Radiofrequency Catheter Ablation in Small Children:. Relationship of Complications to Application Dose

Association of Weight With Ablation Outcomes in Pediatric Wolff-Parkinson-White: Analysis of the NCDR IMPACT Registry

BACKGROUND

Guidelines for electrophysiology study (EPS) and catheter ablation in Wolff-Parkinson-White (WPW) are age based, but size may be a more relevant factor in determination of outcomes.

OBJECTIVES

The goal of this study was to evaluate the association of patient weight with outcomes of catheter ablation for pediatric WPW.

METHODS

A multicenter retrospective cohort study was performed on children aged 1 to 21 years with WPW and first-time EPS from April 2016 to December 2019 recorded in the IMPACT (Improving Pediatric and Adult Congenital Treatment) registry, excluding those with congenital heart disease, cardiomyopathy, and >1 ablation target. A weight threshold of 30 kg was selected, representing 1 SD below the cohort mean. The primary outcome was major adverse events (MAEs); additional outcomes included deferred ablation, use of cryoablation, and ablation success.

RESULTS

A total of 4,456 subjects from 84 centers were evaluated, with 14% weighing <30 kg. Subjects weighing <30 kg were more likely to have preprocedural supraventricular tachycardia (45% vs 29%; P < 0.001) and less likely to have right septal accessory pathways (25% vs 33%; P < 0.001). MAEs were rare, although with higher incidence in the <30 kg cohort (0.3% vs 0.05%; P = 0.04). No difference was seen in likelihood of deferred ablation (9% vs 12%; P = 0.07) or use of cryoablation (11% vs 11%; P = 0.70). Success was higher in the <30 kg cohort: 95% vs 92% (P = 0.009). This effect persisted after adjusting for covariates (odds ratio: 1.6; 95% CI: 1.01-2.70; P = 0.046).

CONCLUSIONS

Weight <30 kg was associated with a small but elevated risk of MAEs. Rates of deferred ablation and cryoablation were similar. Adjusting for factors (including accessory pathway type and location), weight <30 kg remained an independent predictor of acute success.

Pediatric Electrophysiology Device Needs: A Survey from the Pediatric and Congenital Electrophysiology Society Taskforce on Pediatric‐Specific Devices

Background

There are few US Food and Drug Administration (FDA)–approved devices specifically aimed at the pediatric patient with arrhythmia. This has led to a high off‐label utilization of devices in this vulnerable population. The Pediatric and Congenital Electrophysiology Society (PACES), the international organization representing pediatric and congenital heart disease arrhythmia specialists, developed a task force to comprehensively address device development issues relevant to pediatric patients with congenital arrhythmia.

Methods and Results

As a first step, the taskforce developed a 26‐question survey for the pediatric arrhythmia community to assess providers’ understanding of the FDA approval process, specifically in regard to pediatric labeling. There were 92/211 respondents (44%) with a >90% completion rate. The vast majority of respondents believed there was a paucity of devices available for children (96%). More than 60% of respondents stated that they did not understand the FDA regulatory process and were not aware of whether the devices they used were labeled for pediatric use.

Conclusions

Pediatric electrophysiologists are keenly aware of the deficit of available pediatric devices for their patients. The majority do not understand the FDA approval process and could benefit from additional educational resources regarding this. A collaborative forum including PACES, FDA, patients and their families, and Industry would be an important next step in clarifying opportunities and priorities to serve this vulnerable population.

Catheter Ablation of Pediatric Atrioventricular Nodal Re-entrant Tachycardia

Catheter ablation is considered as the standard treatment for all patients with symptomatic drug-refractory tachyarrhythmia. The safety and efficacy of the procedure in the adult population is well-established. Due to the small size of the patient and difficulty in attaining venous access, infants are rarely subjected to radiofrequency ablation. Here, we report a case of drug-refractory AV nodal re-entrant tachycardia in a two-year-old child. Radiofrequency ablation was performed with a 5-Fr sized medium-curve ablation catheter deployed at the slow pathway region where a fractionated A-wave with slow-pathway potential was recorded. After ablation, no recurrence of SVT at the end of 12 months of follow-up was observed.

