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Wolff-Parkinson-White Syndrome

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Ismail Munir

Overview

Wolff-Parkinson-White syndrome (WPW) is a congenital heart defect of the electrical pathways of the heart. It is a type of preexcitation syndrome that leads to attacks of abnormally fast heart rate. 
&nbsp;

In 1930, Louis Wolff, Paul Dudley White, and Sir John Parkinson described the cases of 11 young patients who suffered from sudden attacks of tachycardia and demonstrated ECG abnormalities. Soon more case reports with similar findings began to appear and the disorder became known as Wolff-Parkinson-White (WPW) syndrome. Later, in 1943, researchers discovered the presence of abnormal conducting tissue between the atria and ventricles providing an accessory pathway for electrical impulses. It is unclear what causes the additional route to develop within the heart.

Although WPW syndrome is a congenital disorder, symptoms may not develop until later in life. The majority of WPW syndrome patients debut during childhood. However, there is a second peak of presentation in school-aged children and adolescents. This intriguing bimodal age distribution is attributable to persistent or temporary loss of preexcitation in certain patients between infancy and late adolescence. Moreover, in certain cases, the accessory pathways do not cause any symptoms and it is an incidental finding during an ECG test.

Wolff-Parkinson-White syndrome is one of the most common causes of rapid heart rate in infants and young children. The cardiac abnormality affects one to three per 1,000 people globally<a href="#accordion">[1]</a> <a href="#accordion">[7]</a>. Approximately 60-70% of these people have no other signs of cardiac disease<a href="#accordion">[1]</a>. 
&nbsp;

Based on the appearance of the QRS complex/delta wave on an ECG, WPW syndrome is classified into two types - type A and type B. 
&nbsp;

<ul>
	<li>Type A - This is characterized by an upright positive delta wave/QRS complex in all precordial leads with the V1 lead showing an R amplitude larger than S. </li>
	<li>Type B - This is characterized by a primarily negative delta wave and QRS complex in V1 and V2. Similar to the left bundle-branch block, this turns positive as it progresses to the lateral leads. 
	&nbsp;</li>
</ul>

Another type of WPW syndrome is the familial Wolff-Parkinson-White syndrome. It accounts for a very small percentage of cases and has an autosomal dominant pattern of inheritance. 
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Signs and Symptoms

The signs and symptoms of WPW syndrome can manifest at any time between childhood and middle age. Moreover, they can vary in severity from mild palpitations to cardiac arrest. However, some people may have no symptoms at all.

The most frequent indication of Wolff-Parkinson-White (WPW) syndrome is a heart rate greater than 100 beats per minute (tachycardia).&nbsp;It is sudden and can last for a few seconds to several hours. These episodes can occur while exercising or at rest. Moreover, their frequency varies from person to person with some experiencing them daily, while others only experience a few episodes a year.

Other WPW syndrome symptoms are connected to the high heart rate and underlying cardiac rhythm abnormalities (arrhythmia). Supraventricular tachycardia is the most prevalent arrhythmia associated with WPW syndrome. Supraventricular tachycardia produces instances of a rapid, pounding heartbeat that begins and ceases abruptly. Some people may also have a rapid and chaotic heart rhythm condition, termed atrial fibrillation.

Approximately 80% of WPW syndrome patients experience reciprocating tachycardia, 15-30% have atrial fibrillation (AF), and 5% develop atrial flutter<a href="#accordion">[1]</a>. While ventricular tachycardia is a rare occurrence. 
&nbsp;

In general, signs and symptoms of WPW syndrome may include:

<ul>
	<li>A rapid, fluttering or pounding heartbeat (heart palpitations)</li>
	<li>Chest pain</li>
	<li>Breathing difficulties</li>
	<li>Dizziness or lightheadedness</li>
	<li>Fainting</li>
	<li>Fatigue</li>
	<li>Shortness of breath</li>
	<li>Anxiety 
	&nbsp;</li>
</ul>

