Wolff-Parkinson-White syndrome classification scheme
Wolff-Parkinson-White syndrome Microchapters
Wolff-Parkinson-White syndrome classification scheme On the Web
Wolff-Parkinson-White (WPW) syndrome is the occurrence of arrhythmia in the presence of an accessory pathway. WPW can be classified according to the site of origin, location in the mitral or tricuspid annulus, type of conduction (antegrade vs retrograde), and characteristics of the conduction (decremental vs non decremental). In addition, WPW can be classified based of the type of atrioventricular reciprocating tachycardia (AVRT) it causes, which can be either orthodromic (~95% of the cases) or antidromic.
Classification Based on the Type of Conduction
- Antegrade conduction: also known as manifest, responsible for the "pre-excitation" finding on ECG
- Retrograde conduction: also known as concealed
Most commonly, the accessory pathways conduct in both directions. Isolated retrograde conduction is less common. Isolated antegrade conduction is the least common and is usually associated with accessory pathways in the right side of the heart.
Classification Based on the Characteristics of Conduction
- Decremental conduction (8% of the cases)
- Decremental conduction is the progressive delay in the conduction through the accessory pathway following an increase in the paced rates.
- Non-decremental conduction (92% of the cases)
Classification Based on the ECG Findings
WPW syndrome can be classified based on the location of the accessory pathway, right-sided vs left-sided. In 1945, Rosenbaum classified WPW syndrome into type A and type B based on the characteristic electrocardiographic findings of the right-sided and left-sided accessory pathway.
- Type A: Pre-excitation of the left side of the heart (the accessory pathway communicates the left atrium with the left ventricle)
- Type B: Pre-excitation of the right side of the heart (the accessory pathway communicates the right atrium with the right ventricle)
Classification Based on the Type of AVRT
The most common arrhythmia in WPW syndrome is atrioventricular reciprocating tachycardia (AVRT). AVRT in WPW can be classified into:
- Orthodromic (most common): the antegrade electrical signal moves from the atria to the ventricles through the AV node, whereas the retrograde electrical signal moves from the ventricles to the atria through the accessory pathway.
- Antidromic: the antegrade electrical signal moves from the atria to the ventricles through the accessory pathway, whereas the retrograde electrical signal moves from the ventricles to the atria through either the AV node or a second accessory pathway.
Variants of WPW
- There is a short PR interval, but no delta wave
- LGL is due to intranodal bypass tracts (i.e. there is conduction down the James fibers)
- Normal QRS duration
- PR less than 0.12 seconds
- Normal P wave
- This form of pre-excitation is due to nodoventricular, nodofascicular or fasciculoventricular connections
- The impulse may travel through the AV node normally and this may then be followed by premature conduction to the basal ventricular myocardium
- There is a delta wave with a normal PR interval
- Rarer than WPW or LGL
- In older patients there can be a prolonged conduction down the accessory pathway resulting in a normal PR interval in the presence of WPW which is tough to distinguish from Mahaim fibers
- Blomström-Lundqvist C, Scheinman MM, Aliot EM, Alpert JS, Calkins H, Camm AJ; et al. (2003). "ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias--executive summary. a report of the American college of cardiology/American heart association task force on practice guidelines and the European society of cardiology committee for practice guidelines (writing committee to develop guidelines for the management of patients with supraventricular arrhythmias) developed in collaboration with NASPE-Heart Rhythm Society". J Am Coll Cardiol. 42 (8): 1493–531. PMID 14563598.
- Suzuki T, Nakamura Y, Yoshida S, Yoshida Y, Shintaku H (2014). "Differentiating fasciculoventricular pathway from Wolff-Parkinson-White syndrome by electrocardiography". Heart Rhythm. 11 (4): 686–90. doi:10.1016/j.hrthm.2013.11.018. PMID 24252285.