AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

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• Introduction
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• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
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INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• Multimedia
• References

Background

In 1930, Wolff, Parkinson, and White described a series of young patients who had a bundle branch block pattern on electrocardiography (ECG), a short PR interval, and paroxysms of tachycardia. Case reports began appearing in the literature in the late 1930s and early 1940s, and the term Wolff-Parkinson-White (WPW) syndrome was coined in 1940. In 1943, the existence of an accessory connection between atria and ventricles was confirmed, which is about 50 years after Kent's description of myocardial fibers that were believed to conduct from atria to ventricle.

The term preexcitation was first published by Ohnell in 1944 (the same year that the term delta wave was coined); "preexcitation indicates an additional excitatory spread in the ventricles of the heart, coupled to auricular excitation." WPW syndrome is not the only form of preexcitation, but it is the most common. Initially, through the surgical treatment of WPW syndrome and, now in the era of radiofrequency (RF) ablation, understanding of the pathophysiology of WPW syndrome has become refined in the wake of these elegant descriptions.

The first surgical division of an accessory pathway (AP) was performed at Duke University by Will C. Sealy, MD, in 1968. The first catheter ablation was reported in 1983, using DC energy; this was followed by the first successful RF ablation reported in 1987.

Pathophysiology

The underlying defect in WPW syndrome is the presence of an AP consisting of a myocardial connection at the atrioventricular (AV) junction. These are believed to be residual connections from the formation of the AV junction. The primary feature differentiating WPW syndrome from other AP-mediated supraventricular tachycardias (SVTs) is the ability of the AP to conduct antegradely (ie, from atrium to ventricles) and retrogradely.

The amount of preexcitation present in a person with WPW pattern can be estimated by the width of the QRS and length of the PR interval. Thus, a wider or more preexcited QRS with a short PR interval with absent or nearly absent isoelectric component reveals that most (or all) of the ventricular depolarization occurs through the AP and not through the AV node. However, the QRS width may vary becoming narrower during more rapid heart rates. This is possible because catecholamines, by enhancing AV node conduction, will permit the AV node to contribute more (or entirely) to ventricular depolarization.

The presence of an AP allows a reentrant tachycardia circuit to be established. In orthodromic SVT, the conduction is through the AV node to the ventricles, then back to the atria via the AP. Because the AP can conduct in both directions, experiencing antidromic tachycardia is also possible, in which the conduction from atrium to ventricle occurs via the AP, resulting in a broad complex (ie, wide QRS) tachycardia.

The presence of an antegrade AV connection also allows atrial arrhythmias to be conducted to the ventricles without passing through the AV node. Patients with WPW syndrome can more frequently develop atrial fibrillation (AF), which can potentially be conducted to the ventricles rapidly (see Mortality/Morbidity).

The different patterns of preexcitation have produced various classification systems. Classification by type is largely obsolete, and, currently, classification by anatomic location of the AP is used (see Workup).

Family studies as well as recent molecular genetic investigations indicate that WPW syndrome and associated preexcitation disorders may have a genetic component. It may be inherited as a familial trait with or without associated congenital heart defects (CHD).

Frequency

International

WPW syndrome refers to preexcitation and paroxysms of tachycardia. The WPW pattern refers to the ECG pattern. The incidence of the WPW pattern is unknown but is estimated to be 1-2 cases per 1000 population. This may be an underestimate because it often represents an asymptomatic ECG finding. The incidence of newly diagnosed cases of WPW syndrome is approximately 4 cases per 100,000 population per year.

Mortality/Morbidity

Many individuals with WPW pattern remain asymptomatic throughout their lives. It is estimated that approximately half of them go on to develop WPW syndrome.

The morbidity in WPW syndrome results predominantly from SVT. Even in the absence of rapid ventricular conduction, syncope is an occasional presenting symptom. However, in most patients, the SVT is well tolerated and not life threatening. If a patient experiences incessant tachycardia, cardiomyopathy may develop.

The mortality in WPW syndrome is rare, and related to sudden cardiac death (SCD). The cause of SCD in WPW syndrome is rapid conduction of AF to the ventricles via the AP, resulting in ventricular fibrillation (VF).

