Children's Heartbeat: A Web-Based Program to Spread Knowledge on Arrhythmias in Children.

Expertise in pediatric arrhythmia management is lacking in most low- and middle- income countries (LMIC). Strategies to disseminate education in pediatric electrophysiology are essential to meet this need. Children's Heartbeat was created to meet the growing demand for pediatric electrophysiologic consultation in LMIC. Children's Heartbeat is a virtual video-conferencing program that uses the Extension for Community Healthcare Outcomes model to disseminate knowledge about pediatric arrhythmia management from pediatric electrophysiologists to clinicians in medically under-resourced regions worldwide. Monthly virtual case-based sessions are held with pediatric electrophysiologists and clinicians in medically under-resourced settings to discuss pediatric electrophysiology management. Since its inception, Children's Heartbeat viewership has grown exponentially to include 181 total registrants, 64 average monthly participants, and an additional 121 average viewers of recorded sessions. Attendees have expressed increased confidence in pediatric arrhythmia management. Children's Heartbeat has successfully provided pediatric electrophysiology consultation to medically under-resourced regions globally and have increased clinicians' confidence in caring for children with arrhythmias. Future directions include spreading the program to general pediatric and pediatric cardiology trainees and practicing pediatricians in rural parts of high-income countries and evaluating the direct impact of Children's Heartbeat on the management of arrhythmias in pediatric patients in LMIC.

QTc interval on 24-hour holter monitor: To trust or not to trust?

INTRODUCTION: QT interval represents the ventricular depolarization and repolarization. Its accurate measurement is critical since prolonged QT can lead to sudden cardiac death. QT is affected by heart rate and is corrected to QTc via several formulae. QTc is commonly calculated on the ECG and not the 24-h Holter. METHODS: 100 patients presenting to our institution were evaluated by an ECG followed by a 24-h Holter. QTc measurement on both platforms using Bazett and Fridericia formulae was recorded and compared. RESULTS: Mean age was 14.09 years, with the majority being males. Mean heart rate was 125.87. In the ECG, the mean QTc interval via the Bazett formula was 0.40 s compared with 0.38 s using the Fridericia formula. The mean corrected QT via the Bazett formula was 0.45, 0.39, and 0.42 s for the shortest RR, the longest RR, and the average RR, respectively. In contrast to the Fridericia formula, the corrected QT interval was 0.40, 0.39, and 0.40 s for the shortest RR, the longest RR, and the average RR, respectively. Using the Bazett formula, the highest specificity was reached during the longest RR interval (92.2%), while the highest sensitivity was recorded during the shortest RR interval (40%). As for the Fridericiaformula, sensitivity always reached 0%, while the highest specificity was reached during the average RR interval. CONCLUSION: QTc measured during Holter ECG reached a high specificity regardless of RR interval using the Fridericia and during the longest and the average RR interval for the Bazett formula. The consistently low sensitivity reveals that Holter ECG should not be used to rule out prolonged QT.

Outcomes in Infants with Supraventricular Tachycardia: Risk Factors for Readmission, Recurrence and Ablation.

Supraventricular tachycardia (SVT) is the most common arrhythmia in infants. Once diagnosed, infants are admitted for antiarrhythmic therapy and discharged after observation. There are limited data on risk factors for readmission and readmission rates, while on medication. The objective of this study was to investigate risk factors for readmission and outcomes in infants diagnosed with SVT. This is a single-center retrospective study over a 10-year period of infants under 6 months of age with documented SVT. Infants with congenital heart disease requiring surgical or catheter intervention, gestational age less than 32 weeks or diagnosis of atrial flutter or fibrillation were excluded. The primary outcome was readmission within 31 days of hospital discharge. Long term need for ablation and eventual discontinuation of medications were assessed. Ninety patients were included. Beta blockers were the initial therapy in 66 and 28 required a medication change. Nineteen were readmitted within 31 days of discharge. The only clinical factor associated with early readmission was presence of ventricular pre-excitation (6/19 vs. 8/71, p = 0.03). Patients who were readmitted within 31 days had a longer length of treatment (12 [11.5, 22.0] vs. 10 [7.5, 12.0] months, p = 0.007) and were more likely to undergo ablation (4/19 vs. 2/71, p = 0.017). In this cohort of infants with SVT, readmission was common and ventricular pre-excitation was identified as a risk factor for readmission. Infants who were readmitted within 31 days of discharge had longer length of antiarrhythmic therapy and were more likely to undergo catheter ablation.

