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Rhythm-symptom correlation in pediatric patients with syncope/palpitations or at risk cohorts can be difficult, but important given potential associations with treatable or malignant arrhythmia. We sought to evaluate the use, efficacy and outcomes of implantable loop recorders (ILR) in pediatrics. We conducted a retrospective study of pediatric patients (21 years) with implanted ILR. Patient/historical characteristics and ILR indication were obtained. Outcomes including symptom documentation, arrhythmia detection and ILR based changes in medical care were identified. Comparison of outcomes were performed based on implant indication. Additional sub-analyses were performed in syncope-indication patients comparing those with and without changes in clinical management. A total of 116 patients with ILR implant were identified (79 syncope/37 other). Symptoms were documented 58% of patients (syncope 68% vs nonsyncope 35%; p = 0.002). A total of 37% of patients had a documented clinically significant arrhythmia and 25% of patients had a resultant change in clinical management independent of implant indication. Arrhythmia type was dependent on implant indication with nonsyncope patients having more ventricular arrhythmias. Pacemaker/defibrillator implantation and mediation management were the majority of the clinical changes. In conclusion, IRL utilization in selected pediatric populations is associated with high efficacy and supports clinical management. ILR efficacy is similar regardless of indication although patients with nonsyncope indications had a higher frequency of ventricular arrhythmias as opposed to asystole and heart block in syncope indications. The majority of arrhythmic findings occurred in the first 12 months, and new technology that would allow for less invasive monitoring for 6 to 12 months may be of value.

Background Mortality in cohorts with a single ventricle remains high with multiple associated factors. The effect of heart block during stage I palliation remains unclear. Objective The purpose of this study was to study patient and surgical risks of heart block and its effect on 12-month transplant-free survival in patients with a single ventricle. Methods Patient, surgical, outcome data and heart block status (transient and permanent) were obtained from the National Pediatric Cardiology Quality Improvement Collaborative single ventricle database. Bivariate analysis was performed comparing patients with and without heart block, and multivariate modeling was used to identify variables associated with block. One-year outcomes were analyzed to identify variables associated with lower 12-month transplant-free survival. Results In total, 1423 patients were identified, of whom 28 (2%) developed heart block (second degree or complete) during their surgical admission. Associated risk factors for block included heterotaxy syndrome (odds ratio [OR] 6.4) and atrial flutter/fibrillation (OR 3.8). Patients with heart block had lower 12-month survival, though only in patients with complete heart block as opposed to second degree block. At 12 months of age, 43% (12/28) of patients with heart block died and were more likely to experience mortality at 12 months than patients without block (OR 4.9; 95% confidence interval 1.4–17.5; P = .01). Conclusion Although rare, complete heart block after stage I palliation represents an additional risk of poor outcomes in this high-risk patient population. Heterotaxy syndrome was the most significant risk factor for the development of heart block after stage I palliation. The role of transient block in outcomes and potential rescue with long-term pacing remains unknown and requires additional study.

Arrhythmias are common in single ventricle patients though their effect on outcomes during stage I palliation (S1P) is unclear.The authors sought to study associated risks for arrhythmia in patients undergoing S1P for single ventricle disease and evaluate the outcome of arrhythmias and their treatment strategies on survival.Retrospective patient, surgical, medication, and arrhythmia data were obtained from the NPC-QIC (National Pediatric Cardiology Quality Improvement Collaborative) database. Bivariate analysis of variables associated with arrhythmias, as well as those associated with survival, was performed at the time of stage II palliation. Appropriate variables were included in multivariate modeling.Of the 2,048 patients included in the study, 36% had arrhythmia noted during their S1P hospitalization, with supraventricular tachycardia (12%) and focal atrial tachycardia (11%) the most common. At S1P discharge, 11% of patients were on an antiarrhythmic medication. Arrhythmias were associated with lower survival and increased hospital length of stay. Heterotaxy syndrome, younger age at S1P, male sex, and additional anomalies were associated with increased risk of arrhythmia in multivariable modeling (P ≤ 0.01). Arrhythmia and female sex were associated with increased mortality, whereas antiarrhythmic medication and digoxin use were associated with decreased mortality (P ≤ 0.003, model area under the curve = 0.79). The use of antiarrhythmic medications within the subcohort of arrhythmia patients was also associated with decreased risk of mortality (P lt; 0.0001; odds ratio: 2.0-7.2).Arrhythmias are common during admission for S1P and associated with poor outcomes. The use of antiarrhythmic medications may improve survival, though future studies are needed.

Patients with left ventricular noncompaction (LVNC) are at risk of clinically significant arrhythmias and sudden death. We evaluated whether implantable loop recorders could detect significant arrhythmias that might be missed in these patients during annual Holter monitoring. Selected pediatric and adult patients with LVNC who consented to implantable loop recorder placement were monitored for 3 years (study duration, 10 April 2014–9 December 2019). Fourteen subjects were included (age range, 6.5–36.4 yr; 8 males). Of 13 patients who remained after one device extrusion, one underwent implantable cardioverter-defibrillator placement. Four patients (31%) had significant arrhythmias: atrial tachycardia (n=2), nonsustained ventricular tachycardia (n=1), and atrial fibrillation (n=1). All 4 events were clinically asymptomatic and not associated with left ventricular ejection fraction. In addition, a high frequency of benign arrhythmic patterns was detected. Implantable loop recorders enable continuous, long-term detection of important subclinical arrhythmias in selected patients who have LVNC. These devices may prove to be most valuable in patients who have LVNC and moderate or greater ventricular dysfunction.

