Pediatric Electrophysiology Research Articles

Effect of methadone on QTc in infants

ObjectiveMethadone has been associated with prolongation of the QTc interval (QTc) on electrocardiogram (ECG). In infants, the effects of methadone on the QTc are not well described. Our study's objective is to evaluate the QTc in infants being treated with methadone. MethodsWe conducted a retrospective study in infants receiving methadone. We collected demographic data, methadone dose, and QTc. A blinded-to-disease-state pediatric electrophysiologist determined the QTc. Baseline ECG was defined as an ECG obtained while not on methadone therapy, and QTc on baseline ECG was compared with treatment QTc. A significant change was defined as any absolute QTc greater than 500 or a QTc greater than 460 with an increase from baseline of greater than 40 ms. ResultsA total of 44 infants comprised the study population. The mean gestational age was 32.3 ± 5.51 weeks. The median age of initiation was 66 days. The median dose was 0.52 mg/kg/day in oral methadone equivalents. Nine patients were on high dose methadone (>1 mg/kg/day in oral methadone equivalents). The mean baseline QTc was 421 ± 27 and the mean change on methadone was −2 ms. No patient had a QTc greater than 500 on methadone. One patient had a QTc of 467 and 46 ms change from baseline, with no clinically significant impact. ConclusionIn our study population, methadone did not significantly prolong the QTc. Further prospective study is warranted to determine the utility and frequency of ECGs in infants receiving methadone.

Reducing Unnecessary Diagnostic Testing in Pediatric Syncope: A Quality Improvement Initiative.

Our aim was to reduce the frequency of unnecessary testing used by pediatric cardiologists in the evaluation of pediatric patients with syncope or pre-syncopal symptoms without negatively affecting patient outcomes. Guidelines for cardiac testing in pediatric patients with syncope were developed and disseminated to members of our pediatric cardiology division. Educational brochures and water bottles labeled with tips on preventing syncope were made available to families and providers in our clinics. Compliance to the guidelines was tracked and shared with providers. Segmented regression analysis was used to model cardiac testing utilization and guideline compliance by provider over time before and after the implementation of the guidelines. A pre-intervention cohort of 237 patients (June 2014-May 2015) was compared to 880 post-intervention patients (August 2015-June 2019). There was a significant decrease in the utilization of unnecessary tests [odds ratio (OR) 0.3; 95% confidence interval (CI) 0.14, 0.65; p = 0.002] after the intervention. Charges associated with patient evaluation were significantly lower in the post-intervention cohort (interquartile range $0, $1378 vs $0, $213; p = 0.005). Post-intervention visits to emergency departments within our system were significantly decreased, with no change in the incidence of cardiac arrest, hospitalization for syncope, or referral to pediatric electrophysiologists. We demonstrated a significant reduction in the use of unnecessary testing and associated charges by developing guidelines related to the evaluation of pediatric patients with syncope or pre-syncopal symptoms. There was no demonstrable negative impact on patient outcomes.

Antiarrhythmic Treatment Duration and Tachycardia Recurrence in Infants with Supraventricular Tachycardia.

We sought to assess the effect of a shorter medication treatment course (up to 4-6months of age) on the recurrence of infantile supraventricular tachycardia (SVT). This was a retrospective review of infants with SVT diagnosed at age 0-12months at Rady Children's Hospital (2010-2017). Infants with structural congenital heart disease, automatic tachycardias, atrial flutter, or lack of follow-up data were excluded. Seventy-four infants met criteria. Median age at diagnosis was 6days (IQR 0-21days); 28.4% presented with fetal tachycardia. Median gestational age was 38.4weeks (IQR 36-40), 30% were preterm. Median age at medication discontinuation was 6.7months (IQR 4.6-9.8). Therapy was stopped at younger age in patients managed by pediatric electrophysiologist (vs. general pediatric cardiologist): 4.9 vs. 8.6months (p = 0.03). Thirty-eight patients (51.4%) were treated for < 6months; 32.4% for 6-12months, and 16.2% for > 12months. SVT recurrence was similar for these groups: 13.2% vs. 16.7%, and 33.3%, respectively, (p = 0.27). Most patients with recurrence required emergency care, though none had significant adverse outcomes. Infants with SVT and structurally normal cardiac anatomy, who remain recurrence free on a single agent, have no increased risk of recurrence with shorter treatment courses of 4-6months, compared to traditional treatment duration of 6-12months.

