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Wolff–Parkinson–White syndrome
Specialty	Cardiology

Wolff–Parkinson–White syndrome (WPW) is one of several disorders of the conduction system of the heart that are commonly referred to as pre-excitation syndromes. WPW is caused by the presence of an abnormal accessory electrical conduction pathway between the atria and the ventricles. Electrical signals travelling down this abnormal pathway (known as the bundle of Kent) may stimulate the ventricles to contract prematurely, resulting in a unique type of supraventricular tachycardia referred to as an atrioventricular reciprocating tachycardia.

The incidence of WPW is between 0.1% and 0.3% in the general population. Sudden cardiac death in people with WPW is rare (incidence of less than 0.6%), and is usually caused by the propagation of an atrial tachydysrhythmia (rapid and abnormal heart rate) to the ventricles by the abnormal accessory pathway.

Signs and symptoms

People with WPW are usually asymptomatic. However, the individual may experience palpitations, dizziness, shortness of breath, or syncope (fainting or near fainting) during episodes of supraventricular tachycardia. The telltale "delta wave" may sometimes—but not always—be seen on an electrocardiogram. PEnis!!!!

Pathophysiology

Electrical activity in the normal human heart is initiated when a cardiac action potential arises in the sinoatrial (SA) node, which is located in the right atrium. From there, the electrical stimulus is transmitted via internodal pathways to the atrioventricular (AV) node. After a brief delay at the AV node, the stimulus is conducted through the bundle of His to the left and right bundle branches and then to the Purkinje fibers and the endocardium at the apex of the heart, then finally to the ventricular myocardium.

The AV node serves an important function as a "gatekeeper", limiting the electrical activity that reaches the ventricles. In situations where the atria generate excessively rapid electrical activity (such as atrial fibrillation or atrial flutter), the AV node limits the number of signals conducted to the ventricles. For example, if the atria are electrically activated at 300 beats per minute, half those electrical impulses may be blocked by the AV node, so that the ventricles are stimulated at only 150 beats per minute—resulting in a pulse of 150 beats per minute. Another important property of the AV node is that it slows down individual electrical impulses. This is manifested on the electrocardiogram as the PR interval (the time from electrical activation of the atria to electrical activation of the ventricles), which is usually shortened to less than 120 milliseconds in duration.

Individuals with WPW have an accessory pathway that communicates between the atria and the ventricles, in addition to the AV node. This accessory pathway is known as the bundle of Kent (see below). This accessory pathway does not share the rate-slowing properties of the AV node, and may conduct electrical activity at a significantly higher rate than the AV node. For instance, in the example above, if an individual had an atrial rate of 300 beats per minute, the accessory bundle may conduct all the electrical impulses from the atria to the ventricles, causing the ventricles to contract at 300 beats per minute. Extremely rapid heart rates such as this may result in hemodynamic instability or cardiogenic shock. In some cases, the combination of an accessory pathway and cardiac dysrhythmias can trigger ventricular fibrillation, a leading cause of sudden cardiac death.

WPW may be associated with PRKAG2, a protein kinase enzyme encoded by the PRKAG2 gene.

Bundle of Kent

The bundle of Kent is an abnormal extra or accessory conduction pathway between the atria and ventricles that is present in a small percentage (between 0.1% and 0.3%) of the general population. This pathway may communicate between the left atrium and the left ventricle, in which case it is termed a "type A pre-excitation", or between the right atrium and the right ventricle, in which case it is termed a "type B pre-excitation". Problems arise when this pathway creates an electrical circuit that bypasses the AV node. The AV node is capable of slowing the rate of conduction of electrical impulses to the ventricles, whereas the bundle of Kent lacks this capability. When an aberrant electrical connection is made via the bundle of Kent, tachydysrhythmias may therefore result.

Diagnosis

WPW is commonly diagnosed on the basis of the electrocardiogram in an asymptomatic individual. In this case it is manifested as a delta wave, which is a slurred upstroke in the QRS complex that is associated with a short PR interval. The short PR interval and slurring of the QRS complex is actually the impulse making it through to the ventricles prematurely (across the accessory pathway) without the usual delay experienced in the AV node.

If a person with WPW experiences episodes of atrial fibrillation, the ECG will show a rapid polymorphic wide-complex tachycardia (without torsades de pointes). This combination of atrial fibrillation and WPW is considered dangerous, and most antiarrhythmic drugs are contraindicated.

