Wolff-Parkinson-White Syndrome

Written by Marcus H.

Introduction

During a local high school football game, the star quarterback, a 17-year-old male begins to experience palpitations and periods of vertigo. Concerned with this unusual feeling, he advises is coach, but is told it is just nervousness and to get back on the field. As the star quarterback runs onto the field for the next sequence of play, he collapses to the ground unconscious. Coaches, family, and paramedics rush to his side to find that he is in cardiac arrest. Paramedics are unable to revive him and 48 minutes later, he is pronounced dead. What could possibly make a healthy athletic 17-year-old male, with no known medical history, go into sudden cardiac arrest and die? An autopsy will reveal that the star quarterback died from a lethal arrhythmia, stimulated by a rare medical condition known as Wolff-Parkinson-White syndrome (WPW). This paper will discuss the history, pathophysiology, signs and symptoms, diagnosis, and treatment of Wolff-Parkinson-White syndrome.

What is Wolff-Parkinson-White Syndrome?

Wolff-Parkinson-White syndrome, also known as preexcitation syndrome and WPW, “is a disorder in which an extra electrical connection between the atria and the ventricles is present at birth.” (Beers, 2003, p. 153) This extra electrical connection or accessory pathway, also known as the Bundle of Kent, causes disruption in the hearts normal electrical pathway, which results in an abnormally fast heart rate (tachycardia). Wolff-Parkinson-White syndrome can result from random occurrence or congenital. Random occurrences of Wolff-Parkinson-White syndrome in the general population occur “in about 0.1 to 3.1 per 1,000 persons” (Cleveland Clinic [CC], 2002). Parents with Wolff-Parkinson-White syndrome, or accessory pathways, can pass the condition to their children. Studies have shown that the congenital occurrence of Wolff-Parkinson-White syndrome “could be as high as 5.5 per 1,000 persons” (CC).

History

In this current era of advanced medical technology, it is difficult to envision a time when there was no way to determine what type of heart rhythm a patient was experiencing. The invention of the electrocardiograph (ECG) in the early 1920’s, changed the way physicians viewed the heart and the way they treated cardiac related illnesses. In 1930, three cardiologists, Dr. Herold Wolff and Paul Dudley White of the United States and Sir John Parkinson of Great Britain, “described a distinct electrocardiograph (ECG) pattern in healthy young people with short bursts of tachycardia” (CC, 2002). Physicians later discovered in 1933, that the condition was a result of accelerated impulses traveling through the ventricles. In 1944, after extensive research, physicians established that the exact reason for this condition was due to the presence of extra pathways between the atria and ventricles.

Pathophysiology

To understand the pathophysiology of Wolff-Parkinson-White syndrome, the understanding of electrical conduction in a normal heart must first be established. In a normal heart, the electrical conduction begins in the sinoatrial node located in the right atrium. The sinoatrial node is commonly referred to as the heart’s pacemaker, due to the fact that is sets the pace for the heart. As the sinoatrial node fires, an action potential excites the atria into contracting. Next, the conduction travels to the atrioventricular node, located in the interatrial septum. The conduction decreases in speed while in the atrioventricular node, to allow time for the atria to empty blood into the ventricles. The conduction then travels from the atrioventricular node, to the atrioventricular bundle, or commonly referred to as the bundle of His, located in the interventricular septum. Next, the conduction travels down both right and left bundle branches. Lastly, the conduction travels to the Purkinje fibers, where action potential excites the ventricles into pumping blood into the systemic circulation system. In a heart that has Wolff-Parkinson-White syndrome, the conduction starts in the sinoatrial node, but then may bypass the atrioventricular node by a different bundle of nerves. The conduction then travels to the Purkinje fibers, then back to the sinoatrial node, where the process repeats. The following statement explains additional conduction abnormalities:

Although dozens of locations for bypass tracts can exist in preexcitation, including atriofascicular, fasciculoventricular, intranodal, or nodoventricular, the most common bypass tract is an accessory atrioventricular (AV) pathway otherwise known as a Kent bundle. This is the anomaly seen in WPW syndrome. Conduction through a Kent bundle can be anterograde, retrograde, or both. Another common preexcitation syndrome, Lown-Ganong-Levine (LGL), also has an accessory pathway (the James fibers), which connect the atria serially to the His bundle. The end result is the same, preexcitation and a predisposition to the development of tachydysrhythmias(Hemingway, 2006).

