11/14/24, 10\:38 AM Wolff-Parkinson-White Syndrome

Wol

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Wol
heart, presenting with characteristic ECG
Aetiology\: An accessory pathway leads to stimulation of the ventricles, bypassing the AV node and causing premature
excitation. This results in 'double excitation' of the ventricles. The accessory pathway, sometimes called the 'bundle of Kent'
,
can be left-sided or right-sided and may conduct both anterograde and retrograde.
Risk factors\: Most common in males aged 30-40 years. Most cases are sporadic, but some are due to an inherited mutation
in the PRKAG2 gene (autosomal dominant). Associated with congenital heart disease such as Ebstein’s anomaly.
Clinical features\: Caused by tachyarrhythmias, including palpitations, lightheadedness, presyncope, syncope, and cardiac
arrest. Other symptoms may include chest pain, shortness of breath, and sweating. Symptoms vary from seconds to hours
and can be triggered by exercise, alcohol, or ca
Di
tachycardia), valvular disease, Ebstein’s anomaly, and hypertrophic cardiomyopathy.
Investigations\:
ECG\: Short PR interval \<120ms, delta wave, widened QRS >110ms, incongruous ST segment and T wave changes, prominent
R waves in V1-3. Type A (left-sided) shows positive delta wave in precordial leads; Type B (right-sided) shows negative delta
wave in leads V1 and V2.
Laboratory\: FBC, U&E, LFT, thyroid function tests.
Imaging\: Chest X-ray, echocardiogram to rule out structural heart disease.
Other\: Ambulatory ECG monitoring, exercise stress test, electrophysiology studies.
Management\:
Asymptomatic patients\: Regular follow-up, lifestyle changes to reduce tachyarrhythmia episodes.
Symptomatic episodes\: Vagal manoeuvres (Valsalva manoeuvre), intravenous adenosine if vagal manoeuvres fail,
cardioversion if adenosine fails.
Long-term\: Catheter ablation of the accessory pathway, daily amiodarone to prevent tachyarrhythmias.
Complications\: Related to periods of tachyarrhythmia, including palpitations, dizziness, syncope, and sudden cardiac
death. The risk of sudden cardiac death is approximately 0.1% in asymptomatic and 0.3% in symptomatic patients per year.
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Introduction

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accessory pathway in the heart.
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tachyarrhythmias and clinical symptoms of tachycardia.
The accessory pathway in Wol
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Aetiology

In Wol
electrical conduction to bypass the AV node and stimulate the proximal ventricles prematurely (pre-excitation). This, in
addition to normal electrical conduction through the AV node, leads to ‘double excitation’ of the ventricles.
The location and conduction through the accessory pathway varies between individuals. In most patients, conduction can
move both anterograde (from the atria to the ventricles) and retrograde (from the ventricles to the atria).
In a smaller group (approx. 15% of patients), conduction moves in a retrograde manner only. Anterograde conduction by
itself is rare.
Additionally, the accessory pathway may be left-sided or right-sided. This will a
investigations section).
The accessory pathway in Wol
.
Figure 1. Conduction through a left-sided
accessory pathway leading to pre-
excitation in WPW.
Unlike normal conduction pathways in the heart, conduction through the accessory pathway in WPW is not regulated by
the AV node and can lead to tachyarrhythmias (the heart beating too fast).

Risk factors

Wol
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Most WPW cases are sporadic. However, a small percentage of cases are thought to be due to an inherited mutation in
the PRKAG2 gene. This genetic mutation is autosomal dominant.
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WPW Syndrome is also associated with congenital heart disease, such as Ebstein’s anomaly.

Clinical features

The clinical features of Wol
may be asymptomatic and only diagnosed following a routine ECG.
Typical symptoms of tachyarrhythmias include\:
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Palpitations
Feeling lightheaded
Presyncope
Syncope
Cardiac arrest
Other features may include chest pain, shortness of breath and sweating.
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For more information on history taking in patients with palpitations, see the Geeky Medics OSCE guide to palpitations
history taking.
The duration of these symptoms varies from person to person and can range from seconds to hours. The frequency of
symptoms also varies considerably. Symptoms do not usually have any precipitating factors, however, episodes may be
triggered by strenuous exercise, alcohol or ca
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The main di
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Atrial
Atrial
Atrioventricular nodal re-entry tachycardia (AVNRT)
Ventricular
Ventricular tachycardia
Other conditions that may present similarly include valvular disease, Ebstein’s anomaly (a congenital malformation of the
tricuspid valve) and hypertrophic cardiomyopathy.
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Investigations