• AF develops in one fifth to one third of patients with WPW syndrome; the reasons for this and the effects of AP ablation on its development are unclear. However, a recent study hypothesized that 2 mechanisms are involved in the pathogenesis of AF in patients with WPW syndrome: one would be related to the AP that would predispose the atria to fibrillation, and the other would be independent from the AP and related to increased atrial vulnerability present in these individuals.
• According to the literature, risk factors for development of AF in the setting of WPW syndrome include older patients (who have 2 peaks for AF occurrence, one at 30 and the other at 50 years of age), male gender, and prior history of syncope.
• Certain factors increase the likelihood of VF, including rapidly conducting APs and multiple pathways. Cases have also been reported in association with esophageal studies, digoxin, and verapamil. A few reports document spontaneous VF in WPW syndrome, and SVT may degenerate into AF, thus leading to VF; however, both scenarios are rare in pediatric patients.
• The incidence of sudden cardiac death (SCD) in WPW syndrome is approximately 1 in 100 symptomatic cases when followed for up to 15 years.
• Although relatively uncommon, SCD may be the initial presentation in as many as 4.5% of cases.

Sex

WPW pattern appears to affect both sexes equally. However, WPW syndrome has been found to be more frequent in males.

• A male-to-female ratio of approximately 2:1 has been documented in some series.
• In other series, the syndrome was found to be more frequent in men (1.4 per 1000) than in women (0.9 per 1000).
• A third study found a 3.5-fold higher prevalence of WPW syndrome in men.

Age

Patients with WPW syndrome may present at any age. However, an interesting bimodal age distribution has been reported in the pediatric population due to permanent or transitory loss of preexcitation during infancy in some patients and during late adolescence in others.

• Most patients with WPW syndrome present during infancy.
• A second peak of presentation is noted in school-aged children and in adolescents.

CLINICAL

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History

The presentations of Wolff-Parkinson-White (WPW) syndrome are as diverse as an incidental finding to syncope or sudden death.

Patients usually present with symptomatic orthodromic SVT, which accounts for approximately 95% of the SVT seen in children and infants with WPW syndrome.

Antidromic SVT occurs in the remaining 5% of children and infants with WPW syndrome.

• Orthodromic SVT is usually well tolerated and not a high risk, especially in the pediatric population after young infancy.
• Antidromic SVT presents more frequently with dizziness and syncope. In addition, it may precipitate ventricular tachycardia and fibrillation.
• The infant is often noted to be irritable, to not tolerate feedings, or to demonstrate evidence of congestive heart failure.
• Infants often have a history of not behaving as usual for 1 or 2 days.
• An intercurrent febrile illness is often observed.
• The verbal child usually reports chest pain, palpitations, or breathing difficulty.
• Most children are previously well, and a minority of children have a positive family history of this condition.
• Older patients can usually describe the sudden onset of a pounding heartbeat, which is regular and "too rapid to count." This is accompanied by a concomitant change in their tolerance for activity.
• An irregular rhythm may herald the presence of AF.
• In several series, the incidence of associated congenital heart disease (CHD) is reported to be as high as 30%, most commonly Ebstein anomaly of the tricuspid valve and "corrected" transposition of the great arteries {S,L,L}.
• • Approximately 10% of patients with Ebstein anomaly of the tricuspid valve have WPW syndrome. They usually have more than one AP, and those are usually right sided.
  • Patients with corrected transposition of the great arteries and left-sided Ebstein anomaly may also have WPW. In these patients the AP is left sided or septal.
  • Other congenital heart diseases associated with WPW syndrome include atrial and ventricular septal defects and coronary sinus diverticula.
• Preexcitation is believed to have a genetic substrate because since 3.4% of those with WPW syndrome have first-degree relatives with preexcitation. The familial form is usually inherited as a Mendelian autosomal dominant trait. Although rare, mitochondrial inheritance has also been described. The syndrome may also be inherited with other cardiac and noncardiac disorders, such as familial atrial septal defects, familial hypokalemic periodic paralysis, and tuberous sclerosis. Clinicians have long recognized the association of WPW syndrome with autosomal dominant familial hypertrophic cardiomyopathy. However, it was not until recently that a genetic substrate linking hypertrophic cardiomyopathy to WPW syndrome and skeletal myopathy was described:
• • Patients with mutations in the gamma 2 subunit of AMP-activated protein kinase (PRKAG2) develop cardiomyopathy characterized by ventricular hypertrophy, WPW syndrome, AV block, and progressive degenerative conduction system disease. It is believed that the mutation produces disruption of the annulus fibrosus by accumulation of glycogen within myocytes, which causes preexcitation. This is thought to be the case in Pompe, Danon, and other glycogen storage diseases.
  • Infantile Pompe disease or glycogen storage disease type II is a fatal genetic muscle disorder that is caused by deficiency of acid alpha-glucosidase (GAA). These patients have a shortened PR interval, large left ventricular (LV) voltages, and an increased QT dispersion (QTd).
  • Mutations in the lysosome-associated membrane protein 2 (LAMP2), which cause accumulation of cardiac glycogen are thought to be the etiology of a significant number of hypertrophic cardiomyopathies in children, especially when skeletal myopathy and/or WPW is present.
  • For example, Danon disease is an X-linked lysosomal cardioskeletal myopathy where males are more often and more severely affected than females. It is caused by mutations in the lysosome-associated membrane protein 2 (LAMP2) that produce proximal muscle weakness and mild atrophy, left ventricle hypertrophy and WPW in some, and mental retardation.