Editorial introductions.

Editorial introductions.

Recommendations from the Association for European Paediatric and Congenital Cardiology for training in diagnostic and interventional electrophysiology.

The field of electrophysiology (EP) in paediatric cardiology patients and adults with congenital heart disease is complex and rapidly growing. The current recommendations for diagnostic and invasive electrophysiology of the working group for Cardiac Dysrhythmias and Electrophysiology of the Association for European Paediatric and Congenital Cardiology acknowledges the diveristy of European countries and centers. These training recommendations can be fulfilled in a manageable period of time, without compromising the quality of training required to become an expert in the field of paediatric and congenital EP and are for trainees undergoing or having completed accredited paediatric cardiologist fellowship. Three levels of expertise, the training for General paediatric cardiology EP, for non-invasive EP and invasive EP have been defined. This Association for European EP curriculum describes the theoretical and practicsal knowledge in clinical EP; catheter ablation, cardiac implantable electronic devices, inherited arrhythmias and arrhythmias in adults with congenital heart defects for the 3 levels of expertise.

Subcutaneous Implantable Cardioverter-Defibrillators in Pediatrics and Congenital Heart Disease: A Pediatric and Congenital Electrophysiology Society Multicenter Review.

The primary goal of this study was to evaluate the implant experience and midterm results of subcutaneous implantable cardioverter-defibrillators (S-ICDs) in pediatric patients and those with congenital heart disease. The S-ICD was developed to avoid the lead-related complications associated with transvenous systems. The absence of intravascular or intracardiac components offers potential advantages to pediatric patients and those with congenital heart disease. This international, multicenter, retrospective, standard-of-care study was conducted through the Pediatric & Congenital Electrophysiology Society. Complications at 30 and 360days, inappropriate shocks, and delivery of appropriate therapy were assessed. The study included 115 patients with a median follow-up of 32 (19 to 52) months. Median age was 16.7 years (14.8 to 19.3 years), 29% were female, and 55% had a primary prevention indication. Underlying disease substrate was cardiomyopathy (40%), structural heart disease (32%), idiopathic ventricular fibrillation (16%), and channelopathy (13%). The complication rate was 7.8% at 30days and 14.7% at 360days. Overall, inappropriate shocks occurred in 15.6% of patients, with no single clinical characteristic reaching statistical significance. At implant, 97.9% of patients had successful first shock conversion with 96% requiring≤65 J. Appropriate therapy was delivered to 11.2% of patients with an annual incidence of 3.9% and an acute first shock conversion success rate of 92.5%. This study found that in a heterogeneous population of pediatric patients and those with congenital heart disease, the S-ICD had comparable rates of complications, inappropriate shocks, and conversion efficacy compared with previously published studies on transvenous systems in similar populations.

A comparison of the Grass strobe and new LED photic stimulator for paediatric electroretinogram recordings.

