What is Wolff-Parkinson-White Syndrome?
Wolff-Parkinson-White (WPW) syndrome is a condition a person is typically born with that affects the electrical pathways of the heart. This can lead to abnormal heart rhythms, which can cause symptoms and, in severe cases, potentially life-threatening situations.
Our hearts have a natural electrical system, with signals starting in the right upper chamber (atrium) from an area called the sinoatrial node and then moving through the heart. This helps keep the heart’s upper and lower parts (the atria and ventricles) working together in a synchronized manner.
However, people with WPW syndrome have an extra electrical pathway that can cause the heart signals to bypass their normal route. This could result in abnormal heart rhythms known as tachyarrhythmias.
When doctors look at an electrocardiogram (ECG – a heart tracing), they can often see signs of this extra pathway. These include a shorter than normal time between the start of the heartbeat and the electrical signal reaching the ventricles (short PR interval) and a spike-like pattern (delta wave) at the start of each heartbeat. But, not everyone with these ECG changes has problems – some people may have no symptoms at all. On the other hand, some patients may have this extra pathway but not show these typical ECG changes and still experience episodes of abnormally fast heart rhythms.
The WPW syndrome is associated with symptoms such as feelings of a racing heart (palpitations), episodes of light-headedness, near fainting (presyncope), fainting (syncope), or even heart stoppage (cardiac arrest).
The condition was first described through the observation of patients’ ECGs in the early 1900s by doctors Frank Wilson and Alfred Wedd. Years later, in 1930, Louis Wolff, Sir John Parkinson, and Dr. Paul Dudley White further detailed the condition, which ended up being named after them. They linked the unique traits seen in ECG tracing with the occurrence of rapid heartbeats (paroxysmal tachycardia). The evidence of this extra electrical conducting tissue or bypass tracts was confirmed anatomically in later studies around 1943.
What Causes Wolff-Parkinson-White Syndrome?
The WPW (Wolff-Parkinson-White) pattern is a heart condition caused by a combination of abnormal and normal electrical conduction in the heart. This abnormal pathway, also known as an ‘accessory pathway’, develops during the early stages of heart development and disrupts the usual electrical insulation between the atrium and the ventricle, which are parts of the heart.
The accessory pathway has what’s called ‘non-decremental’ or ‘non-delayed’ conduction, which is different from the usual electrical properties of the AV (atrioventricular) node. The AV node normally controls the rate at which electrical signals pass from the atria to the ventricles.
Now, every accessory pathway is unique – its electrical conducting features can vary depending on factors like the rate of electrical conduction, the path it follows, and its ‘refractory period’, which is the recovery time it takes for a cell to get ready for the next electrical signal. Other factors like where it’s located in the heart and the number of these accessory pathways can also influence how it can contribute to triggering or transmitting an abnormal heart rhythm known as ‘arrhythmia’. This can, then, lead to WPW syndrome, an inherent heart condition characterized by episodes of rapid heart rate.
Risk Factors and Frequency for Wolff-Parkinson-White Syndrome
Wolf-Parkinson-White (WPW) syndrome is a heart condition that can cause a rapid heartbeat. It can sometimes be spotted in people who don’t show any symptoms, such as those found to have a specific heart pattern on an ECG test. Overall, WPW syndrome is quite rare, affecting between 1 to 3 people in every 1,000 (or 0.1% to 0.3% of people).
Identifying symptomless people with WPW can be a challenge, because by nature they don’t show signs of illness. However, experts think that around 65% of teenagers and 40% of people over 30 with a WPW pattern on the ECG don’t have any symptoms. Only about 1% to 2% of people with WPW risk developing an arrhythmia every year. WPW syndrome is most commonly seen in people between the ages of 20 to 24.
- WPW syndrome is quite rare, affecting between 1 to 3 people in every 1,000.
- Identifying people with WPW but without symptoms can be tough, as they do not show signs of illness.
- About 65% of teenagers and 40% of people over 30 have WPW patterns on their ECG but don’t show symptoms.
- Only about 1% to 2% of people with WPW develop an arrhythmia every year.
- WPW is most common in people aged 20 to 24.
Interestingly, family studies have noticed that WPW is slightly more common among close relatives of a person with WPW, about 0.55%. Certain family forms of WPW syndrome have been linked to a specific gene mutation, causing a 3.4% prevalence among close relatives. This particular form is also found in connection with some specific heart diseases, including Ebstein anomaly and hypertrophic cardiomyopathy.
