Radiofrequency catheter ablation for tachyarrhythmias in children and adolescents. The Pediatric Electrophysiology Society

Limited fluoroscopy catheter ablation of accessory pathways in children

BACKGROUND

Limited fluoroscopy ablation using 3D electro-anatomical system (3DS) has been used for arrhythmias in children, however it is not a common practice. We aimed to facilitate a fluoroscopy limited approach for ablation of accessory pathways (AP) in children.

METHODS

Following electrophysiologic (EP) catheter placement a single dual-plane fluoroscopic image (right anterior oblique-30° and left anterior oblique-60° views) was acquired and the 3DS views were rotated to be a perfect match to the fluoroscopy. Ninety-four consecutive pediatric patients [mean age 11.8±4.1 (4.2-18) years, 61.7% males] with Wolf-Parkinson-White syndrome underwent ablation of an AP. Fifty-seven had manifest AP, 54 had left-sided AP (LSAP) and 40 had right-sided AP (RSAP).

RESULTS

The acute success rate was 95.7% (90/94), with a recurrence rate of 1.1% (1/90) at a mean follow-up of 13±5.5 (4.4-22.9) months. Mean procedure and fluoroscopy times were 144±45 (55-262)min and 1.8±1.4 (0.1-5.6)min, respectively. Comparison of the first 20 procedures to the next 74 procedures demonstrated an extended procedure time (171±53min vs 135±38min, p<0.005), however the fluoroscopy time, the number of long applications, the time to effect, and the acute success rate were similar. There were no permanent ablation-related complications.

CONCLUSIONS

A limited fluoroscopy approach for ablation of AP in children using 3DS is easily acquired, adapted, reduces the fluoroscopy time, and has an excellent efficacy and safety profile.

The Current State and Future Potential of Pediatric and Congenital Electrophysiology

Pediatric electrophysiologists specialize in the diagnosis and treatment of rhythm abnormalities in pediatric, congenital heart disease, and inherited arrhythmia syndrome patients. The field originated out of the unique knowledge base that rhythm management in young patients required. In the 1970s, pediatric electrophysiology was recognized as a distinct cardiac subspecialty and it has evolved rapidly since that time. Despite the considerable growth in personnel, technology, and complexity that the field has undergone, further opportunities to progress pediatric electrophysiology exist. In this review, we highlight some of the clinical focus of pediatric and adult congenital electrophysiologists to date and identify areas within this specialty where the pediatric and congenital electrophysiology community could come together in order to drive improvements in rhythm management for patients.

Radiofrequency ablation versus cryoablation for atrioventricular nodal re-entrant tachycardia in children: a value comparison

BACKGROUND

It is unclear whether cryoablation or radiofrequency ablation offers better value for treating atrioventricular nodal re-entrant tachycardia in children. We aimed to compare the value of these procedures for treating atrioventricular nodal re-entrant tachycardia in children, with value being outcomes relative to costs.

METHODS

We performed a retrospective cohort study of all atrioventricular nodal re-entrant tachycardia ablations for children (age⩽18 years) from July, 2009 to June, 2011 at our institution. Costs included fixed costs, miscellaneous hospital costs, and labour costs, and key outcomes were acute and long-term success (6 months) of the ablations. We conducted T-tests and regression analyses to investigate the associations between the ablation procedure type and the cost and success of the ablations.

RESULTS

Of 96 unique cases performed by three paediatric electrophysiologists, 48 were cryoablation only, 42 radiofrequency ablation only, and six were a combination. Acute success was 100% for the cryoablation only and radiofrequency ablation only cases and 83% for the combination cases. There were no notable adverse events. The average total cost was $9636 for cryoablation cases, $9708 for radiofrequency ablation cases, and $10,967 for combination cases (p=0.51 for cryoablation only versus radiofrequency ablation only). The long-term success rate was 79.1% for cryoablation only, 92.8% for radiofrequency ablation only, and 66.7% for the combination (p=0.01 for cryoablation only versus radiofrequency ablation only), but long-term success varied notably by provider.

