Prospective assessment after pediatric cardiac ablation: demographics, medical profiles, and initial outcomes.

INTRODUCTION: A multicenter prospective study was designed and implemented to assess the short- and longer-term results and risks associated with radiofrequency (RF) ablation in children. METHODS AND RESULTS: Patients recruited for the study were aged 0 to 16 years with supraventricular tachycardia due to accessory pathways or AV nodal reentrant tachycardia (AVNRT), excluding patients with nontrivial congenital heart disease. A national registry also was established, and contributing centers were encouraged to enroll all pediatric patients, aged 0 to 21 years, undergoing ablation at their center. This report summarizes acute results of these procedures. For analysis, subjects were divided into three groups: the prospective cohort (n = 481), cohort-eligible registry participants (n = 504), and not cohort eligible registry participants (n = 1,776). Prospectively enrolled cohort patients were similar to cohort-eligible patients in terms of demographic and other patient characteristics. Overall success rates for RF ablation were high (95.7%), with higher success rates for left-sided and particularly left free-wall pathways (97.8%) than right free-wall pathways (90.8%). Complications of both electrophysiologic study and RF ablation were infrequent (4.2% and 4.0%, respectively), and there were no deaths. AV block was uncommon overall (1.2%) and was limited to ablation in AVNRT (2.1%) and septal accessory pathways (3.0%). CONCLUSION: Despite the multicenter and prospective design, the study demonstrates high success rates and low complication rates, which are comparable to prior single-center retrospective studies. These results may serve as the current best benchmark for expected results in the pediatric population, aged 0 to 16 years, both in terms of acute success rates and the occurrence of complications.

Prospective assessment after pediatric cardiac ablation: recurrence at 1 year after initially successful ablation of supraventricular tachycardia.

OBJECTIVES: A multicenter prospective study was performed to assess the results and risks associated with radiofrequency ablation in children. This report focuses on recurrences following initially successful ablation. METHODS: Patients recruited for the study were aged 0 to 16 years and had supraventricular tachycardia due to accessory pathways or atrioventricular nodal reentrant tachycardia (AVNRT), excluding patients with more than trivial congenital heart disease. A total of 481 patients were recruited into the prospective cohort and were followed at 2, 6, and 12 months following ablation. RESULTS: There were 517 successfully ablated substrates out of 540 attempted (95.7%). Loss to follow-up for individual substrates was 3.3%, 10.6%, and 21.2% at 2, 6, and 12 months, respectively. Recurrence was observed in 7.0%, 9.2%, and 10.7% of these substrates at 2, 6, and 12 months, respectively (adjusted for loss to follow-up as an independent source of data censoring). Recurrence rate varied by substrate location (24.6% for right septal, 15.8% for right free wall, 9.3% for left free wall, and 4.8% for left septal), as well as for AVNRT versus all others (4.8% vs 12.9%) at 12 months. The recurrence rate was higher for substrates ablated using power control but was not a function of whether isoproterenol was used for postablation testing. CONCLUSIONS: Recurrence after initially successful ablation occurs commonly in children. It is least common after AVNRT ablation and most common following ablation of right-sided pathways. These results serve as a benchmark for the time course of recurrence following initially successful ablation of supraventricular tachycardia in children.

Unexpected loss of bipolar lead function associated with lead connection design in dual chamber pacemakers.

Unexpected loss of bipolar pacing function can occur in Guidant VIGOR dual chamber pacemakers with QC2 (Quick Connect) headers. In a retrospective review of 305 implanted patients, 23 exhibited unexpected loss of bipolar pacing lead function from < 1 to 51 months postimplant. Atrial lead problems were seen in 17 patients and ventricular lead problems in 6 (P < 0.05 atrial vs ventricular). Significant symptoms developed in six patients including two with syncope as a result of noncapture. No significant change in bipolar sensing function was seen. Reprogramming devices to the unipolar mode restored appropriate pacing thresholds and lead impedance. The changes in bipolar lead function are likely caused by failure of the QC2 header lead connection system over time.

Prospective assessment after pediatric cardiac ablation: design and implementation of the multicenter study.

A multicenter prospective study was designed and implemented as an activity of the Pediatric Electrophysiology Society to assess the risks associated with radiofrequency ablation in children. Patients (age 0-15 years) with supraventricular tachycardia due to accessory pathways or atrioventricular nodal reentry were enrolled and studied prior to ablation and periodically by clinical evaluation, electrocardiogram (ECG), Holter monitor, and echocardiogram. In addition, a national registry was established, to which the contributing centers report all pediatric patients undergoing ablation at their center. Initial electrophysiological study tracings and all noninvasive studies undergo blinded outside review for quality control. Clinical endpoints were death, recurrence, proarrhythmia, and echocardiographic abnormality. A pilot study demonstrated excellent agreement concerning diagnoses of previously reported ablation patients between the reporting center and the blinded reviewer (kappa = 0.938 +/- 0.062). A total of 317 patients were enrolled in the ongoing study from April 1, 1999 to December 31, 2000. The success rate of ablations was 96% with a complication rate of 4.3% for electrophysiological study and 2.9% for the ablation procedure. Comparison of the registry group versus the study group shows that the groups are comparable in terms of patient characteristics, diagnoses, and the results of ablation making it less likely that the sample of prospectively enrolled patients is biased.

Ablación por radiofrecuencia por vía auricular transeptal de un haz accesorio postero-lateral izquierdo / Radiofrequency ablation through the atrial septum in the left posterolateral region accesory pathway

La ablación por radiofrecuencia (ARF) es una técnica revolucionaria en el tratamiento de las arritmias. Su introducción en el arsenal terapéutico es relativamente reciente, con resultados excelentes. En este breve trabajo mostramos un procedimiento de ARF que utiliza una técnica diferente a la habitual. Nuestra paciente de 13 años es portadora de un síndrome de Wolf-Parkinson-White con historia de mareos y palpitaciones. Durante el estudio electrofisiológico se indujo taquicardia ortodrómica, comprobandose que el circuito de la taquicardia utilizaba el haz accesorio en forma retrógrada, que se localizó en la región postero-lateral izquierda. Un catéter de ablación se introdujo en la aurícula izquierda por vía femoral derecha a través del septum auricular, posicionándolo en el área donde se interesaba la vía anómala. Luego de 2 lesiones, utilizando ondas de radiofrecuencia se logró la ablación del haz accesorio, evidenciada por la desaparición de la onda delta y disociación ventrículo auricular por estimulación ventricular a frecuencias bajas. La técnica transeptal es ideal para esta localización, ya que el catéter es más estable, fácilmente manipulable y sin riesgo de dañar la válvula aórtica