Wolff-Parkinson-White syndrome classification scheme: Difference between revisions

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===Classification Based on the ECG Findings===
===Classification Based on the ECG Findings===
This classification is based on the side where the accessory pathway is establishedThe 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.<ref name="pmidhttp://dx.doi.org/10.1016/j.hrthm.2013.11.018">{{cite journal| author=Schmoldt A, Benthe HF, Haberland G| title=Digitoxin metabolism by rat liver microsomes. | journal=Biochem Pharmacol | year= 1975 | volume= 24 | issue= 17 | pages= 1639-41 | pmid=http://dx.doi.org/10.1016/j.hrthm.2013.11.018 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10 }} </ref>
WPW syndrome can be classified based on the location of the accessory pathway, right-sided vs left-sidedIn 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.<ref name="pmid24252285">{{cite journal| author=Suzuki T, Nakamura Y, Yoshida S, Yoshida Y, Shintaku H| title=Differentiating fasciculoventricular pathway from Wolff-Parkinson-White syndrome by electrocardiography. | journal=Heart Rhythm | year= 2014 | volume= 11 | issue= 4 | pages= 686-90 | pmid=24252285 | doi=10.1016/j.hrthm.2013.11.018 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=24252285 }} </ref>


# Type A:
# Type A: Pre-excitation of the left side of the heart (the accessory pathway communicates the left [[atrium]] with the left [[ventricle]])
#* Prominent [[R wave]] in lead V1 and V2.
#* Presence of upright [[delta wave]] in the precordial leads
#* It has been found at EP studies that these patients have early activation of the [[left ventricle]].
#* Small or absent S waves
#* Generally V1 shows either a notched R wave or RS or Rsr' deflection.
#* Generally V1 shows either a notched R wave or RS or Rsr' deflection
#* Mimics a posterior [[MI]], [[RVH]].
#* 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.
# Type B: Pre-excitation of the right side of the heart (the accessory pathway communicates the right [[atrium]] with the right [[ventricle]])
#* EP studies have showed that this form of [[WPW syndrome]]s is due to early activation of the lateral aspect of the [[right ventricle]]
#* Negative delta wave
#* This form is more common.
#* Prominent S wave deflection in the right precordial leads, and upright R waves in the lateral precordial leads
#* May resemble an abnormal Q wave in the right precordial leads and be mistaken for an [[Acute MI|anterior MI]].
#* More common than type A
#* In both type A and B there may be abnormal q waves in leads 2, 3 and aVF.
#* May resemble an abnormal Q wave in the right precordial leads and be mistaken for an [[Acute MI|anterior MI]]


===Classification Based on the Type of AVRT===
===Classification Based on the Type of AVRT===

Revision as of 15:08, 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

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.[1]

  1. Type A: Pre-excitation of the left side of the heart (the accessory pathway communicates the left atrium with the left ventricle)
    • Presence of upright delta wave in the precordial leads
    • Small or absent S waves
    • Generally V1 shows either a notched R wave or RS or Rsr' deflection
    • Mimics a posterior MI, RVH
  1. Type B: Pre-excitation of the right side of the heart (the accessory pathway communicates the right atrium with the right ventricle)
    • Negative delta wave
    • Prominent S wave deflection in the right precordial leads, and upright R waves in the lateral precordial leads
    • More common than type A
    • May resemble an abnormal Q wave in the right precordial leads and be mistaken for an anterior MI

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:

Variants of WPW

Lown-Ganong-Levine Syndrome (LGL)

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

  1. 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.

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