Pacemakers are a mainstay of therapy for patients with congenital and acquired heart block, but ventricular pacing is related to ventricular dysfunction. We sought to evaluate patient and device characteristics associated with ventricular dysfunction in pediatric patients with chronic ventricular pacing. This was a retrospective cohort of pediatric patients with heart block and chronic ventricular pacing. Patient, ECG, and device characteristics were analyzed to determine factors associated with ventricular dysfunction. Longitudinal ECG and echocardiogram parameters were obtained to track changes in QRS and systemic ventricular systolic function over time. In total, 82 patients were included (median age at implant 0.81 years). Over a follow-up time of 6.1 years, 18% developed ventricular dysfunction. Patients with dysfunction had greater current QRS duration (p = 0.002) compared to those with preserved function with a similar time from device implantation. There was no difference between lead location or age at device implantation. QRS duration increased with time from implant and the resultant ΔQRS was associated with ventricular dysfunction (p = 0.01). QRS duration >162 ms was associated with a 5.8 (2–9)-fold increased risk for dysfunction. Transvenous leads were associated with longer QRS duration with no difference compared to epicardial leads in development of ventricular dysfunction. This study demonstrated that the absolute paced QRS duration and Δpaced QRS were association with long-term ventricular dysfunction independent of how long a given patient was paced. Patients in high-risk categories may benefit from close echocardiographic monitoring. Whether permissive junctional rhythm or His bundle/biventricular pacing decreases the rate of dysfunction needs further study.

BACKGROUND The presence of anterograde conduction through an accessory pathway (AP) has been linked to sudden cardiac death. Unfortunately, pre-excitation associated with classic pathways can be difficult to differentiate from benign APs such as nodofascicular fibers. OBJECTIVE Identifying characteristics on electrocardiogram (ECG) and exercise that differentiate classic and benign AP connections in suggested pre-excitation patterns. METHODS Retrospective review of patients presenting between 1995 and 2017 with ventricular pre-excitation on ECG, determined to have either typical left-lateral AP during electrophysiology study (EPS), or benign, or no AP determined by either transesophageal electrophysiology study (TEP), or EPS. RESULTS A total of 96 patients were included, 14.2 years (4-24), 45% female, 90% Caucasian. Of these, 60 (63%) had a classic APs identified on EPS and 58 (97%) underwent successful ablation. Conversely, 36 (37%) had benign pathways identified. ECG findings differed between the groups: PR-interval 102 versus 120 ms (P

Background: Implantable cardioverter defibrillators (ICD) are recommended for secondary prevention after sudden cardiac arrest (SCA). The outcomes of pediatric patients receiving an ICD after SCA remain unclear. The objective of this study is to evaluate outcomes, future risk for appropriate shocks, and identify characteristics associated with appropriate ICD therapy during follow-up. Methods: Multicenter retrospective analysis of patients (age ≤21 years) without prior cardiac disease who received an ICD following SCA. Patient/device characteristics, cardiac function, and underlying diagnoses were collected, along with SCA event characteristics. Patient outcomes including complications and device therapies were analyzed. Results: In total, 106 patients were included, median age 14.7 years. Twenty (19%) received appropriate shocks and 16 (15%) received inappropriate shocks (median follow-up 3 years). First-degree relative with SCA was associated with appropriate shocks ( P P =0.015). In patients >2 years from implantation, younger age ( P =0.02) and positive exercise test ( P =0.04) were associated with appropriate shock. Conclusions: The risk of future device therapy is high in pediatric patients receiving an ICD after SCA, irrelevant of underlying disease. Lack of a definitive diagnosis after SCA was not associated with lower risk of subsequent events and does not obviate the need for secondary prophylaxis.

Introduction: AV nodal reentrant tachycardia (AVNRT) is a common form of SVT in pediatrics. Ablation can be curative; however, the choice between radiofrequency ablation (RF) and cryoablation (Cryo) remains controversial due to a lack of contemporary large comparison studies in the pediatric population. Methods: AVNRT ablation outcomes were retrospectively analyzed utilizing the NCDR ® IMPACT Registry from 4/1/16 to 3/31/19. Data from subjects aged 1-21 years undergoing elective first-time slow pathway (SP) modification for AVNRT were included. Exclusion criteria were age1 targeted arrhythmia mechanism, and >1 ablation catheter/energy source. The primary outcome was acute ablation success, defined as elimination of SP conduction or SP conduction with ≤ 1 AV nodal echo without SVT. Secondary outcomes included major adverse effects (MAE) of AV block, temporary or permanent pacing, death, cardiac arrest, tamponade, or embolic stroke. Results: Among 2235 patients (mean age: 13.6 ± 3.4 years, 59% female), there was comparable use of Cryo (53%, n=1183) and RF (47%, n=1052). Cryo was more commonly used in patients < 8years of age (p < 0.01). Amongst 60 participating centers, 24 sites (40%) used Cryo predominantly (>90%), while 24 sites (40%) used RF predominantly. Acute success was 98.6% for Cryo and 99% for RF (P = 0.27). AV block was reported in 6 (0.005%) patients with Cyro and 3 (0.003%) with RF (p=0.34), without the need for temporary or permanent pacemaker in either group during the hospital admission. No other MAE occurred in either group. Conclusion: In this largest pediatric study of AVNRT ablation, RF and Cryo demonstrated comparable high acute success and rare documentation of AV block that did not result in temporary or permanent pacing. Longitudinal data are important for further comparison of these two modalities with regard to AVNRT recurrence risk and the need for pacemaker implantation outside of the hospitalization period.

Pacemakers are a mainstay of therapy for patients with congenital and acquired heart block, but ventricular pacing is related to ventricular dysfunction. We sought to evaluate patient and device characteristics associated with ventricular dysfunction in pediatric patients with chronic ventricular pacing. This was a retrospective cohort of pediatric patients with heart block and chronic ventricular pacing. Patient, ECG, and device characteristics were analyzed to determine factors associated with ventricular dysfunction. Longitudinal ECG and echocardiogram parameters were obtained to track changes in QRS and systemic ventricular systolic function over time. In total, 82 patients were included (median age at implant 0.81 years). Over a follow-up time of 6.1 years, 18% developed ventricular dysfunction. Patients with dysfunction had greater current QRS duration (p = 0.002) compared to those with preserved function with a similar time from device implantation. There was no difference between lead location or age at device implantation. QRS duration increased with time from implant and the resultant ΔQRS was associated with ventricular dysfunction (p = 0.01). QRS duration162 ms was associated with a 5.8 (2-9)-fold increased risk for dysfunction. Transvenous leads were associated with longer QRS duration with no difference compared to epicardial leads in development of ventricular dysfunction. This study demonstrated that the absolute paced QRS duration and Δpaced QRS were association with long-term ventricular dysfunction independent of how long a given patient was paced. Patients in high-risk categories may benefit from close echocardiographic monitoring. Whether permissive junctional rhythm or His bundle/biventricular pacing decreases the rate of dysfunction needs further study.