CONCLUSIONS

Cryoablation and radiofrequency ablation offer similar value in the short term for the treatment of atrioventricular nodal re-entrant tachycardia in children. Differences in long-term success may vary substantially by physician, and thus may lead to differences in long-term value.

Long-Term Follow-Up After Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia in Children

Background—

Catheter ablation of the slow conducting pathway (SP) is treatment of choice for atrioventricular nodal reentrant tachycardia (AVNRT). Although there are abundant data on AVNRT ablation in adult patients, little is known about the long-term results ≥3 years after AVNRT ablation in pediatric patients.

Methods and Results—

Follow-up data from 241 patients aged ≤18 years who had undergone successful AVNRT ablation were analyzed. Median age at ablation had been 12.5 years, and median follow-up was 5.9 years. Radiofrequency current had been used in 168 patients (70%), whereas cryoenergy had been used in 73 patients (30%). Procedural end point of AVNRT ablation had been either SP ablation (no residual dual atrioventricular nodal physiology) or SP modulation (residual SP conduction allowing for a maximum of one atrial echo beat). After the initial AVNRT ablation, calculated freedom from AVNRT was 96% at 1 year, 94% at 3 years, 93% at 5 years, and 89% at 8 years. Age, sex, body weight, the choice of ablation energy, and the procedural end point of AVNRT ablation did not impact freedom from AVNRT. Six of 22 AVNRT recurrences (27%) occurred ≥5 years after ablation. No late complications including atrioventricular block were noted.

Conclusions—

Cumulatively, catheter ablation of AVNRT continued to be effective in >90% of our pediatric patients during the long-term course. A significant part of recurrences occurred >5 years post ablation. Body weight, energy source, and the end point of ablation had no impact on long-term results. No adverse sequelae were noted.

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-Induced Cardiomyopathies: Mechanisms, Recognition, and Management

Arrhythmia-induced cardiomyopathy (AIC) is a potentially reversible condition in which left ventricular dysfunction is induced or mediated by atrial or ventricular arrhythmias. Cellular and extracellular changes in response to the culprit arrhythmia have been identified, but specific pathophysiological mechanisms remain unclear. Early recognition of AIC and prompt treatment of the culprit arrhythmia using pharmacological or ablative techniques result in symptom resolution and recovery of ventricular function. Although cardiomyopathy in response to an arrhythmia may take months to years to develop, recurrent arrhythmia can result in rapid decline in ventricular function with development of heart failure, suggesting residual ultrastructural abnormalities. Reports of sudden death in patients with normalized left ventricular ejection fraction cast doubt on the complete reversibility of this condition. Several aspects of AIC, including specific pathophysiological mechanisms, predisposing factors, optimal therapeutic strategies to prevent ultrastructural changes, and long-term risk of sudden death remain unresolved and need further research.

A Smartphone Application to Diagnose the Mechanism of Pediatric Supraventricular Tachycardia

Smartphone applications that record a single-lead ECG are increasingly available. We sought to determine the utility of a smartphone application (AliveCor) to record supraventricular tachycardia (SVT) and to distinguish atrioventricular reentrant tachycardia (AVRT) from atrioventricular nodal reentrant tachycardia (AVNRT) in pediatric patients. A prior study demonstrated that interpretation of standard event and Holter monitors accurately identifies the tachycardia mechanism in only 45 % of recordings. We performed an IRB-approved prospective study in pediatric patients undergoing an ablation for SVT. Tracings were obtained by placing the smartphone in three different positions on the chest (PI-horizontal, PII-rotated 60° clockwise, and PIII-rotated 120° clockwise). Two blinded pediatric electrophysiologists jointly analyzed a pair of sinus and tachycardia tracings in each position. Tracings with visible retrograde P waves were classified as AVRT. The three positions were compared by Chi-square test. Thirty-seven patients (age 13.7 ± 2.8 years) were enrolled in the study. Twenty-four had AVRT, and 13 had AVNRT. One hundred and eight pairs of tracings were obtained. The correct diagnosis was made in 27/37 (73 %) with position PI, 28/37 (76 %) with PII, and 20/34 (59 %) with PIII (p = 0.04 for PII vs. PIII and p = NS for other comparisons). A single-lead ECG obtained with a smartphone monitor can successfully record SVT in pediatric patients and can predict the SVT mechanism at least as well as previously published reports of Holter monitors, along with the added convenience of not requiring patients to carry a dedicated monitor.

