Taquicardia incesante del tracto de salida del ventrículo derecho - ¿Taquimiocardiopatía?: El enigma / Incessant right ventricular outflow tract tachycardia - Tachycardiomyopathy? The enigma

RESUMEN Las taquicardias ventriculares de larga duración o incesantes pueden causar insuficiencia cardíaca, disfunción del ventrículo izquierdo y cardiomiopatía, cuadros que revierten una vez resueltas las arritmias. Se trata de un diagnóstico de exclusión: puede existir una cardiopatía de base que empeora con la taquicardia y debe precisarse si la arritmia lleva a la cardiomiopatía (puede existir un subregistro) o viceversa. Se presenta un paciente con taquicardia incesante del tracto de salida del ventrículo derecho, de larga evolución, con repercusión hemodinámica, cardiomiopatía dilatada y disfunción grave del ventrículo izquierdo, rebelde a fármacos antiarrítmicos y con dos ablaciones fallidas, pendiente de biopsia endomiocárdica y nueva ablación de su taquicardia. Se discuten algunas pistas para diferenciar las arritmias del tracto de salida del ventrículo derecho, en sus variantes benignas (las más frecuentes) y malignas. Algunas pistas para diferenciarlas son: la duración del complejo QRS, el intervalo de acoplamiento de la extrasístole y la frecuencia de la taquicardia.

ABSTRACT Long-lasting or incessant ventricular tachycardias may cause heart failure, left ventricular dysfunction, and cardiomyopathy; conditions that reverse once the arrhythmias have been solved. This is a diagnosis of exclusion: there may be a basic heart disease that worsens with the tachycardia and it must be clarified whether the arrhythmia leads to cardiomyopathy (there may be an underregistration) or vice versa. A patient with incessant right ventricular outflow tract tachycardia, with long evolution, hemodynamic repercussion, dilated cardiomyopathy and severe dysfunction of the left ventricle, refractory to antiarrhythmic drugs and with two failed ablations, pending endomyocardial biopsy and new ablation of his tachycardia is presented. Some clues to differentiate right ventricular outflow tract arrhythmias, in their benign (most frequent) and malignant variants, are discussed. Some clues to differentiate them are: the duration of the QRS complex, the coupling interval of premature contractions and the heart rate of the tachycardia.

Efecto electromecánico de los antiarrítmicos clase Ic durante el tratamiento de arritmias auriculares en cardiopatías congénitas / Electromechanical effect of Ic class antiarrhythmic drugs during the treatment of atrial arrhythmias in congenital heart diseases

Introducción: los fármacos antiarrítmicos son la primera línea de tratamiento para el control de las taquiarritmias en el paciente pediátrico. La terapéutica con drogas clase Ic en los pacientes con cardiopatías congénitas ha sido limitada, por los reportes que demostraron incremento de la mortalidad en los sujetos con cardiopatías estructurales. Objetivo: valorar el efecto de los antiarrítmicos clase Ic sobre los fenómenos electro-mecánicos cardiacos en los niños con cardiopatías congénitas con arritmias auriculares. Métodos: se realizó un estudio analítico, observacional, longitudinal y prospectivo en los pacientes con cardiopatías congénitas que desarrollaron arritmias auriculares, tratados con antiarrítmicos clase Ic en el Cardiocentro Pediátrico William Soler Se analizaron variables electrocardiográficas, así como estimación de la función sistodiastólica mediante el ecocardiograma. Resultados: fueron evaluados 46 pacientes, 25 tratados con flecainida (grupo I) y 21 con propafenona (grupo II) durante 4,57±0,86 años. La taquicardia por reentrada intraatrial fue la arritmia de mayor incidencia (58,69 por ciento), mientras que, la tetralogía de Fallot, el defecto cardiaco más común (36,9 por ciento). Las variables electrocardiográficas no sufrieron variaciones nítidas durante el seguimiento. El análisis comparativo intragrupal demostró la preservación de la función sistólica en la totalidad de los sujetos (I, p= 0,275; II, p= 0,262). Comportamiento análogo exhibió la función diastólica, expresada en el índice de Tei (I, p= 0,244; II, p= 0,286). Conclusiones: la utilización de antiarrítmicos clase Ic en los pacientes pediátricos con cardiopatías congénitas no se asocia a largo plazo con alteraciones electrocardiográficas significativas ni compromiso de la función sistodiastólica, por lo que se recomienda su uso en esta población(AU)