Evaluate the efficacy, outcomes, and complications associated with direct current cardioversion (DCCV) in the treatment of arrhythmias in pediatric and adult congenital heart disease (CHD) populations and identify patient and procedural characteristics associated with adverse events.Pediatric and adult patients with CHD are at risk of atrial arrhythmias. DCCV is effective but is associated with potential complications.In this single-center retrospective series, patients who underwent DCCV between January 2010 and May 2015 were identified and categorized as pediatric (18 years) or adult ( 18 years). Records were reviewed for demographic, arrhythmic, and CHD-specific characteristics; acute efficacy; and 3-month arrhythmia recurrence. Complications were categorized as life-threatening (LT) or non-life-threatening (NLT). Univariate followed by multiple variable and logistic regression (LR) analyses were used to identify characteristics associated with complications.We identified 104 patients with 152 discrete DCCV events with median age 17.4 years (0.15-62.2). DCCV efficacy was 89% with 3-month recurrence of 46%. There were 52 complications among 24 patients, median age 17.7 years (0.15-49). Risks associated with NLT complications are as follows: moderate-severe systolic dysfunction (8/152 encounters, P = 0.01) and more than one shock per DCCV encounter (P = 0.01). Six of eight encounters with moderate-severe systolic dysfunction were 18 years (P = 0.1). Risks for LT complications included age 18 years and associated NLT complication. Adults had more frequent arrhythmia recurrence within 3 months than children (P = 0.01).DCCV is effective for arrhythmias but is associated with frequent recurrence, particularly in adult patients. Complications associated with DCCV may be greater than previously reported. Additional support and precautions should be in place for those at greatest risk.

Keeping children safe is a goal for everyone. To stay safe, some children need a wearable cardioverter defibrillator (WCD). WCDs protect individuals who are at risk for life-threatening arrhythmias. The LifeVest® (ZOLL, Pittsburgh, PA, USA) is a WCD that identifies, records, and treats potentially life-threatening abnormal heartbeats, or arrhythmias. The WCD will provide electrical energy to the heart with up to five high-energy shocks if a potentially dangerous cardiac arrhythmia is detected. This type of arrhythmia, if not treated within a short time period (less than 2 minutes), can result in disruption of blood flow to the brain and other vital organs (that is, a sudden cardiac arrest), and death can occur within minutes. A shock delivered by the LifeVest can terminate an arrhythmia and restore a normal heart rhythm and blood flow to the body. In December 2015, the Food and Drug Administration approved the LifeVest for patients under 18 years old. The purpose of this guide is to serve as a resource for parents and educators, to promote awareness of the LifeVest, and to answer questions about the safety of the LifeVest in schools.

Background Complications related to epicardial pacemakers in infants have been reported, though limited data are available on their incidence and associated risk factors. Objective The hypothesis of the study is that younger, smaller patients and larger devices would be associated with complications in neonates and infants. Methods This is a retrospective study of all patients at a single center receiving an epicardial pacemaker at ≤12 months of age (1996–2015). Patient and device characteristics were obtained. Characteristics of patients with and without complications were compared. Results There were 86 patients with a median age of 73 days (interquartile range 13–166 days), of whom 12 (14%) had a complication. Eight (9%) needed surgical intervention, of whom 5 (6%) required explantation. Younger age (9 days vs 89 days; P = .01) and lower weight (2.91 kg vs 4.44 kg; P = .004) at implantation were associated with complications. Device characteristics were not statistically different. Patients ≤3 kg in weight and/or P 21 days were found to be at lower risk with an NPV of 96%; and regardless of age, patients weighing >4 kg had an NPV of 98%. Conclusion Young age and low weight at the time of implantation are risk factors for complications, while device characteristics appear to play a minor role. Reserving pacemaker implantation for patients >3 kg in weight and 5 days of age may predict patients at low risk of developing complications.

The atrial transseptal procedure is used in catheter ablation of left-sided arrhythmias. Studies in adult patients have shown the SafeSept™ transseptal guidewire (SSTG) to be effective in atrial transseptal procedures. We analyzed our 5-year experience with SSTG use in pediatric and congenital heart disease patients undergoing catheter ablation. This is a single-center retrospective analysis of patients undergoing catheter ablation from 2009 to 2014. We identified all procedures where SSTG was used for atrial transseptal or trans-baffle access. Success of transseptal access and complications were recorded and compared to the standard transseptal approach without the SSTG. One hundred twenty-seven patients underwent 132 attempted atrial transseptal or trans-baffle procedures using SSTG. Median age was 14 (1.2–38) years. Arrhythmia substrates included AV reentrant tachycardia (90.2%), atrial tachycardia (4.5%), ventricular tachycardia (2.3%), and AV nodal reentrant tachycardia (2.3%). Transseptal or trans-baffle access was successful in 96.2% of the SSTG cases compared to 98.9% in the standard transseptal group without SSTG (p = NS). The youngest patient with successful atrial transseptal procedure using SSTG was 4 years old. SSTG was used to successfully cross a surgically created atrial baffle in a patient who had undergone the Mustard procedure. There was one major complication in both groups, 0.8% in the SSTG group compared to the standard transseptal group without SSTG, 1.1% (p = NS). The major complication in the SSTG group occurred when the SSTG crossed the aorta into the coronary artery system and mimicked placement in the left atrial appendage, with subsequent placement of a transseptal sheath into the aorta, requiring sternotomy and surgical intervention. SSTG is effective for use in atrial transseptal and surgical trans-baffle access in pediatric and congenital heart disease patients. Placement of the SSTG into the pulmonary vein is necessary to avoid major complications, and if not achieved requires additional methods to determine appropriate left atrial placement.

