used for therapy. If the attending physician discovers a critical constriction in the coronary arteries, he usually eliminates it during the procedure. In the worst case, constrictions in the coronary arteries can lead to a heart attack, as sections of the heart muscle are then not supplied with oxygen. Narrowed vessels can be dilated with a balloon and / or a stent inserted during a cardiac catheter examination.

Forms of cardiac catheter examination

Doctors differentiate between two types of heart catheter examination: the "left heart catheter" and the "right heart catheter".

Left heart catheter

This is used more often because it can often be used to examine diseased parts of the heart:

  • the left ventricle
  • the aortic and mitral valves
  • the coronary arteries (this exam is called a coronary angiography)

The catheter is advanced through an artery in the groin or on the wrist into the large body artery (aorta) to the left ventricle or to the coronary arteries.

Right heart catheter

This measures the pressure in the right ventricle and in the pulmonary arteries. In addition, the volume of blood that the heart pumps in one minute can be checked. To do this, the fine tube is inserted through a vein in the crook of the elbow or in the groin. Doctors often use so-called "flood-in catheters" for this examination, which are placed by means of a small balloon: the air-filled balloon is carried ("flooded") into the right heart and the pulmonary arteries via the venous bloodstream.

How do you prepare for the exam?

If the cardiac catheter is not used because of an emergency, for example an acute heart attack, there is time for preparation. In the preliminary discussion, the patient should mention important particularities and previous illnesses, such as:

  • Allergies to contrast media
  • diabetes
  • Thyroid disorders
  • or renal failure

Anyone who takes medication should also inform the doctor beforehand. This is particularly important with anticoagulants, for example. You may have to take a break from taking it. If a patient takes medication with the active ingredient metformin because of diabetes, these are usually discontinued two days before the cardiac catheter in consultation with the doctor. Otherwise, the contrast agent administered could mean that metformin is no longer adequately excreted and is harmful to the body, especially if the kidneys were previously poorly functioning.

On the evening before the examination, patients are allowed to eat something light and drink something up to six hours before the procedure.

In addition, the patient is informed in writing and orally by the doctor about the procedure and possible risks and must give his consent - this also happens in an emergency.

The examination is carried out in the so-called cardiac catheter laboratory

© W & B / Perkovic

How is the examination performed?

A cardiac catheter examination can be carried out on an outpatient basis, i.e. without an overnight stay in the hospital, or on an inpatient basis, i.e. with admission to the clinic. However, this depends on many factors and is decided in advance in consultation with the doctor. During the examination itself, those treated are usually awake and responsive and sometimes have to follow small instructions such as holding their breath.


First, a specialist doctor (cardiologist) disinfects and anesthetizes the puncture site, which is located in the groin, the elbow or on the wrist. A so-called sluice is placed here; it enables the catheter to be inserted and changed. Then the doctor pushes the catheter up to the coronary arteries or the ventricles under X-ray control. As soon as the catheter has reached its destination (for example the left or right ventricle), it is connected to a pressure measuring device. Now the doctor measures the pressures in the respective heart chambers, the aorta or the pulmonary artery. In this way he can, for example, use the pressure differences to judge whether a heart valve is pathologically narrowed.

Use of contrast media

The doctor then injects an X-ray contrast medium through the catheter into the heart chamber to be examined, as well as the coronary vessels. In this way, he makes the structures visible on the X-ray screen and can examine them in detail. For example, it measures the pumping function of the heart chambers. Scarred muscle tissue after a heart attack can also be discovered because it no longer contracts. If the heart chambers are examined with contrast medium, a feeling of warmth can develop throughout the body for a few seconds. If the doctor only wants to display the coronary arteries, the patient usually does not feel anything, as smaller amounts of contrast medium are injected for this purpose.

After the cardiac catheter

When the examination is over, the catheter is removed from the blood vessel. The access, the so-called sluice, can still be left if another intervention is necessary. Depending on the results of the examination, this may not be the case until the next day. Then the skin at the access point is also closed and given a pressure bandage so that there is no "secondary bleeding". This tight bandage usually has to be left on for a few hours. Exactly how long is determined by the examiner. If the examination was carried out on an outpatient basis, the patient must remain in bed for at least four hours and can then be discharged with an escort after a final check-up has been performed.

