Cardiovascular Collapse with Intravenous Amiodarone in Children: A Multi-Center Retrospective Cohort Study.

OBJECTIVE: To determine the incidence of cardiovascular collapse in children receiving intravenous (IV) amiodarone and to identify the population at risk. DESIGN: A multicenter study of patients ≤ 18 years of age who received intravenous amiodarone between January 2005 and December 2015. A retrospective analysis was performed to identify patients who developed cardiovascular collapse (bradycardia and/or hypotension). RESULTS: Of 456 patients who received amiodarone, cardiovascular collapse occurred in 47 patients (10%). Patient risk factors for collapse in a univariate analysis were as follows: age < 3 months (p = 0.04), depressed cardiac function (p < 0.001), blood pressure below 3rd percentile (p < 0.001), high lactate at baseline (p < 0.001). Administration risk factors included bolus administration (p = 0.04), and bolus administration over ≤ 20 min (p = 0.04). In multivariate analysis, age, baseline blood pressure less than 3rd percentile, and rapid bolus delivery were independent risk factors for cardiovascular collapse in the study group. The mortality rate was significantly higher in the collapse group (28% versus 8%). CONCLUSION: We found an association between IV amiodarone administration and the risk of developing cardiovascular collapse in a significant subset of children. Extreme caution and careful hemodynamic monitoring is recommended when using IV amiodarone in this population, especially in young infants, hemodynamically compromised patients, and in patients receiving rapid amiodarone bolus administration.

Triphasic mitral and tricuspid flows: a sign of diastolic dysfunction in a young patient with severely dilated atria and giant pulmonary veins.

This report presents a case with severe dilation of both atria and giant pulmonary veins manifested with atrial fibrillation. The following cardiac magnetic resonance findings are highly suggestive of restrictive physiology: E/A ratio greater than two, prominent A wave across the pulmonary veins and inferior vena cava, and more interestingly, a triphasic flow across the mitral and tricuspid valves.

The perceptions of caregivers toward physical activity and health in youth with congenital heart disease.

Medical advances have reduced mortality in youth with congenital heart disease (CHD). Although physical activity is associated with enhanced quality of life, most patients are inactive. By addressing medical and psychological barriers, previous literature has reproduced discourses of individualism which position cardiac youth as personally responsible for physical inactivity. Few sociological investigations have sought to address the influence of social barriers to physical activity, and the insights of caregivers are absent from the literature. In this study, caregiver perceptions toward physical activity for youth with CHD were investigated at a Canadian hospital. Media representations, school liability, and parental overprotection construct cardiac youth as "at risk" during physical activity, and position their health precariously. Indeed, from the perspective of hospital staff, the findings indicate the centrality of sociological factors to the physical activity experiences of youth with CHD, and the importance of attending to the contextual barriers that constrain their health and physical activity.

"What I wish you knew": Social barriers toward physical activity in youth with congenital heart disease (CHD).

Despite the benefits of physical activity for youth with congenital heart disease (CHD), most patients are inactive. Although literature has addressed medical and psychological barriers to participation, little is known about the social barriers that youth encounter. This qualitative study explored sociocultural barriers to physical activity from the perspective of 17 youth with CHD. The main theme, "what I wish you knew," was related to all other themes-youths' efforts to resolve "disclosure dilemmas," the barriers they encounter during physical education, and their struggle to understand themselves as normal. The participants' narratives illuminate the centrality of their sociocultural world to physical activity. The findings call on researchers and educators to attend to the social and cultural environments where these youth live and play.

A prospective pediatric clinical trial of digital music players: do they interfere with pacemakers?

BACKGROUND: There has been recent concern in the media about iPod interference with pacemakers. We systematically tested two types of digital music players (DMP) on pacemaker or ICD function in children. METHODS/RESULTS: Patients were monitored by a 6-lead ECG and programmer telemetry. The pacemaker was tested in bipolar and unipolar sensing at normal and maximal sensitivities. The order of DMP tested was randomized. Each DMP was placed on top of the pacemaker pocket, put into "play" mode three times (5 seconds each), with and without programmer wand placed one cm adjacent to DMP. Pacemaker interference was defined as: pacing inhibition, inappropriate pacing, oversensing, or detection of high-rate episodes associated with the use of DMP. Of the 67 patients (mean age 12 +/- 5 years), 62 had pacemakers and five had ICDs; 39 endocardial and 28 epicardial systems. Patients were tested with Sansa (67), iPod 30 GB (51), and other DMPs (43). There was no evidence of interference with pacemaker function by any DMP under any of the study conditions (each performed in triplicate). Reproducible programmer telemetry interference was shown in 11 cases (Medtronic 6/47, St. Jude Medical 5/18, Guidant 0/2) related to use of iPod (6), Sansa (1), or others (4). None of these were associated with any evidence of pacemaker malfunction. CONCLUSION: Interference with pacemaker function could not be shown with iPod or MP3 players. No additional precaution beyond standard is necessary for patients with pacemakers when they are using these players.