In infants, WPW syndrome may present with the following signs and symptoms:

<ul>
	<li>Pale skin</li>
	<li>Skin, lips, and nails may turn blue or gray (cyanosis)</li>
	<li>Restlessness or irritability</li>
	<li>Rapid breathing (tachypnea)</li>
	<li>Poor eating due to intolerance of feedings 
	&nbsp;</li>
</ul>

Children may also complain of chest pain, breathing difficulty, and palpitations. 
&nbsp;

Note: If you notice any of the following signs and symptoms, contact a healthcare professional immediately

<ul>
	<li>Chest pain is associated with vomiting, sweating, or shortness of breath</li>
	<li>Chest pain that lasts more than 15 minutes</li>
	<li>Along with chest pain, there is a pain in the jaw, arms, or back</li>
	<li>Unconsciousness</li>
	<li>Heartbeat doesn&rsquo;t return to normal in a few minutes 
	&nbsp;</li>
</ul>

<h5>WPW Pattern Vs WPW Syndrome</h5>

Patients with ECG abnormalities in the absence of symptomatic arrhythmias are termed to have WPW pattern. Whereas, WPW syndrome involves both ECG abnormalities and symptomatic arrhythmias involving the accessory pathways. 
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Causes

Normally, the heartbeat is regulated by electrical impulses that flow via the atria (upper heart chambers) to a knot of tissue known as the atrioventricular node (AV node), and then to the ventricles (lower heart chambers). These electrical impulses usually halt at the atrioventricular node before instructing the ventricles to contract. 

In Wolff-Parkinson-White (WPW) syndrome, abnormal conductive cardiac tissue between the atria and ventricles serves as an accessory pathway for electrical impulses, which bypasses the AV node. The extra electrical connections cause the electrical signals to travel in a loop, causing episodes of rapid heartbeat. Moreover, the extra pathway also allows heart signals to travel backward, resulting in an irregular heart rhythm. 
&nbsp;

It is unclear as to what leads to the formation of this abnormal cardiac tissue.

Although WPW syndrome is a congenital disorder, no hereditary factors have been found. However, it is often seen to run in families. Researchers have identified mutations in certain genes that may cause a specific type of WPW syndrome called familial Wolff-Parkinson-White syndrome. Moreover, WPW syndrome is also seen to be associated with other structural abnormalities, such as the Ebstein anomaly. 
&nbsp;

Diagnosis

There are currently no screening tests for WPW syndrome.

Based on a patient&rsquo;s medical history, the doctor may first conduct a physical exam. Changes to the heartbeat are common physical findings. If the physical exam is conducted during a tachycardia episode, a heart rate of more than 100 beats per minute or 150 beats per minute may be seen in adults and newborns, infants, and young children respectively. The doctor will then recommend the following tests to establish a diagnosis: 
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Electrocardiogram (ECG) - An electrocardiogram helps measure the heart&rsquo;s electrical activity. It can identify the WPW pattern even when the subject is in a normal rhythm. Conduction via the accessory pathway results in a distinctive ECG pattern which includes a short PR interval (&lt;120 ms), prolonged QRS complex (&gt;120 ms), and delta waves. The ECG among some patients with WPW might fluctuate from day to day, or even hour to hour, depending on various circumstances (such as adrenaline released during periods of stress or the intake of caffeine). These variables can change the proportion of impulses that travel via the accessory route. 
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Electrophysiological (EP) Study - This invasive technique involves the insertion of one or more catheters through a blood vessel in the groin to the heart. Sensors present on the catheter help map or monitor the heart&rsquo;s electrical pathways. Thus, determining the location of the accessory pathways and identifying the cause of tachycardia. Depending on the behavior of the accessory pathway, doctors may also conduct catheter ablation as part of the study. 
&nbsp;