Preliminary assessment of paediatric electrophysiology cardiac implantable electronic device resources around the world.

BACKGROUND: The Pediatric and Congenital Electrophysiology Society (PACES) is a global organisation committed to the care of children and adults with CHD and arrhythmias. OBJECTIVE: To evaluate the global needs and potential inequities as it relates to cardiac implantable electronic devices. METHODS: ARROW (Assessment of Rhythm Resources arOund the World) is an online survey about cardiac implantable electronic devices, sent electronically to physicians within the field of Cardiology, Pediatric Cardiology, Electrophysiology and Pediatric Electrophysiology. RESULTS: ARROW received 42 responders from 28 countries, 50% from low-/middle-income regions. The main differences between low-/middle- and high-income regions include availability of expertise on paediatric electrophysiology (50% versus 93%, p < 00.5) and possibility to perform invasive procedures (35% versus 93%, p < 0.005). Implant of devices in low-income areas relies significantly on patient's resources (71%). The follow-up of the devices is on the hands of paediatric cardiologist/electrophysiologist in higher resources centres (93% versus 50%, p < 0.05). CONCLUSIONS: The ARROW survey represents an initial assessment of the geographical characteristics in the field of Pediatric Electrophysiology. The next step is to make this "state of the art" more extensive to other aspects of the expertise. The relevance of collecting this data before the World Congress of Pediatric Cardiology and Cardiac Surgery (WCPCCS) in 2023 in Washington DC was emphasised in order to share the resulting information with the international community and set a plan of action to assist the development of arrhythmia services for children within developing regions of the world.

Pediatric Catecholaminergic Polymorphic Ventricular Tachycardia: A Translational Perspective for the Clinician-Scientist.

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare and potentially lethal inherited arrhythmia disease characterized by exercise or emotion-induced bidirectional or polymorphic ventricular tachyarrhythmias. The median age of disease onset is reported to be approximately 10 years of age. The majority of CPVT patients have pathogenic variants in the gene encoding the cardiac ryanodine receptor, or calsequestrin 2. These lead to mishandling of calcium in cardiomyocytes resulting in after-depolarizations, and ventricular arrhythmias. Disease severity is particularly pronounced in younger individuals who usually present with cardiac arrest and arrhythmic syncope. Risk stratification is imprecise and long-term prognosis on therapy is unknown despite decades of research focused on pediatric CPVT populations. The purpose of this review is to summarize contemporary data on pediatric CPVT, highlight knowledge gaps and present future research directions for the clinician-scientist to address.

Un-LINQed: Spontaneous extrusion of newer generation implantable loop recorders.

BACKGROUND: Insertable cardiac monitors (ICMs) are often used for long-term monitoring of cardiac rhythm. The Medtronic's LINQ Reveal ™ is a new generation wireless, automated, and patient responsive subcutaneous ECG monitoring device. Despite several advantages to its small size we have noted an unusually high incidence of extrusion at our center. METHODS: & Results: We conducted a retrospective case analysis to review Reveal LINQs implanted at our center. All devices were inserted using the provided insertion tools. Patients with extruded devices were identified and details regarding the site and technique of insertion, incision closure, use of peri-operative antibiotics, and follow-up details were collected. 81 patients underwent 85 Reveal LINQ implants at a tertiary care University Hospital referral center. The most common reason for implant was suspected arrhythmia with or without structural heart disease or unexplained syncope. There were 4 spontaneous extrusions occurring within 7-24 days after insertion with an incidence rate of 4.7%. One extruded device was anchored to subcutaneous tissue, and no pocket/device infections or hematomas were noted. CONCLUSIONS: Device migration and erosion through skin are important potential adverse events for the Reveal LINQ implantable loop recorder. This study reports an unexpectedly high rate of extrusion without infection. The authors suggest that the depth of the incision is the main factor impacting extrusions. Larger studies are recommended, however, and a proposed measure to avoid spontaneous extrusion is the design of a longer manufacturer's blade in order to increase the depth of the incision and insertion.