Background Dilated cardiomyopathy (DCM) is the most common cardiomyopathy in children. Patients with severe cardiac dysfunction are thought to be at risk of sudden cardiac arrest (SCA). After diagnosis, a period of medical optimization is recommended before permanent implantable cardioverter-defibrillator (ICD) implantation. Wearable cardioverter-defibrillators (WCDs) provide an option for arrhythmia protection as an outpatient during this optimization. Objective The purpose of this study was to determine the strategy that optimizes cost and survival during medical optimization of a patient with DCM before ICD placement. Methods A Markov state transition model was constructed for the 3 clinical approaches to compare costs, clinical outcomes, and quality of life: (1) "Inpatient," (2) "Home-WCD," and (3) "Home-No WCD." Transitional probabilities, costs, and utility metrics were extracted from the existing literature. Cost-effectiveness was assessed comparing each paradigm's incremental cost-effectiveness ratio against a societal willingness-to-pay threshold of $50,000 per quality-adjusted life year. Results The cost-utility analysis illustrated that Home-WCD met the willingness-to-pay threshold with an incremental cost-effectiveness ratio of $20,103 per quality-adjusted life year and 4 mortalities prevented per 100 patients as compared with Home-No WCD. One-way sensitivity analyses demonstrated that Home-No WCD became the most cost-effective solution when the probability of SCA fell below 0.2% per week, the probability of SCA survival with a WCD fell below 9.8%, or the probability of SCA survival with Home-No WCD quadrupled from base-case assumptions. Conclusion Based on the existing literature probabilities of SCA in pediatric patients with DCM undergoing medical optimization before ICD implantation, sending a patient home with a WCD may be a cost-effective strategy.

[Author Affiliation]Tricia B. Minton. 1 University of Cincinnati College of Medicine, Cincinnati, Ohio.Joanna Rosing. 2 Department of Anesthesiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.David S. Spar. 3 Division of Pediatric Cardiology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.Jeffrey R. Strawn. 4 Department of Psychiatry, University of Cincinnati College of Medicine, Cincinnati, Ohio.Blanca Garcia-Delgar. 5 Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York.Barbara J. Coffey. 5 Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York.Address correspondence to: Barbara J. Coffey, MD, MS, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1230, New York, NY 10029, E-mail: barbara.coffey@mssm.eduChief Complaint and Presenting ProblemA. was a 16-year-old adolescent girl with a history of congenital long QT syndrome and generalized anxiety and panic disorder with agoraphobia that had resulted in school avoidance. She was referred for anxiety symptoms that were difficult to control in the context of her cardiac condition.History of Present IllnessMother reported that A. had a history of separation anxiety as a young child, and a brief period of depressive symptoms when she was ∼14 years old, but these resolved spontaneously and did not require psychiatric treatment. A. was referred at age 16 for generalized anxiety symptoms, full-symptom panic attacks, and secondary depressive symptoms. Specifically, she endorsed irritability, restlessness, dreadful anticipation, and uncontrollable worries regarding school, her family, her brother, the future, and her friends, which occurred for several hours each day. In addition, she experienced initial insomnia, often lying in bed at night worrying about the next day, the events of the previous day, and her future. Her panic attacks occurred several times each week and included a myriad of somatic and cognitive symptoms, such as dyspnea, palpitations, nausea, tremulousness, sweating, and a sense that she might die.A.'s symptoms had been occurring for nearly a year, but had intensified recently, prompting her and her family to seek treatment from her primary care physician. She was initially treated with sertraline 25 mg and titrated to 100 mg daily, and lorazepam 1 mg daily on an as needed basis. She was also referred to a psychotherapist. Pharmacotherapy and psychotherapy were started in parallel, given the severity of the symptoms. Despite these efforts, A.'s anxiety and panic symptoms increased, and she became unable to attend school. At that time, the only precipitant was significant distress surrounding her brother's diagnosis of bipolar disorder, although it was noted that, contemporaneously, her family attempted to accommodate her anxiety to minimize associated familial conflict. A. denied obsessive-compulsive symptoms, symptoms of mania (other than irritability), and psychotic symptoms. A. was subsequently referred to the emergency department, and treatment in a partial hospitalization program was recommended.During the course of A.'s partial hospitalization, sertraline was titrated to 200 mg daily and lorazepam 1 mg was continued pro re nata for panic attacks. In addition, hydroxyzine 50 mg twice daily and melatonin 6 mg were added to target anxiety and dyssomnia, respectively. Continuing to struggle with severe anxiety, feeling overwhelmed with regard to falling further behind at school, and having "failed," A. developed suicidal ideation (Columbia Suicide Severity Rating Scale [CSSRS] Intensity scores of 1-2) (Posner et al. 2011). Based on concerns that she had developed increasing depressed mood, social withdrawal, some anhedonia, and increased guilt--consistent with a diagnosis of major depressive disorder--extended release of bupropion was initiated at 150 mg qAM. …

Objective While late gadolinium enhancement (LGE) in paediatric patients with hypertrophic cardiomyopathy (HCM) is reported as similar to adults, the relationship between LGE and ECG findings in paediatric patients is unknown. We sought to evaluate the relationship between LGE on cardiac MRI and LV precordial voltage on ECG. Methods This was a retrospective analysis of paediatric patients with HCM aged 9–21 years with cardiac MRI and ECG completed within 60 days of each other. Demographic, MRI and ECG data were compared between patients with and without LGE. Maximal diastolic septal thickness, septal to free wall ratio and LGE presence were compared with LV precordial voltage (SV1, RV6 and SV1+RV6). Results This study included 37 patients (33 male). Mean age was 15.8±2.8 years. Mean maximal LV diastolic septal thickness was 22.1±7.9 mm. Mean septal to free wall ratio was 2.4±1.6 mm. LGE was present in 18 patients, with 16 isolated to the ventricular septum. Comparing patients with and without LGE, there was no difference in age (p=0.2) or body surface area (p=0.9). However, the presence of LGE was associated with significantly increased septal thickness (p=0.03), yet decreased voltages in SV1 (p=0.005), RV6 (p=0.005) and SV1+RV6 (p=0.002) despite increased septal dimensions. Conclusions A significant inverse relationship exists between LGE presence and LV precordial voltage in this population. Unexpectedly low LV precordial voltages in patients with HCM may serve as a clinical surrogate marker for myocardial fibrosis and potential loss of viable myocardial tissue.