Holter Monitor - This is a portable ECG device that provides a record of the heart rhythm over at least 24 hours. It can monitor the heart&rsquo;s activity during normal activities. 
&nbsp;

Other Tests - Doctors may also recommend other tests to rule out other diseases. These include:

<ul>
	<li>Echocardiogram - This helps assess for any structural heart defects associated with WPW syndrome, such as Ebstein anomaly.</li>
	<li>Stress test - During a stress test, ECG is recorded while the person walks on a treadmill to assess whether exercise triggers the ECG abnormality.</li>
	<li>Laboratory Studies - A complete blood count (CBC), liver function tests, blood urea nitrogen (BUN) and creatinine levels, and thyroid profile may be performed to rule out non cardiac conditions that can trigger tachycardia. 
	&nbsp;</li>
</ul>

Treatment

Most patients with the WPW pattern do not require therapy as they may never develop symptoms. Moreover, conduction via the accessory pathway may spontaneously diminish in some young people as they age.

However, certain asymptomatic patients with a WPW pattern (such as those in high-risk occupations or professional athletes) are encouraged to undertake further testing, including electrophysiologic testing, to evaluate if the accessory conducting pathway is associated with a high risk of sudden cardiac arrest.

The goal of treatment is to halt tachycardia and keep it from developing again. 
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<h5>Treating Tachycardia</h5>

To slow down a fast heart rate, doctors may administer the following treatments:

<ul>
	<li>Vagal Maneuvers - These are simple movements and actions that can be performed during an episode. Techniques, such as the &lsquo;Valsalva maneuver&rsquo; affect the vagus nerve and slow down the electric signals in the heart. It involves pinching the nose, closing the mouth, and blowing hard while bearing down as if on the toilet. Other actions include coughing or putting an ice pack on the face.</li>
	<li>Medications - If vagal maneuvers are unable to stop the tachycardia, doctors may turn to medications. Antiarrhythmic drugs, such as adenosine, procainamide, or amiodarone may be administered to help block the abnormal electric signals in the heart. </li>
	<li>Electrical Cardioversion - If medications and vagal maneuvers are ineffective, electric shock is applied to the heart to restore the normal heart rhythm. The electrical shocks are administered via paddles or patches placed on the chest. 
	&nbsp;</li>
</ul>

<h5>Preventing Episodes Of Tachycardia</h5>

There are three main approaches for avoiding tachycardia recurrence: radiofrequency ablation, medicines, and surgery. The decision should be taken in consultation with a cardiac electrophysiologist who has experience treating WPW syndrome.

<ul>
	<li>Catheter Ablation - This treatment is often used nowadays to destroy the excess section of the heart that is creating electrical difficulties in the heart. It is successful in around 95% of instances3. Using fluoroscopy, a wire (electrode catheter) is inserted into the heart and positioned within the chambers of the heart. Following the localization of the accessory pathway, radiofrequency radiation is administered to the location to destroy or &quot;ablate&quot; the accessory pathway, stopping it from transmitting impulses. Some people have multiple accessory conducting pathways that need to be ablated. Occasionally, the accessory pathway can recover from the ablation, and the ablation procedure needs to be repeated. The chance of a significant consequence is modest, under 3%, with the key hazards being blood vessel or nerve injury, bleeding, infection, heart perforation, and heart block needing a pacemaker. The risk of certain issues is determined in part by the location of the accessory pathway and the proximity to essential structures.</li>
	<li>Surgery: Another option for disconnecting the WPW pathway is surgery. Surgical ablation has a near-perfect success rate and a minimal complication rate. However, because radiofrequency ablation is a less intrusive alternative, surgery is now rarely used. If the person is undergoing cardiac surgery for another reason (such as coronary artery bypass surgery or valve surgery), surgical ablation may be chosen, and it is suggested when radiofrequency ablation and medicines are ineffective.In some cases, an artificial pacemaker may be fitted within the heart to help regulate the heart rate. </li>
	<li>Medications: While medications can help some patients with WPW avoid recurrent tachycardia, they are typically reserved for those who are not candidates for catheter ablation or surgery. These individuals may be given drugs to take during an episode or on a regular basis to avoid arrhythmia.</li>
	<li>Lifestyle Changes - Depending on the triggering factors, doctors may advise lifestyle changes, such as avoiding alcohol or strenuous exercise. 
	&nbsp;</li>
</ul>