Expression of circulating microRNA-1 and microRNA-133 in pediatric patients with tachycardia

Paroxysmal or persistent tachycardia in pediatric patients is a common disease. Certain circulating microRNAs (miRNAs) have been associated with arrhythmia. The present study investigated miRNAs in the plasma of pediatric patients with tachycardia. Forty pediatric subjects were included retrospectively: 24 with recurrent sustained tachycardia [seven cases of ventricular tachycardia (VT) and 17 cases of supraventricular tachycardia (SVT)] and 16 healthy controls. Circulating miR-1 and miR-133 in the plasma were detected by fluorescent quantitative polymerase chain reaction. miR-1 levels were significantly decreased in the arrhythmia group compared with those in the controls (P=0.004) whilst miR-133 expression levels were not significantly different between the two groups (P=0.456). Both miR-1 and miR-133 levels showed significant differences between the SVT and VT groups (P=0.004 and P=0.046, respectively), and a significant decrease in miR-1 levels was observed in the SVT group as compared with the controls (P<0.001). No significant difference was observed in the expression levels of miR-133. By contrast, miR-133 levels were significantly increased in the VT group compared with those in the controls (P=0.024), whereas no statistically significant difference was observed in the expression levels of miR-1. Receiver operating characteristic curves showed that 1/miR-1 was significant for the evaluation of tachycardia. Additionally, miR-1 produced enhanced sensitivity and specificity for the evaluation of SVT compared with miR-133, whereas miR-133 was a better marker to assess VT. This study demonstrated that miRNAs may be appropriate markers for pediatric tachycardia; miR-1 levels were decreased in the arrhythmia group compared with those in the healthy controls. Furthermore, patients with SVT had lower miR-1 expression levels while those with VT had higher miR-133 expression levels.

Development of paediatric electrophysiology standards for Florida Children's Medical Services

The Florida Children's Medical Services (CMS) has a long-standing history of ensuring that providers of multiple paediatric subspecialties abide by the highest standards. The cardiac sub-committee has written quality standard documents that participating programmes must meet or exceed. These standards oversee paediatric cardiology services including surgery, catheterisations, and outpatient services. On April, 2012, the cardiac sub-committee decided to develop similar standards in paediatric electrophysiology. A task force was created and began this process. These standards include a catalogue of required and optional equipment, as well as staff and physician credentials. We sought to establish expectations of procedural numbers by practitioner and facility. The task force surveyed the members of the Pediatric and Congenital Electrophysiology Society. Finding no consensus, the task force is committed to generate the data by requiring that the CMS participating programmes enrol and submit data to the Multicenter Pediatric and Adult Congenital EP Quality (MAP-IT™) Initiative. This manuscript details the work of the Florida CMS Paediatric Electrophysiology Task Force.

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.

Current Management of Focal Atrial Tachycardia in Children

Background—

Focal atrial tachycardia (FAT) is an uncommon cause of supraventricular tachycardia in children. Incessant FAT can lead to tachycardia-induced cardiomyopathy. There is limited information regarding the clinical course and management of FAT. This study characterizes current management strategies for FAT in children including the prevalence of spontaneous resolution and the role of catheter ablation.

Methods and Results—

This is a retrospective chart review of pediatric patients with FAT managed between January 2000 and November 2010 at 10 pediatric centers. There were 249 patients with a median age at diagnosis of 7.2 (95% confidence interval, 5.8–10.4) years. Cardiomyopathy was observed in 28%. Resolution of FAT occurred in 89%, including spontaneous resolution without catheter ablation in 34%. Antiarrhythmic medications were used for initial therapy in 154 patients with control of FAT in 72%. Among first-line medications, β-blockers were the most common (53%) and effective (42%). Catheter ablation was successful in 80% of patients. FAT recurrence was less common with electroanatomic mapping compared with conventional mapping techniques (16% versus 35%; P =0.02). Patients were followed for a median of 2.1 (95% confidence interval, 1.8–2.6) years.

