Wolff-Parkinson-White (WPW) Syndrome: Symptoms, Causes and Treatment

Wolff-Parkinson-White (WPW) syndrome is a structural heart rhythm disorder caused by an extra electrical connection that is present from birth between the upper and lower chambers of the heart. Under normal circumstances, electrical signals should travel through a specific pathway in an orderly manner, but in WPW syndrome these signals rapidly pass through this additional shortcut, creating an instantaneous electrical short circuit within the heart. Symptoms of WPW syndrome include sudden episodes of severe palpitations that feel as though the heart is about to jump out of the chest, shortness of breath, dizziness, a fluttering sensation in the chest, fatigue, and fainting (syncope). This structural variation in the heart’s electrical system manifests itself through sudden and uncontrolled episodes of rapid heart rate (tachycardia) that directly affect quality of life.

What Is WPW Syndrome and What Kind of Electrical Problem Does It Cause in the Heart?

Wolff-Parkinson-White, or WPW syndrome, is a congenital condition in which an extra electrical pathway exists between the upper and lower chambers of the heart where it should not normally be present. This additional pathway is medically known as an “accessory pathway” or the “Bundle of Kent.” This condition can be compared to the traffic flow in a city. While cars (electrical signals) traveling along the normal road must slow down at toll booths (the control center), in hearts with WPW syndrome the signals bypass these toll booths entirely by using a shortcut with no speed control.

As these signals travel through the shortcut and reach the lower chambers of the heart in an uncontrolled and extremely rapid manner, the ventricles become activated much earlier than normal. This premature activation is known as pre-excitation. When the heart rhythm is recorded on an electrocardiogram (ECG), this early activation produces a very characteristic pattern known as a “delta wave.” When an electrical circuit, or in other words a short circuit, develops between the normal conduction pathway and this extra shortcut, the heart rate suddenly reaches dangerously high levels. This continuously circulating electrical impulse within the heart triggers episodes of palpitations known as supraventricular tachycardia. Sometimes, this shortcut conducts electricity only from the lower chambers back to the upper chambers. In such cases, the ECG appears completely normal, and this condition is referred to as a “concealed accessory pathway.”

The most feared situation occurs during atrial fibrillation, when the atria contract extremely rapidly and irregularly. In a healthy heart, the control center filters these rapid impulses and protects the ventricles. However, in WPW syndrome, these impulses travel directly to the ventricles through the shortcut. When the ventricles attempt to beat hundreds of times per minute, they completely lose their ability to pump blood effectively. This may progress to a life-threatening condition known as ventricular fibrillation. Therefore, early detection and appropriate management of this condition are critically important.

What Symptoms Does WPW Syndrome Cause in Infants?

Infancy is one of the most challenging periods for diagnosing cardiac rhythm disorders. Since infants cannot verbally describe palpitations, chest discomfort, or a rapidly beating heart, symptoms during this age are generally expressed as systemic findings that appear unrelated to the heart and may be highly misleading. Therefore, it is extremely important for parents to carefully observe sudden behavioral changes in their infants.

During an episode of palpitations, an infant’s heart rate may rise to between two hundred and three hundred beats per minute. This extraordinary speed means that oxygen-rich blood cannot adequately reach the body’s tissues. The most common warning signs during infancy and the neonatal period include:

• Pallor
• Irritability
• Restlessness
• Tachypnea
• Cyanosis

In this list, tachypnea refers to unusually rapid breathing, while cyanosis describes a bluish or grayish discoloration that is particularly noticeable around the lips, skin, and nail beds. Infants frequently become fatigued during feeding and may refuse to breastfeed. Although the infant’s heart can tolerate this excessive rate for a certain period, if these episodes go unnoticed and persist for hours or even days, the heart muscle becomes severely exhausted. Over time, the heart’s ability to pump blood forward weakens, and the condition may rapidly progress to heart failure. Therefore, unexplained restlessness and pallor should always prompt immediate medical evaluation.

What Are the Symptoms of WPW Syndrome in Older Children and Adolescents?

As children grow older and develop better communication skills, the clinical picture becomes much clearer. Older children, adolescents, and young adults are usually able to describe their symptoms very accurately. They often say things such as, “My heart suddenly started pounding as if it were going to jump out of my chest,” or “It feels like there’s a bird fluttering inside me.” These episodes usually begin suddenly and end just as abruptly, almost as though someone has switched off an electrical circuit.

