Validation of qrs-polarity algorithm with special emphasis in parahisian pathways / Validación del algoritmo de la polaridad del qrs con especial énfasis en vías parahisianas

Abstract Background: In 1996 Iturralde et al. published an algorithm based on the QRS polarity to determine the location of the accessory pathways (AP), this algorithm was developed before the massive practice of invasive electrophysiology. Purpose: To validate the QRS-Polarity algorithm in a modern cohort of subjects submitted to radiofrequency catheter ablation (RFCA). Our objective was to determinate its global accuracy and its accuracy for parahisian AP. Methods: We conducted a retrospective analysis of patients with Wolff-Parkinson-White (WPW) syndrome who underwent an electrophysiological study (EPS) and RFCA. We employed the QRS-Polarity algorithm to predict the AP anatomical location and we compared this result with the real anatomic location determined in the EPS. To determine accuracy, the Cohen's kappa coefficient (k) and the Pearson correlation coefficient were used. Results: A total of 364 patients were included (mean age 30 years, 57% male). The global k score was 0.78 and the Pearson's coefficient was 0.90. The accuracy for each zone was also evaluated, the best correlation was for the left lateral AP (k of 0.97). There were 26 patients with a parahisian AP, who showed a great variability in the ECG features. Employing the QRS-Polarity algorithm, 34.6% patients had a correct anatomical location, 42.3% had an adjacent location and only 23% an incorrect location. Conclusion: The QRS-Polarity algorithm has a good global accuracy; its precision is high, especially for left lateral AP. This algorithm is also useful for the parahisian AP.

Resumen Antecedentes: En 1996 Iturralde y colaboradores publicaron un algoritmo basado en la polaridad del QRS para determinar la ubicación de las vías accesorias (VA), este algoritmo fue desarrollado antes de la práctica masiva de la electrofisiología invasiva. Objetivo: Validar el algoritmo de la polaridad del QRS en una cohorte moderna de sujetos sometidos a ablación con catéter por radiofrecuencia (ACRF). Nuestro objetivo fue determinar su precisión global y su precisión para las VA parahisianas. Métodos: Realizamos un análisis retrospectivo de pacientes con síndrome de Wolff-Parkinson-White (WPW) a los que se les realizó estudio electrofisiológico (EEF) y ACRF. Empleamos el algoritmo de la polaridad del QRS para predecir la ubicación anatómica de la VA y comparamos este resultado con la ubicación anatómica real determinada en el EEF. Para determinar la precisión se utilizaron el coeficiente kappa de Cohen (k) y el coeficiente de correlación de Pearson. Resultados: Se incluyeron un total de 364 pacientes (edad media 30 años, 57 % varones). La puntuación k global fue de 0,78 y el coeficiente de Pearson de 0,90. También se evaluó la precisión para cada zona, la mejor correlación fue para las VA laterales izquierdas (k de 0.97). Hubo 26 pacientes con VA parahisianas, que mostraron una gran variabilidad en las características del ECG. Empleando el algoritmo de la polaridad del QRS, el 34,6 % de los pacientes tenía una ubicación anatómica correcta, el 42,3 % tenía una ubicación adyacente y solo el 23 % una ubicación incorrecta. Conclusión: El algoritmo de la polaridad del QRS tiene una buena precisión global; su precisión es alta, especialmente para VA lateral izquierdo. Este algoritmo también es útil para la VA parahisiana.

Patrón de Wolff-Parkinson-White en joven atleta de élite: Algoritmo a seguir / Wolff-Parkinson-White pattern in a young elite athlete: Algorithm to follow

RESUMEN El síndrome de Wolff-Parkinson-White es una cardiopatía no estructural poco frecuente que pertenece a los denominados síndromes de preexcitación ventricular. Está asociada al desarrollo de muerte súbita, pues puede inducir a la aparición de arritmias malignas y su diagnóstico puede establecerse a través de la realización de un electrocardiograma. En caso de presentarse en personas vinculadas a la práctica deportiva, con el desarrollo de ejercicio físico intenso, puede incrementar el riesgo de muerte súbita. Se describe el caso de un atleta de alto rendimiento con diagnóstico de síndrome de Wolf Parkinson White y se presentan las pautas a seguir, según los criterios internacionales para la interpretación del electrocardiograma en deportistas.

ABSTRACT Wolff-Parkinson-White syndrome is a rare and non-structural heart disease, which belongs to the ventricular preexcitation syndromes. It is associated with the development of sudden death, as it can induce the appearance of malignant arrhythmias in the patient and its diagnosis can be established through electrocardiogram. If it takes place in people linked to sport, with the development of intense physical exercise, it can increase the risk of sudden death. The case of a high-performance athlete with a diagnosis of Wolff-Parkinson-White syndrome is described, and the guidelines to be followed according to international criteria for the interpretation of the electrocardiogram in sportsmen and women are presented.