Conclusions—

FAT is managed successfully in most children. Current approaches are variable. Many patients have control of FAT with medications; however, catheter ablation is used for most patients. Spontaneous resolution is common for young children, emphasizing the role for delayed ablation in this group. Ablation is successful for all ages. Lower recurrence occurs when electroanatomic mapping techniques are used.

Radiofrequency catheter ablation therapy in the young: current status

Since 1989, when radiofrequency ablation was introduced into clinical practice for pediatric patients with supraventricular tachycardias, radiofrequency catheter ablation techniques have evolved as the treatment of choice for many forms of tachycardia in young patients. This review discusses the current status of ablation therapy for the four most common forms of supraventricular tachycardias in children, including tachycardias based on accessory atrioventricular pathways, atrioventricular nodal reentrant tachycardia, atrial ectopic tachycardia and the permanent form of junctional reciprocating tachycardia. In addition, the report will focus on the current status and limitations of ablation therapy of ventricular tachycardias and atrial reentry tachycardias in patients after surgical correction of congenital heart defects.

Electrophysiological interventions for treatment of congestive heart failure in pediatrics and congenital heart disease

Heart failure therapy, while well tested in the adult population, therapeutic interventions are less well defined in the pediatric population. Several treatment strategies are available for the adult patient with heart failure, thought few of these therapies have been proven in children. Morbidity and mortality in the pediatric population with a failing heart is significant, and rhythm management as well as strategies to improve hemodynamics are important in the care of these children. This review will address issues of rhythm management and resynchronization therapy in pediatric and congenital heart disease patients with heart failure.

Neurologic complications of catheter ablation/defibrillators/pacemakers

Approaches to the management of patients with cardiac arrhythmias have significantly evolved over the last decade, with advancement in catheter ablation and device implantation techniques. As the techniques and tools evolve, so does our understanding of the possible complications from these procedures. The focus of this chapter is discussion of the neurologic complications involved with catheter ablation, pacemaker and defibrillation implantation, with the focus on timely diagnosis, and management strategies.

Risk factors of recurrence and complication in radiofrequency catheter ablation of atrioventricular reentrant tachycardia in children and adolescents

BACKGROUND

To compare potential risk factors for complications and recurrence after radiofrequency catheter ablation in symptomatic atrioventricular reentrant tachycardia in children and adolescents.

METHODS

We retrospectively reviewed the data of 213 consecutive patients with symptomatic atrioventricular reentrant tachycardia who underwent both electrophysiological study and radiofrequency catheter ablation, divided these patients into two groups, children (age < 12 years) and adolescents (12 < or = rage, 18 years), and compared the location of the accessory pathway, success rate, recurrence rate, complications, presence of congenital heart disease, presence of intermittent ventricular pre-excitation, and presence of Wolff–Parkinson–White syndrome in the two groups.

RESULTS

The position of the accessory pathway was mostly right sided in children (61.3%) and left sided in adolescents (61.5%). Children had significantly more congenital heart disease than adolescents (6.4% versus 0.8%). Univariate analysis showed children or adolescents with right-sided accessory pathways to be 6.84 times and those with accessory pathways on both sides of the septum 25 times more likely to relapse than those with a single accessory pathway. Multivariate analysis indicated that children or adolescents with two accessory pathways were six times, and those with intermittent ventricular pre-excitation nine times more at risk of relapsing following radiofrequency ablation than those with single accessory pathways. All five complications occurred in children.

CONCLUSIONS

The findings suggest that the position and number of accessory pathways and presence of intermittent ventricular pre-excitation are related to risks of recurrence of atrioventricular reentrant tachycardia in children and adolescents.