Balloon dilation and stent: if a vessel is blocked, it can be expanded with the cardiac catheter during the examination

© W & B / Dr. Ulrike Möhle

Treatments with the cardiac catheter

The heart catheter is not only used nowadays as a diagnostic method, but also in the therapy of various heart diseases - for example after or during a heart attack.

Balloon dilation / PTCA

The most common treatment is what is known as balloon dilatation, or PTCA. PTCA stands for percutaneous transluminal coronary angioplasty, translated: coronary artery enlargement carried out through the skin via a vessel. To do this, the doctor pushes a very thin catheter in a larger guide catheter up to the narrowed point of the affected coronary artery. At the tip of the fine tube there is a folded balloon, which is unfolded at the narrow point by administering contrast medium at a pressure of eight to 20 bar. This then widens the bottleneck. During this time, no blood flows from the balloon into the coronary artery, so symptoms similar to those of a pathological narrowing can occur, for example pressure on the chest or behind the sternum. Usually this feeling of pressure only lasts for a short time, after 24 hours at the latest it disappears again in all those treated.


In most cases, a stent applied to the balloon is deployed at the same time. This is a fine vascular support made of stainless steel. This is to prevent the stretched constriction from narrowing again after removing the balloon. The stents or balloons are often coated with drugs designed to prevent scar tissue from growing into the stent.


Heart valve defects such as narrowing of the aortic valve or the mitral valve can also be corrected using a catheter. It is also possible to use a cardiac catheter to close a hole in the atrial septum, the dividing wall between the two atria.


The treatment of certain arrhythmias with the catheter, the so-called catheter ablation, is also of great importance nowadays. These include atrial fibrillation, atrial flutter and other arrhythmias.

What are the risks?

The diagnostic cardiac catheter examination is considered a safe examination procedure. Serious complications are very rare.
At the point where the catheter was inserted, there may be minor bleeding or larger bruises. If there is a previously unknown iodine allergy, the patient may have an allergic reaction to the contrast agent. Appropriate pre-treatment can almost always prevent allergic reactions. The brief feeling of warmth caused by the contrast agent is not an allergic reaction.

It is also not uncommon for the exam to trigger cardiac arrhythmias. Especially when the ventricles are examined. These arrhythmias are usually harmless and can be treated with an electric shock (defibrillation) in an emergency. There may also be a blood pressure reaction called vasovagal syncope. It is usually triggered by pain or fear. This leads to:

  • dizziness
  • Nausea and / or vomiting
  • Sweats
  • Drop in blood pressure

Fluid and medication help very well in this case.

Overall, an operation on the heart is a potentially dangerous affair, which is why all patients are monitored on a ward with an EKG and blood pressure controls after the cardiac catheterization. Outpatients are also only allowed to leave the clinic after a few hours, when the circulation is stable.

Check after the cardiac cathter

If a stent was inserted during the cardiac catheter, the patient will have to take medication for a long time. These counteract the clumping of blood platelets in the vessels so that constrictions do not recur. In general, if you have a heart disease, a catheter examination should be followed by regular check-ups by a cardiologist. The following examinations are often used:

  • Echocardiography (ultrasound examination)
  • Heart scintigraphy
  • Exercise ECG or
  • Long-term ECG

The treating cardiologist decides which examination should be carried out in each individual case.

Prof. Wolfram Delius

© W & B / Bernhard Huber

Consulting expert: Professor Dr. med. Wolfram Delius is a specialist in internal medicine and cardiology. He completed his habilitation at the Medical University Clinic Uppsala, Sweden, and then held an extraordinary professorship for medicine at the Technical University of Munich. The heart specialist worked for a long time as chief physician, most recently for two decades in the cardiology / pulmonology department at the Munich-Bogenhausen Municipal Hospital (academic teaching hospital). He now runs his own practice.

Important NOTE:
This article contains general information only and should not be used for self-diagnosis or self-treatment. He can not substitute a visit at the doctor. Unfortunately, our experts cannot answer individual questions.

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