Wolff-Parkinson-White (WPW) syndrome

To understand Wolff–Parkinson–White syndrome, it is helpful to recall the heart’s normal electrical function:

• The heart is a muscle whose contraction is triggered and coordinated by electrical activity;
• Under normal circumstances, the electrical impulse originates in the sinus node, located in the upper part of the right atrium, which acts as the “conductor” of the heart rhythm;
• This impulse then spreads through the atria, causing them to contract;
• The impulse then reaches the atrioventricular (AV) node, located between the atria and the ventricles;
• The atrioventricular node is normally the only pathway for the electrical impulse to travel from the atria to the ventricles;
• The AV node slightly slows conduction, creating a delay that allows the atria to contract before the ventricles;
• The impulse is then rapidly conducted to the ventricles via the His bundle and its branches, causing ventricular contraction.

This organized conduction system ensures coordinated and efficient contraction of the heart, allowing optimal pumping of blood.

The Kent bundle is an additional (or “accessory”) electrical conduction pathway that bypasses the atrioventricular (AV) node, creating an electrical “shortcut” between the atria and the ventricles.

This anatomical anomaly has several important characteristics:

• Unlike the atrioventricular node, which naturally slows conduction, the Kent bundle can transmit the electrical impulse very rapidly;
• The Kent bundle can conduct the impulse in both directions: from the atria to the ventricles (antegrade conduction) and from the ventricles to the atria (retrograde conduction);
• The presence of these two parallel conduction pathways (the AV node and the Kent bundle) can create a closed electrical circuit, allowing the impulse to loop continuously and trigger a reentrant tachycardia.

During a tachycardia episode, the electrical impulse typically travels down one pathway (often the atrioventricular node) and back up the other (the Kent bundle), creating a self-sustaining closed circuit that accelerates the heart rate, which can reach 180 to 250 beats per minute.

“Bouveret’s disease” is the historical term used to clinically describe the sudden-onset and sudden-ending tachycardia episodes seen in Wolff–Parkinson–White syndrome.

At the end of the 19th century, Dr. Léon Bouveret, a French physician, was the first to describe these very characteristic episodes of palpitations—well before electrocardiography existed and before the electrophysiological mechanism was understood.

He described these episodes as “regular tachycardic palpitations with sudden onset and sudden termination, followed by post-episode polyuria” (a strong urge to urinate abundantly after the episode). This precise clinical description matched what patients were experiencing, without understanding the underlying mechanism.

It was only several decades later, thanks to Willem Einthoven’s invention of the electrocardiogram, that doctors Wolff, Parkinson, and White were able, in 1930, to describe the syndrome that now bears their names, identifying its characteristic electrocardiographic abnormalities and beginning to understand the mechanism of this arrhythmia.

Thus, “Bouveret’s disease” and “Wolff–Parkinson–White syndrome” describe the same condition but from different perspectives: the first term refers to the clinical symptoms, while the second refers to the electrophysiological mechanism and ECG abnormalities.

The clinical manifestations of Wolff–Parkinson–White syndrome vary from one person to another:

• No symptoms: many people with Wolff–Parkinson–White syndrome have no symptoms, and the anomaly may be discovered incidentally during an electrocardiogram performed for another reason;
• Palpitations: sensation of rapid, regular heartbeats with sudden onset and sudden termination (like “flipping a switch”), lasting from a few minutes to several hours;
• Lightheadedness: dizziness, unsteadiness, or a feeling of faintness during episodes;
• Shortness of breath: especially during prolonged episodes;
• Chest pain: may occur during tachycardia episodes;
• Post-episode polyuria: the need to urinate abundantly after an episode, a sign described by Bouveret and quite characteristic;
• Syncope (loss of consciousness): rare, but possible in cases of very rapid tachycardia or extremely fast conduction during atrial fibrillation.

Tachycardia episodes are often triggered by certain factors:

• Physical exertion;
• Stress, anxiety;
• Consumption of stimulants (caffeine, alcohol);
• Fatigue;
• Sometimes with no identifiable trigger.

The frequency of episodes is highly variable: some patients may have only one or two in their lifetime, while others may experience several per week.

In the vast majority of cases, Wolff–Parkinson–White syndrome is not dangerous. Tachycardia episodes are generally well tolerated and end spontaneously or after simple maneuvers.

However, in certain cases, Wolff–Parkinson–White syndrome can carry a potentially serious risk:

• If the accessory pathway has rapid conduction properties and atrial fibrillation occurs (an arrhythmia in which the atria beat chaotically more than 300 times per minute), the electrical impulse can be transmitted to the ventricles at an extremely high rate via the Kent bundle, causing a dangerously fast ventricular rate. This situation can, in rare cases, degenerate into ventricular fibrillation and cardiac arrest;
• Frequent or prolonged tachycardia episodes may, in some patients, lead to cardiomyopathy (weakening of the heart muscle).

Fortunately, it is possible to identify potentially dangerous Kent bundles. During an electrophysiological study, electrophysiologists can measure the refractory period of the accessory pathway (the minimum time between two successive conductions), which helps assess its ability to conduct impulses rapidly and thus the associated risk.

Patients with Wolff–Parkinson–White syndrome who have severe symptoms (syncope, pre-syncope) or an accessory pathway with rapid conduction should undergo specialized electrophysiology evaluation to determine whether treatment is necessary.