Ambulatory Arrhythmia Detection with ZIO® XT Patch in Pediatric Patients: A Comparison of Devices.

Ambulatory electrocardiogram monitoring devices can be used for 24-72 h to detect arrhythmias. A new device, the ZIO® XT Patch has cardiac monitoring capabilities that can be utilized for up to 14 days. The purpose of this study is to describe duration of ZIO use by age, and to compare its time to arrhythmia detection with the Holter monitor in a pediatric population. A single-center, retrospective review of patients < 18 years of age who underwent clinical investigation with ZIO from October 2014 to February 2016 was performed. An age-matched cohort was utilized to compare ZIO to Holter monitor results. Demographic and diagnostic data, time to first arrhythmia, and arrhythmia burden were analyzed. A total of 406 ZIO were prescribed; median age 12.7 years and 50% male subjects. Median duration of ZIO monitoring significantly increased with age (p < 0.001). 499 Holter monitors were prescribed on a statistically different age group. Arrhythmia detection rates were similar between groups, 10% (n = 42) by ZIO and 9% (n = 45) by Holter (p = NS). The majority of arrhythmias (57%) detected by ZIO were after 24 h (p < 0.0001). All arrhythmias detected by Holter monitor occurred within 24 h (p < 0.0001), mean duration of wear was 24.1 h, range 0.5-48 h. The ZIO® XT Patch may be considered as an ambulatory ECG monitor to diagnose arrhythmia in pediatric patients of all ages. Increasing patient age resulted in increasing duration of ZIO monitoring. Majority of arrhythmias detected with ZIO were identified after 24 h, which would have been missed by other short-term monitors.

Role of surface electrocardiogram precordial leads in localizing different anatomic sites of ectopic atrial tachycardia arising from lower right atrium in pediatric population.

BACKGROUND: The study was designed to examine P wave morphology (PWM) in precordial leads (V1 -V6 ) during ectopic atrial tachycardia (EAT) originating from low right atrium (RA) to identify the anatomic sites of these foci in children. METHODS: Twenty-three consecutive pediatric patients (56% females, mean age 8.5 ± 2.5) with EAT originating from the low RA underwent detailed atrial endocardial activation mapping and radiofrequency ablation. PWM during EAT was analyzed using standard 12-lead ECG in relation to successful ablation sites in RA. RESULTS: Ectopic atrial tachycardia originated from coronary sinus ostium (CSo) in 12 patients, nonseptal tricuspid annulus (TA) in five, lower crista terminalis (CT) in three and lower free wall in three. In lead V1 , PWM showed a positive pattern during EAT originating from CSo (8/12) [91.7% sensitivity, 100% specificity, 100% positive predictive value (PPV), 100% negative predictive value (NPV)]. A negative pattern was observed in EAT originating from lower free wall (1/3) and nonseptal TA (5/5) [50% sensitivity, 100% specificity, 100% PPV, 75% NPV], while isoelectric pattern was in EAT originating from lower CT (3/3) [100% sensitivity, 100% specificity, 100% PPV, 100% NPV]. In leads V3 -V6 , PWM showed a negative pattern in at least two consecutive leads during EAT from CSo (12/12), nonseptal TA (5/5) and lower free wall (3/3) while it was positive in EAT originating from lower CT (3/3) [100% sensitivity, 95% specificity, 75% PPV and 100% NPV]. CONCLUSIONS: P wave morphology in precordial leads can help differentiate the anatomic sites of EAT from lower RA with high PPVs and NPVs.

The Safety and Effectiveness of Flecainide in Children in the Current Era.