Physical

• During an episode of SVT, the infant is usually tachypneic and irritable; pallor is common. The pulse is very rapid and diminished in volume. The ventricular rate typically is 200-250 bpm, and the blood pressure is decreased. If the episode has been untreated for several hours, the patient often has poor perfusion, hepatomegaly, and cardiac failure. The child is usually anxious but hemodynamically stable. Tachypnea often accompanies the tachycardia.
• Once the arrhythmia has been terminated, the physical examination findings are generally normal.
• In the presence of CHD or cardiomyopathy findings of the underlying condition often become apparent only after the SVT has been terminated, although the hemodynamic consequences may be poorly tolerated.
• • Patients with Ebstein anomaly of the tricuspid valve may present with cyanosis, tachypnea, and other signs of congestive heart failure in presence of a rapid heart rate. The ECG may show either wide or narrow QRS, SVT, and sometimes QRS with changing morphology if more than one AP is present.
  • Patients with glycogen storage diseases have muscle weakness with normal or increased muscle bulk, macroglossia and hepatomegaly in the case of Pompe disease, and mental retardation in case of Danon disease.

Causes

• APs are considered congenital phenomena that are related to a failure of insulating tissue maturation within the AV ring. A proportion of patients with preexcitation may have a genetic predisposition, as outlined above.
• Preexcitation can be created surgically, such as in certain types of Bjork modifications of the Fontan procedure, if atrial tissue is flapped onto and sutured to ventricular tissue.
• Certain tumors of the AV ring, such as rhabdomyomas, may also cause preexcitation.

DIFFERENTIALS

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Other Problems to be Considered

The differential diagnosis for a narrow complex tachycardia is extensive, and the term SVT is nonspecific. The most common mechanism in pediatrics is AP-mediated SVT, which is a reentrant tachycardia. The main differential during SVT is whether the AP is concealed (ie, conducts only from ventricle to atrium) and thus it is an SVT with narrow QRS.

An automatic mechanism may be differentiated from reentry by the presence of a warm-up or cool-down period (which is due to its relation with catecholamine levels), the inability to initiate or terminate SVT with programmed atrial stimulation, and its usual unresponsiveness to electrical cardioversion. A regular tachycardia of sudden onset and termination that allows for some cycle length oscillation, which can be usually initiated and terminated with programmed atrial stimulation, and that is usually responsive to electrical cardioversion favors a reentrant mechanism.

Few entities that involve paroxysms of SVT with a Wolff-Parkinson-White (WPW) pattern ECG in sinus rhythm may be differentiated from AP-mediated SVT. Examples include the following:

• Occasionally, a low atrial focus produces the appearance of a short PR interval.
• The preexcitation associated with atriofascicular APs (so-called Mahaim) is associated with a normal PR interval.
• Patients with so-called Lown-Ganong-Levine syndrome demonstrate a short PR interval but not a broad QRS morphology. This terminology is currently out of favor but is historically relevant.

