Wolff-Parkinson-White syndrome, WPW

Wolff-Parkinson-White syndrome is a heart condition featuring episodes of an abnormally fast heart rate.

Wolff-Parkinson-White (WPW) syndrome is a cardiac condition with episodes of fast heart rate which may lead to palpitations, dizziness, blackouts and in extreme cases sudden death.

The episodes of fast heart beat with rate over 200 bpm start and stop suddenly and last from seconds up to hours and days. WPW syndrome is a type of supraventricular tachycardia (SVT), ie abnormally fast heart beat originating in top heart chambers. The episodes may happen with no pattern, sometimes several times a day, in other people only once in several months.

Most people with WPW syndrome have just unpleasant palpitations but no serious problems. However in rare cases a combination of irregular pulse (atrial fibrillation) and WPW syndrome with an electrical pathway capable of very fast conduction can cause life-threatening rhythm problems.

Mechanism and symptoms

The heart has four chambers:

  • two upper chambers - left and right atria
  • two bottom chambers - left and right ventricles

A clump of cells called sinoatrial node is the heart natural pacemaker which sends electrical current to the atria and atrioventricular node (AV node). AV node is placed between the right atrium and right ventricle and under normal circumstances it is the only electrical connection between top and bottom heart chambers. Electrical impulses pass through the AV node and down specialized fibres to the muscle of ventricles that respond by contraction that pumps out the blood which can be felt as a pulse on the wrist.

In WPW syndrome, there is an additional connection between atria and ventricles apart from AV node which enables electrical impulses to travel round in a loop pattern, making the heart beat very fast. Contractions of heart muscle become so fast that heart muscle has not time to relax and fill with blood. The heart is therefore running almost empty, and the reduced amount of blood pumped around the body may cause:

  • shortness of breath
  • chest tightness
  • dizziness and lightheadedness
  • blackouts

Diagnosis

Some patients with abnormal (= accessory pathway) connecting atria and ventricles may have no symptoms at all and the condition may be diagnosed incidentally when ECG (electrocardiogram) is arranged for some other reason. ECG will show abnormal delta wave cause by premature activation of ventricles via the accessory pathway. In most cases, WPW is the only cardiac abnormality but sometimes it is related to other problems, eg condition called Epstein anomaly.

Treatment and outlook

In most of the cases, attacks of palpitations in WPW syndrome are benign, last short period of time settle down without treatment. However, in rare cases WPW syndrome may lead to collapses with loss of consciousness and sudden death. Every patient with WPW syndrome should be assessed by cardiologist and considered for EP study (catheter investigation of electrical pathways in the heart) to determine whether medication alone is sufficient or catheter ablation is advisable.

Catheter ablation is the permanent transcatheter treatment of WPW syndrome. It is a procedure involving insertion of catheters through a vein in the groin to the heart. It is then possible to map the electrical signals in the heart and by delivering energy destroy a small amount of tissue of the accessory pathway. The ablation thus interrupts the abnormal circuit and in most people permanently cures WPW syndrome.