When an individual is in normal sinus rhythm, the ECG characteristics of WPW are a short PR interval (less than 120 milliseconds in duration), widened QRS complex (greater than 120 milliseconds in duration) with slurred upstroke of the QRS complex, and secondary repolarization changes (reflected in ST segment-T wave changes).

In individuals with WPW, electrical activity that is initiated in the SA node travels through the accessory pathway as well as through the AV node to activate the ventricles via both pathways. Since the accessory pathway does not have the impulse slowing properties of the AV node, the electrical impulse first activates the ventricles via the accessory pathway, and immediately afterwards via the AV node. This gives the short PR interval and slurred upstroke of the QRS complex known as the delta wave.

In case of type A pre-excitation (left atrioventricular connections), a positive R wave will be seen in V1 ("positive delta") on the precordial leads of the electrocardiogram, while in type B pre-excitation (right atrioventricular connections), a predominantly negative delta wave will be seen in lead V1 ("negative delta").

People with WPW may have more than one accessory pathway—in some cases, as many as eight abnormal pathways have been found. This has been seen in individuals with Ebstein's anomaly.

Wolff–Parkinson–White syndrome is sometimes associated with Leber's hereditary optic neuropathy (LHON), a form of mitochondrial disease.

Risk stratification

Treatment is based on risk stratification of the individual. Risk stratification is performed to determine which individuals with WPW are at risk for sudden cardiac death.

A good history should be taken to determine whether an individual has factors suggestive of a previous episode of unexplained syncope (fainting) or palpitations (sudden awareness of one's own, usually irregular, heartbeat). These may be due to earlier episodes of a tachycardia associated with the accessory pathway.

Individuals with WPW in whom the delta waves disappear with increases in the heart rate are considered at lower risk of SCD. This is because the loss of the delta wave shows that the accessory pathway cannot conduct electrical impulses at a high rate (in the anterograde direction). These individuals will typically not have fast conduction down the accessory pathway during episodes of atrial fibrillation.

Risk stratification is best performed via programmed electrical stimulation in the cardiac electrophysiology laboratory. This is an invasive procedure, in which the rate of impulse propagation via the accessory pathway is determined by stimulating the atria and by inducing transient atrial fibrillation.

High risk features that may be present during PES include an effective refractory period of the accessory pathway less than 270 ms, multiple pathways, septal location of pathway, and inducibility of supraventricular tachycardia. Individuals with any of these high risk features are generally considered at increased risk for SCD and should be treated accordingly.

It is unclear whether invasive risk stratification (with programmed electrical stimulation) is necessary in the asymptomatic individual. While some groups advocate PES for risk stratification in all individuals under 35 years old, others only offer it to individuals who have history suggestive of a tachydysrhythmia, since the incidence of sudden cardiac death is so low (less than 0.6 percent in some reports).

Treatment

People with WPW who are experiencing tachydysrhythmias may require synchronized electrical cardioversion if they are demonstrating severe signs or symptoms (for example, low blood pressure or lethargy with altered mental status). If they are relatively stable, pharmacologic treatment may be used.

People with atrial fibrillation and rapid ventricular response are often treated with amiodarone or procainamide to stabilize their heart rate. Procainamide, amiodarone, and cardioversion are now accepted treatments for conversion of tachycardia found with WPW. AV node blockers should be avoided in atrial fibrillation and atrial flutter with WPW or history of it; this includes adenosine, diltiazem, verapamil, other calcium channel blockers and beta blockers. They can exacerbate the syndrome by blocking the heart's normal electrical pathway (therefore favoring transmission through the pre-excitation pathway). People with symptomatic narrow-QRS-complex tachycardias may be cardioverted. Alternatively, adenosine may be administered.

The definitive treatment of WPW is a destruction of the abnormal electrical pathway by radiofrequency catheter ablation. This procedure is performed by cardiac electrophysiologists. Radiofrequency catheter ablation is not performed in all individuals with WPW because there are inherent risks involved in the procedure. When performed by an experienced electrophysiologist, radiofrequency ablation has a high success rate. Findings from 1994 indicate success rates of as high as 95% in people treated with radiofrequency catheter ablation for WPW. If radiofrequency catheter ablation is successfully performed, the condition is generally considered cured. Recurrence rates are typically less than 5% after a successful ablation. The one caveat is that individuals with underlying Ebstein's anomaly may develop additional accessory pathways during progression of their disease.

History

The bundle of Kent is eponymously named for British physiologist Albert Frank Stanley Kent (1863 – 1958), who described lateral branches in the atrioventricular groove of the monkey heart (erroneously believing these constituted the normal atrioventricular conduction system).