Electrocardiogram (ECG)

Key features of WPW on an ECG in sinus rhythm include\:
Short PR interval \<120ms
Delta wave\: slurred upstroke of the QRS
Widened QRS complex >110ms
Incongruous ST segment and T waves changes
Prominent R waves in V1-3\: this mimics a posterior infarction
Figure 2. ECG showing the key features
of Wol
including a short PR interval, delta waves
and broad QRS complexes.
Type A vs type B
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heart. Type A WPW pattern is a left-sided accessory pathway and type B WPW pattern is a right-sided accessory
pathway.
ECG features will be di
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Type A (left-sided)\: positive delta wave in the precordial leads (V1 - V6)
Type B (right-sided)\: negative delta wave in leads V1 and V2

Laboratory investigations

Blood tests may be useful in ruling out other (non-cardiac) causes of palpitations.
Relevant laboratory investigations include\:
Full blood count
Urea and electrolytes
Liver function tests
Thyroid function tests

Imaging

Relevant imaging investigations include\:
Chest X-ray\: to rule out other (non-cardiac) causes
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Echocardiogram\: to rule out structural heart disease (e.g. Ebstein’s anomaly, hypertrophic cardiomyopathy, valvular
diseases) and assess left ventricular function.

Other investigations

Other relevant investigations may include\:
Ambulatory ECG monitoring (e.g. 72-hour tape)\: this allows the ECG to detect periods of pre-excitation amongst normal
sinus rhythm. This is often used to con
Exercise stress test\: may help to establish the relationship between exercise and tachyarrhythmias associated with
WPW
Electrophysiology studies\: may help identify accessory pathways for ablation

Management

Often, episodes of pre-excitation are short, self-terminating and do not cause problems. In people who only experience
occasional symptoms, no treatment is needed, and they are followed up regularly by a cardiologist.
In patients whose episodes are triggered by stress, exercise or alcohol, simple lifestyle changes may help to reduce the
frequency of tachyarrhythmia episodes.

Management of SVT

During a symptomatic episode, Wol
Vagal manoeuvres are
manoeuvre (forced expiration against a closed glottis) which slows the heart rate via stimulation of the vagus nerve.
If vagal manoeuvres are unsuccessful, intravenous adenosine may terminate the episode by blocking conduction through
the AV node.
Finally, cardioversion may be performed if adenosine is not successful.
Long-term episodes may be prevented by catheter ablation of the accessory pathway, which is e
Alternatively, daily amiodarone can slow the heart rate and prevent tachyarrhythmias.

Complications

Complications of Wol
palpitations, dizziness, syncope and sudden cardiac death.
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Sudden cardiac death in WPW Syndrome is rare, and the overall risk is approximately 0.1% in asymptomatic patients and
0.3% in symptomatic patients per year.
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References

Lovely Chhabra; Amandeep Goyal; Michael D. Benham. Wol
[LINK]
StatPearls. WolLINK]
Vaughan CJ, Hom Y, Okin DA, McDermott DA, Lerman BB, Basson CT. Molecular genetic analysis of PRKAG2 in sporadic
WolLINK]
WolLINK]
Marrakchi, S. Kammoun, I. Kachboura S. Wol
Published July 2014. Available from\: [LINK]
Dr C Tidy, Patient Info. WolLINK]
Robert Buttner, Ed Burns. Pre-Excitation Syndromes. Life in the Fast Lane. Published December 2021. Available from\: [LINK]
WolLINK]
https\://app.geekymedics.com/notebook/2687/ 4/511/14/24, 10\:38 AM Wolff-Parkinson-White Syndrome
Laaouaj J, Jacques F, O’Hara G, et al. Wol
death. H e a r t R h y t h m C a s e R e p o r t s 2016;2\:399. Available from\: [LINK]

Image references

Figure 1. Tom Luck. W o l CC BY 3.0]. Available from\: [LINK]
Figure 2. Robert Buttner, Ed Burns. P r e-E x c i t a t i o n S y n d r o m e s . Life in the Fast Lane. Published December 2021. Available
from\: [LINK]

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Contents

Introduction
Aetiology
Risk factors
Clinical features
Di
Investigations
Management
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