The significance of Wolff-Parkinson-White syndrome is the tachydysrhythmias that it produces, such as atrial fibrillation, atrial flutter, supraventricular tachycardia, ventricular tachycardia, and ventricular fibrillation. Some tachydysrhythmias are worse than others are. For example, atrial fibrillation is a common rhythm found in geriatrics and can occur without a patient experiencing physical signs and symptoms. In retrospect, ventricular fibrillation is a lethal arrhythmia, in which the ventricles beat at a rate of 300 or more beats per minute. In ventricular fibrillation, there is not enough time for the ventricles to contract blood through the systemic circulation system, and without immediate medical intervention, death is imminent.

Signs and Symptoms

Signs and Symptoms of Wolff-Parkinson-White syndrome are synonymous with signs and symptoms of tachydysrhythmias. Common signs include low blood pressure and a heart rate greater than 150 beats per minute. Common symptoms consist of heart palpitations, light-headedness, syncope or fainting, vertigo or dizziness, respiratory distress, and chest pain or chest tightness. In some cases, patients live comfortably with Wolff-Parkinson-White syndrome, never having a tachycardia episode. In the absence of a tachycardia episode, the patient with Wolff-Parkinson-White syndrome will present no signs and symptoms. Unfortunately, most cases of Wolff-Parkinson-White syndrome do not present itself until teenage years, especially while engaged in sports. The increased heart rate, associated with sports, can exacerbate the condition, which can lead to lethal tachycardia episodes.

Diagnosis

The most common way to diagnose Wolff-Parkinson-White syndrome is by electrocardiograph (ECG). It is characterized by a short P-R interval, generally less than 0.12 seconds, and a long QRS duration, generally more than 0.12 seconds. Additionally the upstroke of the QRS often has a slur, called a delta wave(Bledsoe, Porter, & Cherry, 2003, p. 1279). Other medical tests such as the Holter monitor, exercise testing, and electrophysiology testing can diagnose Wolff-Parkinson-White syndrome. In diagnosing a patient with potential Wolff-Parkinson-White syndrome, it is imperative to obtain a complete medical history. Key indicators such as family history, history of atrial fibrillation, palpitations (especially when exercising), and a history of syncope or fainting can assist the physician in properly diagnosing Wolff-Parkinson-White syndrome.

Treatment

Most occurrences of Wolff-Parkinson-White syndrome occur in the pre-hospital setting, therefore, it is crucial for paramedics to have a vast knowledge of the condition and associated signs and symptoms. The role of a paramedic in the pre-hospital setting is not to treat Wolff-Parkinson-White syndrome, but to treat the tachydysrhythmias that it produces. For example, with a patient experiencing asymptomatic supraventricular tachycardia, vagal or valsalva maneuvers are attempted first. The most common vagal or valsalva maneuver is instructing the patient to bear down as if they were having a bowl movement. This stimulates the parasympathetic nervous system and usually promotes bradycardia (slow heart rate). If vagal or valsalva maneuvers fail to decrease the heart rate, pharmacology intervention is attempted. The administration of Adenosine, which slows conduction through the atrioventricular node, is the first line antiarrhythmic agent. If supraventricular tachycardia continues, refractory to Adenosine, Varapamil is administered. If pharmacology methods fail, electrical synchronized cardioversion is the next step. Synchronized cardioversion has a success rate that ranges between 85 - 95%, depending on the location of the extra pathway(Berger, 2006). Once the patient has arrived at the emergency room, continued intervention is applied to ensure the heart is stabilized. An emergency room physician will then order certain tests, listed in the diagnosis section, to confirm the presence of Wolff-Parkinson-White syndrome. When the diagnosis is confirmed, the definitive treatment of Wolff-Parkinson-White syndrome is radiofrequency catheter ablation. This is a surgical procedure, performed exclusively by cardiac electrophysiologists, that destroys the abnormal electrical pathway.

RF ablation is currently the treatment of choice for most adults and many children with symptomatic WPW syndrome (i.e., those who have AV reentrant tachycardia or atrial flutter/fibrillation with conduction of the accessory pathway). Success rates for catheter ablation exceed 90%(Dr. Matthews, 2000-2007).

When radiofrequency catheter ablation is successfully completed, the patient is generally considered cured of Wolff-Parkinson-White syndrome. Reoccurrences of Wolff-Parkinson-White syndrome after radiofrequency ablation is less than 5%.

Conclusion

In conclusion, one can now see how a healthy athletic 17-year-old male, with no known medical history, can go into sudden cardiac arrest and die. Wolff-Parkinson-White syndrome is a condition that can produce lethal tachydysrhythmias, because of an extra electrical connection or accessory pathway between the atria and ventricles. The immediate concerns, concerning treatments, are to reduce the accelerated heart rate. The definitive treatment is radiofrequency ablation, which destroys the extra electrical connection. The ability to identify signs and symptoms of Wolff-Parkinson-White syndrome, and seek immediate medical attention, can give future high school star quarterbacks a second chance at life.

Source: EveryMinuteSucks.com