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| Wolff (Wolfe)-Parkinson-White Syndrome |
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What is Wolff (Wolfe)-Parkinson-White Syndrome? Wolff (Wolfe)-Parkinson-White (WPW) is a very rare cause of sudden death. It results from an additional electrical connection between the atria (upper chambers of the heart) and the ventricles (lower chambers of the heart). This extra or accessory electrical pathway is present in approximately 1.5 per 1,000 people. It runs in families in less than 1% of cases. In the majority it is completely silent and only detected on a routine ECG. In a small proportion of patients the extra electrical pathway allows conduction of the electrical pathway generating an electrical circuit which produces a very rapid heart rate. Most patients tolerate this well but some experience very troublesome palpitations, light-headedness and blackouts. A very small minority of patients may die suddenly from ventricular fibrillation. Synonyms of Wolff Parkinson White Syndrome: Accessory Atrioventricular Pathways Preexcitation Syndrome WPW Syndrome What is the heart's normal condition? In a normal heart, electrical signals use only one path when they move through the heart. This is the atrio-ventricular or A-V node. As the electrical signal moves from the heart's upper chambers (the atria) to the lower chambers (the ventricles), it causes the heart to beat. For the heart to beat properly, the timing of the electrical signal is important. Symptoms: Palpitations are the main symptoms. They can occur at any time and some patients learn to control them by holding their breath for prolonged periods. In many instances the palpitations remain until they are terminated by medical therapy in the accident and emergency department. Light-headedness and near syncope appear to occur more commonly in persons with WPW syndrome who have paroxysmal SVT (PSVT) or atrial fibrillation than in those with AV nodal reentry. Signs: When the patient is experiencing palpitations the heart rate is usually in excess of 150 beats per minute. When the patient has no symptoms there is nothing to find on examination. Frequency: In the US: The prevalence of ventricular preexcitation is thought to be 0.1-0.3% in the general population. Estimates of arrhythmia incidence in patients with preexcitation vary widely, ranging from 12-80% in several surveys. Incidence of preexcitation and WPW syndrome varies from 0.1-3 cases per thousand population (average of 1.5 cases per thousand population) in otherwise healthy persons. In a review of ECG findings from 22,500 healthy aviation personnel, 0.25% exhibited findings consistent with the WPW pattern, with 1.8% incidence of tachycardia. The location of the accessory pathways, in descending order of frequency, is (1) the left free wall, (2) posteroseptal, (3) right free wall, and (4) anteroseptal. The presence of concealed accessory pathways accounts for approximately 30% of patients with apparent SVT referred for EP evaluation. Approximately 80% of patients with WPW syndrome have a reciprocating tachycardia, 15-30% have atrial fibrillation, and 5% have atrial flutter. Ventricular tachycardia is uncommon. Internationally: WPW affects approximately 0.15-0.2% of the general population. Of these individuals, 60-70% have no other evidence of heart disease. Mortality/Morbidity: Death from WPW occurs secondary to the associated arrhythmias or from mistreatment of these arrhythmias with inappropriate medications. Little data are available regarding the mortality rate of such arrhythmias, but most studies report the incidence of sudden death in the 0-4% range. Overall, sudden death occurs rarely, with an estimated frequency rate of 0.1%. Other factors that appear to influence risk are the presence of multiple bypass tracts and a family history of premature sudden death. Sudden cardiac death is unusual without preceding symptoms. Causes: In patients with WPW syndrome, the underlying
cardiac structural abnormality consists of accessory conduction tissue that
bypasses the normal AV node His-Purkinje system pathway. Such pathways are
generally believed to be congenital in nature. Congenital or hereditary: An accessory pathway is quite likely to be congenital, although its manifestations can be detected in later years and it may appear to be acquired. Relatives of patients with preexcitation, particularly those with multiple pathways, have an increased prevalence of preexcitation, suggesting a hereditary mode of acquisition. Associated with congenital cardiac defects: Patients with the Ebstein anomaly may develop WPW syndrome. Patients with the Ebstein anomaly frequently have multiple accessory bypass tracts, mostly right-sided, in the posterior part of the septum or the posterolateral wall. Preexcitation generally occupies the atrialized ventricle. The orthodromic reciprocating tachycardia in such patients exhibits right bundle-branch block (RBBB) and a long ventriculoatrial (VA) interval. Mitral valve prolapse may be a congenital cardiac defect and may cause WPW syndrome. Hypertrophic cardiomyopathy may include idiopathic hypertrophic subaortic stenosis or asymmetric septal hypertrophy. Associated with other acquired cardiac defects - Cardiomyopathies Race: No clear racial predilection appears to exist. Sex: Men are affected more often (60-70%) than women. Typically, those affected are young, otherwise healthy individuals. Age: Although this disease affects people of all ages, it most commonly is recognized in children and young adults presenting to the ED with an arrhythmia. Conduction speed in the accessory pathway appears to attenuate with age. WPW syndrome is found in persons of all ages, from those in fetal and neonatal age groups to elderly individuals. Prevalence decreases with age because of loss of preexcitation. Cases have been described in which electrocardiographic evidence of preexcitation disappears. How is Wolff (Wolfe)-Parkinson-White diagnosed? WPW is diagnosed by performing an ECG. The ECG usually shows two abnormalities when the patient is free of symptoms – a short PR interval and a delta wave. It is often an incidental finding during a routine ECG check as part of a medical insurance or detected by a cardiologist when a patient is referred with palpitations. Treatment: The ideal treatment in patients with symptoms is to destroy the extra electrical pathway, a procedure termed radio frequency catheter ablation. This is done by passing a wire into the heart, often via the large artery (femoral artery) in the leg. The abnormal pathway is located by electrical stimulation and destroyed by passing a high current through it. This takes approximately 2-3 hours and requires one night in hospital. For patients above 25 years without any symptoms there is no need for further tests. Younger patients (under 25 years) are most at risk of sudden death and require further tests to assess their risk of developing life threatening electrical disturbances. This is best done by performing an exercise test under the supervision of a cardiologist. The abrupt disappearance of the delta wave on the ECG as the heart rate increases is a good sign. Obviating the need for any further investigation, however, if this does not happen then further electrophysical testing is recommended before one can be reassured.
Special thanks to emedicine.com and Dr. Mel Herbert’s article Wolff-Parkinson-White Syndrome and Dr. Vibhuti Singh’s article Wolff-Parkinson-White Syndrome. Detailed Research: ACC/AHA Practice Guidelines for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices (Executive Summary, #71-0136 Circulation.1998;97:1325-1335; Full Text, #71-0137 JACC. 1998;31:1175-1209)ACC/AHA Practice Guidelines for Clinical Intracardiac Electrophysiological and Catheter Ablation Procedures, #71-0071 Circulation. 1995;92:673-691 (Published simultaneously in JACC and J Cardiovasc Electrophysiol) Conover MB: Diagnosis and management of arrhythmias associated with Wolff-Parkinson-White syndrome. Crit Care Nurse 1994 Jun; 14(3): 30-9; quiz 40-1. Giardina AC, Ehlers KH, Engle MA: Wolff-Parkinson-White syndrome in infants and children. A long-term follow-up study. Br Heart J 1972 Aug; 34(8): 839-46[Medline]. Organizations related to Wolff Parkinson White Syndrome: American Heart Association National Center Cardiomyopathy Association 40 The Metro Centre Congenital Heart Anomalies, Support, Education, & Resources 2112 North Wilkins Road Congenital Heart Disease Resource Page HOPE (The Heart of Pediatric Electrophysiology) PO Box 519 NIH/National Heart, Lung and Blood Institute Information Center P.O. Box 30105 |
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