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.

Síndrome de Wolff-Parkinson-White com Hipertrofia Ventricular: Preditores de Eventos / Wolff-Parkinson-White Syndrome and Ventricular Hypertrophy: Events Predictors

Fundamentos: A síndrome do PRKAG2 é classificada como uma doença de armazenamento de glicogênio, caracterizada pela presença da síndrome de Wolff-Parkinson-White (WPW), hipertrofia ventricular (HV) e doençado sistema de condução (DSC).Objetivos: Identificar potenciais fatores prognósticos para eventos em indivíduos acometidos por essa doença edescrever as características clínicas. Métodos: Sessenta indivíduos foram acompanhados de março de 2005 a março de 2015, estratificados em doisgrupos: Grupo 1 (G1) - portadores de WPW, HV ou ambos; e Grupo 2 (G2) - indivíduos assintomáticos, comexame físico, eletrocardiograma e ecocardiograma normais. Realizados anamense, exame físico, eletrocardiograma e ecocardiograma. Quando necessário, realizou-se Holter e estudo eletrofisiológico. Resultados: Dos 60 indivíduos selecionados, 18 constituíram o G1. Destes, 11 (61,1%) tinham HV associada à WPW, 6 (33,3%) apresentavam WPW isolada e 1 (5,6%) paciente apresentava HV isolada. A média de idade foi 27,0±16,0 anos e 32 (53,3%) eram do sexo masculino. Apenas indivíduos do Grupo 1 apresentaram eventos isolados: 3 (17,0%) paradas cardíacas, 2 (11,0%) mortes súbitas, 6 (33,0%) implantes de marca-passo, 4 (22,0%) acidentes isquêmicos encefálicos transitórios e 9 (50,0%) eventos combinados. Os potenciais preditores de eventos combinados foram: tamanho de átrio esquerdo (p=0,07) diabetes mellitus (p=0,05) e os bloqueios atrioventriculares (p=0,019). Esses fatores não evidenciaram significância estatística, quando comparados na análise de regressão de Cox. Conclusões: Em portadores de WPW com hipertrofia ventricular ocorreu associação entre diabetes mellitus, bloqueio atrioventricular e tamanho de átrio esquerdo com os principais desfechos.

Background: The PRKAG2 syndrome is classified as a glycogen storage disease, characterized by the presence of the Wolff Parkinson-Whitesyndrome (WPW), ventricular hypertrophy (VH) and conduction system disease (CSD). Objectives: Finding potential prognostic factors for events in individuals affected by this disease and describing the clinical characteristics. Methods: Sixty individuals were monitored from March 2005 to March 2015, being divided into two groups: Group 1 (G1) - patients with WPW, VH or both; and Group 2 (G2) - asymptomatic patients, with normal physical examination, electrocardiogram and echocardiography. It included the performance of medical history, physical examination, electrocardiogram and echocardiogram. Holter and electrophysiological study were performed when necessary. Results: G1 was made of 18 out of the 60 patients selected. Of these, 11 (61.1%) had VH related to WPW, 6 (33.3%) had isolated WPW and 1 (5.6%) patient had isolated VH. The mean age was 27.0±16.0 years and 32 (53.3%) were male. Only the patients in Group 1 had isolated events: 3 (17.0%) cardiac arrests, 2 (11.0%) sudden deaths, 6 (33.0%) pacemaker implants, 4 (22.0%) transient ischemic attacks and 9 (50.0%) combined events. The events predictors in potential combined were: left atrium size (p=0.07) diabetes mellitus (p=0.05) and the atrioventricular blocks (p=0.019). Those factors did not have statistic significance when compared in the Cox regression analysis. Conclusions: In WPV patients with ventricular hypertrophy there was an association of diabetes mellitus, atrioventricular blockand left atrium size with the main outcomes.

Miocardiopatia periparto complicada associada à valva aórtica bicúspide e Síndrome de Wolff-Parkinson-White / Complicated peripartum cardiomyopathy with bicuspid aortic valve and Wolff-Parkinson-White Syndrome

Miocardiopatia periparto é uma síndrome rara, de etiologia ainda desconhecida, caracterizada por disfunção ventricular esquerda nova, no último mês da gestação ou nos primeiros seis meses pós-parto. Os fatores de risco incluem multíparas, gestação gemelar, etnia negra e idade materna >30 anos. Relata-se o caso de miocardiopatia periparto em adolescente de 13 anos, negra, primípara de feto único, com cardiopatiasassociadas (valva aórtica bicúspide e síndrome deWolff-Parkinson-White) que evoluiu com complicações tromboembólicas e desfecho desfavorável.