This study evaluated a new light-emitting diode (LED-S) photic stimulator and compared skin electroretinogram (ERG) responses obtained to those evoked by the Grass Instrument stimulator (GP-S). Two sub-studies were combined to evaluate the difference in responses resulting from the LED-S and GP-S stimuli. The first was a photometry study that matched the LED-S stimuli to the GP-S. In the second study, electroretinograms (ERGs) were recorded under scotopic and photopic conditions using stimuli each stimulator. The stimuli were matched photometrically to measurements obtained from the photometer located 30cm in front of the stimulators. In addition, the ERG responses were recorded from the LED stimulator when photometrically matched to the GP-S blue stimulus presented through a ganzfeld. The amplitudes and time peaks of the resulting ERG a- and b-waves were then measured and compared using paired T-tests. Study 1: The LED-S was matched to the GP-S at various intensity settings measured 30cm away from the stimulator. Measurement through a ganzfeld full-field stimulator (GFFS) demonstrated that the GP-S had a significant hot spot centrally. Study 2: Photometrically matched ERGs evoked by both stimulators while employing the direct head-on measurements demonstrated multiple similarities. Similarities included component morphology, amplitude and implicit time across the two stimulators, excluding the rod-driven stimulus (GP-S setting employing a blue filter). Differences between the rod-driven ERGs evoked by the GP-S and LED-S while employing head-on photometric measurements were due to the significant difference in intensities between the two stimulators. The GP-S and LED-S evoked similar rod-driven ERG responses when they were matched using the GFFS photometrically matched intensities protocol. A hand-held stimulator is essential when recording ERG's in the practice of paediatric visual electrophysiology. The LED-S can match the GP-S stimulus intensities, making it a potential replacement for the GP-S. In addition, the LED-S has uniform intensity across the surface of the device compared to the GP-S, is silent for standard stimuli and can generate prolonged duration stimuli for the recording of on-off ERGs.

QTc Prolongation in Pediatric Patients with Diabetic Ketoacidosis

To investigate the association between diabetic ketoacidosis (DKA) and prolonged QTc interval and to assess for correlation between DKA severity and QTc prolongation. Retrospective observational study in a pediatric hospital. Patients admitted with DKA diagnosed by laboratory criteria and an electrocardiogram (ECG)performed during a period of acidosis were identified using Looking GlassClinical Analytics. Data including age, sex, pH, electrolytes, anion gap, and ECG variables were collected. Patients were excluded if they had a prior diagnosis of prolonged QTc or were taking QTc prolonging medications. Severity of DKA was classified as mild (pH 7.24-7.3), moderate (pH 7-7.24), or severe (pH <7). ECGs were read by a pediatric electrophysiologist and QTc interval was manually calculated utilizing the Bazett formula. Ninety-six patients were included (mean age 15.2±4.2years, pH 7.12±0.12, bicarbonate 8.6±3.7mmol/L, potassium 5.3±1.1 mEq/L). Mean QTc interval for all patients in DKA was 454±32 msec. Mean QTc in the mild group was 441±22 msec, moderate group 460±36 msec, and severe group 461±34 msec. There was a significant difference in QTc interval across DKA severity groups (P=.05). There was a significant association between higher anion gaps and greater QTc intervals (r=0.21, P=.04). Thirty-one percent of pediatric patients with DKA demonstrated QTc prolongation on ECG. Severity of DKA and worsening acidosis were associated with increased prolongation of the QTc. Further study is required to evaluate the clinical impact of these findings.

Changes in genetic variant results over time in pediatric cardiomyopathy and electrophysiology.

Genetic testing for cardiac disorders continues to change. Our objective was to assess trends in variant classification in pediatric arrhythmia and cardiomyopathy. We conducted a retrospective review of patients tested for genetic arrhythmia and cardiomyopathy disorders from 2006-2017. Variants were classified by CLIA laboratories. Trends were assessed by the Spearman correlation. There were 914 variants in 583 patients from 337 families. The total number of tests ordered increased over time, accelerating after 2012. There was a strong positive correlation between the average number of genes tested per panel and year of testing (r=.97, p<.001) and a weak correlation between the year and a decrease in the percentage of clinically actionable variants (r=-.20, p=.005). By 2011, VUS represented >50% of variants reported on panels. Over 12years, 203 genes were interrogated; one or more variants were reported in 91 of 203 genes (45%). 32% of patients had at least one clinically actionable variant; 28% had at least one VUS. Reclassification is an important long-term issue, with 21.5% variants changing clinical interpretation. We observed an increase over time in three areas: total number of tests ordered, average number of genes/panel, and percentage of VUS. Providers may need to interpret results from 90+genes, and ongoing education is critical. Due to their specific training in test result interpretation, we recommend the inclusion of a genetic counselor in pediatric electrophysiology and cardiomyopathy teams.