Introduction: antiarrhythmic drugs are the first line of treatment for the control of tachyarrhythmias in pediatric patients. Therapy with Ic class drugs in patients with congenital heart disease has been limited, mainly due to reports that showed an increase in mortality in patients with structural heart disease. Objective: to assess the effect of Ic class antiarrhythmic drugs on cardiac electro-mechanical phenomena in children with congenital heart disease with atrial arrhythmias. Methods: an analytical, observational, longitudinal and prospective study was performed in patients with congenital heart diseases who developed atrial arrhythmias treated with Ic class antiarrhythmic drugs in William Soler Pediatric Cardiocenter. Electrocardiographic variables were analyzed, as well as the estimation of systo-diastolic function by echocardiography. Results: 46 patients were evaluated, 25 treated with flecainide (group I) and 21 with propafenone (group II) during 4.57 ± 0.86 years. The intra-atrial reentrant tachycardia was the arrhythmia with the highest incidence (58.69 percent); while tetralogy of Fallot was the most common cardiac defect (36.9 percent). The electrocardiographic variables did not undergo sharp variations during the follow-up. The intergroup comparative analysis showed the preservation of systolic function in all subjects (I, p= 0.275; II, p= 0.262). Analogous behavior showed diastolic function, that was expressed in the Tei index (I, p= 0.244; II, p= 0.286). Conclusions: the use of Ic class antiarrhythmic drugs in pediatric patients with congenital heart disease is not associated in the long term with significant electrocardiographic alterations or compromise of systo-diastolic function, so its use is recommended in this population(AU)

Efecto electromecánico de los antiarrítmicos clase Ic durante el tratamiento de arritmias auriculares en cardiopatías congénitas / Electromechanical effect of Ic class antiarrhythmic drugs during the treatment of atrial arrhythmias in congenital heart diseases

Introducción: los fármacos antiarrítmicos son la primera línea de tratamiento para el control de las taquiarritmias en el paciente pediátrico. La terapéutica con drogas clase Ic en los pacientes con cardiopatías congénitas ha sido limitada, por los reportes que demostraron incremento de la mortalidad en los sujetos con cardiopatías estructurales. Objetivo: valorar el efecto de los antiarrítmicos clase Ic sobre los fenómenos electro-mecánicos cardiacos en los niños con cardiopatías congénitas con arritmias auriculares. Métodos: se realizó un estudio analítico, observacional, longitudinal y prospectivo en los pacientes con cardiopatías congénitas que desarrollaron arritmias auriculares, tratados con antiarrítmicos clase Ic en el Cardiocentro Pediátrico William Soler . Se analizaron variables electrocardiográficas, así como estimación de la función sistodiastólica mediante el ecocardiograma. Resultados: fueron evaluados 46 pacientes, 25 tratados con flecainida (grupo I) y 21 con propafenona (grupo II) durante 4,57±0,86 años. La taquicardia por reentrada intraatrial fue la arritmia de mayor incidencia (58,69 por ciento), mientras que, la tetralogía de Fallot, el defecto cardiaco más común (36,9 por ciento). Las variables electrocardiográficas no sufrieron variaciones nítidas durante el seguimiento. El análisis comparativo intragrupal demostró la preservación de la función sistólica en la totalidad de los sujetos (I, p= 0,275; II, p= 0,262). Comportamiento análogo exhibió la función diastólica, expresada en el índice de Tei (I, p= 0,244; II, p= 0,286). Conclusiones: la utilización de antiarrítmicos clase Ic en los pacientes pediátricos con cardiopatías congénitas no se asocia a largo plazo con alteraciones electrocardiográficas significativas ni compromiso de la función sistodiastólica, por lo que se recomienda su uso en esta población(AU)

Introduction: antiarrhythmic drugs are the first line of treatment for the control of tachyarrhythmias in pediatric patients. Therapy with Ic class drugs in patients with congenital heart disease has been limited, mainly due to reports that showed an increase in mortality in patients with structural heart disease. Objective: to assess the effect of Ic class antiarrhythmic drugs on cardiac electro-mechanical phenomena in children with congenital heart disease with atrial arrhythmias. Methods: an analytical, observational, longitudinal and prospective study was performed in patients with congenital heart diseases who developed atrial arrhythmias treated with Ic class antiarrhythmic drugs in William Soler Pediatric Cardiocenter. Electrocardiographic variables were analyzed, as well as the estimation of systo-diastolic function by echocardiography. Results: 46 patients were evaluated, 25 treated with flecainide (group I) and 21 with propafenone (group II) during 4.57 ± 0.86 years. The intra-atrial reentrant tachycardia was the arrhythmia with the highest incidence (58.69 percent); while tetralogy of Fallot was the most common cardiac defect (36.9 percent). The electrocardiographic variables did not undergo sharp variations during the follow-up. The intergroup comparative analysis showed the preservation of systolic function in all subjects (I, p= 0.275; II, p= 0.262). Analogous behavior showed diastolic function, that was expressed in the Tei index (I, p= 0.244; II, p= 0.286). Conclusions: the use of Ic class antiarrhythmic drugs in pediatric patients with congenital heart disease is not associated in the long term with significant electrocardiographic alterations or compromise of systo-diastolic function, so its use is recommended in this population(AU)

Electrocardiographic Markers of Appropriate Implantable Cardioverter-Defibrillator Therapy in Young People with Congenital Heart Diseases.