Peripartum cardiomyopathy is a rare syndrome of unknown etiology, characterized by new left ventricular dysfunction in the last month of pregnancy or during the first six months postpartum. Risk factors include multiparous, twin pregnancy, black ethnicity and maternal age above 30 years. This report describes a case of peripartum cardiomyopathy in black female (13 years old), primiparous, single fetus, associated with cardipatias (bicuspid aortic valve and Wolff- Parkinson-White syndrome) who developed thromboembolic complications with an unfavorable outcome.

Síncope vasovagal em criança com Wolff-Parkinson-White / Vasovagal syncope in child with Wolff-Parkinson-White

Relatamos o caso de uma criança de nove anos de idade, com quadro de síncope há dois anos e eletrocardiograma revelando síndrome de Wolff-Parkinson-White (WPW). História familiar de irmã com síndrome vasovagal. A paciente foi submetida a estudo eletrofisiológico (EEF), para estratificação de risco e ablação da via anômala. Após a ablação, permaneceu com os mesmos sintomas que a fizeram procurar atendimento médico na primeira consulta, sendo então solicitado teste de inclinação (tilt test), que foi positivo para síndrome vasovagal do tipo mista. Conclui-se, portanto, que a causa dos desmaios foi a síndrome vasovagal, sendo as alterações eletrocardiográficas compatíveis com Wolff-Parkinson-White apenas um achado casual. Dois anos após a primeira consulta elaapresenta aumento dos intervalos entre os episódios de síncope.

We report a case of a child nine years old, presented with syncope about two years, with electrocardiogram Wolff-Parkinson-White (WPW) and family history of a sister with vasovagal syndrome. The patient underwent electrophysiological study (EPS) for risk stratification and ablation of the anomalous pathway. After ablation remained with the same symptoms that caused her to seek medical attention at the first consultation, and then asked the tilt test, which was positive for mixed type of vasovagal syndrome. Therefore concluded to be the syncope?s cause, the vasovagal syndrome and electrocardiographic changes compatible with Wolff-Parkinson-White, being just an incidental finding. Two years after the first consultation, she finds with increase interval between episodes of syncope.

Malignant arrhythmia as the first manifestation of Wolff-Parkinson-White syndrome: a case with minimal preexcitation on electrocardiography / Arritmia maligna como primera manifestación del síndrome de Wolff-Parkinson-White: un caso con preexcitación mínima en la electrocardiografía

Wolff-Parkinson-White (WPW) syndrome is defined as the presence of an accessory atrioventricular pathway which is manifested as delta waves and short PR interval on electrocardiography (ECG). However, some WPW cases do not have typical findings on ECG and may remain undiagnosed unless palpitations occur. Sudden cardiac death may be the first manifestation of WPW and develops mostly secondary to degeneration of atrial fibrillation into ventricular fibrillation. In this report, we present a case of undiagnosed WPW with minimal preexcitation on ECG and who suffered an episode of malignant arrhythmia as the first manifestation of the disease.

El síndrome Wolff-Parkinson-White (WPW) se define como la presencia de una vía accesoria atrioventricular que se manifiesta como ondas delta, e intervalos cortos de PR en el electrocardiograma (ECG). Sin embargo, algunos casos de WPW no tienen resultados típicos en el ECG, y pueden permanecer sin diagnosticar a menos que se produzcan palpitaciones. La muerte cardíaca súbita puede ser la primera manifestación de WPW, y se produce principalmente de forma secundaria a la degeneración de la fibrilación auricular en fibrilación ventricular. En este reporte, presentamos un caso no diagnosticado de WPW con preexcitación mínima en el ECG, con un episodio de arritmia maligna como primera manifestación de la enfermedad.