The HAV pattern in pediatric patients with atrioventricular node reentrant tachycardia

ObjectivesThe purpose of this study is to assess the prevalence of a His-Atrial-Ventricular (HAV) pattern, i.e. the atrial electrogram following the His bundle -HB- electrogram and preceding the ventricular one, on the catheter placed in the His position in pediatric patients during typical atrioventricular node reentry (AVNRT). Materials and methodsThe pediatric electrophysiology databases of two separate institutions were queried for patients with a diagnosis of AVNRT. Demographic, clinical data and the electrophysiology study (EPS) information were assessed. ResultsThirty-nine consecutive patients were included. Twenty-five were female. The average age at the time of the EPS was 12 ± 3.7 years. Induction was achieved with atrial pacing in 23, with a single atrial extra stimulus in 8 and with dual atrial extra stimuli in 8. Isoproterenol was needed to induce tachycardia in 21. Tachycardia cycle length averaged 320 ± 50 ms. An HAV pattern was present in 35 (74%) of the patients, and in 100% of the patients younger than 8. ConclusionsAn HAV pattern on the catheter placed in the His position, is common in pediatric patients with AVNRT, occurring in up to 74% of the patients in this population, being more common in younger patients.

Permanent conduction system pacing for congenitally corrected transposition of the great arteries: A Pediatric and Congenital Electrophysiology Society (PACES)/International Society for Adult Congenital Heart Disease (ISACHD) Collaborative Study

Congenitally corrected transposition of the great arteries (CCTGA) is associated with spontaneous atrioventricular block and pacing-induced cardiomyopathy. Conduction system pacing is a potential alternative to conventional cardiac resynchronization therapy (CRT). The purpose of this study was to determine the outcomes of conduction system pacing for CCTGA. Retrospective data were collected from 10 international centers. His bundle (HBP) or left bundle branch pacing (LBBP) was attempted in 15 CCTGA patients (median age 23 years; 87% male). Previous surgery had been performed in 8 and chronic ventricular pacing in 7. Conduction system pacing (11 HBP, 2 LBBP 2; nonselective in 10, selective in 3) was acutely successful in 13 (86%) without complication. In 9 cases, electroanatomic mapping was available and identified the distal His bundle and proximal left bundle branches within the morphologic left ventricle below the pulmonary valve separate from the mitral annulus. Median implant HV interval was 42 ms (interquartile range [IQR] 35-48), R wave 6 mV (IQR 5-18), and threshold 0.5 V (IQR 0.5-1.2) at median 0.5 ms. QRSd was unchanged compared to junctional escape rhythm (124 vs 110 ms; P = .17) and decreased significantly compared to baseline ventricular pacing (112 vs 164 ms; P <.01). At a median of 8 months, all patients were alive without significant change in pacing threshold or lead dysfunction. New York Heart Association functional class improved in 5 patients. Permanent conduction system pacing is feasible in CCTGA by either HBP or proximal LBBP. Narrow paced QRS and stable lead thresholds were observed at intermediate follow-up. Unique anatomic characteristics may favor this approach over conventional CRT.

Editorial introductions

Editorial introductions

Effects of Dexmedetomidine on Myocardial Repolarization in Children Undergoing General Anesthesia: A Randomized Controlled Trial.