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.

Dos décadas de seguimiento exitoso de la primera ablación de arritmias por catéter de radiofrecuencia realizado en la historia de la medicina del Paraguay / Two decades of succesful follow-up of the first radiofrequency catheter arrhythmia ablation done in the history of medicine in Paraguay

La técnica de mapeo endocárdico durante el estudio electrofisiológico ha sido extensamente empleada en el análisis de las taquicardias paroxísticas supraventriculares (TPS). Mediante este mapeo endocárdico y el análisis meticuloso de los electrogramas endocárdicos y los respectivos intervalos de conducción, es posible localizar el sitio de origen de las arritmias y así facilitar su tratamiento ablativo por medio de catéteres de radiofrecuencia. Se describe el caso de un hombre de 29 años con síndrome de Wolff-Parkinson-White (WPW) que manifiestó que presentaba varios episodios documentados de TPS con serio compromiso hemodinámico que motivaba su frecuente internación en terapia intensiva. El mapeo electrofisiológico endocárdico meticuloso demostró la presencia de un haz anómalo de Kent auriculoventricular izquierdo en posición posteroseptal. El período refractario absoluto del haz anómalo de Kent fue de 240 ms. La primera emisión de radiofrecuencia a través de un catéter adecuadamente posicionado previo terminó la taquicardia. La taquicardia permaneció no inducible a partir de entonces. En estas dos décadas de seguimiento clínico, el paciente no ha presentado ni un solo episodio de taquicardia. La curación definitiva generada por la ablación del haz anómalo de Kent ha proporcionado un cambio drástico, total y beneficioso en la calidad de vida al paciente. Los beneficios clínicos y socioeconómicos son mayores cuanto más temprano en la evolución se realice el procedimiento de ablación de arritmias.

Endocardial mapping has been widely used for the analysis of supraventriculartachycardias during electrophysiological study. This mapping and the detailed analysis ofendocardial electrograms and conduction intervals allow for the localization of the site oforigin of the arrhythmias thus facilitating curative treatment with radiofrequency catheterablation. The case describes our 29 years old patient with manifested Wolff-ParkinsonWhitesyndrome that presented frequent, documented episodes of paroxysmal supraventricular tachycardia with serious hemodynamic alteration that needed frequentadmissions to intensive care units despite the use of 2-3 antiarrhythmic agents per day. Adetailed endocardial mapping showed a left posteroseptal accessory pathway. Theaccessory pathway effective refractory period is 240 ms. The first radiofrequency emissionthrough an adequately positioned radiofrequency catheter terminated the tachycardia. Thetachycardia was rendered non-inducible thereafter. In two decades of follow-up, the patienthas not presented a single episode of tachycardia. The definite cure provided by theradiofrequency ablation produced a total, dramatic, and beneficial change in the quality oflife of the patient. The clinical and socio-economical benefits are greater the earlier thearrhythmia ablation procedure is performed.

Seguimiento de 134 pacientes pediátricos con patrón de Wolff-Parkinson-White: evolución natural e intervención médica* / Follow-up of 134 Pediatric Patients with Wolff-Parkinson-White Pattern: Natural Outcome and Medical Treatment

Objetivos Evaluar la evolución de una población pediátrica con patrón de preexcitación ventricular, presencia de taquicardia supraventricular, fibrilación auricular, cardiopatías, mortalidad e intervención médica. Material y métodos Estudio descriptivo observacional. Se registraron pacientes con preexcitación ventricular en el electrocardiograma desde 1976 a 2011. Todos tenían ecocardiograma, 101 pacientes Holter (75,3%) y 69 (51,5%) ergometría. En pacientes seleccionados se realizó ablación por radiofrecuencia. Los datos se expresaron como media y desviación estándar. Resultados Se incluyeron en el estudio 134 pacientes, 80 varones (59,7%). Edad al diagnóstico: 2 días a 18 años, media 6,5 ± 5 años. Seguimiento clínico: 1 mes a 20 años, media 3,6 ± 3,9 años. Consultaron por taquicardia supraventricular 35 pacientes (26,1%), por preexcitación ventricular 16 pacientes (11,9%) y por otras causas 83 pacientes (61,9%); 76 pacientes (56,7%) evidenciaron vía izquierda, 3 pacientes doble vía; 16 pacientes (11,9%) presentaron taquicardia supraventricular durante el seguimiento. En total, 51 pacientes (38%) tuvieron taquicardia ortodrómica a los 6,3 ± 5,8 años, 10 pacientes en el período neonatal; 38 pacientes (28,3%) recibieron antiarrítmicos. No se observó fibrilación auricular. Veintiocho pacientes (20,9%) presentaron cardiopatía, 9 con taquicardia supraventricular. No hubo variables vinculadas con taquicardia supraventricular. En 43 pacientes (32,1%) se realizó ablación por radiofrecuencia. Un paciente murió súbitamente. Otro paciente falleció en el posoperatorio de cardiopatía. Conclusiones 1) Más del 60% de los pacientes permanecieron asintomáticos. 2) No se registró fibrilación auricular. 3) La tasa de muerte súbita fue del 0,75%. 4) Los pacientes con taquicardia supraventricular no sometidos a ablación evolucionaron bien. 5) No se asociaron variables con taquicardia supraventricular. 6) Las vías múltiples siempre desarrollaron taquicardia supraventricular.