Cryoablation with an 8-mm tip catheter for typical AVNRT in children: a single center 5-year experience

BACKGROUND

In children with typical atrioventricular nodal reentrant tachycardia (tAVNRT), cryoablation is preferred over radiofrequency ablation (RFA) because of its safety profile and acceptable long-term success rates. In this study, we have assessed the utility of 8-mm tip cryocatheters for tAVNRT ablation in our center.

METHODS

All pediatric AVNRT patients who underwent cryoablation with an 8-mm tip cryocatheter in our center between 2013 and 2018 were included. EnSite™ (St. Jude Medical Inc., St. Paul, MN, USA) was used in all patients.

RESULTS

A total of 120 patients (64 females, 53%) were included in this study, and the mean age was 13.9 years with a standard deviation of 2.5 years. Eleven patients (9.1%) had structural heart disease, and 12 patients (10%) had additional arrhythmia substrate. The mean number of effective cryolesions was 8 with a standard deviation of 2.3. Fluoroscopy was used in three patients (2.5%). There were minor complications in only four patients (3.3%)-transient first-degree atrioventricular block or transient incomplete right bundle branch block. Acute success rate of cryoablation was 108/120 (90%). In twelve patients, cryoablation was suboptimal, or it failed. The procedure was completed successfully with RFA in the same session in ten patients. Overall acute success rate of ablation (Cryo ± RFA) was 98.5%. During a mean follow-up period of 24.6 months with a standard deviation of 11.3 months, three patients had recurrence (2.5%). Time between the beginning of the effective cryolesion and termination of AVNRT was found associated with acute success of cryoablation (p = 0.013).

CONCLUSIONS

Cryoablation of AVNRT with an 8-mm tip catheter in children appears to be safe, with an acceptable acute success rate and a low recurrence rate. A faster termination of AVNRT during the cryolesion, slowing down before ending with atrioventricular block, is a good indicator for acute success.

Late effects of radiofrequency ablation lesions resulting in a progressive mitral valve perforation in a 2-month-old infant

There has been great concern with the use of radiofrequency ablation in infants since radiofrequency ablation lesions were shown to have a progressing nature in immature myocardium of animals. In this report, we present a 2-month-old infant with life-threatening medically refractory supraventricular tachycardia. Radiofrequency ablation successfully cured arrhythmia; however, late effects of radiofrequency ablation lesions resulted in a progressive mitral valve perforation requiring surgical repair.

Catheter ablation for supraventricular tachycardia in children ≤ 20 kg using an electroanatomical system

PURPOSE

Catheter ablation is the only choice of treatment in some small children with medically refractory supraventricular tachycardia (SVT). Electroanatomical mapping systems (EMS) are more commonly utilized in electrophysiological procedures in recent years, which resulted in a significant decrease in fluoroscopy exposure. The potential benefit of EMS in small children has not been studied. Therefore, we investigated the outcomes of children undergoing catheter ablation weighing ≤ 20 kg using an electroanatomical mapping system.

METHODS

This study evaluated the outcomes, characteristics, and follow-ups of children ≤ 20 kg who underwent SVT ablations between April 2012 and April 2018 in a pediatric electrophysiology center where EMS were routinely used.

RESULTS

In a 6-year period, 1129 children underwent SVT catheter ablation under EMS guidance at our institution. A total of 84 of them were weighing ≤ 20 kg. The acute success rate was 97.6% in 85 tachycardia substrates. No fluoroscopy was used in 58 of the patients, while a median of 5 (4-14) min of fluoroscopy was used in the remaining 26 patients. Recurrences were seen in 4 patients (4.8%) at a mean follow-up of 3.89 ± 2.08 years. Five patients developed non-vital complications (2 right bundle block and 3 temporary complete block that spontaneously resolved during the procedure).

CONCLUSIONS

The outcome of catheter ablation with the guidance of EMS for the treatment of SVT in small children is favorable. Fluoroscopy exposure can be decreased and even eliminated in most patients.