Background— Risk associated with short QT interval has recently received recognition. European studies suggest a prevalence of 0.02% to 0.1% in the adult population, but similar studies in pediatric patients are limited. We sought to determine the prevalence of short QT interval in a pediatric population and associated clinical characteristics and outcomes. Methods and Results— Retrospective review of an ECG database at a single pediatric institution. The database was queried for ECGs on patients ≤21 years with electronically measured QTc of 140 to 340 ms. Patients with QTc of 140 to 340 ms confirmed by a pediatric electrophysiologist were identified for chart review for associated clinical characteristics, symptoms, and outcome. Patients with and without symptoms were compared in an attempt to identify variables associated with outcome. The query included 272 504 ECGs on 99 380 unique patients. Forty-five patients (35 men, 76%) had QTc ≤340 ms, for a prevalence of 0.05%. Median age was 15 years (interquartile range, 2–17), median QT 330 ms (interquartile range, 280–360), and median QTc 323 ms (IQR, 313–332). Women had significantly shorter QTc compared with men (312 versus 323 ms; P =0.03). Two deaths were noted in chart review—one from respiratory failure and the second of unknown pathogenesis in a patient with dilated cardiomyopathy. Conclusions— Short QT interval was a rare finding in this pediatric population, with a prevalence of 0.05%. Male predominance was identified, although the median QT interval was significantly shorter in women. There seem to be no unifying clinical characteristics for this pediatric patient cohort with short QT interval.

Background Implantable cardioverter defibrillators (ICDs) are an important part of therapy for many patients, yet there is little data on population characteristics, complications, or system survival in pediatric patients. Methods A retrospective review of ICD recipients in the National Cardiovascular Data Registry ICD Registry was performed from 2010 to 2016. Patient characteristics and complications between pediatric (≤21 years) and adult populations (>21 years) were compared. Variables associated with complications and early device interventions within the pediatric cohort were evaluated using multivariate modeling. Results There were 562 209 total ICD implants, of which 3461 occurred in the pediatric cohort. Among the pediatric patients, 60% of implants were for primary prevention, and nonischemic cardiomyopathy was the most common underlying disease (60%). Over time, there was an increasing trend of both primary and secondary prevention ICD implantations ( P P P =0.3). However, among the pediatric patients, lower weight, Ebstein anomaly, worse New York Heart Association class, dual chamber, and cardiac resynchronization therapy-defibrillator were associated with greater risk of complications. Although reintervention for generator replacement or upgrade was more common in adults, the time to reintervention was shorter in the pediatric cohort. Conclusions We observed an increasing trend in ICD device implantation among pediatric patients. The pediatric cohort had similar inhospital complication rates compared with adults but had a shorter time to reintervention.

The wearable cardioverter defibrillator can be used to protect against sudden cardiac arrhythmic death in at risk children. The wearable cardioverter defibrillator provides clinicians with multiple types of information such as activity level while wearing the device. The current study examined physical activity in pediatric populations while wearing the wearable cardioverter defibrillator and compared age, sex, and diagnostic groups in activity levels. The study sample included 231 children, aged 8–17, who wore a wearable cardioverter defibrillator between 2009 and 2017. All device based information and activity counts were retrieved from the data sent via remote monitoring. Pediatric patients were active for 73 min per day, with a median step count of 7361. These data were collected during their average of 39 days of wear time over an average of 21 h daily. There were no associations between sex, diagnostic groups, or end of use reason and wear time or activity; however, age was negatively associated with changes in activity level for patients aged 8–11. Results indicated significant increases in step count over the first three weeks of wear in all ages χF2 (3, n = 50) = 34.27, p

Background: Certain pediatric patients are at risk for sudden cardiac death. The wearable cardioverter-defibrillator (WCD) can be used in clinical situations in which implantable cardioverter-defibrillator placement is not ideal. The objectives of the study are to examine the effectiveness, safety, and compliance of the WCD in the identification and treatment of life-threatening ventricular arrhythmias in pediatric patients. Methods: All United States pediatric patients Results: In total, 455 patients were identified. The median age was 15 (3–17) years, median duration of WCD use was 33 (1–999) days and median patient wear time was 20.6 (0.3–23.8) hours per day. The population was divided into 2 groups: (1) patients with implantable cardioverter-defibrillator problem, n=63 and (2) patients with nonimplantable cardioverter-defibrillator problem, n=392. Wear time per day was >20 hours in both groups. Wear duration was shorter in the implantable cardioverter-defibrillator problem group, 26 days versus 35 days, P Conclusions: The WCD has overall adequate compliance with appropriate wear times and wear durations in pediatric patients. The WCD is safe and effective in treating ventricular arrhythmias that can lead to sudden cardiac death in pediatric patients.

BACKGROUND Traditional indices to evaluate biventricular (BiV) pacing are load dependent, fail to assess dynamic changes, and may not be appropriate in patients with congenital heart disease (CHD). We therefore measured the force-frequency relationship (FFR) using tissue Doppler-derived isovolumic acceleration (IVA) to assess the dynamic adaption of the myocardium and its variability with different ventricular pacing strategies. METHODS This was a prospective pilot study of pediatric and young adult CHD patients with biventricular or multisite pacing systems. Color-coded myocardial velocities were recorded at the base of the systemic ventricular free wall. IVA was calculated at resting heart rate and with incremental pacing. FFR curves were obtained by plotting IVA against heart rate for different ventricular pacing strategies. RESULTS Ten patients were included (mean: 22 ± 7 years). The FFR identified a best and worst ventricular pacing strategy for each patient, based on the AUC at baseline, submaximal, and peak heart rates (P

Sudden cardiac death in the young (SCDY) is the leading cause of death in young athletes during sport. Screening young athletes for high-risk cardiac defects is controversial. The purpose of this study was to assess the utility and feasibility of a comprehensive cardiac screening protocol in an adolescent population. Adolescent athletes were recruited from local schools and/or sports teams. Each subject underwent a history and/or physical examination, an electrocardiography (ECG), and a limited echocardiography (ECHO). The primary outcome measure was identification of cardiac abnormalities associated with an elevated risk for sudden death. We secondarily identified cardiac abnormalities not typically associated with a short-term risk of sudden death. A total of 659 adolescent athletes were evaluated; 64% men. Five subjects had cardiac findings associated with an elevated risk for sudden death: prolonged QTc >500 ms (n = 2) and type I Brugada pattern (n = 1), identified with ECG; dilated cardiomyopathy (n = 1) and significant aortic root dilation; and z-score = +5.5 (n = 1). History and physical examination alone identified 76 (11.5%) subjects with any cardiac findings. ECG identified 76 (11.5%) subjects in which a follow-up ECHO or cardiology visit was recommended. Left ventricular mass was normal by ECHO in all but 1 patient with LVH on ECG. ECHO identified 34 (5.1%) subjects in whom a follow-up ECHO or cardiology visit was recommended. In conclusion, physical examination alone was ineffective in identification of subjects at elevated risk for SCDY. Screening ECHO identified patients with underlying cardiac disease not associated with immediate risk for SCDY. Cost of comprehensive cardiac screening is high.

