Wolff (Wolfe)-Parkinson-White (WPW) results from an additional electrical connection between the atria (upper chambers of the heart) and the ventricles (lower chambers of the heart). This extra or accessory electrical pathway is present in approximately 1.5 per 1,000 people. It runs in families in less than 1% of cases. In the majority of cases it is completely silent and only detected on a routine ECG. In a small proportion of patients the extra electrical pathway allows conduction of the electrical pathway generating an electrical circuit which produces symptoms.

Symptoms and clinical picture

Palpitations are the main symptoms due to an abnormally rapid heart rate. They can occur at any time and some patients learn to control them by holding their breath for prolonged periods. In many instances the palpitations remain until they are terminated by medical therapy in the accident and emergency department.

When the patient is experiencing palpitations the heart rate is usually in excess of 150 beats per minute. When the patient has no symptoms there is nothing to find on examination.

Most patients tolerate this well but some experience very troublesome palpitations, light-headedness and blackouts. A very small minority of patients may die suddenly from ventricular fibrillation. WPW is a very rare cause of sudden death.

ECG readings

The ECG usually shows two abnormalities when the patient is free of symptoms � a short PR interval and a delta wave.

Treatment

The ideal treatment in patients with symptoms is to destroy the extra electrical pathway, a procedure termed radio frequency ablation. This is done by passing a wire into the heart via the large artery (femoral artery) in the leg. The abnormal pathway is located by electrical stimulation and destroyed by passing a high current through it. This takes approximately 2-3 hours and requires one night in hospital.