- WPW is more common among close relatives of a person with WPW, at about 0.55%.
- Certain family forms of WPW have been observed, linked to a gene mutation, causing a 3.4% prevalence among close relatives.
- This form of WPW is also often found in connection with specific heart diseases, including Ebstein anomaly and hypertrophic cardiomyopathy.
Signs and Symptoms of Wolff-Parkinson-White Syndrome
People with Wolff-Parkinson-White (WPW) syndrome who have never had a rhythm problem (arrhythmia) won’t show any symptoms. This means that their medical history and physical examinations will mostly look normal. An electrocardiogram (ECG, a test that records the electrical signals in your heart), which might have been done in the past, could have revealed the abnormal pattern used to diagnose the condition. Even if patients know they have WPW, normal or sometimes normal ECG results are possible because the extra electrical pathway in the heart might only be active or visible some of the time. There’s also the possibility of the WPW pattern or syndrome running in families.
However, WPW patients who do experience an arrhythmia, or irregular heartbeat, will often have symptoms related to this problem. These can include:
- Heart palpitations (feeling like your heart is racing, pounding, or fluttering)
- Chest pain
- Shortness of breath
- Dizziness or lightheadedness
- Feeling like they’re about to faint (presyncope) or actually fainting (syncope)
- Sudden collapse
- In extreme cases, sudden death
These symptoms might come and go, or they might not let up if the arrhythmia continues. They might also only start showing while the person is at the doctor’s office. The doctor’s examination will focus on assessing the patient’s heart, lungs, and neurological status. Unless the arrhythmia has stopped, in which case the exam might look normal, continued arrhythmia symptoms usually cause noticeable changes in vital signs, such as a fast heart rate (tachycardia). Blood pressure can be normal, high, or low depending on how severe the arrhythmia is, if the patient has other health conditions, and how well the patient’s body can adapt to the arrhythmia. Similarly, the rate of breathing can vary depending on the patient’s distress level and ability to maintain proper blood circulation. The doctor’s examination might show different signs based on how severe the arrhythmia is. These can range from signs of discomfort and distress to problems with body tissue and organ function, signs of shock where the heart isn’t pumping enough blood (cardiogenic shock), and unresponsiveness.
Testing for Wolff-Parkinson-White Syndrome
If you’re being evaluated for Wolff-Parkinson-White (WPW) syndrome, your doctor might start by ordering a simple electrocardiogram test, more commonly known as an ECG or EKG. This test checks for a pattern that’s common in WPW syndrome, including a quick heartbeat, a longer than usual heartbeat, and a particular form of heartbeat known as a “slurred delta wave”. This pattern happens because of an extra electrical pathway in the heart, which affects how the heart’s normal electric signal travels. However, not seeing this pattern on an ECG doesn’t mean you don’t have the extra pathway. Sometimes, the pathway only works under certain conditions or in a certain direction. It might only work when the electric signal starts in the lower chambers of your heart instead of the upper chambers, and won’t cause the typical WPW syndrome pattern when the heart is beating normally.
As for what happens after the ECG, it really depends on your specific case. Things like age, overall health, risk factors, and so on can influence the next steps. If you’re young and otherwise healthy, and aren’t experiencing any symptoms, your doctor might recommend a wait-and-see approach with regular check-ups. However, if you’re at higher risk for heart rhythm problems, you may need to see a specialist to discuss further testing or treatments. Note that having WPW syndrome can make it harder to diagnose other conditions that also rely on EKG for diagnosis, so additional tests or expert advice may be needed.
If you’re experiencing symptoms of a fast heartbeat or have recently had a heart rhythm problem, an ECG will be done to check your current heart rate, rhythm, and how the beats look. But you’d also need more evaluation. This would involve checking your overall health state, including your pulse, blood pressure, heart rhythm, and oxygen levels in your blood. If you’ve had episodes of fast heartbeats before, they’d want to know that. They’d also want to know if any of your family members have WPW syndrome or have suddenly died due to heart problems. They’d ask you about your current symptoms and what was going on when your heart rhythm problem started. A physical exam would be carried out to check if you’re mentally alert and look for signs of shock or heart failure. If you’re critically ill, you’d get treated right away. If you’re stable, you’d get a more comprehensive ECG test. Other tests, like x-rays, blood tests, heart ultrasounds, or more specialized tests might also be done, depending on your situation.