The primary symptoms caused by this electrical short circuit in older children include:

• Palpitations
• Chest pain
• Fatigue
• Dizziness
• Blurred or darkened vision
• Presyncope (feeling faint)
• Syncope (fainting)

Presyncope refers to feeling faint or experiencing temporary visual dimming, while syncope indicates complete loss of consciousness. Fainting is one of the most important warning signs in patients with heart rhythm disorders. If a child loses consciousness during an episode of palpitations, it indicates that the heart is beating so rapidly and inefficiently that blood flow to the brain has fallen below a critical level. Since this may indicate more serious, life-threatening rhythm disturbances, it requires immediate and comprehensive evaluation.

Sometimes symptoms may be very subtle, leading to misdiagnosis. Children experiencing persistent fatigue, mild nausea, and recurrent chest pain may not initially be suspected of having a heart condition. There are documented cases of children who received entirely unrelated treatments for years until a simple ECG performed in the emergency department during an episode of a heart rate reaching two hundred fifty beats per minute finally established the correct diagnosis. These cases illustrate how deceptively this condition can progress.

Can WPW Syndrome Occur Together with Other Congenital Heart Diseases?

The presence of an accessory electrical pathway is not always an isolated finding. In a significant proportion of cases, it is accompanied by other congenital anatomical abnormalities or heart diseases. During fetal development, the heart undergoes a highly complex process of cellular migration and structural formation. Any disturbance during this process may simultaneously affect both the heart’s anatomy and its electrical conduction system.

The structural heart conditions most commonly associated with this syndrome include:

• Cardiomyopathy
• Rhabdomyoma
• Ebstein anomaly
• Congenitally corrected transposition of the great arteries (ccTGA)

In particular, Ebstein anomaly, in which the tricuspid valve is positioned lower than normal within the right side of the heart, has a particularly strong association with accessory pathways. In addition, inherited diseases characterized by excessive thickening of the heart muscle and atrial septal defects may also coexist. Benign cardiac tumors known as rhabdomyomas, which occur during childhood, may likewise serve as the source of persistent rhythm disturbances.

Electrical impulses traveling prematurely through the accessory pathway prevent the heart walls from contracting simultaneously and in harmony. When one side of the heart contracts before the other, mechanical dyssynchrony develops. Over time, this lack of coordination reduces the heart’s pumping performance and may cause enlargement and weakening of the heart muscle. Fortunately, once the accessory pathway is successfully eliminated, coordinated contraction of the heart rapidly returns, and cardiac function generally normalizes.

How Is WPW Syndrome Diagnosed and Which Tests Are Required?

Diagnosing suspected WPW syndrome generally requires advanced technology and a stepwise evaluation process. The first and most important step is obtaining a resting surface electrocardiogram (ECG). This completely painless test takes only a few minutes but provides invaluable information when interpreted by experienced clinicians. A shortened electrical conduction interval together with the characteristic waveform created by the accessory pathway confirms the diagnosis.

However, the accessory pathway does not always conduct electrical impulses consistently. Sometimes it conducts electricity, while at other times it remains completely silent. In such situations, a routine ECG may appear entirely normal. Therefore, more comprehensive diagnostic methods become necessary. The primary diagnostic tools include:

• Electrocardiography (ECG)
• 24-hour Holter monitoring
• Echocardiography (ECHO)

Holter monitoring continuously records the child’s heart rhythm for twenty-four to forty-eight hours through electrodes attached to the chest. This allows rhythm abnormalities occurring during sleep, play, or school activities to be captured. Echocardiography is an ultrasound examination that provides detailed information about the heart’s structure, valves, pumping function, and any accompanying anatomical abnormalities.

In addition, exercise testing provides highly valuable information in cooperative older children. As the child exercises on a treadmill or bicycle, the heart rate gradually increases. If the characteristic ECG findings disappear as the heart rate rises during exercise, this demonstrates that the accessory pathway cannot conduct electrical impulses at higher heart rates. This finding strongly indicates a low-risk accessory pathway and provides considerable reassurance for both physicians and families. In children with episodes of fainting or near-fainting, tilt-table testing may also be performed to evaluate blood pressure and rhythm reflexes.

