The locations of the accessory pathways are regionalized to the left-free wall (58%), posterior septal (24%), right free-wall (13%), and anterior septal (5%) sites, respectively. Morphologically, accessory pathways are the strands of normal myocardium that bridge the AV groove at any point around the annulus fibrosus on either side of the heart except that portion of the mitral valve annulus between the right and left fibrous trigones. It also results from the anomalous myocardial tissue spanning the fibrinous bridges between the atria and ventricles. The accessory pathway (AP), which leads to pre-excitation, results from a developmental failure to eradicate the remnants of the atrioventricular connections present during cardiogenesis. The purpose of this review article is to discuss the comprehensive approach to an asymptomatic patient with a WPW pattern in ECG and also to highlight a few salient features of different accessory pathways whenever feasible. Figure 1 shows the characteristic WPW pattern in the ECG.įigure 1: Sinus rhythm with typical WPW pre-excitation pattern manifesting as a short PR interval, delta wave, and wide QRS complex. In the absence of a documented tachyarrhythmia or related symptoms, the ECG findings alone are referred to as the WPW pattern. The characteristic ECG features are (i) shortened PR interval ( 120 ms) as it is formed by the sum of normal ventricular activation and ventricular pre-excitation through the accessory tract. The WPW syndrome affects 0.1-0.3% of the general population. When electrical impulses are conducted via this accessory tract, it leads to premature ventricular activation described as pre-excitation. WPW pattern is a ventricular pre-excitation wherein an accessory bypass tract known as the bundle of Kent serves as the connection between the atrial to the ventricular myocardium bypassing the atrioventricular (AV) node. However, it is not uncommon to incidentally find a Wolff-Parkinson-White (WPW) pattern in a routinely performed electrocardiography (ECG) without any arrhythmia. White together described a set of eleven cases of an electrocardiographic pattern consisting of a “functional bundle branch” and a “short PR interval” in the healthy young people with paroxysms of tachycardia. It was in 1930, when Louis Wolff, John Parkinson, and Paul D. In 1921, a phenomenon of “intraventricular block and a PR interval of 0.08 ms” in a 19-year-old patient with paroxysms of tachycardia was first described by A.M. A shared-decision making must be performed before offering catheter ablation whose procedural success rate is high. The cardiac evaluation may thus be considered in asymptomatic patients with WPW to determine the individual risk for future symptomatic arrhythmia. On the other hand, a high-risk pathway in EP study is suggested by the presence of the shortest pre-excited RR interval (SPERRI) during atrial fibrillation of ≤ 250 ms or accessory pathway effective refractory period (APERP) ≤ 240 ms. A low-risk pathway is considered when the pre-excitation is intermittent on ambulatory monitoring or when it disappears completely or abruptly during exercise testing. The inherent properties of the accessory pathway determine the risk of sudden cardiac death. A substantial proportion of adults with WPW patterns on ECG may remain asymptomatic but the lifetime risk for fatal arrhythmias still exists. The objective of this review article is to update the most recent evidence on the management of young patients with asymptomatic WPW patterns. A comprehensive approach to asymptomatic adults with Wolff-Parkinson-White (WPW) pattern discovered incidentally on routine electrocardiography (ECG) is debatable.
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