Research accomplishments in pediatric electrophysiology: a historical review

Arrhythmia management in young patients plays a small but important role within the broader discipline of cardiac electrophysiology (EP). By virtue of its sharp focus on developmental cardiology, congenital heart defects, and hereditary channelopathies, pediatric EP has contributed in significant ways to improved understanding of rhythm disorders in patients of all ages. Scientific progress in the field was recently reviewed at the 2012 meeting of the Heart Rhythm Society, where historical details of pioneering investigations in pediatric EP were highlighted. In this article, we hope to summarize those details and acknowledge the roles of individuals and organizations that were instrumental in developing the subspecialty.

Consequence of use of lower dose flat plate fluoroscopy in pediatric patients undergoing ablation for supraventricular tachycardia

Traditional imaging for ablation of supraventricular tachycardia has been fluoroscopy, although 3-dimensional electroanatomic mapping (3D) has been demonstrated to reduce radiation exposure. This study compares a technique for the reduction of radiation, low-dose fluoroscopy (LD), with standard-dose fluoroscopy (SD) and 3D with SD (3D-SD). This was a single institutional retrospective cohort study. All patients undergoing initial ablation for atrioventricular reentrant tachycardia (AVRT) or atrioventricular nodal reentrant tachycardia (AVNRT) from 2009 to 2012 were reviewed and divided into 3 groups: (1) SD, (2) 3D (CARTO or NavX) with SD, or (3) LD. LD uses the same equipment as SD but includes customized changes to the manufacturer's lowest settings by decreasing the requested dose to the detector. Primary outcomes were fluoroscopy time and dose area product exposure. One hundred eighty-one patients were included. The median age was 15.0 years (3.3-20.8); 59% had AVRT, 35% had AVNRT, and 6% had both AVRT and AVNRT. LD decreased the dose area product (DAP) compared with SD (637.0 vs 960.1 cGy*cm², p = 0.01) with no difference in fluoroscopy time. 3D-SD decreased fluoroscopy time compared with SD (9.9 vs 18.3 minutes, p <0.001) with DAP of 570.1.0 versus 960.1 cGy*cm² (p = 0.16). LD and 3D-SD had comparable DAP (637.0 vs 570.1 cGy*cm², p = 0.67), even though LD had significantly longer fluoroscopy time (19.9 vs 9.9 minutes, p <0.001). In conclusion, LD during catheter ablation of AVRT and AVNRT significantly reduced the DAP compared with SD and had similar radiation exposure compared with 3D with SD.

The Multicenter Pediatric and Adult Congenital EP Quality (MAP-IT) Initiative-rationale and design: report from the pediatric and congenital electrophysiology society's MAP-IT taskforce

Multicenter clinical registries are increasingly recognized as valuable tools for establishing benchmarks, facilitating patient-centered quality improvement and research. In 2010, the Pediatric and Congenital Electrophysiology Society convened a taskforce of its members to design, construct, and implement a clinical registry known as the Multicenter Pediatric and Adult Congenital EP Quality (MAP-IT) Initiative. The present aim of the MAP-IT Initiative is to create an infrastructure by which we can measurably improve patient-centered outcomes and reduce complications associated with electrophysiology studies and catheter ablation in pediatric and congenital heart disease patients. The purpose of this writing is to report the progress to date from three of the four subcommittees of the MAP-IT taskforce. Specifically, we present our initial set of key data elements and definitions, recommended database table structure, and considerations regarding wide-scale implementation of the registry. Development of a risk/complexity score for use in the MAP-IT registry is presented in a separate companion manuscript. It is our intent that these manuscripts will serve to introduce the electrophysiology and pediatric cardiology community to the MAP-IT initiative and provide a rationale for its design and recommended implementation strategy.

Cryoablation of anteroseptal accessory pathways in children with limited fluoroscopy exposure