The efficacy of radiofrequency ablation in the treatment of pediatric arrhythmia and its effects on serum IL-6 and hs-CRP

The aim of this study was to investigate the efficacy of radiofrequency ablation in the treatment of pediatric arrhythmia and to assess the changes in serum interleukin-6 (IL-6) and hs-CRP levels after treatment. Hundred and six children with tachyarrhythmia who were admitted to Xuzhou Children's Hospital from November, 2014 to December, 2015 were recruited for study. The efficacies of radiofrequency in the treatment of different types of arrhythmia were analyzed. Successful ablation was found in 104 cases (98.11%) and recurrence was found in 7 cases (6.73%). Among 62 cases of atrioventricular reentrant tachycardia (AVRT), successful ablation was found in 60 cases (96.77%) and recurrence was found in 3 cases (4.84%). Among 33 cases of atrioventricular nodal reentrant tachycardia (AVNRT), successful ablation was found in 33 cases (100%) and recurrence was found in 2 cases (6.06%). Among 5 cases of ventricular tachycardia (VT), successful ablation was found in 5 cases (100%) and no recurrence was found. Among 4 cases of atrial tachycardia (AT), successful ablation was found in 4 cases (100%) and recurrence was found in 1 case (25%). Among 2 cases of atrial flutter (AFL), successful ablation was found in both (100%) and recurrence was found in 1 case (50%). After operation, the levels of IL-6 and hs-CRP were increased and were continually increased within 6 h after operation. The levels of IL-6 and hs-CRP at 24 h after operation were reduced but still higher than preoperative levels. The duration of radiofrequency and ablation energy were positively correlated with the levels of IL-6 and hs-CRP, while the number of discharges was not significantly correlated with either. In conclusion, radiofrequency ablation is a safe and effective treatment for pediatric arrhythmia. Postoperative monitoring of IL-6 and hs-CRP levels is conducive to understanding postoperative myocardial injury and inflammatory response.

Non-fluoroscopic cardiac ablation of neonates with CHD

In current practice, children with anatomically normal hearts routinely undergo fluoroscopy-free ablations. Infants and children with congenital heart disease (CHD) represent the most difficult population to perform catheter ablation without fluoroscopy. We report two neonatal patients with CHD in whom cardiac ablations were performed without fluoroscopy. The first infant had pulmonary atresia with intact ventricular septum with refractory supraventricular tachycardia, and the second infant presented with Ebstein's anomaly of the tricuspid valve along with persistent supraventricular tachycardia. Both patients underwent uncomplicated, successful ablation without recurrence of arrhythmias. These cases suggest that current approaches to minimising fluoroscopy may be useful even in challenging patients such as neonates with CHD.

Radiofrequency Catheter Ablation of Accessory Atrioventricular Pathways in Infants and Toddlers ≤ 15 kg

Accessory atrioventricular pathways (AP) are the most common substrate for paroxysmal supraventricular tachycardia in infants and small children. Up-to-date data on AP ablation in infants and small children are limited. The aim of the present study was to gain additional insight into radiofrequency (RF) catheter ablation of AP in infants and toddlers focusing on efficacy and safety in patients with a body weight of ≤ 15 kg. Since 10/2002, RF ablation of AP was performed in 281 children in our institution. Indications, procedural data as well as success and complication rates in children with a body weight ≤ 15 kg (n = 22) were compared with children > 15 kg (n = 259). Prevalence of structural heart anomalies was significantly higher among children ≤ 15 kg (27 vs. 5.7 %; p = 0.001). Procedure duration (median 262 vs. 177 min; p = 0.001) and fluoroscopy time (median 20.6 vs. 14.0 min; p = 0.007) were significantly longer among patients ≤ 15 kg. Procedural success rate did not differ significantly between the two groups (82 vs. 90 %). More RF lesions were required for AP ablation in the smaller patients (median 12 vs. 7; p = 0.019). Major complication rate was significantly higher in children ≤ 15 kg (9 vs. 1.1 %; p = 0.05) with femoral vessel occlusion being the only major adverse event in patients ≤ 15 kg. Catheter ablation of AP in children was effective irrespective of body weight. In children ≤ 15 kg, however, procedures were more challenging and time-consuming. Complication rate and number of RF lesions in smaller children were higher when compared to older children.

