Wolff-Parkinson-White syndrome classification scheme: Difference between revisions
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===Classification Based on the Type of AVRT=== | ===Classification Based on the Type of AVRT=== | ||
The most common arrhythmia in WPW syndrome is atrioventricular reciprocating tachycardia. AVRT in WPW can be classified into: | |||
* Orthodromic (most common): the antegrade electrical signal moves from the [[atria]] to the [[ventricle]]s through the [[AV node]], and then from the [[ventricle]]s to the [[atria]] through the accessory pathway. | |||
* Antidromic: the antegrade electrical signal moves from the [[atria]] to the [[ventricle]]s through the [[accessory pathway]], and then from the [[ventricle]]s to the [[atria]] through either the [[AV node]] or a second accessory pathway. | |||
===Variants of WPW=== | ===Variants of WPW=== | ||
Revision as of 14:32, 30 July 2014
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]
Overview
Classification
Classification Based on the Type of Conduction
The accessory pathway in WPW can be classified into:
- 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, and isolated antegrade conduction is rare 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
This classification is based on the side where the accessory pathway is established. The type A preexcitation presents the accessory pathway in the left side of the heart (comunicates the left atrium with the left ventricle). The type B preexcitation presents the accessory pathway in the right side of the heart (comunicates the right atrium with the right ventricle). Each type of preexcitation presents its own electrocardiographyc characteristics.[1]
- Type A:
- Prominent R wave in lead V1 and V2.
- It has been found at EP studies that these patients have early activation of the left ventricle.
- Generally V1 shows either a notched R wave or RS or Rsr' deflection.
- Mimics a posterior MI, RVH.
- Type B:
- Prominent S wave deflection in the right precordial leads, and upright R waves in the lateral precordial leads.
- EP studies have showed that this form of WPW syndromes is due to early activation of the lateral aspect of the right ventricle
- This form is more common.
- May resemble an abnormal Q wave in the right precordial leads and be mistaken for an anterior MI.
- In both type A and B there may be abnormal q waves in leads 2, 3 and aVF.
Classification Based on the Type of AVRT
The most common arrhythmia in WPW syndrome is atrioventricular reciprocating tachycardia. 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, and then 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, and then from the ventricles to the atria through either the AV node or a second accessory pathway.
Variants of WPW
Lown-Ganong-Levine Syndrome (LGL)
- 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
Mahaim Type Preexcitation
- 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
References
- ↑ Schmoldt A, Benthe HF, Haberland G (1975). "Digitoxin metabolism by rat liver microsomes". Biochem Pharmacol. 24 (17): 1639–41. PMID http://dx.doi.org/10.1016/j.hrthm.2013.11.018 Check
|pmid=value (help).