Treatment Options for Wolff-Parkinson-White Syndrome
Patients who display a Wolff-Parkinson-White (WPW) pattern on their heart test, but have no symptoms, usually don’t need immediate treatment. However, seeing a heart specialist could be helpful to determine if they’re at risk of developing a fast irregular heartbeat known “tachyarrhythmia”. If the risk is high, the patient can benefit from preventive medications or treatments to weaken the extra electrical pathway in their hearts. These decisions should carefully consider the level of risk, the characteristics of the extra pathway, other heart-related conditions they might have, and any other health issues. Weighing the risks of potentially life-threatening irregular heartbeats against the benefits and risks of medications and treatments is essential.
In general, people without symptoms but with a WPW pattern are usually at a low risk of cardiac arrest. Those who have had a cardiac arrest almost always had symptoms of fast, irregular heartbeats before the event. So, most of these patients can be managed simply by close observation and reassurance. They’re typically advised to promptly report any occurrences of rapid heart palpitations or fainting. Additionally, some patients may have to undergo tests to further estimate their risk. Tests can either be non-invasive, which don’t require any instruments to be inserted into the body, or invasive. No test is perfect due to possible false positives or negatives, but non-invasive tests are generally the preferred initial approach.
Patients who have tested positive for the WPW pattern but have no current symptoms or irregular heartbeat patterns typically don’t need immediate treatment. However, they should still be evaluated and treated because they’ve shown that their extra electrical pathway can start and maintain an irregular heartbeat. This puts them at higher risk of recurring arrhythmias. Treatment usually involves a procedure called catheter ablation that interrupts the extra electrical pathway. This procedure is typically the first treatment choice due to its high success rate and low risk.
A patient with known WPW pattern or a history of fast, irregular heartbeats who presents with an acute, fast, irregular heartbeat will require immediate medical treatment. The method of treatment will depend on whether the patient has a pulse and whether their heart rhythm is stable. People with a stable rhythm may be given medication based on the type of arrhythmia and the characteristics of the extra pathway. Certain medications may be dangerously bad or even fatal for some arrhythmia types and should be avoided.
In cases of a fast, irregular heartbeat, procainamide and ibutilide are the drug options. Amiodarone can also be used, but some evidence suggests it’s less effective and carries a higher risk of inducing ventricular fibrillation, a fast, abnormal heart rhythm that can be life-threatening. Whenever there is uncertainty about the diagnosis of a wide, complex fast heartbeat, it is advised that the condition be managed.
Patients who display a WPW pattern and present with a stable heart rhythm may experience orthodromic AVRT, a very rapid heart rate that originates in the atria (the upper chambers of the heart). Some therapeutic recommendations include vagal maneuvers, a specific exercise to slow the heart rate, as well as a trial of adenosine, a drug to improve heart function. The guidelines from 2015 ACC/AHA/HRS recommend beta-blockers or calcium channel blockers as secondary treatment options if the first courses of treatments aren’t successful, while electric cardioversion, a procedure to restore the heart’s normal rhythm, is reserved for refractory arrhythmias. If the diagnosis is uncertain, certain medications should be used with caution. It may be wise to manage the condition as an unspecified wide, complex fast heartbeat.
What else can Wolff-Parkinson-White Syndrome be?
In the process of diagnosing WPW (Wolff-Parkinson-White) pattern and syndrome, doctors consider a wide range of possible conditions. These conditions may present similar symptoms, heart rhythm patterns, or disorders (dysrhythmias). The WPW pattern is identified from an ECG (heart tracing), which shows a short PR interval and a wide QRS complex combined with a slurred delta wave. Therefore, any medical condition that can cause similar ECG results would be part of the differential diagnosis, which includes, but isn’t limited to:
- Heart attack (myocardial infarction)
- Bundle branch block
- Heart abnormalities (congenital or acquired)
- Heart muscle enlargement (hypertrophy)
- Early junctional or ventricular complexes
- Ventricular bigeminy
- Accelerated idioventricular rhythms
- Electrical alternans
- Artificial heart rhythm (pacemaker)
- Metabolic or electrolyte abnormalities
If a patient with WPW pattern on a resting ECG has a history of or symptoms indicating an episode of a fast heart rate (tachyarrhythmia), the differential diagnosis would consider other causes or ways these arrhythmias can present. For example, an extra (accessory) pathway that is involved in starting and maintaining an arrhythmia can lead to different types of heart rhythm disorders based on the pathway’s behavior. Therefore, the differential diagnosis needs to consider causes of both wide and narrow, regular, or irregular heartbeats. They are categorized as follows:
- Regular narrow heartbeat (tachycardia) – Can be due to sinus tachycardia, atrial tachycardia, atrial flutter with regular AV block, AVNRT, AVRT, junctional tachycardia, etc.
