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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Wolff-Parkinson-White syndrome (WPW) is a syndrome of pre-excitation of the ventricles of the heart due to an accessory pathway known as the Bundle of Kent. The diagnosis is made when a patient with pre-existing WPW patern in the ECG developes an arrythmia which involves an accesory pathway. The treatment is focused on recovering sinus rythm. Atrial Fibrillation in a patient with WPW is lifethretening and should be managed urgently.

Causes

Life Threatening Causes

Life-threatening causes include conditions which result in death or permanent disability within 24 hours if left untreated. Wolff-Parkinson-White syndrome can be a life-threatening condition and must be treated as such irrespective of the underlying cause.

Common Causes

WPW is a congenic disease

Diagnosis

Shown below is an algorithm summarizing the initial aproach to Wolff-Parkinson-White syndrome according to the 2003 ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias.

AVRT: AV reentrant tachycardia

Characterize the symptoms: ❑ Asymptomatic ❑ Palpitations ❑ Dyspnea ❑ Fatigue ❑ Chest discomfort ❑ Lightheadedness ❑ Syncope ❑ Polyuria Characterize the timing of the symptoms: ❑ Onset ❑ Duration ❑ Frequency

Identify possible triggers: ❑ Infection ❑ Caffeine ❑ Alcohol ❑ Nicotine ❑ Congenital heart disease ❑ Congestive heart failure ❑ Valvular disease ❑ Hypovolemia ❑ Acidosis ❑ Hyperthyroidism ❑ Hypoxia ❑ Anxiety ❑ Hypokalemia ❑ Hyperkalemia ❑ Hypoglycemia ❑ Hypothermia ❑ Toxins ❑ Stress ❑ Pulmonary embolism ❑ Coronary thrombosis ❑ Trauma

❑ Examine the patient ❑ Monitor the blood pressure ❑ Monitor the heart rate ❑ Order and monitor the ECG ❑ Assess and support ABC ❑ Give oxygen if needed ❑ Treat reversible causes if identified

Orthodromic AVRT The impulse travels from the atrium to the ventricle through the AV node and returns to the atrium through the accesory pathway. 90-95% of WPW ❑ Narrow QRS complexes ❑ Ventricular rate between 150-250 bpm (or more) usually regular ❑ PR interval less than one half of the tachycardia RR interval

Antidromic AVRT The impulse travels from the atrium to the ventricle through theaccesory pathway and from the ventricle to the atrium through the AV node. Less than 10% of WPW ❑ Wide QRS complexes ❑ Ventricular rate between 150-250 bpm (or more) usually regular ❑ PR interval more than one half of the tachycardia RR interval

Managment

Shown below is an algorithm summarizing the initial aproach to Wolff-Parkinson-White syndrome according to the 2003 ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias.

Initial aproach ❑ Determine blood pressure ❑ Determine heart rate ❑ If possible, catheter ablation (class I, level of evidence B)

Stable patient

Unstable patient

❑ Assess the ECG

❑ Catheter ablation (class I, level of evidence B) ❑ Urgent electrical cardioversion (class I, level of evidence C)

Orthodromic AVRT

Antidromic AVRT

Treatment. ❑ Use Vagal maneuvers (class I, level of evidence B) ❑ Carotid sinus massage ❑ Valsalva maneuver If not effective initiate IV AV nodal blocking agent ❑ Administer Adenosine, 6 mg (initial dose) that could be followed by 12 mg if initial dose not effective. Administer IV followed by 10 cc of saline solution (class I, level of evidence A) Contraindications: second- or third-degree A-V block, sinus node disease If not effective ❑ Administer Verapamil, given in boluses of 5 mg every two to three minutes up to cumulative 15 mg (class I, level of evidence A). Additional ECG monitoring should be perforemed in patients with renal insufficiency. In cirrhosis, reduce dose to 20% and 50% of normal Contraindications: hypotension (systolic pressure less than 90 mm Hg) or cardiogenic shock, patients with known hypersensitivity to verapamil hydrochloride If not effective ❑ Administer Procainamide, give intravenusly 20 to 50 mg/minute until the arrythmia is controlled or reach 17 mg/kg. Must monitor blood pressure every 5 to 10 minnutes (class I, level of evidence B). Reduce the loading dose to 12 mg/kg in severe renal impairment. Reduce the dosage to 50% in hepatic impaiment Contraindications: complete heart block, lupus erythematosus, idiosyncratic hypersensitivity, torsades de pointes

Treatment. ❑ Administration of: ❑ Ibutilide is the prefered treatment, administer 1 mg in an infusion over 10 minutes, if the tachycardia is not controlled give another 1 mg infusion over 10 minutes (class I, level of evidence B) Contraindications: hypersensitivity to ibutilide or any component of the formulation, QTc >440 msec Or ❑ Procainamide, 20 to 50 mg/minute until the arrythmia is controlled or reach 17 mg/kg. Must monitor blood pressure every 5 to 10 minnutes (class I, level of evidence B). Reduce the loading dose to 12 mg/kg in severe renal impairment. Reduce the dosage to 50% in hepatic impaiment Contraindications: complete heart block, lupus erythematosus, idiosyncratic hypersensitivity, torsades de pointes ❑ Adenosine should be used with caution because may produce AF 6 mg (initial dose) that could be followed by 12 mg if initial dose not effective. Administer IV followed by 10 cc of saline solution Contraindications: second- or third-degree A-V block, sinus node disease

Wolff-Parkinson-White syndrome with Atrial fibrillation

Shown below is an algorithm summarizing the managment of Wolff-Parkinson-White syndrome with Atrial fibrillation according to the ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation.

Initial aproach ❑ Control ventricular response ❑ If possible: terminate AF ❑ If possible: catheter ablation of the accesory pathway (class I, level of evidence B)

Stable patient

Unstable patient

❑ Restore sinus rythm (class I, level of evidence C) ❑ Ibutilide administer 1 mg in an infusion over 10 minutes, if the tachycardia is not controlled give another 1 mg infusion over 10 minutes (class I, level of evidence C) Contraindications: hypersensitivity to ibutilide or any component of the formulation, QTc >440 msec Or ❑ Procainamide administer 20 to 50 mg/minute until the arrythmia is controlled or reach 17 mg/kg. Must monitor blood pressure every 5 to 10 minnutes (class I, level of evidence C). Reduce the loading dose to 12 mg/kg in severe renal impairment. Reduce the dosage to 50% in hepatic impaiment Contraindications: complete heart block, lupus erythematosus, idiosyncratic hypersensitivity, torsades de pointes Or ❑ Amiodarone, administer 5-7 mg/kg over 30-60 minutes (initial dose), then 1.2-1.8 g daily continuous infusion or in divided oral doses until 10 g total (class IIb, level of evidence B) Contraindications: cardiogenic shock, severe sinus-node dysfunction ❑ Avoid AV blocking agents (class III, level of evidence B), such as: ❑ Digitalis glycosides ❑ Nondihydropyridine calcium channel antagonists

❑ Catheter ablation (class I, level of evidence B) ❑ Urgent electric cardioversion (class I, level of evidence B)

Do's

❑ Catheter ablation should be performed is possible (class I, level of evidence B)

Don'ts

❑ AV blocking agents, during WPW with AF will promote conduction down the accessory pathway and may sometimes directly enhance the rate of conduction over the accessory pathway (class III, level of evidence B)

References

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