This retrospective study sought to determine the safety and effectiveness of flecainide in children with normal hearts and those with congenital heart disease (CHD) or cardiomyopathy (CMO). Baseline and follow-up data at two pediatric cardiology sites were queried (2000-2015); a total of 175 patients (20 with CHD and two with CMO) receiving flecainide were assessed. When comparing patients with CHD to those with normal hearts, patients with CHD were younger at diagnosis (median age 19 days; IQR 3-157.5 days vs normal heart patients median age 21 days; IQR 7-172 days, p = 0.4) and severe cardiac dysfunction was more prevalent (30% in CHD patients vs 8% in normal heart patients, p = 0.009). Treatment duration did not differ between the two groups (CHD patients median duration 52 weeks; IQR 27-91.5 weeks vs normal heart patients median duration 55 weeks; IQR 32-156 weeks, p = 0.5). Cardiac dysfunction resulting in flecainide discontinuation occurred in two patients (1%), one with CHD and one without. Three patients experienced proarrhythmia (2%) and there were no cardiac arrests during follow-up. There was one death in this cohort in a patient with severe CHD and an RSV infection (<1%). Arrhythmia control did not differ between the groups (90% in CHD patients vs 77% in normal heart patients, p = 0.2). Flecainide was well tolerated in this cohort, with fewer than 3% discontinuing medication due to flecainide-associated adverse events. Contrary to adult studies, there was no difference in the incidence of adverse events between patients with normal hearts and patients with CHD. Flecainide is a safe and effective antiarrhythmic medication, even for children with underlying CHD.

Repolarization Vector Magnitude Differentiates Kawasaki Disease from Normal Children.

INTRODUCTION: Kawasaki disease (KD) is the leading cause of acquired heart disease in children. The 12-lead electrocardiogram (ECG) changes in patients during the acute phase of KD include flattened T waves and prolonged corrected QT intervals (QTc). We set out to determine the 12-lead ECG and vectorcardiography predictors for identification of patients with KD and which of these predictors would be clinically useful for early identification of those with coronary artery anomalies (CAA). METHODS: A blinded, retrospective case-control study of patients with KD and age-matched controls was performed. Deep Q waves, QTc, spatial QRS-T angles, and T-wave vector magnitude (root mean square of the T wave, RMS-T) were assessed. Comparisons between groups were performed to test for significant differences. RESULTS: Fifty patients with KD (mean age 3.1 ± 3.1 years, 26% female) were compared to 50 previously healthy control patients (mean age 3.8 ± 2.9 years, 44% female). Of the KD patients, 32 (64%) were diagnosed as incomplete KD and 28 (56%) of them had CAA. When compared to the control group, KD patients had abnormal Q waves (72% vs 44% P = 0.005), shorter QTc values (395.1 ± 24.7 ms vs 410.4 ± 34.7 ms, P = 0.013), and lower RMS-T (0.42 ± 0.02 mV vs 0.63 ± 0.03 mV P < 0.001), respectively. Incomplete KD was also discriminated from controls by the same parameters. No differences were noted between KD patients with versus without CAA. CONCLUSION: The RMS-T differentiates complete and incomplete KD from controls. KD patients with CAA were not differentiated from those without CAA.

Universal ECG changes in pediatric patients undergoing procainamide challenge.

BACKGROUND: Procainamide is known to prolong PR, QRS, and QTc intervals in adults and is utilized to unmask the distinct electrocardiographic signatures, including right bundle branch block pattern and right precordial ST segment elevation seen with Brugada syndrome. This study analyzes a pediatric case series of procainamide challenges done to evaluate for possible Brugada syndrome. Our goal was to quantify the impact of procainamide on electrocardiographic intervals in all pediatric patients, regardless of the eventual determination of Brugada syndrome status. METHODS: We retrospectively reviewed all children undergoing procainamide challenge, consecutively from March 2009 to September 2012. Patients received intravenous procainamide over 15 minutes. All electrocardiograms (ECGs) performed during the drug challenge were reviewed. Analysis and ECG measurements were performed by investigators blinded to clinical diagnoses. RESULTS: All patients undergoing procainamide infusion had prolongation of their PR (mean +14%; 0-45%), QRS (+13%; 2-49%), and QTc (+15%; 4-30%) intervals regardless of testing outcome. QTc prolongation to >460 ms following procainamide infusion occurred in 76% of patients. No sustained arrhythmias or adverse events occurred. CONCLUSIONS: ECG changes including prolongation of the PR, QRS, and QTc intervals were seen in all children who underwent procainamide challenge for evaluation of possible Brugada syndrome. An increase in the PR, QRS, and QTc intervals of at least 20% occurred in all children without any adverse events. The QTc prolongation was not completely explained by the QRS prolongation.

Pediatric antiarrhythmics and toxicity: A clinical review.