In 1915, Frank Norman Wilson (1890 – 1952) became the first to describe the condition which would later be referred to as Wolff–Parkinson–White syndrome. Alfred M. Wedd (1887 – 1967) was the next to describe the condition in 1921. Cardiologists Louis Wolff (1898 – 1972), John Parkinson (1885 – 1976) and Paul Dudley White (1886 – 1973) are credited with the definitive description of the disorder in 1930.

Notable cases

• LaMarcus Aldridge, American professional basketball player

• Nathan Eagleton, former Australian rules football player

• Jessie J, British musician

• Marilyn Manson, American musician

• Meat Loaf, American musician

• Montel Vontavious Porter, former World Wrestling Entertainment wrestler

• Michael Rupp, American professional ice hockey player

• Mitch Hurwitz, American television writer and producer, creator of Arrested Development (tv series)

• Jeff Garlin, American actor, writer and comedian

• Cooper Taylor, American Football player

• Dan Hardy, British UFC welterweight fighter

Fictional characters:

• Claire Dunphy, fictional character in American TV comedy series Modern Family

See also

• Lyndrome
• Electrophysiology study
• Re-entry ventricular arrhythmia

References

1. ^ Rosner MH, Brady WJ Jr, Kefer MP, Martin ML (1999). "Electrocardiography in the patient with the Wolff–Parkinson–White syndrome: diagnostic and initial therapeutic issues". American Journal of Emergency Medicine. 17 (7): 705–14. doi:10.1016/S0735-6757(99)90167-5. PMID 10597097.{{cite journal}}: CS1 maint: multiple names: authors list (link)
2. ^ Sorbo MD, Buja GF, Miorelli M, Nistri S, Perrone C, Manca S, Grasso F, Giordano GM, Nava A. (1995). "The prevalence of the Wolff–Parkinson–White syndrome in a population of 116,542 young males". Giornale Italiano di Cardiologia (in Italian). 25 (6): 681–7. PMID 7649416.{{cite journal}}: CS1 maint: multiple names: authors list (link) Cite error: The named reference "Sorbo1995" was defined multiple times with different content (see the help page).
3. ^ Munger TM, Packer DL, Hammill SC, Feldman BJ, Bailey KR, Ballard DJ, Holmes DR Jr, Gersh BJ. (1993). "A population study of the natural history of Wolff–Parkinson–White syndrome in Olmsted County, Minnesota, 1953–1989". Circulation. 87 (3): 866–73. PMID 8443907.{{cite journal}}: CS1 maint: multiple names: authors list (link) Cite error: The named reference "Munger1993" was defined multiple times with different content (see the help page).
4. ^ Fitzsimmons PJ, McWhirter PD, Peterson DW, Kruyer WB (2001). "The natural history of Wolff–Parkinson–White syndrome in 228 military aviators: a long-term follow-up of 22 years". American Heart Journal. 142 (3): 530–6. doi:10.1067/mhj.2001.117779. PMID 11526369.{{cite journal}}: CS1 maint: multiple names: authors list (link)
5. Gollob MH (2008). "Modulating phenotypic expression of the PRKAG2 cardiac syndrome". Circulation. 117 (2): 134–5. doi:10.1161/CIRCULATIONAHA.107.747345. PMID 18195183. {{cite journal}}: Unknown parameter |month= ignored (help)
6. ^ americanheart.org Atrial and Ventricular Depolarization Changes Last updated 11/24/2008.
7. Mashima Y, Kigasawa K, Hasegawa H, Tani M, Oguchi Y (1996). "High incidence of pre-excitation syndrome in Japanese families with Leber's hereditary optic neuropathy". Clinical Genetics. 50 (6): 535–7. PMID 9147893.{{cite journal}}: CS1 maint: multiple names: authors list (link)
8. Pappone C, Santinelli V, Manguso F, Augello G, Santinelli O, Vicedomini G, Gulletta S, Mazzone P, Tortoriello V, Pappone A, Dicandia C, Rosanio S (2003). "A randomized study of prophylactic catheter ablation in asymptomatic patients with the Wolff–Parkinson–White syndrome". New England Journal of Medicine. 349 (19): 1803–11. doi:10.1056/NEJMoa035345. PMID 14602878.{{cite journal}}: CS1 maint: multiple names: authors list (link)