Arrhythmia diagnosis and management throughout life in congenital heart disease

Arrhythmias, covering bradycardia and tachycardia, occur in association with congenital heart disease (CHD) and as a consequence of surgical repair. Symptomatic bradycardia can occur due to sinus node dysfunction or atrioventricular block secondary to either unrepaired CHD or surgical repair in the area of the conduction system. Tachyarrhythmias are common in repaired CHD due to scar formation, chamber distension or increased chamber pressure, all potentially leading to abnormal automaticity and heterogeneous conduction properties as a substrate for re-entry. Atrial arrhythmias occur more frequently, but ventricular tachyarrhythmias may be associated with an increased risk of sudden cardiac death, notably in patients with repaired tetralogy of Fallot or aortic stenosis. Defibrillator implantation provides life-saving electrical therapy for hemodynamically unstable arrhythmias. Ablation procedures with 3D electroanatomic mapping technology offer a viable alternative to pharmacologic or device therapy. Advances in electrophysiology have allowed for successful management of arrhythmias in patients with congenital heart disease.

Radiofrequency ablation on veno-arterial extracorporeal life support in treatment of very sick infants with incessant tachymyopathy

AIMS

To evaluate the use of extracorporeal membrane oxygenation (ECMO) in supporting infants who require radiofrequency ablation (RFA) for incessant tachyarrhythmias, with particular emphasis on modifications required to standard ablation techniques.

METHODS AND RESULTS

Three cases of RFA carried out in infancy on ECMO support were reviewed retrospectively. Two infants with permanent junctional reciprocating tachycardia (PJRT) and one with ventricular tachycardia (VT) presented in a low cardiac output state, owing to cardiomyopathy caused by incessant tachycardia. In each case antiarrhythmic drug therapy caused haemodynamic collapse, requiring emergency ECMO support. Drug therapy on ECMO was not successful. In one patient, the tachycardia was controlled on ECMO with antiarrhythmic drugs, but recurred following ECMO decannulation. Each patient had a successful RFA on ECMO support. Power delivery was low during ablation lesions. In the PJRT cases power as low as 3-5 Watts was effective. In the VT ablation, an irrigated tip RFA catheter was required when cooling remained poor even after temporarily stopping ECMO flow.

CONCLUSION

Extracorporeal membrane oxygenation provides a haemodynamically stable and safe platform for antiarrhythmic drug therapy and RFA in infants with incessant tachyarrhythmias. Once ECMO has been commenced, if the tachyarrhythmia remains difficult to control with antiarrhythmic drugs, RFA should be strongly considered, to avoid the risk of tachycardia recurrence following ECMO decannulation. Power delivery during ablation lesions may be low because of inadequate cooling of the catheter tip. Reducing or stopping flow in the ECMO circuit may not provide adequate cooling and an irrigated tip catheter may be required.

Optimizing outcomes of catheter ablation in infants and toddlers

Since the introduction of transcatheter ablation in the late 1980s, there has been significant technical development. With a very high success rate and low complication rate, ablation has now become the standard of care in children and adults. However, long-term data remain insufficient and the application of ablation therapy in small children is debatable. In this review, current treatment strategies and results in toddlers and infants will be discussed. There has been improvement in success rate and complication rate for ablation in small children. Technological advancements in non-fluoroscopic electroanatomical mapping systems (3D systems) have led to the reduction of radiation and have facilitated ablations in complex cases. However, long-term effects of ablation lesions in small children remain a potential concern.

Anatomic Challenges In Pediatric Catheter Ablation

Pediatric patients present unique anatomic challenges for catheter ablation. Small patient size requires special adaptation and understanding to perform safe procedures when clinically indicated. The anatomic variations of congenital heart disease also create problems that require pre-procedural preparation for each case in addition to a specialized understanding of a vast anatomic variation and surgical repairs. This understanding coupled with the knowledge of the pathophysiology of arrhythmia disorders and the biophysics of catheter ablation technology are required to perform successful and safe ablation procedures in this special population.

Radiofrequency ablation of drug-refractory arrhythmias in small children younger than 1 year of age: single-center experience