Entities that involve wide QRS SVT must be differentiated from VT. Examples include the following:

• Aberrantly conducting orthodromic SVT, which is wide QRS SVT with the AV node as the antegrade limb but with bundle branch block must be differentiated from VT.
• Antidromic tachycardia, which is wide QRS SVT due to ventricular preexcitation through an AP must also be differentiated from VT and from Mahaim fiber tachycardia.

WORKUP

Section 5 of 11  

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Lab Studies

• The extent of the workup is determined by the acuity of the patient's illness. In the patient who has cardiogenic shock or is unconscious, direct current (DC) cardioversion is indicated as soon as an arrhythmia is identified to be causative. Once the patient is hemodynamically stable or in the context of assessment following an arrest, measuring blood gases, electrolytes, lactate levels, and drug screening may be appropriate.

Imaging Studies

• Echocardiography should focus on cardiac function and dimensions to rule out cardiomyopathy and associated CHD (eg, hypertrophic cardiomyopathy, Ebstein anomaly, L-transposition of the great vessels). Significantly depressed function may be observed in the setting of an acute arrhythmia but should typically normalize in the absence of an incessant tachycardia.

Other Tests

• Obtaining a 12-lead ECG is necessary in stable patients. The characteristic features are a short PR interval, often with no isoelectric line between the end of the P wave and the beginning of the QRS complex. The QRS is usually broad and has accompanying ST changes. In patients demonstrating intermittent preexcitation, ECG findings may appear normal or even demonstrate 2 distinct QRS patterns.
• The most common location of the AP is in decreasing order of frequency, the left free wall, the posteroseptal and right free wall, and lastly the midseptal and anteroseptal regions of the heart.
• Several algorithms are available to predict the location of the AP, which assist in planning an ablation and in counseling about the risks of the procedure. These algorithms may not be totally accurate because maximal preexcitation is needed, and usually the QRS in Wolff-Parkinson-White (WPW) pattern is a fusion between AV node and AP depolarization (ie, absent AP depolarization may be present at certain points due to enhanced AV node conduction, although the AP is present), precordial lead placement may be variable, as well as chest shape and size and heart shape, size, and location. A practical concept is that a negative delta wave usually signals where the AP is.
• • A negative delta wave in a left-sided lead such as I and aVL indicates a left-sided AP.
  • A negative delta in a right-sided lead such as V1 predicts a right-sided AP.
  • An isoelectric delta in V1 predicts an anteroseptal AP.
  • A negative delta in the inferior leads (II, III, and aVF) indicates a posteroseptal AP.
  • A positive delta in the inferior leads predicts an anteroseptal AP.
• A more specific algorithm for location of the AP based on the polarity of the delta wave or first 40 ms of the QRS predicts the following AP location:
• • A negative delta wave in lead I and aVL; positive or isoelectric in II, III, aVF (inferior leads), and V1-4; and negative or isoelectric in V5-6 predicts a left lateral wall location.
  • A positive delta wave in lead I and aVL; negative in II, III, and aVF; positive in V1-5; and negative or isoelectric in V6 predicts a left posterior free wall AP location.
  • A positive delta wave in lead I and aVL with negative delta in II, III, and aVF; isoelectric or positive in V1; and positive in the rest of the precordial leads predicts a posteroseptal AP.
  • A positive delta wave in I and II, negative in aVR, isoelectric or negative in aVF, isoelectric in V1, isoelectric or positive in V2-3, and positive in V4-6 predicts a right free wall AP location.
  • A positive delta wave in I, II, and aVF; negative in aVR; isoelectric or positive in V1; and positive in V2-6 predicts a left anteroseptal location for the AP.
  • A positive delta wave in I, II, and aVF; negative in aVR; negative or isoelectric in V1-3; and positive in V4-6 is predictive of a right anteroseptal AP.
• During orthodromic tachycardia, a narrow complex QRS is evident with the P wave often detectable as a subtle deflection within the T wave.
• During antidromic tachycardia, a wide complex QRS is seen and may or may not be distinguished from ventricular tachycardia (in which case it must be treated as such).
• Further workup generally consists of Holter monitoring to detect intermittent preexcitation and occult episodes of SVT.
• An exercise test may also be helpful in studying the behavior of the AP at higher heart rates; however, this test has limited predictive value.
• In the presence of WPW syndrome without documented SVT and in the presence of symptoms, a transtelephonic transient cardiac event monitor or a longer-term monitoring system may be appropriate.

