Electrophysiological demonstration of nonselective His-Purkinje system capture with para-Hisian pacing.

BACKGROUND: The adverse effects of conventional right ventricular (RV) apical pacing prompted the search for more physiological pacing sites, such as selective and nonselective His bundle pacing (HBP), a variant of nonselective HBP (para-Hisian pacing), and mid-septal pacing. However, knowledge of their true benefit on the physiology of ventricular activation, lead stability, and pacing thresholds is limited. METHODS AND RESULTS: We included 152 consecutive patients (mean age 61 ± 24, 63% men) in this retrospective study. Of these, 137 patients with different bradyarrhythmias underwent active fixation lead implantation at the RV apex (n = 54), para-Hisian region (n = 66), or mid interventricular septum (n = 17). Fifteen patients with ventricular preexcitation due to an accessory pathway not undergoing pacing were included as controls. A 12­lead ECG was recorded in all patients, and cardiac electrical synchrony was assessed using the Synchromax® cross-correlation cardiac synchrony index (CSI). RESULTS: QRS duration was prolonged in all pacing sites: from 114 ± 28 to 160 ± 29 (RV apex), from 110 ± 28 to 122 ± 29 (para-Hisian), and from 121 ± 24 to 154 ± 30 (mid interventricular septum). The CSI was significantly improved only in patients undergoing para-Hisian pacing, despite a slight widening of the QRS interval. There was no difference in pacing thresholds and sensed R-wave voltage between pacing sites. Only 1 lead, implanted at the para-Hisian region (1.5%), was dislodged towards the mid septum 48 h after implantation but did not require repositioning. CONCLUSIONS: QRS duration was not associated with changes in CSI, meaning that QRS width does not significantly affect electrical synchrony.

Slow pathway elimination using antegrade conduction improvement with fast atrial pacing during AVNRT radiofrequency ablation: a proof-of-concept study.

BACKGROUND: Radiofrequency (RF) ablation of slow pathway (SP) is usually performed in sinus rhythm while monitoring the occurrence of a slow junctional rhythm (JR). JR although sensitive, is not specific for elimination of SP conduction. Our objective was to prospectively evaluate feasibility and safety of SP elimination using fast atrial rate pacing (FAP) during RF delivery. METHODS: Consecutive patients admitted for atrioventricular nodal re-rentrant tachycardia (AVNRT) ablation were included. The rate of proximal coronary sinus (CS) pacing was set to a value constantly yielding antegrade SP conduction, while carefully monitoring the AH interval. RF delivery (at the lower part of Koch's triangle) was considered successful if the AH shortened ≥ 14 ms or if transition from Wenckebach (WK) periods to a 1:1 conduction occurred. RESULTS: 24 patients were included (54 ± 20 y). Typical AVNRT was induced in all (cycle length 349 ± 83 ms). RF delivery during CS pacing (335 ± 73 ms) led to AH shortening by 51 ± 25 ms in 13 patients. In 10 patients, a transition from 3:2 or 4:3 WK periods to 1:1 conduction occurred during the successful pulse. In one patient, atrial fibrillation was systematically induced during FAP, requiring conventional ablation. Non-inducibility, and SP conduction disappearance was obtained in all patients. No patient developed AV block. After a follow-up of 12 ± 3 months, no recurrences were observed. CONCLUSION: SP ablation using FAP during RF delivery allows direct visualisation of its disappearance. In our cohort of patients, this technique was feasible without safety compromise.

The first Latin American Catheter Ablation Registry.

AIMS: To assess the results of transcatheter ablation of cardiac arrhythmias in Latin America and establish the first Latin American transcatheter ablation registry. METHODS AND RESULTS: All ablation procedures performed between 1 January and 31 December 2012 were analysed retrospectively. Data were obtained on the characteristics and resources of participating centres (public or private institution, number of beds, cardiac surgery availability, type of room for the procedures, days per week assigned to electrophysiology procedures, type of fluoroscopy equipment, availability and type of electroanatomical mapping system, intracardiac echo, cryoablation, and number of electrophysiologists) and the results of 17 different ablation substrates: atrio-ventricular node reentrant tachycardia, typical atrial flutter, atypical atrial flutter, left free wall accessory pathway, right free wall accessory pathway, septal accessory pathway, right-sided focal atrial tachycardia, left-sided focal atrial tachycardia, paroxysmal atrial fibrillation, non-paroxysmal atrial fibrillation, atrio-ventricular node, premature ventricular complex, idiopathic ventricular tachycardia, post-myocardial infarction ventricular tachycardia, ventricular tachycardia in chronic chagasic cardiomyopathy, ventricular tachycardia in congenital heart disease, and ventricular tachycardias in other structural heart diseases. Data of 15 099 procedures were received from 120 centres in 13 participating countries (Argentina, Bolivia, Brazil, Chile, Colombia, Cuba, El Salvador, Guatemala, Mexico, Peru, Dominican Republic, Uruguay, and Venezuela). Accessory pathway was the group of arrhythmias most frequently ablated (31%), followed by atrio-ventricular node reentrant tachycardia (29%), typical atrial flutter (14%), and atrial fibrillation (11%). Overall success was 92% with the rate of global complications at 4% and mortality 0.05%. CONCLUSION: Catheter ablation in Latin America can be considered effective and safe.

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.

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.(AU)

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.(AU)

Estudio cooperativo sobre umbral crónico de estimulación, valorado como carga transferida en 153 pacientes con marcapasos definitivo y electrodos de alta bicompatibilidad / Cooperative study of chronic threshold simulation evaluated as a locading charge in 153 patients with permanent pacemaker using high bicompatibilitty electrodes

En la presente comunicación se exponen los resultados de la evaluación del umbral crónico de estimulación en 153 pacientes con parcapasos definitivo y electrodos de superficie fractal. El grupo estudado, estaba constituido por 58 mujeres y 85 hombres, a quienes se habla implantado un marcapasos definitivo, multprogramable, unicameral (VVM), con electrodo bipolar endocavitario de superficie fractal, ubicado en apex de ventriculo derecho (Biotronik, TIR 60 BP, con 6 mm2 de superficie de estimulación). El análisis de los dados obtenidos (expresados como carga transferida, en microcoulombios), demonstró muy bajos umbrales cronicos 0,81 mc, SDñ0,39, (rango 0,65 -2,54 mc). Considerando un margen de seguridad del 100 'por cento' por sobre el umbral cronico hallado, se determina que en la población estudada, la reprogramación de la saida de 4,8 voltios a 2,4 voltios (en ambos casos con 0,5 milesegundos de ancho de pulso), es posible en el 73,8 'por cento' de los casos (113 pacientes), permitiendo un incremento en el tiempo de prestación para todo el grupo del orden del 20,9 'por cento'. Las consecuencias de esta modificación en la carga transferida incidem directamente en el paciente (optimizacion del sensado y recambio de generador menos frecuente), y socialmente (um ahorro de recursos que puedem ser empleados en otros aspectos de la salud pública).