Objectives The aim of the study was to evaluate the outcome of a pediatric population with ventricular preexcitation pattern, supraventricular tachycardia, atrial fibrillation, cardiomyopathies, mortality and medical treatment. Methods From 1976 to 2011, a descriptive observational study was conducted on patients with ventricular preexcitation in the electrocardiogram. All patients underwent an echocardiogram, 101 (75.3%) Holter monitoring, and 69 (51.5%) an ergometric test. Radiofrequency ablation was performed in selected patients. Data were expressed as mean and standard deviation. Results The study population consisted of 134 patients, 80 (59.7%) of whom were male. Age at diagnosis ranged from 2 days to 18 years, with a mean of 6.5±5 years. Clinical follow-up lasted 1 month to 20 years, with a mean of 3.6±3.9 years. Thirty five patients (26.1%) consulted for supraventricular tachycardia, 16 (11.9%) for ventricular preexcitation, and the remaining 83 patients (61.9%) for other abnormalities. Seventy-six patients (56.7%) evidenced left conduction pathway and 3 patients a double conduction pathway. Sixteen patients (11.9%) presented supraventricular tachycardia during follow-up. Overall, 51 patients (38%) had orthodromic tachycardia at 6.3±5.8 years, 10 patients during the neonatal period. Thirty-eight patients (28.3%) received antiarrhythmic drugs. No atrial fibrillation was observed. Twenty-eight patients (20.9%) presented cardiomyopathy, 9 with supraventricular tachycardia. No association was found between supraventricular tachycardia and another variable. Forty-three patients (32.1%) underwent radiofrequency ablation. A patient suffered sudden death and another patient died during the postoperative period of corrective surgery. Conclusions 1) More than 60% of patients remained asymptomatic. 2) No atrial fibrillation was recorded. 3) Sudden death rate was 0.75%. 4) Patients with supraventricular tachycardia not submitted to ablation had a favorable outcome. 5) Supraventricular fibrillation was not associated with any variable. 6) Multiple conduction pathways always developed supraventricular tachycardia.

Ablación por radiofrecuencia de una vía accesoria lateral izquierda por abordaje transradial / Radiofrequency ablation of a left free-wall accessory pathway by transradial approach

La ablación por radiofrecuencia de las vías accesorias izquierdas en el síndrome de Wolff-Parkinson-White, convencionalmente se realiza por vía transaórtica retrógrada desde una de las arterias femorales. Nosotros informamos el caso de un paciente portador de una vía anterolateral izquierda, con dificultades para el acceso a través de las arterias ilíacas, cuya vía pudo ser ablacionada utilizando la arteria radial derecha.

Radiofrequency ablation of left free-wall accessory pathways in the Wolff-Parkinson-White syndrome is conventionally made by retrograde transaortic approach from one of the femoral arteries. We report the case of a patient with a left anterolateral pathway, with difficulties in the approach through the iliac arteries, which pathway was ablated from the right radial artery.

Associação da Anomalia de Ebstein com a Síndrome de Wolff-Parkinson-White: relato de caso / Association of Ebstein´s Anomaly with Wolff-Parkinson-White Syndrome: case report

Primeiramente relatada por Wilhelm Ebstein em 1866,a anomalia de Ebstein corresponde a uma doença cardíacacongênita incomum, levando a uma má formaçãoda valva tricúspide. Pode se apresentar com dispnéia,cianose, arritmias, cardiomegalia e insuficiência ventriculardireita. O ecocardiograma confirma o diagnóstico.Descrevemos o caso de uma paciente feminina, 38 anos,com hipertensão arterial sistêmica e fibromialgia, apresentandoSíndrome de Wolff-Parkinson-White associadaà anomalia de Ebstein.

First reported by Wilhelm Ebstein in 1866, Ebstein´sAnomaly is an unusual congenital cardiac disease, leadingto a tricuspid valve bad formation. It can presentsdyspnea, cyanosis, arrythmia, cardiomegaly and rightventricular failure. Echocardiography firms the diagnosis.We describe a female patient, 38 years old, withsystemic arterial hypertension and fibromyalgia, presentingWolff-Parkinson-White Syndrome associated withEbstein´s Anomaly.