- Irregular narrow tachycardia – May be caused by atrial fibrillation, atrial flutter with variable AV block, multifocal atrial tachycardia, sinus tachycardia with ectopic complexes or any regular narrow tachycardia with variable conduction or ectopic complexes.
- Regular wide tachycardia – Possible causes are ventricular tachycardia, accelerated idioventricular rhythm, paced rhythm, artifact, any SVT with aberrant ventricular conduction or accessory pathway or any metabolic/electrolyte abnormalities.
- Irregular wide tachycardia – May come from Torsades de pointes, nonsustained ventricular tachycardia, any irregular narrow tachycardia with abnormal conduction, metabolic/electrolyte abnormalities, or any regular wide tachycardia with variable conduction or frequent ectopic complexes.
What to expect with Wolff-Parkinson-White Syndrome
WPW pattern is an uncommon heart condition, seen in an ECG, where most people don’t ever experience symptoms, associated heart rhythm disruption, or the most dreaded complication—sudden cardiac death. Two population studies suggest that the rate of sudden cardiac death for patients with WPW pattern ranges from 0.0002 to 0.0015 per year.
Certain risk factors make a patient more susceptible to sudden cardiac death, such as being male, being under the age of 35, a history of irregular heartbeat conditions like atrial fibrillation or AVRT, having multiple extra conduction paths in the heart, and the central location of the extra path called the accessory pathway. In particular, the capacity for the accessory pathway to conduct electrical signals rapidly increases this risk.
Even though WPW pattern has a low occurrence rate and serious complications are not common, it’s still a significant medical condition. However, the outlook for patients with WPW pattern has substantially improved in the last 80 years with the development of medications to manage heart rhythms and techniques to eliminate problematic heart tissue.
For patients who have WPW syndrome, a high-risk profile, or a strong preference, a procedure done with a thin tube called a radiofrequency catheter can often cure the condition. This procedure has been found to be highly successful with low complication rates.
Possible Complications When Diagnosed with Wolff-Parkinson-White Syndrome
The biggest concern with WPW (Wolff-Parkinson-White) syndrome is the high risk of sudden cardiac death.
Research has shown that this often happens due to an irregular and rapid heartbeat leading to a sudden stop in heart function or ventricular fibrillation. Alternatively, other conditions such as tachycardia – a heart rhythm disorder – or atrial fibrillation, can also lead to sudden cardiac death. This situation can occur when a shortcut pathway between the heart’s chambers is able to quickly send signals, allowing for swift transmission of impulses from the atria to the ventricles. This issue can be initiated or worsened by certain medications, so it is estimated to be carefully considered in the treatment plan of patients with WPW syndrome who experience rapid heart rates at rest. The coronary conditions that these patients are most at risk for are ones with excessively fast heartbeat rates, like atrial fibrillation and flutter.
On top of this, if these irregular heart rhythms happen often or for an extended period, it could lead to heart failure. Unstable heart function during these times of irregular heartbeat can trigger or worsen pre-existing medical conditions. If a patient of WPW syndrome faints due to a sudden irregular heartbeat, they are at high risk for severe injuries.
Common Concerns:
- Sudden cardiac death
- Heart rhythm disorders caused by a fast heartbeat
- Fainting spells, which can lead to severe injuries
- Onset or worsening of pre-existing medical conditions
- Heart failure
Preventing Wolff-Parkinson-White Syndrome
Wolf-Parkinson-White (WPW) syndrome is a condition caused by a problem with the heart’s electrical system that you are born with – we call these kinds of conditions “congenital”. This problem causes abnormal heart rhythms, or “dysrhythmias”. There is no known way to prevent WPW from developing. Once WPW syndrome has started causing rapid heart rhythms, a test called an electrophysiologic study can be done. This study helps doctors identify and assess the risks of the abnormal pathway in your heart.
If done correctly, a procedure called catheter radiofrequency ablation can resolve the problem by targeting and eliminating the abnormal pathway in the heart. However, this might not be a preferable or viable option for all patients. In such cases, medications that control heart rhythm, known as “antiarrhythmic” drugs, can be a suitable alternative.