How Are Acute WPW Syndrome Episodes Managed in Emergency Situations?

When a child presents to a healthcare facility with persistent palpitations, immediate intervention becomes essential. The management strategy depends entirely on the child’s clinical condition and vital signs. If the child is conscious, has stable blood pressure, and is not critically ill, the primary objective is to interrupt the abnormal electrical circuit within the heart using medication.

For this purpose, a special medication is administered rapidly through an intravenous line. This drug temporarily blocks the heart’s main conduction center for only a few seconds. This brief interruption essentially resets the heart’s electrical system, similar to restarting a computer, allowing the palpitations to stop instantly and restoring normal rhythm. If this initial treatment is unsuccessful, stronger antiarrhythmic medications are administered. The main treatment options for terminating an acute episode include:

• Adenosine (contraindicated in patients with WPW syndrome and atrial fibrillation)
• Amiodarone
• Esmolol
• Cardioversion

If the child arrives at the emergency department unconscious, with blood pressure too low to measure, or in shock, there is no time to wait for medications to take effect. In such situations, a controlled low-dose electrical shock is delivered externally to the heart under light anesthesia without delay. This treatment, known as synchronized electrical cardioversion, immediately eliminates the electrical chaos and allows the heart’s natural pacemaker to regain control, making it a life-saving intervention.

Which Medications Are Used for Long-Term Treatment of WPW Syndrome and Which Should Be Avoided?

After the acute episode has been controlled, the most important goal is preventing future attacks of palpitations. Long-term oral preventive medications are prescribed for this purpose. In infants and young children, medications that suppress the body’s stress and adrenaline responses are generally safe and effective. Commonly used preventive medications include:

• Propranolol
• Sotalol

When taken regularly, these medications significantly reduce both the frequency and severity of palpitations. During sotalol therapy, regular ECG monitoring is important to ensure that other electrical properties of the heart remain unaffected.

On the other hand, there is one critically important rule regarding rhythm disorder treatment. Certain medications that are highly beneficial for other types of arrhythmias or heart failure must never be used in children with this specific syndrome because of their mechanism of action. These dangerous medications include:

• Digoxin
• Verapamil

These medications slow conduction through the heart’s normal pathway and control center while having no effect on the accessory pathway—in fact, they may even facilitate faster conduction through it. If extremely rapid and irregular electrical activity develops in the atria, hundreds of impulses may travel directly to the ventricles through the accessory pathway because the normal route has been suppressed. This can lead to ventricular fibrillation and cardiac arrest. Furthermore, some medications may cause severe hypotension and bradycardia in infants younger than one year of age, making careful treatment planning essential.

How Is the Risk of WPW Syndrome Evaluated in Children Without Symptoms?

One of the most challenging situations encountered in clinical practice involves children known to have an accessory pathway but who have never experienced palpitations or fainting. The absence of symptoms does not necessarily indicate the absence of danger. Therefore, determining whether these silent pathways may cause life-threatening rhythm disturbances in the future is extremely important.

Both semi-invasive and fully invasive techniques are used for risk assessment. In younger children, transesophageal studies are generally preferred. Because the esophagus lies very close to the atria, a thin wire can be advanced through the nose or mouth without entering the bloodstream or using radiation to evaluate the heart’s electrical conduction properties. This procedure is known as a transesophageal electrophysiological study.

For more definitive risk assessment, an invasive electrophysiological study is performed. Very thin recording catheters are inserted into the heart through blood vessels in the groin. Today, advanced three-dimensional mapping systems that eliminate the need for X-ray radiation are widely used to protect children from radiation exposure. During the procedure, medications are administered to accelerate the heart rate and evaluate the conduction capacity of the accessory pathway. The principal high-risk measurements include:

• APERP interval
• SPERRI interval

These measurements, expressed in milliseconds, indicate how rapidly the accessory pathway can conduct electrical impulses. If the recovery time of the pathway is extremely short or it is capable of conducting a very high number of impulses to the ventricles, it represents a significant life-threatening risk. In addition, identifying multiple accessory pathways within the heart is associated with a higher risk profile and an increased likelihood of recurrence following treatment.