Antiarrhythmic medications are fundamental in the acute and chronic management of pediatric arrhythmias. Particularly in the pediatric patient population, associated antiarrhythmic toxicities represent important potential adverse effects. Emergency medicine clinicians must be skilled in the detection, workup, and management of antiarrhythmic toxicity. This is a clinical review of the indications, pharmacology, adverse effects, and toxicologic treatment of antiarrhythmics commonly used in the pediatric patient population.

Ablation of accessory pathways in different anatomic locations using focal pulsed field ablation.

BACKGROUND: Ablation of accessory pathways (APs) is the cornerstone for treatment of patients with Wolff-Parkinson-White syndrome and manifestation of atrioventricular reentrant tachycardia. Pulsed field ablation (PFA) is a new type of nonthermal energy source delivered to the underlying tissue via the ablation catheter and used for ablation of arrhythmic substrates. OBJECTIVE: The purpose of this study was to determine the efficiency and long-term outcome of ablation of APs of different localizations using a focal pulsed electrical field. METHODS: Electrophysiological study was performed in patients with indication for AP ablation. An ablation catheter was used to map the position of AP insertion. Pulsed electric field was delivered through a standard ablation catheter. In left-sided APs, the first ablation attempt was within the coronary sinus (CS). Patient follow-up was scheduled 1-3 months after the ablation. Additional check-up was performed after 6 and 12 months. RESULTS: Fourteen 14 patients (3 pediatric) were treated. Termination of AP conduction was achieved in all procedures. The cohort consisted of 3 right free wall, 3 posteroseptal, and 8 left-sided APs. Ablation through CS was successfully used in 7 of 8 patients with left-sided APs. No complications were reported. Median follow-up was 5.5 months. Conduction recurrence through AP was documented in 1 patient. CONCLUSION: Focal PFA for AP shows promising results in terms of efficacy and safety. A high rate of successful termination of left-sided APs by ablation within CS may represent a new standard approach. The safety and efficacy profile of PFA seems to be transferable to the pediatric population.

Transesophageal pacing studies reduce readmission but prolong initial admission in infants with supraventricular tachycardia: A cost-comparison analysis.

Background: Supraventricular tachycardia (SVT) is a common arrhythmia. Infants with SVT are often admitted to initiate antiarrhythmics. Transesophageal pacing (TEP) studies can be used to guide therapy prior to discharge. Objective: The objective of this study was to investigate the impact of TEP studies on length of stay (LOS), readmission, and cost in infants with SVT. Methods: This was a 2-site retrospective review of infants with SVT. One site (Center TEPS) utilized TEP studies in all patients. The other (Center NOTEP) did not. Patients with structural heart disease, patients with gestational age <34 weeks, and patients diagnosed after 6 months were excluded. At Center TEPS, repeat TEP studies were performed after titration of medication until SVT was not inducible. Primary endpoints were LOS and readmission for breakthrough SVT within 31 days of discharge. Hospital reimbursement data were utilized for cost-effectiveness analysis. Results: The cohort included 131 patients, 59 in Center TEPS and 72 in Center NOTEP. One patient was readmitted in Center TEPS vs 17 in Center NOTEP (1.6% vs 23.6%; P ≤ .001). Median LOS was longer for Center TEPS at 118.0 (interquartile range [IQR] 74.0-189.5) hours vs Center NOTEP at 66.9 (IQR 45.5-118.3) hours (P = .001). Twenty-one patients had multiple TEP studies. Median length of readmission for Center NOTEP was 65 (IQR 41-101) hours. Including readmission costs, utilization of TEP studies resulted in a probability-weighted cost of $45,531 per patient compared with $31,087 per patient without TEP studies. Conclusion: Utilization of TEP studies was associated with decreased readmission rates but longer LOS and greater cost compared with SVT management without TEP studies.

Beyond Anatomy: Use of Sinus Propagation Mapping to Identify the Slow Pathway for Cryoablation in Pediatric Patients.