Procedures

• An esophageal electrophysiology study can be used to assess the behavior of the AP, the inducibility of SVT, and the response to drug therapy. This procedure can be performed safely as an outpatient procedure requiring only sedation. An invasive electrophysiology study can also be performed for these risk-stratification indications, but this is usually reserved for patients undergoing RF ablation.
• If AF is induced during either an intraesophageal or an electrophysiologic study the shortest RR interval between 2 consecutive preexcited QRSs is measured. If the interval is less than 220 ms then the risk of sudden death due to VF is believed to be high. Specifically, according to a study the most discriminating parameter to predict VF in patients with WPW was the shortest RR interval during atrial fibrillation of 172 +/- 23 ms (versus 230 +/- 50 ms). Those patients were considered to be at high risk for developing VF and sudden death should AF occur.
• A recent study showed that during electrophysiologic testing for risk stratification in asymptomatic children with WPW pattern a high proportion experienced sustained AVRT and/or AF with the shortest RR between 2 consecutive preexcited QRSs of 250-230 ms (mean 237.5+/-9.6 ms). The authors concluded that those results may be indicative of the necessity of radiofrequency ablation in all asymptomatic individuals with WPW pattern.
• An intracardiac electrophysiologic study will show the following:
• • During sinus rhythm in presence of WPW the HV interval will be negative. This means that the His deflection occurs after the beginning of the QRS deflection. The more preexcitation, the later the His deflection (ie, more toward the end of the QRS). This occurs whenever the AP is conducting more rapidly than the AV node and thus, the depolarizing wavefront from the AP reaches the ventricle earlier than that from the AV node. The earlier the depolarization from the AP reaches the ventricle with respect to the depolarization from the AV node, the more preexcitation (ie, the wider the QRS and the shorter the RP interval).
  • During antidromic SVT a premature atrial extrastimulation that shortens the SVT cycle length with no change in QRS morphology or that terminates SVT with an atrial depolarization (ie, not followed by a QRS) rules out ventricular tachycardia. In the first case, there is proof that the premature atrial depolarization conducts to the ventricles through the AP. In the second case, the premature atrial depolarization reaches the AP's effective refractory period terminating the SVT in the antegrade limb, also proving that the AP participated in the SVT (ie, it is an AP-mediated SVT and not a ventricular tachycardia).

Histologic Findings

An extremely detailed postmortem assessment of histology from multiple sections around the AV ring may identify APs, but this approach is impractical for assessment of every patient with unexplained sudden death.