Síncope vasovagal em criança com síndrome de Wolff-Parkinson-White: relato de caso / Vasovagal syncope in a child with Wolff-Parkinson-White syndrome: case report

Relata-se o caso de uma criança de nove anos de idade, com quadro de síncope havia dois anos, com eletrocardiograma compatível com síndrome de Wolff-Parkinson-White e história familiar de uma irmã com síncope vasovagal. A paciente foi submetida ao estudo eletrofisiológico para estratificação de risco e ablação da via anômala. Após ablação,permaneceu com os mesmos sintomas, o que a fizeram procurar atendimento médico. Foi então solicitado teste de inclinação (tilt test), o qual foi positivo para síncope vasovagal do tipo mista. Portanto, conclui-se ser a causa dos desmaios a síncope vasovagal, e as alterações eletrocardiográficas compatíveis com Wolff-Parkinson-White seremapenas um achado casual. Após dois anos da primeira consulta, ela se encontra com aumento dos intervalos entre os episódios de síncope.

The authors report a case of a nine years old child presented with syncope for about two years, with electrocardiogram compatible with Wolff-Parkinson-White and a family history revealing a sister with vasovagal syncope. The patient underwent electrophysiological study for risk stratification and ablation of the anomalous pathway. Afterthe ablation procedure, she remained with the same symptoms that caused her to initially seek medical attention, and then performed the tilt test, which was positive for vasovagal syncope of the mixed type. Therefore, the vasovagal syncope was concluded to be the syncope´s cause, and the electrocardiographic changes compatible withWolff Parkinson White were just an incidental finding. Two years after the first consultation, she finds herself with an increased interval between syncopal episodes.

Contributions of the Instituto Nacional de Cardiología in the diagnosis and treatment of the Wolff-Parkinson-White syndrome / Contribuciones del Instituto Nacional de Cardiología al diagnóstico y tratamiento del síndrome de Wolff-Parkinson-White

Since the first description of the disease now known as Wolff-Parkinson-White syndrome, much knowledge has been gained through several experimental and clinical studies all over the world. The Instituto Nacional de Cardiología Ignacio Chávez in Mexco City has not been the exception. In this report, we describe the clinical, electrocardiographic and electrophysiologic contributions of past and present researchers at the Institute, as well as the experience in the diagnosis and treatment of the W-P-W syndrome at this Instituto Nacional de Cardiología Ignacio Chávez.

Desde la primera descripción de la enfermedad que ahora conocemos como Wolff-Parkinson-White, se ha acumulado una fuente importante de conocimientos a través de múltiples estudios clínicos y experimentales realizados en todo el mundo. El Instituto Nacional de Cardiología Ignacio Chávez no ha sido la excepción, en esta revisión se describen las contribuciones de los investigadores de dicho Instituto, tanto en los aspectos clínicos, electrocardiográficos y electrofisiológicos. Asimismo se presenta la experiencia del Instituto en el diagnóstico y tratamiento de esta entidad.

Identificaçäo dos electrogramas intracavitários preditivos de sucesso na ablaçäo de vias anômalas por radiofrequência / Identification of Endocavitary Electrograms Predictive of Identification of Endocavitary Electrograms Predictive of Success for Radiofrequency Ablation of Accessory Atrioventricular Connections

PURPOSE--To analyze the characteristics of atrial (A) and ventricular (V) electrograms, AV and VA intervals relation to determine a precise radiofrequency ablation site. METHODS--A and V electrograms (EG) recorded at successful (group 1) and unsuccessful (group 2) sites in 22 patients submitted to RF catheter ablation were identified. Specific criteria as morphology, AV and VA intervals relation and the presence of an accessory pathway were analyzed. RESULTS--The shortest AV interval with a VEG that precedes the delta wave in the onset of the QRS recorded at the EKG leads was the best outcome predictor. The AV connection potential was only recorded in five out of 22 patients and did not interfere with the result when not present. The interval measured between the onset of the V electrogram and the onset (delta wave) of the QRS complex (V-d) varied from -4.9 to -11msec (m = 7.5 + 1.6) in G1 and from -6 to 15msec (m = 9.6 +/- 3) in G2 (p = 0.03). Unsuccessful sites had the VEG preceding the delta wave but the AV interval was not short. Success in the retrograde mapping of target site seems to be the presence of an atrial potential that occurs simultaneously with the nadir (S wave) of the QRS complex. CONCLUSION--Specific criteria such as morphology of the local VEG, a short AV or VA intervals and a VEG that precede the onset (delta wave) of the QRS identified a successful site for RF ablation. When present the accessory pathway potential indicates a high chance of a successful ablation; however when not present did not decrease the chance of success