Implantable cardioverter-defibrillators (ICDs) are increasingly utilized in patients with congenital heart disease (CHD). Prediction of the occurrence of shocks is important if improved patient selection is desired. The electrocardiogram (ECG) has been the first-line tool predicting the risk of sudden death, but data in CHD patients are lacking. We aim to evaluate the predictive value of electrocardiographic markers of appropriate therapy of ICD in young people with CHD. We conducted a prospective, longitudinal study, in twenty-six CHD patients (mean age 24.7 ± 5.3 years) who underwent first ICD implantation. Forty-two age- and diagnosis-matched controls were recruited. Twelve-lead ECG and 24 h Holter analysis were performed during a mean follow-up of 38.9 months. Data included heart rate, heart rate variability, QRS duration (QRSd), QTc interval and its dispersion, Tpeak-Tend (Tp-Te) interval and its dispersion, presence of fragmented QRS (fQRS), T wave alternans, atrial arrhythmias, and non-sustained ventricular tachycardia. Implant indication was primary prevention in ten cases (38.5%) and secondary prevention in 16 (61.5%). Overall, 17 subjects (65.3%) received at least one appropriate and effective ICD discharge. fQRS was present in 64.7% of cases with ICD therapy compared with patients without events or controls (p < 0.0001). Tp-e and Tp-e dispersion were significantly prolonged in patients with recurrences (113.5 and 37.2 ms) versus patients without ICD discharge (89.6 and 24.1 ms) or controls (72.4 and 19.3 ms) (p < 0.0001 and p < 0.0001, respectively). On univariate Cox regression analysis QRSd (hazard ratio: 1.19 per ms, p = 0.003), QTc dispersion (hazard ratio: 1.57 per ms, p = 0.002), fQRS (hazard ratio: 3.58 p < 0.0001), Tp-e (hazard ratio: 2.27 per ms, p < 0.0001), and Tp-e dispersion (hazard ratio: 4.15 per ms, p < 0.0001), emerged as strong predictors of outcome. On multivariate Cox analysis fQRS, Tp-e and Tp-e dispersion remained in the model. The presence of fQRS, and both Tp-e and Tp-e dispersion are useful ECG tools in daily clinical practice to identify CHD patients at risk for appropriate ICD therapy.

Key Role of Pacing Site as Determinant Factor of Exercise Testing Performance in Pediatric Patients with Chronic Ventricular Pacing.

Chronic right ventricular (RV) apical pacing has been associated with deterioration of functional capacity and chronotropic incompetence during exercise testing in children. The effects of alternative pacing site on exercise performance in pediatric population remain unknown. We evaluated the influence of ventricular pacing site on exercise capacity in pediatric patients with complete congenital atrioventricular block requiring permanent pacemaker therapy. Sixty-four children paced from RV apex (n = 26), RV midseptum (n = 15) and left ventricular (LV) apex (n = 23) were studied cross-sectionally. Treadmill exercise stress testing was performed according to modified Bruce protocol. LV apical pacing was associated with greater exercise capacity. In comparison with the other study groups, children with RV apical pacing showed significantly lower VO2peak (37 ± 4.11; p = 0.003), O2 pulse (8.78 ± 1.15; p = 0.006), metabolic equivalents (7 ± 0.15; p = 0.001) and exercise time (6 ± 3.28; p = 0.03). Worse values in terms of maximum heart rate (139 ± 8.83 bpm; p = 0.008) and chronotropic index (0.6 ± 0.08; p = 0.002) were detected in the RV apical pacing group although maximal effort (respiratory exchange ratio) did not differ among groups (p = 0.216). Pacing from RV apex (odds ratio 9.4; confidence interval 2.5-18.32; Wald 4.91; p = 0.0036) and low peak heart rate achieved (odds ratio 3.66; confidence interval 0.19-7.4; Wald 4.083; p = 0.015) predicted significantly decrease in exercise capacity. Duration of pacing, gender, VVIR mode, baseline heart rate and QRS duration had not significant impact on exercise capacity. The site of ventricular pacing has the major impact on exercise capacity in children requiring permanent pacing. Among the sites assessed, LV apex is related to the better exercise performance.

Diastolic function in paced children with cardiac defects: septum vs apex.

