Cardiac catheterisation shows from the inside whether your coronary arteries are narrowed. Through a thin tube, usually inserted at the wrist, a contrast agent enters the vessels and makes narrowings visible on the X-ray image. At Dein Team Herzzentrum in Zürich, this examination is used when non-invasive tests do not give a clear answer, or when your symptoms point to a relevant impairment of the heart's blood supply. What happens, how long it takes and how high the risk really is: read it here, step by step.
What is cardiac catheterisation and when is it done?
Cardiac catheterisation, medically termed coronary angiography, is the most accurate method of directly imaging narrowings in the coronary arteries. A thin catheter is guided through an artery at the wrist or in the groin up to the heart. Contrast agent flows through it into the vessels, showing a cast of the vessel interior on the X-ray and making narrowings visible.
The 2024 ESC guideline recommends this invasive examination when the pre-test probability of coronary heart disease is high, when symptoms do not respond to medication, and when angina occurs even at low levels of exertion or the risk of an event is high [ESC 2024, Eur Heart J]. For low to intermediate probability, the same guideline recommends a computed tomography scan of the coronary arteries as the first test [ESC 2024, Eur Heart J]. Cardiac catheterisation therefore comes at the end of a stepwise work-up and does not replace it. If the diagnosis remains unclear after the non-invasive tests, coronary angiography can confirm or rule it out. Its greatest practical value is that it combines a precise diagnosis with the option of treating a relevant narrowing in the same procedure.
Left heart catheterisation: imaging the coronary arteries
In left heart catheterisation, also called arterial catheterisation, the tube is inserted through an artery. Contrast agent passes through it into the coronary arteries. Calcifications and narrowings that cut the heart muscle off from blood and oxygen become directly visible.
The typical symptom picture of such coronary heart disease is angina pectoris: a pressure or tightness behind the breastbone that may radiate into the arm, neck or upper abdomen. These symptoms often occur under exertion and ease again at rest. If a coronary artery becomes acutely and completely blocked, this is called a heart attack.
The great advantage of coronary angiography is that it combines diagnosis with possible treatment. If the image shows a relevant narrowing, it can frequently be corrected in the same procedure. A second examination on another day is then unnecessary.
Where needed, further structures can be imaged in the same procedure: the left ventricle, the heart valves or the aorta.
When a narrowing is found: FFR and stent
Not every visible narrowing needs treatment. For moderate narrowings, the ESC guideline recommends measuring their functional significance before any treatment, for example by means of fractional flow reserve (FFR) [ESC 2024, Eur Heart J]. This determines the pressure drop across the narrowing. An FFR value of 0.80 or below is considered relevant.
There is a good reason for this measurement. The FAME trial showed that FFR-guided treatment led to fewer serious cardiac events within one year than treatment guided by the image alone [Tonino 2009, N Engl J Med]. At Dein Team Herzzentrum we therefore prefer to measure once more in borderline findings before we treat.
If a narrowing is relevant, it can be widened in the same procedure and held open with a vascular support, a stent. This step is called percutaneous coronary intervention (PCI).
Right heart catheterisation: measuring pressure in the pulmonary circulation
Right heart catheterisation serves a different purpose. Through a vein in the arm, neck or groin, the tube is guided through the right side of the heart into the pulmonary vessels to measure the pressure there. This allows an accurate assessment of raised pressure in the pulmonary circulation, the consequences of heart valve defects or heart failure. This measurement is the reference method when raised pulmonary pressure is suspected and non-invasive findings remain unclear. Both types of catheterisation can be performed together or separately, depending on which question is in the foreground.
The procedure: before, during and after the examination
Beforehand, there is a detailed consultation and an outpatient examination. There we clarify with you the reason, the procedure and possible risks, and discuss your medications, such as blood thinners, and any known contrast agent intolerance. As a rule, an ECG, a blood sample and, depending on the findings, further non-invasive tests are added before the date for the catheterisation is fixed. This preparation ensures that all important values are available on the day of the procedure.
This is how the procedure runs:
- The puncture site at the wrist or in the groin is numbed with a local anaesthetic. You remain awake and responsive.
- The catheter is advanced to the heart under X-ray guidance. As a rule you do not feel this, because the vessels themselves have no pain fibres.
- When the contrast agent is injected, a brief sensation of warmth may occur.
- If a relevant narrowing is found, treatment with a stent can follow directly.
Diagnosis alone often takes only 20 to 30 minutes. Afterwards the puncture site is closed, at the wrist usually with a pressure bandage. With access via the wrist, you are mobile again sooner than via the groin.
How high is the risk?
Coronary angiography is considered a safe routine procedure. Significant complications occur in fewer than one per cent of cases; the risk of a serious complication such as stroke, heart attack or death is, by international figures, in the order of about 1 in 1,000 [gesundheitsinformation.de, IQWiG]. More common, but harmless, are small bruises at the puncture site.
Access via the wrist lowers this risk further. A meta-analysis across the whole spectrum of patients with coronary heart disease showed lower mortality and markedly fewer serious bleeds and vascular complications with radial access than via the groin [Ferrante 2016, JACC Cardiovasc Interv]. The 2024 ESC guideline therefore recommends access via the wrist as the preferred standard [ESC 2024, Eur Heart J].
The risk also depends on your baseline condition. Older age and severe accompanying illnesses can increase it. That is precisely what the preliminary consultation is for: we weigh up with you what your findings gain in diagnostic value and which risks realistically stand against it. An examination that changes nothing about the treatment is not among them.
Frequently asked questions about cardiac catheterisation
Am I awake during the examination? Yes. The puncture site is numbed with a local anaesthetic and you remain responsive. A mild sedative is possible on request. A general anaesthetic is not needed for the examination.
Does cardiac catheterisation hurt? You feel the puncture as a brief prick, and hardly anything after that. The vessels themselves have no pain fibres; the catheter cannot be felt inside them. When the contrast agent is given, a brief sensation of warmth may occur.
How long does the examination take? Diagnosis alone usually takes 20 to 30 minutes. If treatment with a stent is added, the procedure is extended accordingly.
Will I be treated straight away if a narrowing is found? Often, yes. A relevant narrowing can be widened and fitted with a stent in the same procedure. In borderline findings, we first measure the functional significance by FFR before we treat.
How quickly will I be fit again afterwards? After access via the wrist, you are mobile again quickly. You should avoid exertion and heavy lifting in the first few days. We discuss the exact timetable with you, depending on whether the procedure was purely diagnostic or also involved treatment.
Do I need a referral for the examination? At Dein Team Herzzentrum in Zürich, you can arrange an appointment without a referral. The examination makes sense when non-invasive tests already point to a relevant impairment of the heart's blood supply.
Is contrast agent a problem for my kidneys? If your kidney function is impaired or you have a known intolerance, we plan the amount and preparation accordingly. Tell us in advance if you have a known kidney disease or a known reaction to contrast agent.
This article explains the general procedure and does not replace the personal consultation with your cardiologist. What is sensible in an individual case depends on your findings.