Objective: To optimize patient resource utilization and safety, we created a standard-of-care guideline for pediatric drug ingestion hospital admissions. Methods: A multidisciplinary committee developed specific telemetry guidelines for pediatric drug ingestion hospital admissions at a tertiary pediatric hospital. The guidelines stipulated inpatient admission with telemetry monitoring for the following criteria: (1) corrected QT interval (interval between the Q wave and T wave on a standard EKG)≥ 500 ms, (2) ingestion of an antiarrhythmic medication, or (3) ingestion of a tricyclic antidepressant. We created guidelines for electrocardiogram frequency for nontelemetry admissions. We implemented these guidelines in November 2015 in partnership with the Emergency Medicine Department and Poison Control Center. We reviewed medical records of all these admissions between January 1, 2015, and July 31, 2016, and divided patients into preintervention (January 1, 2015 to November 30, 2015) and postintervention (December 1, 2015 to July 31, 2016) groups. We used statistical process control charts and methodology to monitor changes over time. Results: There were a total of 622 drug ingestion admissions during the study period. We admitted 69 patients (11%) to the cardiac acute care unit (CACU) for telemetry monitoring. The preintervention period included 61 admissions (5.5 CACU admissions per month). The postintervention period included 8 admissions (1.1 CACU admissions per month). This difference reflects an overall absolute decrease of 87%. There was no evidence of an increase in the rate of intensive care unit utilization, rapid response events, or adverse events in the postintervention period. Conclusions: A standardized admission protocol for pediatric drug ingestions can safely improve resource utilization.

Patients with congenital heart disease (CHD) are at increased risk of cardiac arrhythmias. The utility of ambulatory (Holter) monitoring in predicting these arrhythmias remains unclear. We sought to evaluate the clinical utility and cost effectiveness of Holter monitoring in patients with CHD. A retrospective study of patients with CHD who had undergone Holter monitoring was performed. The Holter data from patients with tetralogy of Fallot (TOF), d-transposition of the great arteries (d-TGA) after an atrial switch operation, and patients with a single ventricle after Fontan palliation were reviewed. The Holter indication included evaluation of clinical symptoms or as a part of routine screening. The Holter results were deemed clinically significant if they resulted in a change in patient treatment. Sudden cardiac events included death or aborted sudden death and appropriate defibrillator therapies. A total of 589 Holter studies were performed in 189 patients (100 with TOF, 38 with d-TGA, and 51 with Fontan). The results of Holter monitoring performed for clinical symptoms had a low positive predictive value (0.08) for clinically significant changes in management. On routine monitoring, the sensitivity was low (0.40) but the negative predictive value was high (0.96) for future clinically significant arrhythmias. The frequency of clinically significant findings and associated cost-effectiveness improved with older patient age and Fontan and d-TGA CHD type. Nonsustained ventricular tachycardia was associated with sudden cardiac events in patients with TOF but not in those with d-TGA or Fontan palliation. In conclusion, Holter monitoring is generally inefficient for symptomatic evaluation; however, within specific age and CHD type subgroups, such as patients with repaired TOF >25 years old, it could be useful in clinical management and risk assessment as a part of routine care.

Cardiac rhythm monitoring has been facilitated by the use of implantable loop recorders. New models of these devices are 87% smaller than before allowing for easier implantation and use in the paediatric population. Recommendations are for closure with adhesive. We report a device extrusion in a 6-year-old patient. Based on this, our practice has changed to include subcutaneous sutures this complication.

Symptomatic upper-extremity deep venous thrombosis (UEDVT) after pacemaker placement in adults has been reported, but the occurrence of UEDVT in pediatric patients is poorly defined, and no treatment guidelines exist. This report describes a 14-year old girl with a history of complete atrioventricular block who experienced a symptomatic UEDVT 8 months after placement of a transvenous pacemaker. The girl was treated initially with anticoagulation including subcutaneous enoxaparin and a heparin drip, which did not resolve the venous obstruction. In the interventional laboratory, a venogram demonstrated complete obstruction of the left subclavian vein, which was treated successfully with catheter-directed alteplase, direct thrombus removal by manual suctioning, and balloon angioplasty. Warfarin therapy was continued for an additional 6 months, with follow-up venous ultrasounds demonstrating left subclavian vein patency. Soon after completing warfarin therapy, the girl presented with minimal edema of her left distal extremity and was thought to have post-thrombotic syndrome, which resolved quickly. She continued to receive aspirin therapy, with no recurrence of symptoms. In conclusion, symptomatic UEDVT after pacemaker placement in a pediatric patient can be treated successfully with both anticoagulation and interventional therapies. Further studies are needed to evaluate the incidence of thrombus formation among children with transvenous pacemaker placement together with the development of guidelines based on the safety and effectiveness of differing treatments.