TREATMENT

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Medical Care

• Short-term management of Wolff-Parkinson-White (WPW) syndrome
• • Patients presenting in cardiac arrest or with hemodynamic compromise require management of the airway, breathing, and circulation, as is standard; this includes having a defibrillator available and providing appropriate monitoring. Once the patient is determined to be experiencing an arrhythmia, DC cardioversion is indicated.
  • In the stable patient, a variety of vagal maneuvers may be attempted. A bag of ice slurry to the face is very effective in infants. Older children may be able to perform a Valsalva maneuver. Creative alternatives abound, such as having a patient blow with his thumb in his mouth. Unilateral carotid sinus massage may also be attempted. Ocular compression should not be performed because it has been associated with retinal injury.
  • When conservative measures fail, intravenous access is necessary. Adenosine is the first-line agent and is effective in approximately 90% of reentrant narrow complex tachycardias. Adenosine must be administered as a rapid bolus because of its short half-life. Most adenosine failure is caused by inadequate administration of the drug. A defibrillator must be available in the event that new arrhythmias emerge, particularly atrial fibrillation postadenosine.
  • Procainamide and esmolol are available in the resistant cases but should only be administered by physicians familiar with these medications. Verapamil should not be administered patients younger than 1 year because of risk of severe hypotension, severe bradycardia, or heart failure in this population of patients; this drug has also been reported to accelerate the ventricular rate in AF, leading to rapid conduction that results in VF.
• Long-term management of WPW syndrome
• • Treatment must be individualized for each patient and should include individual risk assessment. Despite the importance of risk stratification to assess the risk of sudden death, few reliable noninvasive markers exist. The adult literature has focussed on preexcited R-R intervals in AF as an indicator of the ability to rapidly conduct. In a series of 60 pediatric patients, a preexcited R-R interval of less than 220 milliseconds identified patients at high risk for cardiac arrest; thus, if an AP can conduct impulses at a rate of 4 per second, it can be considered a high-risk pathway. Ambulatory monitoring and treadmill testing can provide additional noninvasive information if the preexcitation disappears suddenly at a discrete heart rate. However, care should be exercised when interpreting these noninvasive test results. Invasive risk assessment with subsequent radiofrequency ablation should be done in patients presenting with syncope or aborted SCD.
  • Long-term oral medication is the mainstay of therapy in patients not undergoing RF ablation. Some of the drugs available are listed below. Note that digoxin and verapamil are contraindicated in the long-term therapy of WPW syndrome because these drugs, by prolonging AV node conduction will favor antegrade conduction through the AP. This would favor ventricular fibrillation should AF occur.

Surgical Care

In the era of RF ablation, eradicating AP function in almost any patient with the WPW pattern on ECG is feasible. However, because RF ablation is not without its risks, perform an assessment of the risk-to-benefit ratio for all patients. Individuals with low-risk APs, such as adults who have never had symptoms and who do not participate in extremes of competition, are not usually considered candidates for RF ablation of an AP. Patient preference is the most common indication for RF ablation in symptomatic patients not at high risk. The procedure is relatively safe, with a complication rate of approximately 1% in most centers. Success rates range from approximately 85-95%, with a 5% recurrence risk.

Activity

• Patients with appropriately evaluated and treated WPW syndrome should be able to participate in all activities, assuming that patients with high-risk pathways receive treatment with RF ablation or a pathway-specific antiarrhythmic agent. Generally, if a patient is significantly altering his or her lifestyle because of the disease, he or she is probably not receiving adequate or appropriate therapy.
• In many jurisdictions, the presence of preexcitation excludes patients from participating in the armed services and piloting commercial flights.

MEDICATION

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Emergency treatment in patients with hemodynamic instability is directed to convert the rhythm to sinus through a brief episode of AV block. Adenosine is the drug of choice for immediate conversion of narrow complex SVT, but it should not be used and is contraindicated for preexcited atrial fibrillation. Esmolol has also been used with some success.

Beta-blockers are probably the most common medication used to treat SVT in the presence of preexcitation. They are moderately effective and have frequent, but rarely life-threatening, adverse effects (except in the presence of reactive airway disease). The efficacy of beta-blockers in reducing the risk of accelerated conduction of atrial fibrillation in patients with Wolff-Parkinson-White (WPW) syndrome is unclear. More potent medications, such as flecainide, propafenone, sotalol, or amiodarone, may have more effect on AP conduction or refractoriness than beta-blockers, and they are preferred by some. The use of digoxin or verapamil for long-term therapy appears to be contraindicated for many WPW patients because these medications, by increasing the refractory period in the AV node may enhance antegrade conduction through the AP. In addition, digoxin may shorten the refractory period of the AP further enhancing its antegrade conduction.

Drug Category: Antiarrhythmic agents

These agents alter the electrophysiologic mechanisms responsible for arrhythmia.

