Wpw syndrome I45.6

The WPW syndrome was first described in 1930 by Wolff, Parkinson and White and named after them (Greten 2010).

A WPW syndrome is the presence of one or more accessory pathways between the atrium and the ventricle, which can lead to preexcitation during sinus rhythm and to paroxysmal supraventricular tachycardia (Kasper 2015).

The WPW syndrome belongs to the group of paroxysmal supraventricular tachycardias (PSVT) and here to the subgroup of atrio-ventricular tachycardia (AVRT). In WPW syndrome, a distinction is made between a:

• Type A (also known as sternal-positive) where there is: a left accessory AV bundle, also known as left ventricular preexcitation (Cote 2013)
• Type B (also called sternal negative) with right accessory AV bundle, also called right ventricular preexcitation (Cote 2013, Stierle 2017)

The WPW syndrome is the most common of the preexcitation syndromes and occurs in about 01 % - 3 % of the population (Biro 2005). The initial manifestation is found in 50% before the age of 20, but the disease can become symptomatic at any age (Pinger 2019).

Associated cardiac malformations:

In WPW syndrome, about 7% to 20% of patients have additional heart defects, especially:

• Mitral valve prolapse
• hypertrophic obstructive cardiomyopathy
• Atrial septal defect
• Ventricular septal defect
• M. Ebstein (Pinger 2019)
• Danon disease
• Fabry disease (Kasper 2015)

The defect is congenital. There is a hereditary autosomal dominant inheritance (Biro 2005). The cause is an incomplete formation of the annulus fibrosus (which normally separates atrium and ventricle) (Kasper 2015).

The accessory pathways between the atrium and the ventricle can trigger excitation parallel to the AV node, but can also transmit excitation faster than the AV node. The latter results in the occurrence of a delta wave in the ECG (Biro 2005 / Herold 2020). The fasciculo- ventricular fibres between the His bundle and the ventricular septum can lead to preexcitation, but not to arrhythmias.

Concealed accessory leads only lead to a retrograde transition from the ventricle to the atrium, where no preexcitation occurs during sinus rhythm. Supraventricular tachycardias are possible, however (Kasper 2015).

There are 3 different groups of patients in terms of symptomatology:

Group 1: The patients are asymptomatic. There are no paroxysmal tachycardia.

Group 2: These patients have intermittent tachycardias.

• Orthodromic AVRT (most frequent form): An antegrade circular excitation above the AV node and a retrograde excitation above the accessory pathways are present. The symptomatology begins and ends abruptly.
• Antidromic form (rarer): Here the excitation is antegrade via the accessory pathways and retrograde via the AV node.

Group 3: Patients in this group show potentially life-threatening tachyarrhythmias. The accessory pathways have a short refractory period. Atrial fibrillation, ventricular tachycardia, ventricular fibrillation and sudden cardiac death may occur (Herold 2020).

Resting ECG: There may be a normal surface ECG in the case of accessory pathways that cause only retrograde excitation. In such cases one speaks of a so-called "hidden WPW syndrome" (Herold 2020).

Otherwise, the following changes may be present:

• in the antidromic form (see also "clinical picture"):
  • intermittent or permanent tachycardia (frequency 150 - 220 beats per minute)
  • PQ time < 0.12 s (Biro 2005)
  • typical delta waves due to premature excitation of one or both ventricles
  • Deformation and extension of the QRS complex
  • Change in repolarization (Gertsch 2007)
• in the orthodromic form (see also "clinical picture"):
  • narrow QRS complexes
  • no delta wave (Herold 2020)
  • Type A (see "Classification"): positive main QRS- Alignment direction V1 and V2
  • Type B (see "Classification"): negative main QRS- Alignment direction V1 and V2
• in the case of tachycardia there are:
  • Reentry tachycardia at 80
  • Atrial fibrillation at 10
  • Atrial flutter at about 4 % (Stierle 2017)

Long-term ECG: In case of intermittent tachycardia only, a long-term ECG should be performed (Herold 2020). If no events can be recorded during the 24-hour recording, the use of an implantable event recorder, also known as "Insertable Cardiac Monitors" (ICMs) or "Implantable Loop Recorders" (ILRs) is recommended (Rörig 2014).

Intracardiac ECG: The intracardiac ECG is used for the exact localization of the accessory pathways. It can also be used to identify patients with short refractory time of the accessory pathways. This is of great prognostic importance, since patients with a shortened refractory period are potentially at risk of sudden cardiac death (Herold 2020).

Exercise ECG: Patients in whom the exercise ECG shows a loss of the delta wave have a long refractory period and are usually not at risk of sudden cardiac death (Biro 2005).

• Lown- Ganong- Levine- Syndrome (LGL- Syndrome): Here you can find:
  • no delta wave.
  • PQ- time is < 0.12 s
  • the disease has no clinical relevance
• AV- Kno,ten- Rentrytachycardia without preexcitation syndrome (Biro 2005)

At first an irritation of the vagus nerve should be tried:

• Valsalva- pressing attempt (after deep inhalation pressing should be done as long as possible)
• drink a large, preferably cold and acidic drink in rapid succession
• Immersion of the face in cold water
• Ice tie (Herold 2020)

If the vagus irritation does not result in an improvement of the symptoms, medication is necessary. This should be done with:

• Ajmalin: Recommended dosage: e.g. Gilurytmal 50 mg slowly i. v. under ECG control

Verapamil, digitalis and adenosine are always contraindicated in preexcitation syndrome with atrial fibrillation. These drugs can shorten the refractory period in the accessory pathways and thus trigger ventricular fibrillation (Herold 2020).

If there are indications of an imminent cardiogenic shock, a cardioversion is indicated. In case of recurrent AVRT, HFS / cyto-catheter ablation is recommended as part of a selective intervention. The success rate is over 95%.

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4. Greten H et al (2010) Internal Medicine Thieme Verlag 90
5. Herold G et al (2020) Internal medicine. Herold Publisher 283 - 284
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10. Stierle U et al (2014) Clinical Guide to Cardiology. Elsevier Urban and Fischer 420 - 423