Características electrocardiográficas de vías fascículo-ventriculares en pediatría: estudio comparativo con las vías accesorias anteroseptalesderechas / Electrocardiographic characteristics of fasciculo-ventricular accessory pathways in children: A comparative study with right anteroseptal accessory pathways

Resumen Objetivos: Las vías accesorias (VAc) fascículo-ventriculares (FV) tienen una localización anatómica similar a las VAcanteroseptales derechas (ASD) y comparten características electrocardiográficas. El objetivo es comparar características electrocardiográficas de las VAC FV con las de las ASD en pediatría. Métodos: Se incluyeron pacientes con preexcitación manifiesta sometidos a estudio electrofisiológico. Las VAc FV se definieron por un intervalo HV ≤ 32ms y un alargamiento del AH sin modificación del HV, del grado o patrón de preexcitación ventricular durante la estimulación auricular. Tres observadores independientes y ciegos analizaron los ECG en cada grupo. Resultados: De 288 pacientes, 15 (5.2%) presentaban VAC FV y 14 VAC ASD (4.9%). El intervalo PR fue más largo en las VAc FV que en las ASD (113 ± 21 vs. 86 ± 13 ms respectivamente; p = < 0.001) y la duración del QRS fue menor (95 ± 12 vs. 137 ± 24 ms respectivamente; p = < 0.001). El ECG de las VAc FV presentó una deflexión rápida de baja amplitud previa al inicio del QRS en 13 de 15 pacientes (87%) y en 2 con VAc AV ASD (14%); (p = 0.003). Conclusiones: El intervalo PR fue más largo y el complejo QRS más angosto en la VAC FV respecto de las ASD. La presencia de una deflexión rápida de baja amplitud previa al inicio del QRS permitiría diferenciarlas de las aurículo-ventriculares ASD de manera no invasiva.

Abstract Objectives: Fasciculo-ventricular (FV) accessory pathways (AP's) and right anteroseptal (RAS) AP's share similar anatomic locations and electrocardiographic characteristics. The objective of this article is to compare these features in children. Methods: All patients with manifest pre-excitation who underwent an electrophysiological study were included. Fasciculo-ventricular AP's were defined by the presence of an HV inter- val ≤ 32 ms and a prolongation of the AH without changes in the HV interval, or the level of pre-excitation during atrial pacing. Three independent and blind observers analysed the ECG's in both groups. Results: Out of 288 patients, 15 (5.2%) had FV AP's and 14 (4.9%) right AS AP's. The PR interval was longer in FV AP's than in RAS (113 ± 21 vs 86 ± 13 ms respectively; P < .001) and the QRS was narrower (95 ± 12 vs 137 ± 24 ms respectively; P < .001). The ECG in patients with FV AP's showed a rapid low amplitude deflection at the begining of the QRS in 13 out of 15 patients (87%) and in 2 (14%) the RAS AP group (P = .003). Conclusions: The PR interval was longer and the QRS complex was narrower in patients with FV AP's. The presence of a rapid low amplitude deflection at the beginning of the QRS complex would allow to differentiate them from RAS AP's non-invasively.

Accuracy of the Electrocardiogram in Localizing the Accessory Pathway in Patients with Wolff-Parkinson-White Pattern / Acurácia do Eletrocardiograma na Localização da Via Acessória em Pacientes com Padrão de Wolff-Parkinson-White

Abstract Background: There are currently several electrocardiographic algorithms to locate the accessory pathway (AP) in patients with Wolff-Parkinson-White (WPW) syndrome. Objective: To compare the ability of electrocardiographic algorithms in identifying the location of the AP in patients with WPW pattern referred for ablation. Methods: Observational, cross-sectional, retrospective study with 111 patients with WPW syndrome referred for AP ablation. The electrocardiogram (ECG) obtained prior to the ablation was analyzed by an experienced observer who consecutively applied seven algorithms to identify non-invasively the AP. We then compared the location estimated with this assessment with that obtained in the electrophysiological study and calculated the agreement rates. Results: Among the APs, 59 (53.15%) were distributed around the mitral annulus and the remaining 52 (46.85%) were located around the tricuspid annulus. The overall absolute accuracy of the algorithms evaluated varied between 27% and 47%, increasing to between 40% and 76% when we included adjacent locations. The absolute agreement rate by AP location was 2.00-52.20% for septal APs (n = 51), increasing to 5.90-90.20% when considering adjacent locations; 7.70-69.20% for right APs (n = 13), increasing to 42.90-100% when considering adjacent locations; and 21.70-54.50% for left APs (n = 47), increasing to 50-87% when considering adjacent locations. Conclusion: The agreement rates observed for the analyzed scores indicated a low discriminative ability of the ECG in locating the AP in patients with WPW.

Resumo Fundamento: Existem atualmente vários algoritmos eletrocardiográficos para localizar a via acessória (VA) em pacientes com síndrome de Wolff-Parkinson-White (WPW). Objetivo: Comparar a capacidade discriminativa dos algoritmos eletrocardiográficos na localização da VA no padrão de WPW em pacientes encaminhados para ablação. Métodos: Estudo observacional, transversal e retrospectivo, incluindo 111 pacientes com síndrome de WPW encaminhados para ablação da VA. O eletrocardiograma (ECG) prévio à ablação foi analisado por um observador experiente que aplicou consecutivamente sete algoritmos para identificar a VA de forma não invasiva. A localização estimada com esta avaliação foi comparada à obtida no estudo eletrofisiológico e as taxas de acerto foram calculadas. Resultados: Entre as VAs, 59 (53,15%) estavam distribuídas ao redor do anel mitral e as restantes 52 (46,85%) em torno do anel tricúspide. O acerto global absoluto dos algoritmos em estudo variou entre 27% e 47%, aumentando para 40% a 76% quando incluímos localizações adjacentes. O acerto absoluto em função da localização da VA foi o seguinte: para as VAs septais (n = 51) variou entre 2% e 52,20% (5,90% e 90,20% incluindo localizações adjacentes), para as VAs direitas (n = 13) variou entre 7,70% e 69,20% (42,90% e 100%, incluindo localizações adjacentes), para as VAs esquerdas (n = 47) variou entre 21,70% e 54,50% (50% a 87%, incluindo as localizações adjacentes). Conclusões: Os índices de acerto observados para os escores analisados indicaram uma reduzida capacidade discriminativa do ECG na localização da VA em pacientes com WPW.