What Is the Recommended Approach for Children with WPW Syndrome Who Participate in Sports?

Sports play an unquestionable role in the physical and psychological development of children. However, when heart rhythm disorders are involved, particularly in competitive or high-intensity sports, careful evaluation becomes essential. During running, swimming, or competitive athletic events, adrenaline levels rise to their maximum. This increased sympathetic activity dramatically accelerates the heart rate.

If a young athlete has an accessory pathway capable of conducting electrical impulses at high speeds, the surge in adrenaline during exercise may trigger dangerous rhythm disturbances. While invasive treatment may be postponed in asymptomatic children younger than five years of age, the approach is entirely different for athletic children and adolescents wishing to participate in competitive sports.

According to current international consensus guidelines, even in children who have never experienced palpitations, catheter ablation—the definitive treatment—is recommended as the first-line option before participation in competitive sports to eliminate the risk of sudden cardiac arrest during training and competition. This allows young athletes to continue their sporting careers safely and confidently without concern for their heart condition.

How Is Catheter Ablation, the Definitive Treatment for WPW Syndrome, Performed?

Although medications are effective in suppressing episodes of palpitations, they do not eliminate the disease itself. The definitive and curative treatment for WPW syndrome is an interventional procedure known as catheter ablation. This procedure is performed using a completely minimally invasive approach without opening the chest, in specially designed electrophysiology laboratories. Hair-thin flexible catheters are advanced into the heart through veins or arteries in the groin.

The electrical activity inside the heart is mapped with millimetric precision, and the exact location of the accessory pathway is identified. Once located, energy is delivered directly to this tiny area of tissue, permanently eliminating its ability to conduct electrical impulses. Two primary energy sources are currently used for this purpose:

• Radiofrequency
• Cryoablation

With the radiofrequency technique, high-frequency radio waves are delivered through the catheter tip to heat and destroy the abnormal tissue. This method has an excellent success rate and creates permanent elimination of the accessory pathway. However, if the pathway lies very close to the heart’s normal and critically important conduction center, there is a possibility of inadvertently damaging healthy tissue during the heating process.

At this point, the considerably safer freezing technique becomes the preferred option. A special gas is delivered through the catheter, cooling the target tissue to approximately minus thirty degrees Celsius. At this temperature, electrical conduction is temporarily interrupted. If it becomes apparent that the wrong tissue has been targeted or the normal conduction system has been affected, the procedure is immediately stopped. The tissue rapidly warms, normal function returns within seconds, and no permanent damage occurs. Once the correct location has been confirmed, the temperature is lowered further to complete permanent freezing. Thanks to this outstanding safety mechanism, the risk of complications requiring permanent pacemaker implantation has been reduced to nearly zero.

What Is the Recovery Process Like After WPW Syndrome Ablation?

Following a successful ablation procedure, detailed testing is repeated to confirm that no additional concealed accessory pathways remain within the heart. Once everything is confirmed to be satisfactory, the catheters are removed and gentle pressure is applied to the groin access sites to stop any bleeding. Children generally remain in the hospital for observation for only one night and are discharged the following day.

During the first seven to ten days after discharge, strenuous physical activities should be avoided to allow the groin access site to heal properly. Children whose procedures have been successfully completed and who remain free of recurrence during follow-up no longer require lifelong medication. Since the dangerous accessory pathway has been permanently eliminated, they can safely return to school, social activities, and all forms of sports without any physical restrictions, enjoying the lives of healthy individuals.

Frequently Asked Questions

Prof. Dr. İbrahim Cansaran TANIDIR

Prof. Dr. İbrahim Cansaran Tanıdır is an internationally recognized specialist with nearly 20 years of clinical, academic, and interventional experience in the fields of congenital heart diseases, pediatric interventional cardiology, hybrid procedures, and radiation-reduced / fluoroscopy-free catheterization techniques.

To date, he has performed more than 10,000 pediatric cardiac catheterization procedures both in Turkey and abroad, and has pioneered advanced interventional and hybrid applications in complex structural heart diseases in our country.

His academic productivity represents a scientifically strong authority with 110 SCI/SCIE publications, 1,440 citations, and an H-index of 18 (Google Scholar, 2025).