Cardiac Catheterization

Cardiac catheterization is a procedure in which a doctor threads a thin, flexible tube called a catheter through a blood vessel and into the heart to examine how well it is working or to treat a problem found there.

Once the catheter reaches the heart, the doctor can measure blood pressure inside the heart's chambers, check how much oxygen is in the blood, inject a special dye to make the coronary arteries (the blood vessels that feed the heart muscle) visible on X-ray, and — if needed — perform a treatment such as opening a blocked artery in the same session. The entire procedure is guided by live X-ray images on a screen, so the doctor can see exactly where the catheter is at all times.

Doctors recommend cardiac catheterization when they need detailed information about the heart that cannot be obtained from non-invasive tests alone, or when a blocked or narrowed blood vessel needs to be treated directly.

• Coronary artery disease — narrowing or blockage of the arteries that supply the heart muscle, often causing chest pain (angina) or a heart attack.
• Heart attack (myocardial infarction) — to quickly locate and open a blocked coronary artery during an emergency.
• Heart valve disease — to assess how well the valves inside the heart are opening and closing.
• Heart failure — to measure pressures inside the heart and identify the underlying cause.
• Congenital heart defects — structural problems present from birth that may need to be assessed or repaired.
• Abnormal results from earlier tests such as an ECG (electrocardiogram, a recording of the heart's electrical activity), echocardiogram (an ultrasound image of the heart), or stress test that suggest a serious heart problem.
• Before major heart surgery, to give the surgeon a complete picture of the heart's condition.

There are situations where the risks of the procedure may outweigh the benefits, and the doctor will weigh these carefully before recommending it. Catheterization is usually postponed or approached with extra caution when:

• The patient has a serious kidney problem, because the dye used can put extra strain on the kidneys.
• There is an active infection or fever.
• The patient is taking blood thinners and the levels are not yet in a safe range for the procedure.
• Severe uncontrolled high blood pressure or very abnormal blood clotting is present.
• The patient is pregnant, due to X-ray exposure to the baby.

Cardiac catheterization is performed routinely in hospitals worldwide, but like any procedure that enters the body, it carries recognised risks that your medical team will discuss with you beforehand.

• Bruising, swelling, or minor bleeding at the insertion site (the wrist or groin) — the most common occurrence and usually resolves on its own.
• Allergic reaction to the contrast dye (the special liquid injected to make arteries visible), ranging from a mild skin rash to, rarely, a more serious reaction.
• Damage to the kidney from the contrast dye, particularly in patients who already have reduced kidney function.
• Blood clot or damage to the artery at the insertion site, which may require further treatment.
• Irregular heartbeat (arrhythmia) triggered during the procedure — this is usually brief and resolves without intervention.
• Stroke or mini-stroke (transient ischaemic attack), caused by a small blood clot or air bubble travelling to the brain — this is uncommon.
• Heart attack during the procedure — very uncommon but recognised.
• Infection at the insertion site or, rarely, inside the heart.
• Radiation exposure from the X-ray guidance used during the procedure — the dose is kept as low as possible.

Preparing well for cardiac catheterization helps the team work safely and reduces the chance of complications. Your care team will give you instructions tailored to your specific situation, but the following gives a general picture of what to expect.

Before the procedure, patients are usually asked to fast — to stop eating and drinking — for a period of several hours. The exact fasting window depends on the hospital's guidelines and whether the procedure is planned or urgent. Smoking and alcohol are best avoided for at least a few days beforehand, as both can affect blood flow and the body's ability to heal. If you take blood thinners, diabetes medication, or any regular prescription drugs, your doctor will decide which ones to continue, pause, or adjust before the procedure — never stop medication on your own.

Several tests are typically done in the days before, or on the morning of, the procedure to make sure you are safe to undergo it. These may include:

• Blood tests — to check kidney function, blood clotting ability, and blood count.
• An ECG (electrocardiogram) — to record the heart's electrical activity as a baseline.
• An echocardiogram (ultrasound of the heart) — if not done recently.
• A chest X-ray — to look at the size and position of the heart and lungs.
• Allergy screening — you will be asked whether you have ever reacted to contrast dye, iodine, or shellfish.

On the day of the procedure, the following steps typically occur, though the exact sequence and number of steps may vary between hospitals and individual patients:

• 1. You change into a hospital gown and a nurse reviews your medical history, medications, and allergy information.
• 2. A small needle is placed into a vein in your arm (an intravenous or IV line) so that fluids and medications can be given during the procedure.
• 3. The insertion site — usually the wrist (radial artery) or the groin (femoral artery) — is shaved if needed, cleaned, and numbed with a local anaesthetic (a numbing injection) so you feel little or no pain at that spot.
• 4. A short plastic tube called a sheath is inserted into the artery at the numbed site. The catheter is then threaded through this sheath and guided toward the heart using live X-ray images.
• 5. Contrast dye is injected through the catheter. You may feel a brief warm or flushing sensation throughout your body — this is normal.
• 6. X-ray images (called angiograms) are taken to show the coronary arteries and the inside of the heart's chambers clearly.
• 7. If a blockage is found and the doctor decides to treat it in the same session, a small balloon may be inflated inside the artery to widen it (a procedure called angioplasty), and a small mesh tube called a stent may be placed to keep the artery open.
• 8. Once the examination or treatment is complete, the catheter and sheath are removed. Pressure is applied to the insertion site to stop bleeding, or a small closure device may be used.
• 9. You are moved to a recovery area where your heart rate, blood pressure, and the insertion site are monitored closely.

After cardiac catheterization, most patients spend several hours — and sometimes one night — in the hospital so that nurses can monitor the heart and check the insertion site for bleeding or bruising. How long you stay and how quickly you recover depends on whether the procedure was diagnostic only or included a treatment such as stenting, and on your overall health.

• Rest at the insertion site: if the catheter was inserted through the groin, you will usually be asked to lie flat for a few hours to reduce the risk of bleeding. If it was through the wrist, you may be able to sit up sooner. A pressure band or dressing will be applied and checked regularly.
• Hydration: drinking plenty of water after the procedure helps the kidneys flush out the contrast dye. The nursing team may also give fluids through the IV line for this purpose.
• Activity restrictions: most patients are advised to avoid heavy lifting, strenuous exercise, and driving for at least a day or two after a diagnostic catheterization. After a treatment procedure such as angioplasty or stenting, restrictions usually last longer — your doctor will give specific guidance.
• Wound care: keep the insertion site clean and dry. Watch for signs of a problem: increasing pain, swelling, redness, warmth, unusual discharge, or a lump (haematoma, a collection of blood under the skin). Report any of these to your medical team promptly.
• Medications: your doctor may prescribe blood thinners or other heart medications after the procedure, particularly if a stent was placed. It is important to take these as directed and not to stop them without asking your doctor first.
• Follow-up appointments: a review visit is usually scheduled within a few weeks to check how the insertion site has healed, review test results, and assess heart function. Further imaging or tests may be arranged depending on what was found.
• Lifestyle: a heart-healthy lifestyle — a balanced diet, regular gentle activity as advised by your doctor, not smoking, and managing stress — supports recovery and helps reduce the chance of future heart problems.