Dexmedetomidine is a highly selective α2-adrenergic agonist, which is increasingly used in pediatric anesthesia and intensive care. Potential adverse effects that have not been rigorously evaluated in children include its effects on myocardial repolarization, which is important given that the drug is listed as a possible risk factor for torsades de pointes. We investigated the effect of 3 different doses of dexmedetomidine on myocardial repolarization and transmural dispersion in children undergoing elective surgery with total IV anesthesia. Sixty-four American Society of Anesthesiologists I-II children 3-10 years of age were randomized to receive dexmedetomidine 0.25 µg/kg, 0.5 µg/kg, 0.75 µg/kg, or 0 µg/kg (control), as a bolus administered over 60 seconds, after induction of anesthesia. Pre- and postintervention 12-lead electrocardiograms were recorded. The interval between the peak and the end of the electrocardiogram T wave (Tp-e; transmural dispersion) and heart rate-corrected QT intervals (myocardial repolarization) were measured by a pediatric electrophysiologist blinded to group allocation. Data were analyzed using an analysis of covariance regression model. The study was powered to detect a 25-millisecond difference in Tp-e. Forty-eight children completed the study, with data analyzed from 12 participants per group. There were no instances of dysrhythmias. Tp-e values were unaffected by dexmedetomidine administration at any of the studied doses (F = 0.09; P = .96). Mean (99% CI) within-group differences were all <2 milliseconds (-5 to 8). Postintervention, corrected QT interval increased in the control group, but decreased in some dexmedetomidine groups (F = 7.23; P < .001), specifically the dexmedetomidine 0.5 and 0.75 µg/kg doses. Within groups, the mean (99% CI) differences between pre- and postintervention corrected QT interval were 12.4 milliseconds (-5.8 to 30.6) in the control group, -9.0 milliseconds (-24.9 to 6.9) for dexmedetomidine 0.25 µg/kg, -18.6 milliseconds (-33.7 to -3.5) for dexmedetomidine 0.5 µg/kg, and -14.1 milliseconds (-27.4 to -0.8) for dexmedetomidine 0.75 µg/kg. Of the bolus doses of dexmedetomidine studied, none had an effect on Tp-e and the dexmedetomidine 0.5 and 0.75 µg/kg doses shortened corrected QT intervals when measured at 1 minute after dexmedetomidine bolus injection during total IV anesthesia. There is no evidence for an increased risk of torsades de pointes in this context.

Wolff-Parkinson-White pattern and risk of sudden death

In this volume of The Journal, Chubb et al report the results of a survey of pediatric cardiac electrophysiologists on the management of patients identified with the Wolff-Parkinson-White (WPW) pattern on electrocardiogram (ECG) with no symptoms. They report that many electrophysiologists are being more aggressive about using invasive electrophysiology studies with subsequent ablation as treatment than the most current guidelines would suggest. The reason this discussion is important for all pediatricians to understand is that recent studies have suggested that pediatric patients with asymptomatic WPW are at substantially higher risk of sudden death than adults with WPW. Studies have also shown that evaluating risk of sudden death using non-invasive approaches is challenging at best. Thus, when pediatric patients with asymptomatic WPW are identified, it is important for them to be referred to a pediatric electrophysiologist for further evaluation and possible ablation of the accessory conduction pathway. Article page 88▸ Management of Asymptomatic Wolff-Parkinson-White Pattern by Pediatric ElectrophysiologistsThe Journal of PediatricsVol. 213PreviewTo determine the present-day approach of pediatric cardiac electrophysiologists to asymptomatic Wolff-Parkinson-White (WPW) pattern and to contrast to both published consensus statements and a similar survey. Full-Text PDF

Mothers with long QT syndrome are at increased risk for fetal death: findings from a multicenter international study