Both men and women are affected by WPW. The etiology of WPW is unknown in the majority of instances, although physicians have uncovered abnormalities in a gene that may be to blame. A limited proportion of people may be at risk if they acquired this gene from one of their parents. 

Moreover, WPW syndrome is a prevalent cause of tachycardia in China, and if you are of Chinese origin, you may be at higher risk.

WPW syndrome can often occur simultaneously with other structural abnormalities, such as Ebstein anomaly (defect in the tricuspid valve).&nbsp; 
&nbsp;

WPW syndrome isn&rsquo;t usually a serious condition. However, at times, it can be associated with the following complications:

<ul>
	<li>Low blood pressure</li>
	<li><a href="https://merisehat.pk/disease/congestive-heart-failure">Heart failure</a></li>
	<li>Heart attack</li>
	<li>Loss of consciousness</li>
	<li>Sudden cardiac death 
	&nbsp;</li>
</ul>

Other than medications and vagal maneuvers, doctors may advise the following measures to prevent episodes and complications:&nbsp;

<ul>
	<li>Stop smoking</li>
	<li>Quit alcohol</li>
	<li>Keep cholesterol levels in check</li>
	<li>Eat a healthy diet</li>
	<li>Exercise regularly but only after consultation with a cardiologist</li>
	<li>Maintain a healthy weight 
	&nbsp;</li>
</ul>

Key Points

<ul>
	<li>Wolff-Parkinson-White syndrome (WPW) is a congenital heart defect of the electrical pathways of the heart. The disorder produces irregular heartbeats. &nbsp; &nbsp;</li>
	<li>&nbsp;Normally, the heartbeat is regulated by electrical impulses that flow via the atria to a knot of tissue known as the atrioventricular node, and then to the ventricles. Usually, electrical impulses halt at the atrioventricular node before instructing the ventricles to contract.</li>
	<li>Wolff-Parkinson-White (WPW) syndrome is characterized by aberrant conductive cardiac tissue between the atria and ventricles that serves as a channel for a reentrant tachycardia circuit in conjunction with supraventricular tachycardia (SVT). It includes preexcitation, which happens as a result of an atrial impulse being sent not through the regular conduction system, but by an additional atrioventricular (AV) muscle link known as an accessory pathway (AP), which bypasses the AV node.</li>
	<li>It is unclear as to what causes the formation of accessory pathways in WPW syndrome. </li>
	<li>The most frequent indication of Wolff-Parkinson-White (WPW) syndrome is a heart rate greater than 100 beats a minute (tachycardia).</li>
	<li>Some persons who have an additional electrical channel do not exhibit any indications or symptoms of a rapid pulse. This syndrome is called Wolff-Parkinson-White (WPW) pattern. It is frequently identified during a usual cardiac test.</li>
	<li>Wolff-Parkinson-White syndrome is one of the most common causes of rapid heart rate in infants and young children&nbsp; &nbsp; </li>
	<li>Wolff-Parkinson-white syndrome is investigated using a number of tests; however, physical examination and taking medical history remain on top of the list. </li>
	<li>WPW is often diagnosed using a conventional ECG, although in certain cases, additional testing is necessary.</li>
	<li>There are three main approaches for avoiding tachycardia recurrence: radiofrequency ablation, medicines, and surgery. The decision should be taken in consultation with a heart rhythm specialist (cardiac electrophysiologist) who has experience treating the WPW syndrome. 
	&nbsp;</li>
</ul>