The use of radiofrequency ablation (RFA) for the management of supraventricular tachycardia (SVT) in infants and small children remains controversial. The aim of this study was to evaluate the safety and efficacy of RFA in critically ill small children (<1 year of age) with drug-resistant tachycardia accompanied by arrhythmogenic cardiomyopathy and heart failure. The study included 15 patients age 5.3 ± 3.7 months. Wolff-Parkinson-White syndrome and atrial tachycardia were detected in eight (53.3 %) and seven (46.7 %) of patients, respectively. Patients with structural heart pathology, including congenital heart diseases and laboratory-confirmed myocarditis, were excluded from the study. Indications for RFA included drag-refractory SVT accompanied by arrhythmogenic cardiomyopathy and heart failure. Unsuccessful ablation was observed in two 1-month-old patients who underwent successful ablation 3 months later. The follow-up period ranged from 0.5 to 8 years (average 3.9). Only one patient (6.7 %) had tachycardia recurrence 1 month after RFA. The short- and long-term RFA success rates were 86.7 and 93.3 %, respectively. The study did not show any procedure-related complications. Heart failure disappeared within 5-7 days. Complete normalization of heart chamber sizes was documented within 1 month after effective RFA. A three-dimensional CARTO system (Biosense Webster, Inc., USA) was used in three patients with body weight >7 kg. The use of the CARTO system resulted in a remarkable decrease of the fluoroscopy time without vascular injury or other procedure-related complications in all cases. Our study suggests that RFA may be considered the method of choice for SVT treatment in small children when drug therapy is ineffective and arrhythmogenic cardiomyopathy progresses.

Outcomes of interventional electrophysiology in children under 2 years of age

BACKGROUND

Despite the increasing utilisation of interventional electrophysiology in adults and older children with arrhythmias, there are few data reflecting the safety and efficacy of this procedure in the age group under 2 years.

AIM

We describe our experience in assessing the efficacy and safety with this group of children.

METHODS

We undertook a retrospective review of all infants under 2 years of age who underwent an interventional electrophysiology procedure between 1995 and 2009 to determine indications, procedural details, short- and long-term success, and complication rate.

RESULTS

A total of 23 interventional electrophysiology procedures were performed in 17 patients initially under 2 years of age. Of these, three patients had congenital heart disease. The most common indication was arrhythmia resistant to pharmacological agents (59%), with the remaining cases being arrhythmia complicated by cardiovascular instability (41%). There was initial success in 15 patients after the first procedure, with early recurrence in four. Following six repeat procedures, there was long-term success in 15 patients (88%), with three repeat procedures being performed after 2 years of age. There was one non-procedural death related to persisting arrhythmia. There were three minor complications. In one patient, cryotherapy was used successfully.

CONCLUSIONS

The interventional electrophysiology procedure is a viable therapeutic option in infants under 2 years with arrhythmia resistant to other conventional medical management.

Anomalous origin of the left coronary artery from the pulmonary artery associated with an accessory atrioventricular pathway and managed successfully with surgical and interventional electrophysiological treatment: a case report

Introduction

The combination of anomalous left coronary artery origin from the pulmonary artery and an accessory pathway has not been reported previously in the medical literature. In medicine, the coexistence of two clinical causes can lead to the same clinical findings, and this can make the researcher's attempt to distinguish between the two of them and, hence, the correct diagnosis and treatment difficult.

Case presentation

A six-month-old boy from Pakistan was brought to our hospital with tachypnea and supraventricular tachycardia and, on the basis of echocardiography and multi-slice computed tomography, was diagnosed with an anomalous left coronary artery origin from the pulmonary artery. The presence of an anomalous left coronary artery origin from the pulmonary artery was not initially recognized, and left ventricular dysfunction was considered as a result of supraventricular tachycardia. He underwent direct re-implantation of the left coronary artery to the aorta using the trapdoor flap technique. Recurrent episodes of supraventricular tachycardia resistant to maximal pharmacological treatment occurred post-operatively. A left posterolateral accessory pathway was successfully ablated by using a trans-septal approach.

Conclusions

It should not be forgotten by anyone that many times in medicine what seems obvious is not correct. It can be difficult to distinguish two clinical entities, and frequently one is considered a result of the other. This is the first report of the coexistence of an anomalous left coronary artery origin from the pulmonary artery and recurrent supraventricular tachycardia due to an accessory pathway in a child that was treated successfully with combined surgical and interventional electrophysiological treatment. This case may represent a first educational step in the field of congenital heart disease, that is, that anomalies such as an anomalous left coronary artery origin from the pulmonary artery may be concealed in a child with other serious cardiac problems, in this case mitral regurgitation, dilation of the left ventricle, and recurrent episodes of tachycardia.