In children with structural congenital heart disease (CHD), the effects of chronic ventricular pacing on diastolic function are not well known. On the other hand, the beneficial effect of septal pacing over apical pacing is still controversial.The aim of this study was to evaluate the influence of different right ventricular (RV) pacing site on left ventricular (LV) diastolic function in children with cardiac defects.Twenty-nine pediatric patients with complete atrioventricular block (CAVB) and CHD undergoing permanent pacing were prospectively studied. Pacing sites were RV apex (n = 16) and RV septum (n = 13). Echocardiographic assessment was performed before pacemaker implantation and after it, during a mean follow­up of 4.9 years.Compared to RV septum, transmitral E-wave was significantly affected in RV apical pacing (95.38 ± 9.19 vs 83 ± 18.75, p = 0.038). Likewise, parameters at the lateral annular tissue Doppler imaging (TDI) were significantly affected in children paced at the RV apex. The E´ wave correlated inversely with TDI lateral myocardial performance index (Tei index) (R2= 0.9849, p ≤ 0.001). RV apex pacing (Odds ratio, 0.648; confidence interval, 0.067-0.652; p = 0.003) and TDI lateral Tei index (Odds ratio, 31.21; confidence interval, 54.6-177.4; p = 0.025) predicted significantly decreased LV diastolic function.Of the two sites studied, RV septum prevents pacing-induced reduction of LV diastolic function.

Estimulación cardíaca en pediatría: ¿sigue siendo el ventrículo derecho el sitio óptimo? / Cardiac pacing in pediatrics: Is still the right ventricle the optimal pacing site?

La estimulación cardíaca permanente se indica en pediatría, con mayor frecuencia, debido al bloqueo aurículo-ventricular. El ventrículo derecho ha sido tradicionalmente el sitio estimulado, dada la factibilidad del acceso, la estabilidad del electrodo y elmantenimiento de umbrales crónicos adecuados. Sin embargo, dicha estimulación se asocia a un patrón disincrónico de activación ventricular, que puede producir remodelado y deterioro de la función ventricular izquierda. En la población pediátrica,donde la estimulación se inicia muchas veces desde edades tempranas y con unalarga expectativa de vida, constituye una premisa la preservación de la función cardíaca, por lo que la prevención de la disincronía mediante la utilización de sitios alternativos de estimulación, más que una prioridad, constituye un reto. El presente artí-culo tiene el objetivo de mostrar los efectos de la estimulación ventricular derecha, así como las evidencias demostradas del beneficio e implicaciones clínicas y prácticasde los sitios alternativos de estimulación en la población pediátrica(AU)

Dual-Chamber Stimulation with Single-Lead VDD Pacing System in Mustard Surgery.

Sinus node disease is a problem encountered in patients after the Mustard surgery, requiring a pacemaker implantation. The knowledge of the complexity anatomy is crucial because of the possible challenges associated with this procedure. We report a case of a 24-year-old woman presented with symptomatic bradycardia, in which a bicameral stimulation using a single-lead VDD pacing system was successfully performed.

Implantación de marcapaso bicameral a través de vena cava superior izquierda persistente / Dual-chamber pacemaker implantation through persistent left superior vena cava

La persistencia de la vena cava superior izquierda es una anomalía congénita que se presenta como resultado de un trastorno degenerativo en la vena cardinal anterior izquierda. Se encuentra en el 3 por ciento de los sujetos sanos y hasta el 10 por ciento de los que presentan cardiopatías congénitas. Su hallazgo es generalmente accidental, durante la realización de procedimientos agresivos, que pueden complicar la implantación de dispositivos cardíacos antiarrítmicos. Se presenta el caso de una paciente con vena cava superior izquierda persistente y ausencia de vena cava superior derecha, con antecedentes de corrección quirúrgica de conexión anómala de venas pulmonares, que evolutivamente desarrolló enfermedad del nodo sinusal y requirió implantación definitiva de marcapaso bicameral(AU)

Novel Vascular Malformation in an Affected Newborn with Deletion Del(4)(q31.3).

We report on a newborn male patient with a terminal deletion in the long arm of the chromosome 4 with a congenital heart defect unreported before in association with this syndrome. The patient had multiple congenital anomalies including a pointed duplicated fingernail, low set posteriorly rotated ears, large anterior fontanel, micrognathia, glabellar capillary vascular malformation, and Interrupted Aortic Arch type C. The patient died due to multiple congenital malformations; a peripheral chromosome analysis showed 46, XY, del(4)(q31.3) de novo. The only reported case with the same deletion was a male newborn that exhibited the pattern of minor anomalies of deletion 4q31 syndrome. The parents were cytogenetically normal. We compare clinical signs to other cases with a deletion in long arm of chromosome 4.