Electrophysiology study (EP study)

This procedure is normally performed under sedation, often as a day case procedure, and takes around 1-2 hours. It is quite common for people to sleep through much of the procedure and not to remember it fully afterwards. Several small tubes are inserted under local anaesthetic into the vein in the groin. Through these tubes, 3-4 fine electrical wires (catheters) are passed up to the heart using X-ray. Testing is carried out to evaluate the electrical properties of the heart. This involves checking whether there are one or two connections within the AV node and whether there is any evidence of an accessory pathway (muscle fibres which constitute an extra electrical connection between the upper and lower chambers of the heart). We then try to bring on the specific rhythm disturbance that is causing the person their symptoms.

If appropriate, the area within the heart that is giving rise to the faster rhythm is then cauterised to prevent this from happening in the future. The success rate is high, in the order of 90-95%, albeit depending somewhat on the exact nature of the arrhythmia. A small number of patients need the procedure more than once to achieve a final successful result. In order to perform ablation it is usually necessary to induce the palpitations and arrhythmia and occasionally this is not possible.

Bruising is common, but is self-limiting and vascular damage and cardiac perforation are rare. There is a small risk of inadvertent damage of the normal conduction system of the heart, but every precaution is taken to minimise this and the average risk is approximately 1 in 200 procedures. If this happens, a pacemaker may be needed. The risk of serious problems, such as heart attack, stroke or death, it is very low at 1 in 2000.