Slow pathway modification via cryoablation is a common treatment of atrioventricular nodal re-entrant tachycardia (AVNRT) in pediatric patients. Sinus propagation mapping (SPM) is a tool that has been used to augment identification of the AVNRT slow pathway. We hypothesize that the use of SPM will decrease the total number of ablations performed and decrease the number of ablations until the slow pathway is successfully modified without a significant increase in procedure time. We conducted a retrospective review of patients who underwent cryoablation for AVNRT from August 2016 through March 2021. We excluded patients >21 years of age, those who underwent radiofrequency ablation; those with prior AVNRT ablation, additional pathways, or arrhythmias; and those with congenital heart disease. Out of 122 patients identified by the IMPACT database query, 103 met the inclusion criteria. Fifty-two patients (50.5%) had SPM completed during their procedures. The median number of ablations needed until successful slow pathway modification was two ablations in patients who underwent SPM and four ablations in the non-SPM group (P = .03). There was no significant difference in the total number of ablations between groups. The median total procedural time was longer in the SPM group (152 vs. 125 min; P = .01). SPM can be utilized to further improve the successful treatment of AVNRT with cryotherapy by lowering the number of ablations needed until successful slow pathway modification. However, the technique requires some additional time to collect sufficient data points to create the sinus map.

Postnatal Outcomes in Infants With a History of Fetal Supraventricular Tachycardia.

BACKGROUND: Fetal supraventricular tachycardia (SVT) is rare and proposed predictors of postnatal outcomes in fetal SVT have not been validated. Valid predictors can guide postnatal management. OBJECTIVES: The authors correlated fetal characteristics to the incidence of postnatal SVT and compared SVT outcomes in infants with and without a history of fetal SVT. METHODS: Mother-fetus dyads with fetal SVT and a structurally normal heart were described and compared with a second cohort of infants with a postnatal diagnosis of SVT. RESULTS: SVT was observed in 78 fetuses and 76 survived to delivery. Maternally administered transplacental antiarrhythmics were used in 49 mother-fetus dyads. Rhythm control was achieved in 37 of 49 (76%). Among fetuses with intermittent SVT, there was no ventricular dysfunction or hydrops. Postnatal SVT occurred in one-half of infants (37 of 76), and 94% presented within the first 2 days of life. The following fetal characteristics were associated with postnatal SVT on univariable analysis: sustained SVT (87% vs 56%), ventricular dysfunction (41% vs 15%), lack of conversion to sinus rhythm (49% vs 10%), and earlier gestational age at delivery (37.6 weeks vs 38.9 weeks; P ≤ 0.01 for each comparison). Compared with infants with a postnatal diagnosis of SVT, infants with a fetal diagnosis presented earlier (median age 0 days vs 17 days; P < 0.01) and had a lower incidence ventricular dysfunction at presentation (5% vs 42%; P < 0.01). CONCLUSIONS: One-half of infants with fetal SVT had postnatal SVT, nearly all within 2 days of life. These data and predictors of postnatal SVT may influence parental counseling and postnatal clinical decision-making.

A Single-center Experience Comparing First- Versus Second-generation Insertable Cardiac Monitors in Pediatric Patients.

Insertable cardiac monitors (ICMs) have undergone advancements in size and functionality over the past decade, resulting in the introduction of small, easily insertable devices capable of long-term remote monitoring. We define first-generation ICMs as implantable cardiac monitoring devices that require an incision and surgical creation of a subcutaneous pocket and second-generation ICMs as devices implanted using a custom-made tool for subcutaneous insertion, respectively. The aim of this study was to understand the differences between first- and second-generation pediatric ICM implants, implant indications, and time to diagnosis. We performed a retrospective, single-center chart review of patients who underwent ICM implantation from 2009-2019, spanning a 5-year course of first-generation ICM implantations and 5-year course of second-generation ICM implantations. Demographic data, past medical history, implant indication, and time to diagnosis were obtained. A total of 208 patients were identified over the 10-year time period, including 38 (18%) who underwent implantation with a first-generation device and 170 (82%) who underwent implantation with a second-generation device. Implant indications for first-generation ICMs included syncope (71%), palpitations (16%), inherited arrhythmia syndrome (IAS) management (5%), and premature ventricular contractions/ventricular tachycardia (VT) (8%); implant indications for second-generation ICMs included syncope (48%), palpitations (19%), IAS management (40%), premature ventricular contractions/VT (11%), atrial fibrillation (2%), tachycardia (3%), and heart block (0.5%). The average time to diagnosis was 38 weeks for patients with first-generation devices and 55 weeks for those with second-generation devices. With innovations in ICM technologies, there are expanding indications for ICM implantation in pediatric patients for long-term monitoring, specifically regarding the management of IAS patients.