La electrofisiología del Wolff-Parkinson-White en el paciente asintomático con actividad o riesgo profesional alto / The electrophysiology of Wolff-Parkinson-White in the asymptomatic patient with activity or with high professional risk

Objetivo: Describir las características electrofisiológicas en individuos con Wolff-Parkinson-White asintomático con actividad deportiva o alta responsabilidad profesional. Métodos: Se evaluaron 19 individuos, edad media 33 ± 13 años (grupo A). Las características electrofisiológicas fueron comparadas con un grupo control similar con WPW sintomático (grupo B). Resultados: En estado basal el periodo refractario anterógrado y la conducción anterógrada 1:1 sobre el fascículo accesorio fueron más largos en el grupo A (300 ± 48 ms vs 262 ± 32 ms, p < 0.05) y (355 ± 108 ms vs 307 ± 86 ms, p < 0.05), respectivamente. Ningún individuo del grupo A tuvo un periodo refractario anterógrado < 250 ms; y 58% no tuvieron conducción retrógrada sobre el fascículo accesorio vs 4% del grupo B (p< 0.001). La inducción de taquicardia fue significativamente menor (5.2%) en el grupo A vs grupo B (95%) (p < 0.001). Se indujo fibrilación auricular (FA) sólo en uno del grupo A vs en 32% grupo B (p< 0.001). Conclusión: Se confirman las características electrofisiológicas benignas en individuos asintomáticos comparados con sintomáticos. La deficiente conducción anterógrada junto con ausencia de conducción retrógrada explica la baja frecuencia de taquiarritmias y no apoyaría la investigación rutinaria en toda la población asintomática, pero debido a las posibles consecuencias, se mantiene la indicación sistemática con fines de ablación preventiva en el subgrupo de individuos asintomáticos con actividad deportiva o alta responsabilidad profesional.

Objective: Describe the electrophysiological characteristics in subjects with asymptomatic Wolff-Parkinson-White with sports activities or high professional responsibility. Methods: Nineteen subjects, mean age 33 ± 13 years (group A). The electrophysiological characteristics were compared with a matched group with symptomatic WPW (group B). Results: At baseline the anterograde refractory period and the anterograde conduction 1:1 over the accessory pathway were longer in group A (300 ± 48 ms vs 262 ± 32 ms, p <0.05 and 355 ± 108 ms vs 307 ± 86 ms, p <0.05), respectively. None of group A had a anterograde refractory period < 250 ms and 58% showed absence of retrograde conduction over the accessory pathway vs 4% of group B (p < 0.001). Induction of tachycardia was significantly less in group A (5%) than in group B (92%) (p < 0.001). Atrial fibrillation was induced in only one of group A vs 32% of group B (p< 0.001). Conclusion: We confirm the benign electrophysiological characteristics in asymptomatic compared to symptomatic subjects. Poor anterograde conduction along with absence of retrograde conduction explains the low frequency of tachyarrhythmias and would not support the routine investigation of all asymptomatic subjects. But, due to possible consequences, remains the systematic indication for preventive ablation in the subgroup of asymptomatic subjects with sporting activities or high professional responsibility.

Anomalía de Ebstein “tipo B”: caso clínico / Ebstein’s anomaly “type B”: case report

La anomalía de Ebstein es una rara enfermedad cardíacacongénita, con incidencia 1/200.000 nacidos vivos, presenta un espectro morfológico amplio caracterizado por diferentes grados de desplazamiento y adherencia de la valvas septal y posterior de la válvula tricúspide hacia el ventrículo derecho, comunicación interauricular o foramen oval permeable, asociada a degeneración del miocardio subyacente a las valvas posterior y septal incriminadas. El reservorio venoso auricular aumenta su volumen al desplazarse el orificio tricuspídeo efectivo dentro de la cámara de entrada del ventrículo derecho, afectándose su función sistolo-diastólica y aparece cianosis secundaria a cortocircuito a nivel auricular. En 20% - 30% se asocia a síndrome de Wolff-Parkinson-White (WPW). Presentamos el caso clínico de un adolescente de 16 años con anomalía de Ebstein y taquicardia supraventricular, quién presentó evento cerebrovascular isquémico a los 7 años, la evaluación clínica y ecocardiográfica resultó en anomalía de Ebstein tipo B, se realizó ablación por radiofrecuencia eficaz de vía accesoria posterolateral derecha guiada por sistema de navegación, sin embargo, 7 meses después reingresa por disnea progresiva y acentuación de la cianosis, se realiza resonancia magnética y cateterismo cardíaco; para calcular volumen ventricular funcional del ventrículo derecho y medir presiones pulmonares, realizándole corrección bi-ventricular con técnica de Carpentier y reemplazo valvular tricuspídeo (Prótesis Medtronic Advantage N°23), con resultado satisfactorio y evolución clínica a clase funcional I-II NYHA.