The gradual loss of ventricular preexcitation during exercise stress testing (EST) has an unclear risk of an association with life-threatening arrhythmia and could be related to the accessory pathway (AP) location. We compared the loss of preexcitation during EST with the risk assessment during invasive electrophysiology testing and determined whether the loss of preexcitation correlates with the AP location. We retrospectively reviewed patients aged ≤21 years with ventricular preexcitation who had undergone both EST and an electrophysiology study. The patients were divided into 3 groups: sudden loss (SL), gradual loss (GL), or no loss (NL) of preexcitation during EST. A total of 76 patients were included, with 11 (14%) in the SL group, 18 (24%) in the GL group, and 47 (62%) in the NL group. The SL group demonstrated a longer cycle length with 1-to-1 conduction by way of the AP during incremental atrial pacing compared with the NL group (375 ± 135 ms vs 296 ± 52 ms, p = 0.002), with no difference between the GL and NL groups (325 ± 96 vs 296 ± 52 ms, p = NS). Of the patients with 1-to-1 AP conduction of

Supraventricular tachycardia (SVT) is the most frequent form of symptomatic tachyarrhythmia in infants. The purposes of this study were to describe practice patterns of the management of infants hospitalized with SVT and factors associated with 30-day hospital readmission. This was a multi-institutional, retrospective review of the pediatric health information system database of SVT hospitalizations from 2003 to 2013. High-volume centers (HVC) were defined as those at the upper quartile of admissions. Infants with an ICD-9 code of paroxysmal SVT were included. Antiarrhythmics investigated included amiodarone, atenolol, digoxin, esmolol, flecainide, procainamide, propafenone, propranolol, and sotalol. Frequency of antiarrhythmic use based on center volume was the primary end point. Rate of 30-day SVT readmission was the secondary end point. Analysis of factors associated with readmission was assessed by Chi-square analysis and expressed as odds ratio and 95 % confidence interval. A total of 851 patients (60 % male, 44 % neonates) were hospitalized at 43 hospitals. Propranolol, digoxin, and amiodarone were the most frequently utilized antiarrhythmics. HVCs represented 12 hospitals comprising 494 (58 %) patients. Although HVCs were more likely to utilize propranolol (OR 2.5, CI 1.5–4.1), there was no significant difference in the 30-day readmission rate between patients treated at HVCs versus non-HVCs (p = 0.9). The majority of infants with SVT are treated with a small number of antiarrhythmic medications during index hospitalization. Although hospital-to-hospital variation in antiarrhythmic choice exists, there appears to be no difference in readmission. The remaining practice variation may be related to intrinsic patient characteristics.

A 16-year-old female patient with Wolff-Parkinson-White syndrome and supraventricular tachycardia underwent radiofrequency (RF) catheter ablation of an accessory pathway in the left lateral area. During RF ablation she developed reversible ST segment elevation secondary to coronary artery spasm. Coronary angiography demonstrated the ablation catheter in close proximity to the circumflex coronary artery, with no evidence of coronary artery injury. Subsequently, conduction by way of the accessory pathway was successfully eliminated with cryoablation with no further coronary spasm or injury.

Pediatric patients with cardiomyopathy (CM) are at risk for sudden cardiac death (SCD), likely driven by arrhythmic etiologies.Describe arrhythmia burden and Holter utility in pediatric CM including: hypertrophic CM (HCM), dilated CM (DCM), and restrictive CM (RCM).Retrospective cohort study of patients21 years with CM. Patient demographics, arrhythmic history, and genetic status were reviewed including outcomes of death, aborted SCD, and device shocks. Holter findings were analyzed over the prior 5 years including clinically significant findings and resulting changes to management. Analysis for the composite outcomes of death, aborted SCD, and appropriate shock were performed using logistic regression with backward elimination.One hundred and forty-six patients were included: 83 HCM, 54 DCM, and nine RCM (mean 13 ± 6 years). A total of 23% of patients had defibrillators. There were six deaths (two SCD), four patients with appropriate device therapies, and four aborted SCD episodes. In total, 305 Holter monitors were reviewed. Six Holters had significant findings, all nonsustained ventricular tachycardia. Two Holters resulted in changes in management, both defibrillator implantations. Twelve patients had one or more of the conditions defining the composite outcome. Using logistic regression, clinical history of ventricular arrhythmia, frequent premature ventricular complexes, and CM type were included as potential independent predictors in the final model and clinical ventricular arrhythmia and RCM disease were associated with the composite outcome.SCD and device therapies were relatively rare. Routine Holter screening rarely demonstrated significant findings or changed clinical care. Clinical history of ventricular arrhythmia was associated with poor clinical outcome.

The elevated levels of circulating catecholamines (CAs) with age may be related to the increased expression of CA biosynthetic enzymes, tyrosine hydroxylase (TH) and dopamine beta hydroxylase (DbetaH) in the adrenal medulla of senescent compared with younger animals. Neuropeptide Y (NPY) is co-synthesized and co-released with CAs in the adrenal medulla. NPY inhibits the stimulated secretion of CAs, however, its role in regulation of the genes encoding CA biosynthetic enzymes is not clear. We hypothesized that NPY up-regulates TH, DbetaH and NPY expression in the adrenal medullae of young and old Fischer-344 rats. NPY increased mRNA expression of TH, DbetaH, NPY and also enhanced TH protein level in the adrenal medullae of young rats by 50%, 35%, 45% and by 20%, respectively. We also examined the effect of NPY on TH and NPY mRNA in the hypothalamus. Basal expression of TH mRNA was decreased in the hypothalamus with age. DNA binding activities of activator protein-1 and cAMP response element binding protein were also augmented only in the young by 140% and 125%, respectively. We conclude that NPY stimulates the CA biosynthetic pathway in the adrenal medulla and positive auto-regulation of NPY might be involved in this process. The stimulatory effect of NPY on adrenomedullary CA biosynthetic pathway is blunted with age.

Electrocardiograms (ECGs) are performed to determine an individual's cardiac rhythm. Approximately 25,000 ECGs are performed yearly throughout our hospital system. Historically only 68% of all ECGs were performed with the proper order linked to the electronic ECG reading system (MUSE). Failure to link the orders to the electronic reading system leads to problems in patient safety, reporting and hospital revenue. Our aim was to increase the percentage of linked ECG orders in MUSE compared to total ECGs performed from 68% to 95%. We created a detailed process map of ECG order linking to the MUSE electronic system. FMEA and Pareto chart creation were used to determine etiology of process failures. Multiple interventions (LOR1 to LOR3) were implemented utilizing the PDSA technique. Process control charts were used to evaluate change. FMEA and Pareto chart determined most common failures were related to: 1) ECG order not electronically acquired properly, 2) duplicate ECGs and 3) ECG order was not electronically placed. We performed multiple interventions including: 1) ECG performance education, 2) created reminders on the ECG machines, 3) specialized electronic linking system for physician readers and 4) bar-code scanners for all ECG machines. These changes improved ECG order linking to MUSE from 68% to 95% over 6-months. In direct comparison between fiscal year (FY) FY2014 to FY2015, the number of ECGs performed increased 2% while billing increased by 23%. Utilization of quality improvement methodology allowed us to identify failures for ECG order linking. We established multiple successful interventions amongst different hospital locations and improved our compliance, billing and reporting of ECGs.

