what is wolff

7/30/2019 What is Wolff

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What is Wolff-Parkinson-White syndrome?

Wolff-Parkinson-White syndrome is a condition characterized by abnormal electrical pathways in the

heart that cause a disruption of the heart's normal rhythm (arrhythmia).

The heartbeat is controlled by electrical signals that move through the heart in a highly coordinatedway. A specialized cluster of cells called the atrioventricular node conducts electrical impulses from

the heart's upper chambers (theatria) to the lower chambers (theventricles). Impulses move

through the atrioventricular nodeduring each heartbeat, stimulating the ventricles to contract slightly

later than the atria.

What are the symptoms of Wolff-Parkinson-White syndrome

People with Wolff-Parkinson-White syndrome are born with an extra connection in the heart, called

an accessory pathway, that allows electrical signals to bypass the atrioventricular node and move

from the atria to the ventricles faster than usual. The accessory pathway may also transmit electrical

impulses abnormally from the ventricles back to the atria. This extra connection can disrupt thecoordinated movement of electrical signals through the heart, leading to an abnormally fast

heartbeat (tachycardia) and other arrhythmias. Resulting symptoms includedizziness, a sensation of

fluttering or pounding in the chest (palpitations), shortness of breath, andfainting(syncope). In rare

cases, arrhythmias associated with Wolff-Parkinson-White syndrome can lead tocardiac arrest and

sudden death. The most common arrhythmia associated with Wolff-Parkinson-White syndrome is

calledparoxysmal supraventricular tachycardia.

What are the complications of Wolff-Parkinson-White syndrome?

Complications of Wolff-Parkinson-White syndrome can occur at any age, although some individuals

born with an accessory pathway in the heart never experience any health problems associated withthe condition.

What other heart conditions is Wolff-Parkinson-White syndrome associated

with?

Wolff-Parkinson-White syndrome often occurs with other structural abnormalities of the heart or

underlyingheart disease. The most common heart defect associated with the condition is Ebstein

anomaly, which affects the valve that allows blood to flow from the right atrium to theright

ventricle(the tricuspid valve). Additionally, Wolff-Parkinson-White syndrome can be a component of

several othergeneticsyndromes, including hypokalemic periodicparalysis (a condition that causes

episodes of extreme muscle weakness), Pompe disease (a disorder characterized by the storage of

excess glycogen), andtuberous sclerosis (a condition that results in the growth of noncancerous

tumors in many parts of the body).

How common is Wolff-Parkinson-White syndrome?

Wolff-Parkinson-White syndrome affects 1 to 3 in 1,000 people worldwide. Only a small fraction of

these cases appear to run in families.
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Wolff-Parkinson-White syndrome is a common cause of an arrhythmia known as paroxysmal

supraventricular tachycardia. Wolff-Parkinson-White syndrome is the most frequent cause of this

abnormal heart rhythm in the Chinese population, where it is responsible for more than 70 percent of

cases.

What genes are related to Wolff-Parkinson-White syndrome?

Mutations in the PRKAG2gene cause Wolff-Parkinson-White syndrome.

A small percentage of all cases of Wolff-Parkinson-White syndrome are caused by mutations in the

PRKAG2 gene. Some people with these mutations also have features ofhypertrophic

cardiomyopathy, a form of heart disease that enlarges and weakens the heart (cardiac) muscle. The

PRKAG2 gene provides instructions for making a proteinthat is part of anenzymecalled AMP-

activated protein kinase (AMPK). This enzyme helps sense and respond to energy demands within

cells. It is likely involved in the development of the heart before birth, although its role in this process

is unknown.

Researchers are uncertain how PRKAG2 mutations lead to the development of Wolff-Parkinson-

White syndrome and related heart abnormalities. Research suggests that these mutations alter the

activity of AMP-activated protein kinase in the heart, although it is unclear whether the genetic

changes overactivate the enzyme or reduce its activity. Studies indicate that changes in AMP-

activated protein kinase activity allow a complex sugar called glycogen to build up abnormally

within cardiac muscle cells. Other studies have found that altered AMP-activated protein kinase

activity is related to changes in the regulation of certain ion channels in the heart. These channels,

which transport positively charged atoms (ions) into and out of cardiac muscle cells, play critical

roles in maintaining the heart's normal rhythm.

In most cases, the cause of Wolff-Parkinson-White syndrome is unknown.

How do people inherit Wolff-Parkinson-White syndrome?

Most cases of Wolff-Parkinson-White syndrome occur in people with no apparentfamily historyof the

condition. These cases are described as sporadic and are not inherited.

Familial Wolff-Parkinson-White syndrome accounts for only a small percentage of all cases of this

condition. The familial form of the disorder typically has an autosomal dominant pattern

ofinheritance, which means one copy of the altered gene in eachcell is sufficient to cause the

condition. In most cases, a person with familial Wolff-Parkinson-White syndrome has inherited the

condition from an affected parent.
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Treatment

People with WPW who are experiencingtachydysrhythmiasmay require synchronized

electrical cardioversion if they are demonstrating severe signs or symptoms (for example,low blood

pressure or lethargy with altered mental status). If they are relatively stable,pharmacologic treatment may

be used.

People with atrial fibrillation and rapid ventricular response are often treated

withamiodarone[11] orprocainamide[12] to stabilize their heart rate. Procainamide, amiodarone, and

cardioversion are now accepted treatments for conversion of tachycardia found with WPW.[13] AV node

blockers should be avoided in atrial fibrillation and atrial flutter with WPW or history of it; this includes

adenosine,diltiazem,verapamil, othercalcium channel blockersandbeta blockers.[14]They can

exacerbate the syndrome by blocking the heart's normal electrical pathway (therefore favoring

transmission through the pre-excitation pathway). People with symptomatic narrow-QRS-complex

tachycardias may be cardioverted. Alternatively, adenosine may be administered.

The definitive treatment of WPW is a destruction of the abnormal electrical pathway by

radiofrequency catheter ablation. This procedure is performed by cardiac electrophysiologists.

Radiofrequency catheter ablation is not performed in all individuals with WPW because there are inherent

risks involved in the procedure. When performed by an experienced electrophysiologist, radiofrequency

ablation has a high success rate.[15]Findings from 1994 indicate success rates of as high as 95% in

people treated with radiofrequency catheter ablation for WPW.[16]If radiofrequency catheter ablation is

successfully performed, the condition is generally considered cured. Recurrence rates are typically less

than 5% after a successful ablation.[15]The one caveat is that individuals with underlying Ebstein's

anomaly may develop additional accessory pathways during progression of their disease.
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