Ebstein’s anomaly is a rare congenital heart disease, with incidence 1/200.000 live births, has a broad morphologics pectrum characterized by different degrees of displacement and adherence of the septal and posterior leaflets of the tricuspid valve into the right ventricle atrial septal defect or patent foramen ovale associated with myocardial degeneratio nunderlying the posterior and septal leaflets incriminated. The atrial venous reservoir increases in volume by moving the effective tricuspid orifice in the right ventricle inlet chamber, affecting systolic-diastolic function and appears cyanosis secondary to shunt at the atrial level. In 20% - 30% is associated with Wolff-Parkinson-White (WPW). We report the case of a 16-year Ebstein’s anomaly and supraventricular tachycardia, who presented ischemic stroke event at age 7-year, the clinical and echocardiographic assessment of Ebstein’s anomaly resulted in type B, was performed radiofrequency ablation of accessory pathway effective right postero-lateral guided navigation system, but seven months later readmitted because of progressive dyspnoea and cyanosis accentuation is performed cardiac MRI and catheterization to calculate volume right ventricle and measure functional pulmonary pressures, performing bi-ventricular correction technique Carpentier tricuspid valve replacement (Medtronic Advantage prosthesis No. 23), with satisfactory results and clinical functional class NYHA I-II.

WPW and preexcitation syndromes.

Wolff-Parkinson-White syndrome is a disorder characterized by presence of an accessory pathway which predisposes patients to tachyarrhythmias and sudden death. Among patients with WPW syndrome, atrioventricular reentrant tachycardia (AVRT) is the most common arrhythmia, accounting for 95% of re-entrant tachycardias. It has been estimated that one-third of patients with WPW syndrome have atrial fibrillation (AF). AF is a potentially life-threatening arrhythmia. If an accessory pathway has a short anterograde refractory period, then rapid repetitive conduction to the ventricles during AF can result in a rapid ventricular response with subsequent degeneration to ventricular fibrillation (VF). The accessory pathway may be located anywhere along the atrioventricular valve Most of the patients are young and do not have structural heart disease hence it is important to risk stratify these patients so as to prevent the sudden death. Management of asymptomatic patients with WPW syndrome has always remained controversial Catheter ablation of accessory pathways has become an established mode of therapy for symptomatic patients and asymptomatic patients employed in high-risk professions.

'Hibernating' accessory pathway.

A 13-year-old boy presented with recurrent narrow QRS tachycardia from which he had been suffering for one year. An electrophysiology study revealed a concealed left lateral accessory pathway with inducible orthodromic atrioventricular re-entry tachycardia using the same pathway. The accessory pathway was ablated in January 2004. After the ablation, atrioventricular block was demonstrated (with adenosine), as was ventriculo-atrial block, and the patient had paroxysmal tachycardia one month later. This time, however, the electrocardiogram in sinus rhythm showed a negative delta wave in V1, suggestive of a right-sided accessory pathway. Another electrophysiology study showed no conduction across the left accessory pathway found earlier. The right accessory pathway, which had 'emerged' after the ablation, had an antegrade effective refractory period of 440 msec and a retrograde effective refractory period of <250 msec. Orthodromic atrioventricular re-entry tachycardia using this accessory pathway was easily inducible. The tricuspid annulus was mapped and the second accessory pathway was localized to the right anterolateral region. This was ablated successfully. This is a unique instance of a symptomatic 'hibernating' accessory pathway emerging in adolescence.

Left Ventricular Non-Compaction Associated with WPW Syndrome

Noncompaction of the ventricular myocardium is an embryonic cardiomyopathy that is increasingly being recognized. Noncompaction of LV myocardium, right ventricular myocardium, or both can occur in isolation, in congenital heart diseases, in valvular heart diseases, in neuromuscular disorders, skeletal abnormalities and in endocrinologic abnormalities. Clinical manifestations of ventricular non-compaction include congestive heart failure, arrhythmia, sudden cardiac death and embolic events. This report is illustrative of non-compaction left ventricle associated with WPW syndrome in a 12-year-old girl presented with aborted sudden cardiac death and heart failure

Supraventricular tachycardia in children.