Pediatric patients with left ventricular noncompaction (LVNC) and severe ventricular dysfunction are at risk for sudden death. The aims of this study were to (1) evaluate outcomes, (2) describe arrhythmic burden on Holter monitoring, and (3) analyze the utility of Holter monitoring and its impact on care in pediatric patients with LVNC and preserved or mild ventricular dysfunction. This was a retrospective study including patients21 years of age with LVNC and ejection fractions ≥45%. Demographic and outcome data were analyzed. Individual and cumulative Holter data were evaluated for all patients. Arrhythmias, conduction system disease, and symptoms were analyzed for each Holter recording. The incidence of significant findings and the impact on care were determined for each study. Outcome and Holter data were compared between patients on the basis of the ejection fraction (≥55% [normal] or ≥45% to55% [mild]). This study included 72 patients, 65 with normal function and 7 with mild dysfunction (mean age 13 years). There was a single death in the cohort, which was sudden in nature. Simple ventricular ectopy was common on Holter monitoring and more common in patients with mild dysfunction (86% vs 27%, p = 0.005). Significant Holter findings (4% vs 6%) and changes to patient care (2% vs 4%) improved with cumulative Holter monitoring. In conclusion, in contrast to patients with severe dysfunction, pediatric patients with LVNC and normal or mild dysfunction have significantly better outcomes. However, worsening LV systolic function was correlated with increasing ventricular ectopy. The role of Holter monitoring is unknown, but it may have utility in patient care if used as part of ongoing screening.

Although ventricular premature complexes (VPCs) have been shown to correlate with decreased cardiac function in adults, the correlation of left ventricular (LV) function to VPCs in asymptomatic children remains unclear. The aim of this study was to determine the correlation of VPC burden with LV function in asymptomatic pediatric patients with structurally normal hearts. This was a retrospective analysis of patients aged ≤21 years with echocardiograms and 24-hour Holter monitors with ≥0.5% VPCs completed within 60 days of each other. LV fractional shortening (FS) was compared with VPC burden and VPC characteristics. Normal LV function was defined as FS ≥28%. Correlation between VPC burden and LV function was determined by regression analysis. Wilcoxon's rank-sum test was used to compare LV function with VPC characteristics. This study included 123 patients (77 male [63%]). The median age was 11.6 years (interquartile range 5.8 to 14.3). The median VPC burden was 11.2% (interquartile range 4.8% to 18.9%), and median FS was 36% (interquartile range 33% to 38%). There was no significant correlation between VPC burden and LV FS (p = 0.50). The presence of uniform versus multiform VPCs (p = 0.29), ventricular couplets (p = 0.37), or runs of ventricular ectopy (p = 0.19) were not associated with a decrease in LV FS. Twenty-two patients (18%) had VPC burden >24%, none of which had decreased LV FS. In conclusion, there was no significant relation between VPC burden or VPC characteristics and LV systolic function in this pediatric population with structurally normal hearts.

fetal bradycardia of unknown etiology. The pregnancy was Introduction Congenital long QT syndrome (LQTS) is a familial channelopathy with variable penetrance of genetic mutations that lead to QT prolongation. The most common type of familial LQTS is type 1 (LQT1) due to loss of function mutations in the KCNQ1 gene. The majority of KCNQ1mutations involve the alpha subunit of the rapid or slow (IKs) currents of the potassium ion channel. The KCNQ1 gene codes for KvLQT1, a voltage-gated potassium channel protein that mediates IKs. Defects in IKs result in lack of QT shortening with increase in heart rate, which can result in an R on T phenomenon and progression to life-threatening ventricular arrhythmia. Contrarily, gain of function mutation of the KCNQ1 gene has been associated with sinus bradycardia, short QT syndrome, and familial atrial fibrillation. Classically considered a potassium channelopathy, familial atrial fibrillation has recently been associated with various ion channel genes including KCNQ1, SCN5A, and KCNJ2. The potassium channel mutations result in a shortened atrial action potential, while the sodium channel mutations lead to prolonged atrial repolarization, which create an environment susceptible to reentrant pathways. These alterations in atrial excitability may play a role in the frequency of atrial arrhythmias in patients with LQTS. Atrial arrhythmias have been reported in 2%–30% of the population with LQTS, manifesting as polymorphic atrial tachycardia and atrial fibrillation. In this report, we describe one family with a KCNQ1 gene mutation that has been previously reported in LQT1 but whose phenotype in this case is that of atrial fibrillation with no evidence of prolonged QT on electrocardiogram (ECG).

Accessory pathways with "high-risk" properties confer a small but potential risk of sudden cardiac death. Pediatric guidelines advocate for either risk stratification or ablation in patients with ventricular pre-excitation but do not advocate specific methodology. We sought to compare the cost of differing risk-stratification methodologies in pediatric patients with ventricular pre-excitation in this single institutional, retrospective cohort study of asymptomatic pediatric patients who underwent risk stratification for ventricular pre-excitation. Institutional methodology consisted of stratification using graded exercise testing (GXT) followed by esophageal testing in patients without loss of pre-excitation and ultimately ablation in high-risk patients or patients who became clinically symptomatic during follow-up. A decision analysis model was used to compare this methodology with hypothetical methodologies using different components of the stratification technique and an "ablate all" method. One hundred and two pediatric patients with asymptomatic ventricular pre-excitation underwent staged risk stratification; 73% of patients were deemed low risk and avoided ablation and the remaining 27% ultimately were successfully ablated. The use of esophageal testing was associated with a 23% (p ≤0.0001) reduction in cost compared with GXT stratification alone and a 48% (p ≤0.0001) reduction compared with the "ablate all" model. GXT as a lone stratification method was also associated with a 15% cost reduction (p ≤0.0001) compared with the "ablate all" method. In conclusion, risk stratification of pediatric patients with asymptomatic ventricular pre-excitation is associated with reduced cost. These outcomes of cost-effectiveness need to be combined with the risks and benefits associated with ablation and risk stratification.