The Value of Continuous Electrocardiographic Monitoring in Pediatric Cardiology: A Local Center Experience.

Objectives This study aims to evaluate the value of Holter monitoring in pediatric cases and look for the best predictor for abnormal Holter monitoring. Methodology All patients referred with cardiac symptoms associated or possibly related to abnormal cardiac rhythm from January 2019 to December 2020 were retrospectively reviewed. The demographic, clinical, 12-lead electrocardiography (ECG), echocardiography, and Holter monitoring results were reviewed. Multinomial logistic regression analysis was used to assess the correlation between gender, age, type of symptoms, ECG, and echo abnormalities, and Holter monitoring results were analyzed. Results During the study period, a total of 189 Holter monitoring was performed for 187 patients. The mean age at the performance of Holter monitoring was 88.6 ± 57 months. The female/male ratio was 1.5:1. The commonest indications for Holter monitoring were abnormal 12-lead ECG (30.7%), palpitations (30.7%), syncopal attacks (12.7%), and chest pain (6.9%). Patients with congenital heart disease (CHD) pre- or post-cardiac intervention constitute 9% of the total Holter monitoring cases. Apart from sinus arrhythmia, 12-lead ECG was abnormal in 57 (30%) patients, with premature atrial complexes (PACs) being the most common abnormality. Echocardiography was abnormal in 67 (35.4%) cases, with secundum atrial septal defect (ASD) (6.3%) and mitral valve prolapse (5.8%) being the commonest abnormalities. The Holter monitoring was completely normal in 89 (47.1%) cases. The commonest Holter abnormalities were PACs (12.7%), supraventricular tachycardia (SVT) (5.8%), and premature ventricular complexes (PVCs) (4.8%). There were 24 patients with SVT, and eight of them had normal Holter monitoring. One patient with SVT had ablation by the electrophysiologist. Using the multinomial logistic regression analysis, significantly abnormal 12-lead ECG, the presence of CHD, and abnormal echocardiography predict the presence of abnormal Holter results with a statistically significant p-value. Conclusion Most pediatric arrhythmias are benign. Holter monitoring provides reassurance for the patient and family. Abnormal Holter monitoring is more often observed in patients with paroxysmal or persistently abnormal 12-lead ECG with or without associated cardiac abnormalities or cardiac interventions. The yield of Holter monitoring is low in children referred because of chest pain, palpitations, or syncope with no other cardiac symptoms and with a structurally and functionally normal heart.

Coronary sinus morphology in pediatric patients with supraventricular tachycardia.

PURPOSE: The anatomic basis of atrioventricular node reentrant tachycardia (AVNRT) remains incompletely characterized in children. Differences in coronary sinus (CS) size and morphology have been observed in adults with AVNRT but have not been well characterized in children. METHODS: Children (< 18 years) brought to the EP lab with supraventricular tachycardia for ablation underwent CS venography. A blinded pediatric interventional cardiologist performed CS measurements, which were indexed to body surface area. Patients were excluded if they were < 25 kg or had significant congenital heart disease. RESULTS: Forty-six patients (age 14.2 ± 3.3 years) met inclusion criteria, 17 with AVNRT and 32 with an accessory pathway (AP). CS ostium (LAO projection, end-systole) was 7.8 ± 2.9 mm/m2 for the AVNRT group versus 6.0 ± 2.5 mm/m2 for the AP group (p = 0.04). CS "windsock" morphology was more prevalent in the AVNRT group (16/17, 94.1%) than the AP group (11/32, 34.3%) (p < 0.001). Within the AVNRT group, there was no correlation between CS ostium size and tachycardia cycle length (R = 0.01, p = 0.96), fast-pathway ERP (FPERP) (R = 0.42, p = 0.12), or A2-H2 at the FPERP (R = 0.25, p = 0.39). CONCLUSIONS: Children with AVNRT have larger CS ostia and more prevalent windsock morphology. CS size/morphology did not correlate with EP properties of the AVNRT substrate. These features may explain the basis for the development of the electrophysiologic substrate for dual AV node physiology in children.