Several different mechanisms are responsible for paroxysmal supraventricular tachycardia in children. Different forms of tachycardia occur at different age. Atrio-ventricular reentry tachycardia results from the presence of congenital atrio-ventricular bypass tracts and is frequently encountered at all ages. Infants may present with ectopic atrial tachycardia or atrial flutter. Atrio-ventricular node reentry tachycardia becomes more frequent in adolescence. Atrial scarring resulting from open heart surgery predisposes to complex intra-atrial reentry. Certain forms of congenital and acquired heart disease are associated with specific types of arrhythmia. Many children with paroxysmal supraventricular tachycardia do not require any therapy. The decision to proceed with treatment should be based on the frequency and severity of symptoms and on the effect of arrhythmia on the quality of life. Infants require medical treatment because of the difficulty to recognize symptoms of tachycardia and a risk of heart failure. Patients with Wolff-Parkinson-White syndrome as well as those with significant heart disease are at risk of sudden death. Syncope in children with paroxysmal tachycardia may indicate a severe fall in cardiac output from extremely rapid heart rate. Patients with potentially life-threatening arrhythmia should not participate in competitive physical activities. Treatment options have undergone significant evolution over the past decade. Indications for the use of specific antiarrhythmic medications have been refined. Contemporary catheter ablation procedures employ different forms of energy allowing for safe and effective procedures. Catheter ablation is the treatment of choice for symptomatic paroxysmal tachycardia in school children and in some infants who failed medical treatment. Surgery is the preferred treatment in few selected cases. The goal of this review is to present the state of the art approach to the diagnosis and management of paroxysmal supraventricular tachycardia in infants, children and adolescents.

Could Kent bundle automaticity be responsible of wide QRS complex tachycardia?

La automaticidad del haz de Kent en general se ha confirmado por la presencia de bloqueos de fase tres y fase cuatro y, más raramente, por la demostración de latidos aislados o repetitivos. A continuación presentamos el caso de un paciente con síndrome de Wolff-parkinson-White (WPW) que durante un estudio electrofisiológico intracavitario presentó una taquicardia de QRS ancho y disociación auriculoventricular evidente. La morfología de "super Wolff" era la misma que la demostrada previamente en flutter o fibrilación auricular conducida a los ventrículos por medio de una vía anómala. Concluimos que este ritmo podría ser originado en el haz de Kent

Ablación con radiofrecuencia de una vía accesoria lateral izquierda durante fibrilación auricular pre-excitada / Localization and radiofrequency catheter ablation of left-sided accessory pathway during atrial fibrillation

La fibrilación durante un estudio electrofisiológico en pacientes con síndrome de Wolff-Parkinson-White es un problema relativamente frecuente que requiere en muchas ocasiones, de la administración de antiarrítmicos o cardioversión eléctrica, prolongando el tiempo del procedimiento. El propósito de este reporte es demostrar que es factible el mapeo y la ablación de una vía accesoria manifiesta durante fibrilación auricular y que así se puede acortar la duración del estudio. Durante el estudio electrofisiológico del paciente desapareció la pre-excitación y espontáneamente o por la manipulación de los catéteres, presentó fibrilación auricular pre-excitada. Decidimos realizar el mapeo de la vía durante esta arritmia porque mostraba máxima pre-excitación y pensamos que esto pudiera facilitar el registro del potencial de Kent y el sitio de éxito de la ablación. Con el catéter de ablación en la posición lateral izquierda y subvalvular se obtuvo un electrograma ventricular precoz y una deflexión rápido previa a la actrivación ventricular que corresponde al potencial del haz de Kent y que no observamos durante latidos no pre-excitados. Al aplicar la radiofrecuencia con control de temperatura al 70ºC, se eliminó la conducción anterógrada de la vía en los primeros tres segundos y continuamos la radiofrecuencia durante 2 minutos. El tiempo del procedimiento fue de 60 minutos. Concluimos que realizar el mapeo y ablación de una vía accesoria manifiesta durante fibrilación auricular es posible y que además de acortar la duración del procedimiento de ablación puede evitar cardioversiones eléctricas repetidas

Clinical and electrophysiological characteristics in Korean patients with WPW syndrome

This study was designed to investigate the clinical and electrophysiologic characteristics of WPW syndromes in Korea. A total of 400 symptomatic WPW syndrome patients were consecutively recruited. The most common documented symptomatic tachyarrhythmia was orthodromic atrioventricar reentrant tachycardia (75.3%), followed by atrial fibrillation (31.3%), and antidromic atrioventricular reentrant tachycardia (6.2%). There was a higher incidence of multiple bypass tract in patients with antidromic tachycardia than in those with orthodromic tachycardia (30.4 vs 4.3%, P < 0.001). The inducibility of tachyarrhythmia with electrophysiologic study in this study population was 95.8%. The most frequent location of the accessory pathway was the left free wall (48.0%), followed by the right free wall (29.1%), posterior septum (17.5%) and anterior septum (3.5%). These results indicated that 1) clinical and electrophysiological characteristics of Korean patients with WPW syndrome were similar to those of western countries and 2) the electrophysiologic study was important in the evaluation of patients with WPW syndrome.

