In those with WPW complicated by atrial fibrillation, cardioversion or the medication procainamide may be used. The condition is named after Louis Wolff, John Parkinson, and Paul Dudley White who described the ECG findings in 1930. Signs and symptoms
People with WPW are usually asymptomatic when not having a fast heart rate. However, individuals may experience palpitations, dizziness, shortness of breath, or infrequently syncope (fainting or near fainting) during episodes of supraventricular tachycardia. WPW is also associated with a very small risk of sudden death due to more dangerous heart rhythm disturbances. Pathophysiology
Electrical activity in the normal human heart begins when a cardiac action potential arises in the sinoatrial (SA) node, which is located in the right atrium. From there, the electrical stimulus is transmitted via internodal pathways to the atrioventricular (AV) node. After a brief delay at the AV node, the stimulus travels through the bundle of His to the left and right bundle branches and then to the Purkinje fibers and the endocardium at the apex of the heart, then finally to the ventricular myocardium.The AV node serves an important function as a "gatekeeper", limiting the electrical activity that reaches the ventricles. In situations where the atria generate excessively rapid electrical activity (such as atrial fibrillation or atrial flutter), the AV node limits the number of signals conducted to the ventricles.
While some groups advocate PES for risk stratification in all individuals under 35 years old, others only offer it to individuals who have history suggestive of a tachydysrhythmia, since the incidence of sudden cardiac death is so low (less than 0.6% in some reports).Other methods of risk stratification include observing the ventricular rate during spontaneous atrial fibrillation on a 12-lead ECG. RR intervals of less than 250 ms suggest a higher risk pathway. During exercise testing, abrupt loss of pre-excitation as heart rate increases also suggest a lower risk pathway. However, this approach is hampered by the normal improvement in AV node conduction during exercise which can also mask pre-excitation despite ongoing conduction down the accessory pathway. Treatment
According to the ACLS protocol, people with WPW who are experiencing rapid abnormal heart rhythms (tachydysrhythmias) may 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, medication may be used. Medications
WPW pattern with hemodynamically stability and orthodromic AVRT leading to a regular narrow complex tachycardia may be managed similarly to other regular narrow complex supraventricular tachycardias: first with vagal maneuvers followed by a trial of adenosine (first-line therapy). The 2015 ACC/AHA/HRS guidelines recommend beta-blockers or calcium channel blockers as second-line agents, electric cardioversion is reserved for refractory arrhythmias.