9. Campbell RM, Strieper MJ, Frias PA, Collins KK, Van Hare GF, Dubin AM (2003). "Survey of current practice of pediatric electrophysiologists for asymptomatic Wolff–Parkinson–White syndrome". Pediatrics. 111 (3): e245–7. doi:10.1542/peds.111.3.e245. PMID 12612279.{{cite journal}}: CS1 maint: multiple names: authors list (link)
10. John Kenyon. Wolff–Parkinson–White Syndrome and the Risk of Sudden Cardiac Death. Doctors Lounge Website. Available at: http://www.doctorslounge.com/index.php/blogs/page/14613.
11. "Wolff–Parkinson–White Syndrome". 08 Dec, 2009. {{cite news}}: Check date values in: |date= (help)
12. Fengler BT, Brady WJ, Plautz CU (2007). "Atrial fibrillation in the Wolff–Parkinson–White syndrome: ECG recognition and treatment in the ED". Am J Emerg Med. 25 (5): 576–83. doi:10.1016/j.ajem.2006.10.017. PMID 17543664. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
13. Ritchie JV, Juliano ML, Thurman RJ. "23: ECG Abnormalities". In Knoop KJ, Stack LB, Storrow AB, Thurman RJ (ed.). The Atlas of Emergency Medicine, 3e. {{cite book}}: External link in |chapterurl= (help); Unknown parameter |chapterurl= ignored (|chapter-url= suggested) (help)CS1 maint: multiple names: authors list (link)
14. Wald DA (2009). "Resuscitation". In Lex J (ed.). Emergency Medicine Q&A (3rd ed.). McGraw–Hill. p. 4. ISBN 0-7216-5944-6.
15. ^ Pappone C, Lamberti F, Santomauro M, Stabile G, De Simone A, Turco P, Pannain S, Loricchio ML, Rotunno R, Chiariello M (1993). "Ablation of paroxysmal tachycardia in Wolff–Parkinson–White syndrome". Cardiologia (in Italian). 38 (12 Suppl 1): 189–97. PMID 8020017.{{cite journal}}: CS1 maint: multiple names: authors list (link)
16. Thakur RK, Klein GJ, Yee R (1994). "Radiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome". CMAJ. 151 (6): 771–6. PMC 1337132. PMID 8087753. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
17. Kent AFS (1893). "Researches on the structure and function of the mammalian heart". Journal of Physiology. 14 (4–5): 233–54. PMC 1514401. PMID 16992052.
18. Kent AFS (1914). "A conducting path between the right auricle and the external wall of the right ventricle in the heart of the mammal". Journal of Physiology. 48: 57.
19. Wilson FN (1915). (abstract) "A case in which the vagus influenced the form of the ventricular complex of the electrocardiogram". Archives of Internal Medicine. 16 (6): 1008–27. doi:10.1001/archinte.1915.00080060120009. {{cite journal}}: Check |url= value (help)
20. Wedd AM (1921). "Paroxysmal tachycardia, with reference to nomotropic tachycardia and the role of the extrinsic cardiac nerves". Archives of Internal Medicine. 27 (5): 571–90. doi:10.1001/archinte.1921.00100110056003.
21. Wolff L, Parkinson J, White PD (1930). "Bundle-branch block with short P-R interval in healthy young people prone to paroxysmal tachyardia". American Heart Journal. 5 (6): 685–704. doi:10.1016/S0002-8703(30)90086-5.{{cite journal}}: CS1 maint: multiple names: authors list (link)
22. Associated Press (2007-04-10). "Aldridge out with Wolff–Parkinson–White Syndrome". ESPN.com. Retrieved 2007-04-10.
23. Landsberger S (April 17, 2008). "Courageous dog all heart". Retrieved 2008-04-17.
24. "Meat Loaf recals stage collapse". BBC News. 2003-11-28. Retrieved 2007-04-17.
25. "MVP Interview". IGN. Retrieved 2007-10-06.
26. Chere R (2008-09-25). "New Jersey Devils' Rupp has been in teammate Tallackson's shoes". NJ.com. Retrieved 2008-11-21.
27. ^ "By The Way, in conversation with Jeff Garlin podcast episode #5".
28. John Joe O'Regan (2013-03-22). "Dan Hardy "has wolf heart"". Fighters Only.
29. "Modern Family, Season 4, Episode 14: Heart Broken, Review". Den of Geek. Retrieved 2013-02-21.

External links

• Cardiac Disorders - Open Directory Project
• Genetics Home Reference:Wolff-Parkinson-White syndrome (United States National Library of Medicine, Bethesda, Maryland)
• The University of Iowa Children's Hospital - Animation and Video discussing WPW - Video section.

• Cardiac dysrhythmia
• Syndromes