Early intrinsic deflection--a marker for successful radiofrequency ablation of overt accessory pathways.

Precise localization of accessory pathways (APs) is crucial to minimize radiofrequency (RF) energy applications in the Wolff-Parkinson-White (WPW) syndrome. Although several markers have been described for identifying APs, no gold standard has thus far been established. The present study attempted to validate the hypothesis that an early intrinsic deflection (ID) would be identifiable in the unipolar ventriculogram, if this was recorded at or near the site of endocardial breakthrough of the AP. The electrograms of 23 patients with the WPW syndrome who underwent RF ablation were analysed using a computer-based system. A total of 50 electrograms (19 successful and 31 unsuccessful RF energy applications) were studied. The downstroke of the unipolar ventriculogram was measured at 1 msec intervals for the dV/dt; the maximal dV/dt (the most rapid segement of the downstroke) was considered as the ID. The following parameters were found to differentiate between successful and unsuccessful RF ablation attempts: (i) Timing of the ID relative to the delta wave onset (ID-delta = plus 11 +/- 21 msec versus minus 18 +/- 22 msec, p < 0.001). (ii) Timing of the ID relative to the onset of the unipolar ventriculogram (Vu-ID = 14 +/- 7 msec versus 29 +/- 15 msec, p < 0.001). (iii) Maximal dV/dt in the initial 20 msec of the unipolar ventriculogram (367 +/- 146 microV/msec versus 207 +/- 97 microV/msec, p < 0.001). The other parameters (probable AP potential, bipolar ventriculogram timing, continuous electrical activity, unipolar signal morphology) were not helpful in this regard. Hence, the identification of the ID and measurement of its timing is helpful in localising overt APs for successful delivery of RF energy.

Adenosina para la supresión de taquicardia supraventricular paroxística en un recién nacido: primer caso en México / Adenosine for the supression of paroxysmal supraventricular tachycardia in a newborn. first case in Mexico

Se presenta el caso de un paciente de 20 días de edad en quien se detectó taquicardia supraventricular por reentrada atrioventricular ortodrómica con frecuencia de 300/minutos. Se intentó la supresión de ésta mediante maniobras vagales y posteriormente con digoxina. Debido a que no se logró el control del ritmo cardiaco, se administró adenosina endovenosa a dosis de 0.05 mg/kg, obteniéndose de inmediato una respuesta favorable y posteriormente ritmo sinusal normal. En los siguientes meses, bajo tratamiento con digoxina, el niño se ha mantenido con frecuencias cardiacas normales. Este es el primer paciente pediátrico que se maneja con adenosina en México. Aunque en otros países la experiencia también es limitada, las características de la adenosina permiten recomendarla como fármaco de primera elección en el tratamiento de la taquicardia supraventricular paroxística

Un nuevo algoritmo electrocardiográfico para la localización de las vías accesorias utilizando únicamente la polaridad del complejo QRS / A new electrocardiographic algorithm for the localization of accessory pathways using only the polarity of the QRS complex

Entre abril de 1992 y junio de 1994, se realizó ablación con radiofrecuencia de vías anómalas en 250 pacientes con taquicardias supraventriculares por reentrada auriculoventricular, la cual fue exitosa en 232 pacientes (93 por ciento). De esta población, estudiamos 102 pacientes con preexitación manifiesta en el electrocardiograma basal. Ninguno de ellos tenía cardiopatías congénitas o adquiridas que pudieran afectar la morfología del complejo QRS. Analizamos unicamente la polaridad del complejo QRS en las derivaciones DIII, V1 y V2, y con esto logramos elaborar un algoritmo para localizar la inserción de la vía accesoria en cinco sitios con un 88 por ciento de probabilidad de éxito. Este análisis electrocardiográfico en pacientes con síndrome de Wolff-Parkinson-White facilita el diagnóstico topográfico de la zona de preexitación y mejora los resultados de la ablación transcatéter con radiofrecuencia