Most fetal deaths are unexplained. Long QT syndrome is a genetic disorder of cardiac ion channels. Affected individuals, including fetuses, are predisposed to sudden death. We sought to determine the risk of fetal death in familial long QT syndrome, in which the mother or father carries the long QT syndrome genotype. In addition, we assessed whether risk differed if the long QT syndrome genotype was inherited from the mother or father. This was a retrospective review of pregnancies in families with the 3 most common heterozygous pathogenic long QT syndrome genotypes in KCNQ1 (LQT1), KCNH2 (LQT2), or SCN5A (LQT3), which occur in approximately 1 in 2000 individuals. The purpose of our study was to compare pregnancy and birth outcomes in familial long QT syndrome with the normal population and between maternal and paternal carriers of the long QT syndrome genotype. We hypothesized that fetal death before (miscarriage) and after (stillbirths) 20 weeks gestation would be increased in familial long QT syndrome compared with the normal population and that the parent of origin would not affect birth outcomes. Our study was a multicenter observational case series of 148 pregnancies from 103 families (80 mothers, 23 fathers) with familial long QT syndrome (60 with LQT1, 29 with LQT2, 14 with LQT3) who were recruited from 11 international centers with expertise in hereditary heart rhythm diseases, pediatric and/or adult electrophysiology, and high-risk pregnancies. Clinical databases from these sites were reviewed for long QT syndrome that occurred in men or women of childbearing age (18-40 years). Pregnancy outcomes (livebirth, stillbirth, and miscarriage), birthweights, and gestational age at delivery were compared among long QT syndrome genotypes and between maternal vs paternal long QT syndrome-affected status with the use of logistic regression analysis. Most offspring (80%; 118/148) were liveborn at term; 66% of offspring (73/110) had long QT syndrome. Newborn infants of mothers with long QT syndrome were delivered earlier and, when the data were controlled for gestational age, weighed less than newborn infants of long QT syndrome fathers. Fetal arrhythmias were observed rarely, but stillbirths (fetal death at >20 weeks gestation) were 8 times more frequent in long QT syndrome (4% vs approximately 0.5%); miscarriages (fetal death at ≤20 weeks gestation) were 2 times that of the general population (16% vs 8%). The likelihood of fetal death was significantly greater with maternal vs paternal long QT syndrome (24.4% vs 3.4%; P=.036). Only 10% of all fetal deaths underwent postmortem long QT syndrome testing; 2 of 3 cases were positive for the family long QT syndrome genotype. This is the first report to demonstrate that mothers with long QT syndrome are at increased risk of fetal death and to uncover a previously unreported cause of stillbirth. Our results suggest that maternal effects of long QT syndrome channelopathy may cause placental or myometrial dysfunction that confers increased susceptibility to fetal death and growth restriction in newborn survivors, regardless of long QT syndrome status.

Management of Asymptomatic Wolff-Parkinson-White Pattern by Pediatric Electrophysiologists

To determine the present-day approach of pediatric cardiac electrophysiologists to asymptomatic Wolff-Parkinson-White (WPW) pattern and to contrast to both published consensus statements and a similar survey. A questionnaire was sent to 266 Pediatric and Congenital Electrophysiology Society physician members in 25 countries; 21 questions from the 2003 survey were repeated, with new questions added regarding risk stratification and decision making. We received 113 responses from 13 countries, with responders having extensive electrophysiology experience (median 15years [IQR 8.5-25years]). Only 12 (11%) believed that intermittent pre-excitation and 37 (33%) that sudden loss of pre-excitation on exercise test were sufficient evidence of accessory pathway safety to avoid an invasive electrophysiology study. Optimal weight for electrophysiology study was 20kg (IQR 18-22.5kg), and 61% and 58% would then ablate all right-sided or left-sided accessory pathways, respectively, regardless of electrophysiological properties, whereas only 23% would ablate all septal accessory pathways (P<.001). Compared with 2003, respondents were more likely to consider inducible arrhythmia (77% vs 26%, P<.001) as sufficient indication alone for ablation. In the context of recent literature regarding the reliability of risk-stratification tools, most operators are now performing electrophysiology study for asymptomatic Wolff-Parkinson-White regardless of noninvasive findings. Many will then proceed to default ablation of all accessory pathways distant from critical conduction structures.

Non-vitamin K antagonist oral anticoagulants in adults with a Fontan circulation: are they safe

BackgroundIn Fontan patients with atrial arrhythmias (AA), non-vitamin K antagonist oral anticoagulants(NOACs) have a class III recommendation according to the Pediatric & Congenital Electrophysiology Society (PACES)/Heart Rhythm Society (HRS) guideline...

Management of Asymptomatic Wolff-Parkinson-White Pattern in Young Patients: Has Anything Changed?

