Wolff-Parkinson-White (WPW) syndrome is a condition where the heart ventricles become pre-excited. In the normal heart beat, first the sinoatrial (SA) node signals the atria of the the heart to contract, This is then followed by the atrioventricular (AV) node signalling the heart ventricles to contract. The electrical signal for this contraction travels from the SA node to the AV node via the electrical pathway of the bundle of his.
In Wolff-Parkinson-White (WPW) syndrome another additional electrical pathway called the bundle of Kent allows for electrical signals to travel from the SA to the AV node. This will result in ventricular pre-excitation (the ventricles may become over stimulated) and paroxyomal reentrant tachycardia (raised heart rate).
The above white arrows shows the abnormal, additional electrical activity pathway to the ventricles through the bundle of kent. In Wolff-Parkinson-White syndrome the normal pathway of electrical activity is maintained and the additional electrical stimulus to the ventricles through the bundle of kent causes ventricular pre-excitation.
The above shows the pathway of normal electrical stimulus through the heart via the bundle of His. in red with numbering
This is a hereditary disease, with the affected gene being carried on chromosome 7, band q3.
MacRae et al. 1995. Familial Hypertrophic Cardiomyopathy with Wolff-Parkinson-White Syndrome Maps to a Locus on Chromosome 7q3. Journal of Clinical Investigation. 96: 1216-1220.