FOLLOW-UP

Section 8 of 11  

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Further Outpatient Care

• Follow-up care with a cardiologist is indicated for patients with Wolff-Parkinson-White (WPW) syndrome.
• Current guidelines do not always recommend a routine electrophysiology study in patients with asymptomatic WPW, especially in children who are younger than 12 years. However, some advocate noninvasive testing for risk stratification in patients with asymptomatic WPW with an intraesophageal electrophysiologic study.
• Asymptomatic patients who have a low-risk pathway and no SVT can be monitored expectantly.
• Radiofrequency ablation is indicated in asymptomatic individuals with WPW pattern who engage in high-risk occupations, or in those where the WPW pattern precludes them from following their chosen career or activities.
• Symptomatic individuals with orthodromic tachycardia should undergo risk assessment and should be offered therapy according to their symptoms. RF ablation can be curative and carried out with a high degree of success, a low complication rate, and a low recurrence rate.
• Symptomatic individuals with antidromic tachycardia (ie, antegrade conduction through the AP) probably should be offered ablation because of the following:
• • In these patients, it is likely that the AP has fast antegrade conduction, and, thus, the likelihood of developing a dangerous ventricular rhythm is higher.
  • Approximately 30% of these patients have multiple APs.

Transfer

• Ideally, if transfer of patients with WPW syndrome and other causes of SVT is indicated, they undergo conversion of their rhythm in the referring institution and are transferred in sinus rhythm.

Deterrence/Prevention

• Screening of school-aged children or athletes through preparticipation evaluation has been suggested but, so far, has not been considered cost-effective.

Prognosis

• Once identified and appropriately treated, WPW syndrome is associated with an excellent prognosis, including the potential for permanent cure through RF catheter ablation.

Patient Education

• For excellent patient education resources, visit eMedicine's Heart Center. Also, see eMedicine's patient education article Supraventricular Tachycardia.

MISCELLANEOUS

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Medical/Legal Pitfalls

• Failure to recognize this disorder or incorrect treatment resulting in deterioration can result in medicolegal vulnerability.
• Controversies exist regarding athletes with Wolff-Parkinson-White (WPW) syndrome. Risk-stratification testing has false-negative results, with potential for adverse outcomes despite test results in patients deemed at low risk.

Special Concerns

• Patients interested in certain professions (eg, professional athlete, pilot) may be excluded based on WPW syndrome.

MULTIMEDIA

Section 10 of 11  

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Media file 1:  This ECG belongs to an asymptomatic 17-year-old male who was incidentally discovered to have WPW pattern. It shows sinus rhythm with evident preexcitation. To locate the AP, the initial 40 ms of the QRS (delta wave) are evaluated. Note that the delta wave is positive in lead I and aVL, negative in III and aVF, isoelectric in V1, and positive in the rest of the precordial leads. Therefore, this is likely a posteroseptal AP.
	View Full Size Image
Media type:  ECG

Media file 2:  This is a 12-lead ECG from an asymptomatic 7-year-old boy with WPW pattern. Delta wave is positive in leads I and aVL; negative in II, III, and aVF; isoelectric in V1; and positive in the rest of the precordial leads. This again predicts a posteroseptal location for the AP.
	View Full Size Image
Media type:  ECG

REFERENCES

Section 11 of 11

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• Arad M, Maron BJ, Gorham JM, et al. Glycogen storage diseases presenting as hypertrophic cardiomyopathy. N Engl J Med. Jan 27 2005;352(4):362-72. [Medline].
• Arad M, Moskowitz IP, Patel VV, et al. Transgenic mice overexpressing mutant PRKAG2 define the cause of Wolff-Parkinson-White syndrome in glycogen storage cardiomyopathy. Circulation. Jun 10 2003;107(22):2850-6. [Medline]. [Full Text].
• Arad M, Benson DW, Perez-Atayde AR, et al. Constitutively active AMP kinase mutations cause glycogen storage disease mimicking hypertrophic cardiomyopathy. J Clin Invest. Feb 2002;109(3):357-62. [Medline]. [Full Text].
• Atie J, Brugada P, Brugada J, et al. Clinical and electrophysiologic characteristics of patients with antidromic circus movement tachycardia in the Wolff-Parkinson-White syndrome. Am J Cardiol. Nov 1 1990;66(15):1082-91. [Medline].
• Attoyan C, Haissaguerre M, Dartigues JF, et al. Ventricular fibrillation in Wolff-Parkinson-White syndrome. Predictive factors. Arch Mal Coeur Vaiss. Jul 1994;87(7):889-97. [Medline].
• Basson CT. A molecular basis for Wolff-Parkinson-White syndrome. N Engl J Med. Jun 14 2001;344(24):1861-4. [Medline].
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Article Last Updated: Jan 8, 2007