The approach to pediatric asymptomatic Wolff-Parkinson-White (WPW) patients is controversial. The objective of this review is to update the last consensus of specialists of the Pediatric and Congenital Electrophysiology Society/Heart Rhythm Society on this subject in order to summarize the most recent evidence on the management of young patients with asymptomatic WPW pattern. A systematic review of the literature published between 2008 and 2018 was performed taking into account the protocol of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) in PubMed (including Cochrane), Embase, and Web of Science. Observational, experimental, and multicentric studies were included. Out of a total of 37 articles selected, 4 were considered eligible. Most studies considered a cutoff age of 8 or greater as recommended in the 2012 consensus. The identification of a shortest pre-excitatory RR interval (SPERRI) ≤ 250ms seems to be the best predictor for risk stratification. The importance of routine isoprenaline use to improve the sensitivity of the electrophysiological study to identify patients at high risk of sudden death was consensual. Prophylactic ablative therapy has been indicated in asymptomatic children with an accessory pathway (AP) who have a low SPERRI and/or a low effective anterograde period of the AP and/or multiple APs. Despite the evidence found in the most recent studies, more studies are warranted in this setting.

Transseptal Puncture for Catheter Ablation in Children.

Transseptal puncture (TP) is used in pediatric patients to access the left atrium in left-sided arrhythmia catheter ablation. Performing this procedure can be difficult and risky, especially in small children. In this study, we aimed to evaluate the safety and feasibility of TPs in children ≤ 30kg. Between April 2012 and April 2018, a retrospective evaluation was conducted of the clinical features, procedural outcomes, and follow-ups of ≤ 30kg pediatric patients who required TPs for left-sided ablations at a pediatric electrophysiology center in which a three-dimensional mapping system was routinely used. A total of 45 pediatric patients who were ≤ 30kg, underwent TPs: 10 patients ≤ 20kg (Group 1) and 35 patients > 20kg and ≤ 30kg (Group 2). The TP success rate was 97.8%. The median procedure and fluoroscopy times were 120min and 5.43min, respectively. One patient developed self-limited pericardial effusion during the procedure; however, there were no incidences of cardiac tamponade. There was no significant difference between the two groups in terms of the procedure time and fluoroscopy time, and pericardial effusion was only observed in Group 2. TPs are safe and feasible in small children. These procedures can be performed with low complication rates in children weighing ≤ 30kg.

Localization of Accessory Pathways in Pediatric Patients With Wolff-Parkinson-White Syndrome Using 3D-Rendered Electromechanical Wave Imaging

This study sought to demonstrate the feasibility of electromechanical wave imaging (EWI) for localization of accessory pathways (AP) prior to catheter ablation in a pediatric population. Prediction of AP locations in patients with Wolff-Parkinson-White syndrome is currently based on analysis of 12-lead electrocardiography (ECG). In the pediatric population, specific algorithms have been developed to aid in localization, but these can be unreliable. EWI is a noninvasive imaging modality relying on a high frame rate ultrasound sequence capable of visualizing cardiac electromechanical activation. Pediatric patients with ventricular pre-excitation presenting for catheter ablation were imaged with EWI immediately prior to the start of the procedure. Two clinical pediatric electrophysiologists predicted the location of theAP based on ECG. Both EWI and ECG predictions were blinded to the results of catheter ablation. EWI and ECG localizations were subsequently compared with the site of successful ablation. Fifteen patients were imaged with EWI. One patient was excluded for poor echocardiographic windows and the inability to image the entire ventricular myocardium. EWI correctly predicted the location of the AP in all 14 patients. ECG analysis correctly predicted 11 of 14 (78.6%) of the AP locations. EWI was shown to be capable of consistently localizing accessory pathways. EWI predicted the site of successful ablation more frequently than analysis of 12-lead ECG. EWI isochrones also provide anatomical visualization of ventricular pre-excitation. These findings suggest that EWI can predict AP locations, and EWI may have the potential to better inform clinical electrophysiologists prior to catheter ablation procedures.