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Wolff-Parkinson-White Syndrom (WPW)

Wolff–Parkinson–White syndrome (WPW) is one of several disorders of the heart’s electrical system that are commonly referred to as pre-excitation syndromes. WPW is caused by an abnormal accessory pathway between the atria and the ventricles. This abnormal conduction pathway, known as the "Bundle of Kent ", connects the atria and the ventricles causing a short-circuit in the AV Node. This pathway can sometimes allow extremely rapid conduction to the ventricles without the any delay usually provided by the AV node. This produces Wolff Parkinson White (WPW) syndrome, which is characterized by conduction of the atrial depolarization current to the ventricles immediately after atrial contraction. With Wolff-Parkinson-White syndrome, the usual short span of baseline between the P-wave and QRS is replaced by a steep upward curving "delta wave" representing a “too-early” or "pre-excitation" stimulation of a portion of the ventricles. This is easy to detect in most leads as a gentle upward curve or slope called a delta wave connects the P-wave and QRS complex (see below). Wolff-Parkinson-White syndrome (WPW) is characterized as a Supraventricular Tachycardia rhythm (SVT). This rapid paced rhythm is caused by the heart’s electrical signal to loop through the abnormal accessory pathway between the atria and the ventricles. The electrical signal traveling down this abnormal pathway, known as the Bundle of Kent, may stimulate the ventricles to contract prematurely, resulting in a unique type of SVT referred to as “atrioventricular reciprocating tachycardia”, which produces this unique rhythm. WPW’s abnormal pathway does not share the rate-slowing properties such as with the AV node. Normally the AV node serves as a "gatekeeper", limiting the rate of electrical signals that it allows to get through to the ventricles. In situations where the atria generate excessively rapid electrical activity (such as A-fib or A-flutter), the AV node will limit the number of signals conducted to the ventricles. However with WPW, this accessory pathway may conduct electrical activity at a significantly higher rate. For instance, in the example above, if the atrial rate was 300 beats per minute, the accessory pathway may directly conduct all the electrical impulses from the atria to the ventricles, causing the to contract at 300 beats per minute. Extremely rapid heart rates such as this may result in hemodynamic instability cardiogenic shock. In some cases, the combination of an accessory pathway and cardiac dysrhythmias can trigger V-Tach or V-Fib, a leading cause of sudden cardiac death. Symptoms Some people with WPW have only a few episodes of rapid heart rate while others may have a rapid heart rate once or twice a week, or more. Usually with WPW, the patient will have symptoms depending on the heart rate, and sometimes there may be no symptoms at all. This condition is determined or discovered upon 12 lead test results. Symptoms from WPW include: Chest pain or chest tightness Dizziness Lightheadedness Fainting Palpitations Shortness of breath Exams, Tests and Treatment; A physical exam done during a tachycardia episode will show a heart rate faster than 100 beats per minute. A normal heart rate is 60 to 100 beats per minute in adults, and under 150 beats per minute in newborns, infants, and small children. Blood pressure will be normal or low in most cases. The long-term treatment for WPW syndrome usually involves needing a catheter ablation.. The type of ablation that is performed, enters into the area of the abnormal pathway, and is closed using a special type of energy called radiofrequency or by freezing it (cryoablation). Open heart surgery can provide means to burn or freeze the extra pathway shut, thus providing a permanent cure for WPW. In most cases, this procedure is done only if there are other reasons for needing open heart surgery. Is Wolf White Parkinson syndrome hereditary? Wolff-Parkinson-White (WPW) syndrome is one of a classification of pre-excitation disorders that have been found to have a genetic component. Recent research has identified the gene (PRKAG2) with WPW associated with hypertrophic cardiomyopathy (HCM) and conduction system disease. Outlook (Prognosis) Catheter ablation cures this disorder in most people. The success rate for the procedure ranges between 85% to 95%. Success rates will vary depending on the location and number of extra pathways.

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