Due to its safety profile, cryoablation is used increasingly in pediatric patients, especially for septal arrhythmia substrates. Recent advances in electroanatomical-mapping technologies have resulted in a decrease or complete elimination of fluoroscopy exposure during catheter ablation procedures. The aim of this study was to assess the efficacy and safety of cryoablation of anteroseptal accessory pathways (APs) using electroanatomical-mapping system guidance with limited fluoroscopy exposure. A total of 24 patients underwent cryoablation of anteroseptal APs between July 2010 and April 2012. Cryomapping was performed with a 6 mm-tip catheter at -30 °C before the lesions were delivered. An 8 mm-tip catheter was used in one patient. The EnSite system (St. Jude Medical, St Paul, MN) was used in all procedures. The mean age was 11.9 ± 4.3 years. Acute success rate was 95.8 % (23 of 24). The mean procedure and cryoablation durations were 168 ± 58 min and 1,463 ± 525 s, respectively. Limited fluoroscopy was used only in 7 patients, and the mean fluoroscopy time was 1.7 ± 1.8 min (range 0.1-4 min) in these patients. Recurrence was noted in 2 patients (8.7 %) who underwent a second successful cryoablation procedure. The patient who underwent a failed attempt during the first procedure was successfully treated with a repeat procedure. The resultant long-term success rate was 100 % at a mean follow-up period of 14.2 ± 7.7 months. There were no complications except for transient atrioventricular block in one patient. Cryoablation of anteroseptal APs can be performed effectively and safely in children using a limited fluoroscopic approach with the help of electroanatomical-mapping systems.

COMPASS: a novel risk-adjustment model for catheter ablation in pediatric and congenital heart disease patients

BACKGROUND

Robust risk-adjustment algorithms are often necessary if data from clinical registries is to be used to compare rates of important clinical outcomes between participating centers. Although such algorithms have been successfully developed for surgical and catheter-based cardiac interventions in children, outcomes of pediatric and congenital catheter ablation have not been modeled with respect to case mix.

METHODS

A working group was appointed by the Pediatric and Congenital Electrophysiology Society to develop a risk-adjustment algorithm for use in conjunction with a modernized, multicenter registry database. Expert consensus was used to develop relevant outcome measures, an inclusive list of possible predictors, and estimates of associated incremental risk. Historical data from the Pediatric Radiofrequency Ablation Registry was reanalyzed using multivariate regression to create statistical models of ablation outcomes.

RESULTS

Acute ablation failure and serious adverse event rates were modeled as outcomes. Statistical modeling was performed on 4486 cases performed in 19 centers. For ablation failure rate, a simple model including general category of arrhythmia mechanism and presence of structural congenital heart disease accounted for ∼71% of outcome variance. The model was useful for identification of between-center variability in the historical data set. Although expert consensus predicted the need for a more complex model, predicted univariate effects were similar to those generated by statistical modeling. Serious adverse events were too infrequent to permit statistical association with any predictive variable, but could be compared with the mean rate observed among all centers.

CONCLUSION

A substantial component of the intercenter variability of acute ablation outcomes in a historical database of pediatric and congenital ablation patients may be accounted for by a simple statistical model, exposing variations in outcome specific to centers. This will be a useful initial model for use a modern registry for pediatric catheter ablation outcomes.

Multiple accessory pathways in the young: the impact of structural heart disease

BACKGROUND

The presence of multiple accessory pathways (MultAP) is described in structural heart disease (SHD) such as Ebstein's anomaly and cardiomyopathies. Structural defects can impact the tolerability of tachyarrhythmia and can complicate both medical management and ablation. In a large cohort of pediatric patients with and without SHD undergoing invasive electrophysiology study, we examined the prevalence of MultAP and the effect of both MultAP and SHD on ablation outcomes.

METHODS

Accessory pathway number and location, presence of SHD, ablation success, and recurrence were analyzed in consecutive patients from our center over a 16-year period.

RESULTS

In 1088 patients, 1228 pathways (36% retrograde only) were mapped to the right side (TV) in 18%, septum (S) in 39%, and left side (MV) in 43%. MultAP were present in 111 pts (10%), involving 250 distinct pathways. SHD tripled the risk of MultAP (26% SHD vs 8% no SHD, P < .001). Multivariable adjusted risk factors for MultAP included Ebstein's (OR 8.7[4.4-17.5], P < .001) and cardiomyopathy (OR 13.3[5.1-34.5], P < .001). Of 1306 ablation attempts, 94% were acutely successful with an 8% recurrence rate. Ablation success was affected by SHD (85% vs 95% for no SHD, P < .01) but not by MultAP (91% vs 94% for single, P = .24). Recurrence rate was higher for SHD (17% SHD vs 8% no SHD, P < .05) and MultAP (19% MultAP vs 8% single, P < .001).