Cryoablation of accessory pathways in the coronary sinus in young patients: a multicenter study from the Pediatric and Congenital Electrophysiology Society's Working Group on Cryoablation.

INTRODUCTION: This is a multicenter retrospective study evaluating the immediate- and mid-term outcomes of cryoablation of accessory pathways in the coronary sinus in children or in patients with congenital heart disease. METHODS AND RESULTS: Twenty-one patients (median age 13.0 years, range 2-40) from six institutions were included. The accessory pathways were concealed in 11 and manifest in 10. Of 12 patients who had coronary sinus angiography, two had large coronary sinus diverticula, one had a dilated coronary sinus due to a left superior vena cava to coronary sinus, and one had a "pouch" at the mouth of the coronary sinus. Six patients underwent ablation procedures with cryoablation alone, while in the remaining 15 patients, both cryoablation and radiofrequency ablation were utilized. The ablation procedure included left-sided endocardial mapping via a retrograde or transseptal approach in 13 (62%). Procedural success was achieved with cryoablation in the coronary sinus in 15/21 (71%). Four patients (19%) had successful radiofrequency ablation at the right or left posterior septum. Two patients (10%) had unsuccessful procedures. Of the 15 patients with initially successful cryoablation procedures, six (40%) had arrhythmia recurrences at a median of 17 days (range 1-120). Recurrences could not be explained by differences in patient or procedural variables. CONCLUSION: Cryoablation in the coronary venous system in young patients is feasible but associated with a high arrhythmia recurrence rate. Cryoablation techniques and/or equipment need to be improved in order to safely create more permanent lesions in this arrhythmia substrate.

Evaluation of computerized interpretation of the pediatric electrocardiogram.

The purpose of this research was to determine the frequency and factors affecting disagreement between pediatric cardiologist (MD1 or MD2) and the computer-assisted interpretation (CAI) of pediatric electrocardiograms from patients with heart disease (HD, n = 586) or normal heart (n = 561). Significant disagreement was found in HD (146/586, 25%) compared with normal heart (64/561, 11%) (P < .001). The CAI overinterpreted prolonged QT, sinus rhythm with ectopy, and right ventricular hypertrophy; CAI underinterpreted sinus rhythm, sinus arrhythmia, and right bundle branch block (P < .05). Increased disagreement was independently associated with HD (odds ration [OR], 2.2), younger patient age at the time of the electrocardiogram, if the computer interpretation had more than 3 separate diagnostic statements (OR, 3.2) and if the overreading cardiologist was MD1 (OR, 2.9). Although CAI is helpful, pediatric cardiologists were more likely to disagree with the computer in rhythm diagnosis, recognition of bundle branch block, hypertrophy, and QT interval analysis.

QT hysteresis in long-QT syndrome children with exercise testing.