Ablation of an idiopathic left ventricular tachycardia originating from the posterior mitral annulus in a toddler

Ablation of a mitral annulus (MA)-ventricular tachycardia (VT), a rare form of idiopathic left VT, has not yet been described in patients <2 years of age. We describe a case of a toddler with an incessant, poorly tolerated idiopathic VT (190 bpm) refractory to medical therapy, which was successfully ablated in the left ventricle at the infero-posterior part of the MA. Different diagnostic and ablation steps are described. Mitral annulus-ventricular tachycardia, a rare form of idiopathic left VT, can safely and successfully be ablated in very young children.

Contrasting effects of convective flow on catheter ablation lesion size: cryo versus radiofrequency energy

BACKGROUND

Cryoablation has now become an alternative to treat many cardiac arrhythmias, and may be the treatment of choice in some patient populations. We compared the effects of convective flow on large-tip cryo and radiofrequency (RF) lesions dimensions.

METHODS

Cryoablation and RF ablation were performed on porcine heart sections in a saline bath with varying directed flow rates. Cryoablation was performed for 4 minutes on 50 tissue pieces with tip temperature controlled at -80 degrees C. RF ablation was performed on 50 tissue pieces for 60 seconds at 60 degrees C tip temperature. The pieces were placed in culture media for 24 hours, and then sectioned, stained, and measured.

RESULTS

Cryoablation and RF lesion sizes varied significantly with flow such that higher flow rates produced smaller cryoablation lesions and larger RF lesions (mean cryoablation volumes: 854 +/- 402, 808 +/- 217, 781 +/- 217, 359 +/- 114, and 292 +/- 117 mm(3), and mean RF volumes: 211 +/- 35, 304 +/- 79, 439 +/- 125, 525 +/- 187, and 597 +/- 126 mm(3) for 0, 1, 2, 3, and 5 L/min flow rates, respectively, P < 0.0005). Trabeculated pieces had larger cryoablation lesions and smaller RF lesions than nontrabeculated ones at higher flow rate (P < 0.005). Cryoablation lesion volume increased as the time to reach -80 degrees C decreased (r(2)= 0.72).

CONCLUSION

In contrast to RF ablation, cryoablation lesion size is smaller at high flow rates, and larger at low flow rates due to the warming effects of local convective flow. The effects of high flow are reduced in areas of trabeculation, and the time to reach -80 degrees C predicts cryoablation lesion size.

Catheter ablation in children and adolescents

Adult and pediatric interventional electrophysiology practices have been diverging for the past 10 years, and so we review current pediatric ablation practice. Radiofrequency ablation (RFA) is safe and efficacious as documented by recent prospective, multi-center pediatric studies. Computer assisted mapping systems used for complex arrhythmias in adult patients have been successfully deployed in selected pediatric substrates. With increased computational power, decreased catheter size, and increased maneuverability, we expect increased use in the pediatric population. Finally, cryoablation has demonstrated efficacy and safety in locations traditionally associated with increased risk when using RFA, particularly around the AV node. As larger, multi-institutional studies are undertaken, the benefits of this technology in pediatric patients will be better defined.

Low-energy radiofrequency catheter ablation as therapy for supraventricular tachycardia in a premature neonate

A premature neonate with hydrops was born at 32 weeks of gestation after successful direct fetal amiodarone therapy via cordocentesis for incessant supraventricular tachycardia. After birth the tachycardia could not be controlled despite high doses of amiodarone and flecainide and the patient developed severe respiratory and circulatory failure. After 3 weeks, weighing 2 kg, he underwent successful and uncomplicated catheter ablation of a left free-wall accessory pathway using low-energy radiofrequency.

CONCLUSION

radiofrequency catheter ablation is rarely used in neonates, but when used with caution may provide the optimal treatment.

Advances in the approach to treatment of supraventricular tachycardia in the pediatric population

Supraventricular tachycardia is relatively common in children. Although most forms are not life threatening, treatment options depend on appropriate diagnosis. In certain patients, medical treatments are adequate for controlling symptoms. For those in whom medical therapy is inadequate or undesirable, invasive electrophysiology techniques are a viable treatment option. Increasing experience with radiofrequency catheter ablation techniques has led to improved success rates and decreased complication rates. New technologies, such as nonradiographic mapping systems and novel ablation catheters, are additional tools that can improve the ability of pediatric electrophysiologists to approach treating tachycardia mechanisms that have previously been too challenging to treat safely.