CONCLUSIONS

MultAP are found in 10% of pediatric patients, and are more common in SHD compared to those with normal hearts. Both the presence of MultAP and SHD negatively influence ablation outcomes.

Single-catheter radiofrequency ablation of a permanent junctional reciprocating tachycardia in a premature neonate

A 34-week premature neonate presented with drug-refractory permanent junctional incessant tachycardia and haemodynamic compromise. The patient underwent successful radiofrequency catheter ablation using a single-catheter approach. The child remains in sinus rhythm, without pharmacological treatment, 2 years after the procedure.

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.

Asymptomatic Wolff-Parkinson-White Syndrome: Who Should Be Treated?

This article discusses the merits of electrophysiology study (EPS) and/or ablation for asymptomatic preexcitation Wolff-Parkinson-White (WPW) ECG pattern. Sudden deaths in asymptomatic patients are too few to merit broad screening and aggressive intervention. It also discusses the risks of ablation and the low predictive accuracy of EPS. When WPW is an incidental finding, the decision to proceed with investigation and ablation can be made considering patients' situations and preferences. An invasive strategy is targeted at patients concerned about the low risk of life-threatening arrhythmia as a first presentation after a discussion of the risks and benefits.

High-dose sotalol is safe and effective in neonates and infants with refractory supraventricular tachyarrhythmias

Our objective was to assess the efficacy and safety of high-dose sotalol in neonates and infants with refractory supraventricular tachycardia (SVT). SVT in neonates and infants can be refractory to primary therapies; therefore, secondary agents, e.g., sotalol, are often required to obtain control of SVT. Age-factor nomogram dosing of sotalol is widely used; however, our institution uses greater doses based on body surface area (approximately 150-200 mg/m(2)/d). A retrospective review of 78 inpatients receiving sotalol, after failing another antiarrthymic medication, at our institution from 2001 to 2008 was performed. Corrected QT intervals (QTc), 24-h Holter-monitoring results, and outpatient records were reviewed to assess safety and efficacy for patients ≤ 2 years of age. Median patient age at the time of initiation of therapy was 24 days (range 3-728). Forty-eight patients (62%) were neonates, and 36 (46%) had congenital heart disease. The median sotalol dosage was 152 mg/m(2)/day (range 65-244). The SVT of 70 patients (90%) was controlled with sotalol. No patients experienced significant QTc prolongation or proarrhythmia. Mean duration of follow-up was 3.3 ± 0.24 years. High-dose sotalol allows for safe and rapid control of refractory tachyarrhythmias in this young age group.

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.

Safety and results of cryoablation in patients <5 years old and/or <15 kilograms

Current recommendations discourage elective radiofrequency ablation in patients <5 years old and/or weighing <15 kg, primarily because of the greater complication rate. To describe the current use, complications, and immediate outcomes of cryoablation in this patient population, a multicenter retrospective review of all patients <5 years old and/or weighing <15 kg who were treated with cryoablation for arrhythmia was performed. Eleven centers contributed data for 68 procedures on 61 patients. Of those, 34% were elective and 24% (n = 16) were both cryoablation and radiofrequency ablation. The median age and weight at ablation was 3.5 years (range 8 days to 9.9 years) and 15.2 kg (range 2.3 to 23), respectively. Congenital heart disease was present in 23% of the patients. The immediate success rate of cryoablation alone was 74%. No major complications occurred with cryoablation only; however, 2 of the 16 patients who underwent cryoablation and radiofrequency ablation had major complications. Of the 50 patients receiving cryoablation, 8 (16%) had variable degrees of transient atrioventricular block. The recurrence rate was 20% after cryoablation and 30% after cryoablation plus radiofrequency ablation. In conclusion, cryoablation appears to have a high safety profile in these patients. Compared to older and larger patients, the efficacy of cryoablation in this small, young population was lower and the recurrence rates were higher. Cryoablation's effect on the coronary arteries has not been fully elucidated and requires additional research.