BACKGROUND: Congenital long QT syndrome (LQTS) is an inherited ion channel disorder resulting in abnormal cardiac repolarization that can cause syncope and sudden death associated with a prolonged rate-corrected QT interval and polymorphic ventricular tachycardia. Several studies in adults showed that LQTS patients have altered QT adaptation to heart rate changes compared with normal subjects which forming a "hysteresis loop" in the QT-circle length plot. This study was to observe the QT interval changing during exercise testing in children long QT syndrome (LQTS) patients, explore the new diagnosis methods of LQTS. METHODS: The subjects were divided into 3 groups according to 1993 LQTS diagnostic criteria. Group 1: LQTS group (n = 17) who scored > or = 4 points indicating definite LQTS. Group 2: Middle group (n = 16), patients who have prolonged QT interval but scored 1.5 to 3.5. Group 3: Normal control group (n = 18). The average age of all study population is (12.3 +/- 5.8) years. No case had beta-adrenergic antagonists administration before exercise testing. All subjects were underwent tread mill exercise testing and electrocardiograph in whole exercise testing and recovery were recorded. QT and heart rate changing during whole exercise testing period were recorded. DeltaQT, the QT interval at 1, 2, 4, 6 minutes into recovery subtract from the QT interval at a similar heart rate during exercise, were calculated. RESULTS: In all three groups, QT intervals were shortening with the increasing of heart rate, but QTc had no significant change. DeltaQT at 1 minute ((45 +/- 11) ms), 2 minutes ((37 +/- 15) ms), 4 minutes ((23 +/- 12) ms) into recovery in LQTS group were significantly greater than that of the other two groups (P < 0.05, P < 0.01, P < 0.01, respectively). There was no DeltaQT significant difference between middle group and normal control group at recovery time. During the recovery phase in LQTS group, the QT interval remained shortened despite a decelerating heart rate, forming a hysteresis "loop" in the curve relating the QT interval to the cycle length. CONCLUSIONS: In children LQTS patients, there is significant QT hysteresis loop in the relation of QT interval with heart rate during recovery of exercise testing, which could be useful to the early diagnosis for LQTS.

Hemodynamic effects of sustained postoperative cardiac resynchronization therapy in infants after repair of congenital heart disease: Results of a randomized clinical trial.

BACKGROUND: It is unknown whether continuous cardiac resynchronization therapy (CRT) can lead to sustained improvement in hemodynamics after surgery for congenital heart disease (CHD). OBJECTIVE: We investigated whether CRT improves cardiac index (CI) and blood pressure in infants after biventricular repair of CHD. METHODS: We randomized infants younger than 4 months after biventricular CHD surgery to standard care or standard care plus CRT for 48 hours or until extubation if sooner. Change in the primary outcome of CI and blood pressure over time was compared between groups. For subgroup analysis, QRS duration was considered prolonged if greater than the 98th percentile. RESULTS: Forty-two patients were randomized: 21 controls and 21 patients receiving CRT (median weight 4 kg). There were no identified adverse events from pacing. The change in CI over time was not different between patients receiving CRT and controls, but trended toward improvement in patients with wide QRS who received CRT (n = 9) vs controls with wide QRS (n = 8) (+1.65 (0.86) L/(min·m2); P = .06). Controls with wide QRS experienced the smallest increase in CI (0.33 L/(min·m2)). Blood pressure was significantly higher in infants with wide QRS who received CRT than in controls (+7.14 (3.08) mm Hg; P = .02). Serum lactate level, catecholamine use, ventilation time, and length of intensive care unit stay were similar between the 2 groups. CONCLUSION: CRT improved blood pressure and a trend toward higher CI in infants after repair of biventricular CHD with prolonged QRS duration. These findings warrant further study of CRT to improve postoperative recovery in infants with electrical dyssynchrony.

Development and impact of arrhythmias after the Norwood procedure: A report from the Pediatric Heart Network.

OBJECTIVES: The study objective was to determine the predictors of new-onset arrhythmia among infants with single-ventricle anomalies during the post-Norwood hospitalization and the association of those arrhythmias with postoperative outcomes (ventilator time and length of stay) and interstage mortality. METHODS: After excluding patients with preoperative arrhythmias, we used data from the Pediatric Heart Network Single Ventricle Reconstruction Trial to identify risk factors for tachyarrhythmias (atrial fibrillation, atrial flutter, supraventricular tachycardia, junctional ectopic tachycardia, and ventricular tachycardia) and atrioventricular block (second or third degree) among 544 eligible patients. We then determined the association of arrhythmia with outcomes during the post-Norwood hospitalization and interstage period, adjusting for identified risk factors and previously published factors. RESULTS: Tachyarrhythmias were noted in 20% of subjects, and atrioventricular block was noted in 4% of subjects. Potentially significant risk factors for tachyarrhythmia included the presence of modified Blalock-Taussig shunt (P = .08) and age at Norwood (P = .07, with risk decreasing each day at age 8-20 days); the only significant risk factor for atrioventricular block was undergoing a concomitant procedure at the time of the Norwood (P = .001), with the greatest risk being in those undergoing a tricuspid valve procedure. Both tachyarrhythmias and atrioventricular block were associated with longer ventilation time and length of stay (P < .001 for all analyses). Tachyarrhythmias were not associated with interstage mortality; atrioventricular block was associated with mortality among those without a pacemaker in the unadjusted analysis (hazard ratio, 2.3; P = .02), but not after adding covariates. CONCLUSIONS: Tachyarrhythmias are common after the Norwood procedure, but atrioventricular block may portend a greater risk for interstage mortality.

