Cardiac catheterisation

What it is

Thin tubes are passed through an artery or vein to the heart to measure pressures and oxygen levels in its chambers, inject contrast into the coronary arteries and chambers, and, in electrophysiology studies, map the electrical circuits and burn or freeze the tissue causing an arrhythmia (ablation).

Why it is done

• Mapping coronary artery narrowing in angina or after a heart attack (before angioplasty or bypass)
• Assessing valve disease and heart failure by measuring pressures, including pulmonary hypertension
• Diagnosing and ablating arrhythmias such as atrial fibrillation, SVT and atrial flutter
• Closing holes in the heart, replacing valves through a catheter (TAVI), biopsy of heart muscle

Before the procedure

• Blood tests including kidney function and clotting; ECG; sometimes echo or CT
• Fasting 4-6 hours; metformin and blood thinners managed
• Local anaesthetic to the wrist or groin, light sedation; awake throughout

Step by step

1. A sheath is placed in the radial artery (coronaries), femoral artery (left heart) or femoral vein (right heart, electrophysiology)
2. Catheters are advanced under X-ray screening to the coronary origins or heart chambers
3. Contrast injections film the arteries from several angles; pressures are recorded through the catheter
4. In electrophysiology, several electrode catheters map the rhythm; pacing provokes the arrhythmia and the culprit tissue is ablated
5. Sheaths are removed and the site compressed or closed with a plug

Afterwards

• Lie flat for 2-6 hours after femoral access; a wrist band for radial
• Home the same day for diagnostic studies; drink fluids to clear contrast
• Results explained immediately with a plan for medication, stents or surgery

Recovery

Normal activities within a day or two; avoid heavy lifting for a week. Ablation for atrial fibrillation is followed by anticoagulation for at least two months.