Baseline Electrocardiogram

The diagnosis of Wolff–Parkinson–White syndrome is primarily based on a resting electrocardiogram (ECG), which may reveal characteristic abnormalities:

• Short PR interval (< 120 ms): due to rapid conduction from the atrium to the ventricle via the accessory pathway;
• Delta wave: an initial slurring of the QRS complex, corresponding to early activation of part of the ventricle through the accessory pathway;
• Widened QRS complex: resulting from the fusion between early activation via the accessory pathway and normal activation through the atrioventricular node.

It is important to note that these abnormalities can be intermittent or hidden if the accessory pathway is not conducting in an anterograde direction (from the atria to the ventricles) at the time of the exam.

Recording During an Episode

Recording an ECG during a tachycardia episode is very useful to confirm the diagnosis and identify the mechanism:

• Holter ECG: continuous recording of the heart rhythm for 24 to 48 hours;
• Event recorder: a device allowing the patient to record their heart rhythm during symptoms;
• Connected health applications: some smartwatches or apps can now record a simplified ECG, sometimes capturing an episode.

Electrophysiological Study

An electrophysiological study (EPS) is the gold-standard test for accurately characterizing Wolff–Parkinson–White syndrome and assessing its risk:

• Performed under local anesthesia, this procedure involves introducing catheters through a vein (usually femoral) up to the heart;
• It allows precise localization of the accessory pathway, evaluation of its conduction properties (particularly its refractory period), and assessment of its potential risk;
• It can also induce tachycardia under controlled conditions, confirming the mechanism;
• In most cases, it is immediately followed by radiofrequency ablation if indicated.

This electrophysiological study is performed at the Institut Mutualiste Montsouris by the rhythmology specialists of Rythmopôle Paris.

The treatment of Wolff–Parkinson–White (WPW) syndrome aims to eliminate episodes of tachycardia and remove any potential risk of serious complications. Two main approaches are possible:

Medication

Antiarrhythmic drugs can be used to control symptoms by slowing conduction through the accessory pathway or by preventing tachycardia episodes:

• Treatment of acute episodes: vagal maneuvers (Valsalva maneuver, immersing the face in cold water), intravenous adenosine in a hospital setting;
• Continuous preventive treatment: beta-blockers, calcium channel blockers, class Ic antiarrhythmics (flecainide, propafenone) or class III (amiodarone, sotalol);
• “Pill-in-the-pocket” treatment: taking medication only during an episode to attempt to stop it.

This approach has the advantage of avoiding an intervention but has several drawbacks:

• Variable and often incomplete effectiveness;
• Need for long-term treatment, with the risk of side effects;
• Does not eliminate the potential risk associated with a dangerous accessory pathway.

Catheter ablation

Radiofrequency catheter ablation is the treatment of choice for WPW syndrome, particularly in cases involving a dangerous accessory pathway or symptoms poorly controlled by medication:

• Principle: cauterizing (not removing) the accessory pathway using thermal energy (radiofrequency) delivered via a catheter;
• Procedure: usually performed immediately after an electrophysiological study, under local anesthesia, via the femoral vein;
• Effectiveness: immediate success rate exceeds 95%, with a recurrence risk of less than 5%;
• Practical aspects: outpatient procedure (admission in the morning, discharge the same day), with a return to normal activities within a few days;
• Outcome: definitive cure in the vast majority of cases, allowing discontinuation of all medication.

Catheter ablation is formally indicated in cases of a dangerous accessory pathway (rapid conduction). It is also recommended for symptomatic patients, especially those who prefer a definitive treatment over long-term medication.

This procedure is performed at Institut Mutualiste Montsouris by the electrophysiologists of Rythmopôle Paris, who have developed extensive expertise with over 1,175 ablation procedures performed annually.

After Catheter Ablation

Follow-up after a successful ablation of the accessory pathway is generally straightforward:

• Check-up at 1–3 months with ECG to confirm the absence of pre-excitation recurrence;
• If success is confirmed, no further specific follow-up is usually required;
• No restrictions for physical or professional activities;
• No medication is necessary.

While on Medication

For patients treated with medication (if ablation is refused or contraindicated):

• Regular rhythmology follow-up to assess treatment effectiveness and adjust doses if necessary;
• Periodic ECG to monitor for possible changes;
• Monitoring for potential side effects of the medication;
• Regular reassessment of the benefit/risk balance between medical therapy and ablation.

In Case of an Asymptomatic Accessory Pathway Discovered Incidentally

Management of patients with asymptomatic ventricular pre-excitation (incidentally found on ECG) depends on risk assessment:

• Electrophysiological study recommended to evaluate the accessory pathway’s conduction properties;
• Ablation recommended if the accessory pathway shows high-risk characteristics (short refractory period);
• For low-risk pathways, simple monitoring may be proposed, especially in older patients or those with significant comorbidities.

Rythmopôle Paris offers comprehensive expertise in the management of Wolff-Parkinson-White syndrome:

• A team of experienced electrophysiologists specializing in the diagnosis and treatment of cardiac rhythm disorders;
• An advanced technical platform at Institut Mutualiste Montsouris, enabling high-precision electrophysiological studies and ablation procedures;
• A high volume of activity (over 1,175 ablations per year), placing the team among the French leaders in the field, with optimal success rates;
• Primarily outpatient care, allowing a quick return home and to normal activities;
• Personalized follow-up tailored to each patient;
• A safety-focused approach, with protocols refined through extensive experience.