Pre-excitation syndrome is a heart condition in which part of the cardiac ventricles are activated too early. Pre-excitation is caused by an abnormal electrical connection or

accessory pathway An accessory pathway is an additional electrical connection between two parts of the heart. These pathways can lead to abnormal heart rhythms or arrhythmias associated with symptoms of palpitations. Some pathways may activate a region of ventricula ...

between or within the cardiac chambers. Pre-excitation may not cause any symptoms but may lead to palpitations caused by abnormal heart rhythms. It is usually diagnosed using an electrocardiogram, but may only be found during an electrophysiological study. The condition may not require any treatment at all, but symptoms can be controlled using medication or

catheter ablation Catheter ablation is a procedure used to remove or terminate a faulty electrical pathway from sections of the heart of those who are prone to developing cardiac arrhythmias such as atrial fibrillation, atrial flutter and Wolff-Parkinson-White syn ...

Types

Several types of pre-excitation syndrome have been described.

Pathophysiology

Normally, the atria and the ventricles are electrically isolated, and electrical contact between them exists only at the "

atrioventricular node The atrioventricular node or AV node electrically connects the heart's atria and ventricles to coordinate beating in the top of the heart; it is part of the electrical conduction system of the heart. The AV node lies at the lower back section of t ...

". In all pre-excitation syndromes, at least one more conductive pathway is present. Physiologically, the normal electrical depolarization wave is delayed at the

to allow the atria to contract before the ventricles. However, there is no such delay in the abnormal pathway, so the electrical stimulus passes to the ventricle by this tract faster than via normal atrioventricular/

bundle of His The bundle of His (BH) or His bundle (HB) ( "hiss"Medical Terminology for Health Professions, Spiral bound Version'. Cengage Learning; 2016. . pp. 129–.) is a collection of heart muscle cells specialized for electrical conduction. As part of t ...

system, and the ventricles are depolarized (excited) before (pre-) normal conduction system.

References

External links

Cardiac arrhythmia Syndromes affecting the heart {{circulatory-disease-stub