Transcatheter cryoablation of tachyarrhythmias in children: initial experience from an international registry.

OBJECTIVES: We sought to describe the early pediatric experience of transcatheter cryoablation, and identify whether specific arrhythmia substrates and/or ablation locations were particularly suited to cryoablation. BACKGROUND: Radiofrequency (RF) ablation has become established therapy for pediatric tachyarrhythmias. However, challenges remain in terms of the safety and efficacy of RF ablation in specific locations; new methods may address these issues. METHODS: Prospective data were available for 64 patients age 13 +/- 4 (mean +/- SD) years undergoing cryoablation at 14 centers participating in the Cryocath International Patient Registry. Dysrhythmia duration was 5.0 +/- 4.2 years, with diagnoses of atrioventricular node re-entrant tachycardia (AVNRT) (n=30), anteroseptal (n=11), midseptal (n=5), or other (n=15) accessory pathway (AP) mediated AV re-entry, ventricular tachycardia (VT) (n = 3), and ectopic atrial tachycardia (EAT) (n=2). Two patients had more than one arrhythmia substrate. Transcatheter cryoablation was offered by cardiologist preference after written informed procedural consent of each patient and/or legal guardian. Cryomapping was performed at -30 degrees C and cryoablation was delivered with 4-min applications at -75 degrees C. RESULTS: Acute success was achieved in 45 of 65 (69%) cryoablation patients, with best success rates in AVNRT (83%) and right septal AP (75%), and lower success rates in other AP (43%), VT (66%), and EAT (0%). No device-related adverse events were reported. The success of radiofrequency (RF) ablation applied in 14 cryoablation failures was 4 of 4 for AVNRT patients, 1 of 1 for anteroseptal AP patients, 5 of 6 for other AP patients, 0 of 1 for VT patients, and 0 of 2 for EAT patients. CONCLUSIONS: Transcatheter cryoablation is a safe and well-tolerated alternative to RF ablation in pediatric patients on the basis of our initial experience. Success is highest in AVNRT and in substrates recognized as technically challenging or risky for RF ablation.

Natural history of postoperative heart block in congenital heart disease: implications for pacing intervention.

After half a century of major progress in congenital heart disease management, atrioventricular conduction block continues to complicate 1-3% of surgical procedures. Unless treated with an implanted pacemaker, permanent postoperative heart block is associated with 28-100% mortality. Postoperative heart block often proves to be transient, typically resolving within 10 days of onset. The duration of postoperative heart block is widely used as a key determinant for permanent pacemaker implantation. Current professional pacemaker implantation guidelines are largely based on this criterion. However, available natural history data suggest that other factors, such as residual conduction system injury, likely play a role in increasingly recognized cases of very late postoperative mortality and morbidity in patients who have experienced transient postoperative heart block. As growing numbers of congenital heart disease patients survive into adulthood, and artificial pacemaking capabilities continue to improve, it might be necessary to reconsider and refine currently accepted pacing indications for postoperative heart block.

Cox-Maze IV in Total Anomalous Pulmonary Venous Drainage After Sutureless Repair.

Modifications of conventional ablation strategies can make arrhythmia surgery more efficient after primary sutureless repair of total anomalous pulmonary venous drainage. We present a surgical technique performed in a 3-year-old patient who experienced ongoing atrial arrhythmia after sutureless repair. A new modified Cox-Maze IV procedure was performed, which respects the special characteristics of patients after sutureless repairs, showing good short-term results.

Optimizing outcomes of catheter ablation in infants and toddlers.

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

Cryotherapy ablation of parahisian accessory pathways in children.

BACKGROUND: Because of its safety profile, cryoablation has become an alternative therapy for septal arrhythmias, including parahisian accessory pathways (APs). Data regarding its efficacy, safety, and late outcome for parahisian APs in children are limited. OBJECTIVE: The purpose of this study was to evaluate the safety and efficacy of cryoablation of parahisian APs in children. METHODS: Fifty-nine cryoablations of parahisian APs were performed in 50 patients [76% males; median age 16.5 years (range 5.3-20 years)]. Thirty-three had manifest APs and 17 had concealed APs. The time to effect was defined as the duration of time from reaching -30°C to the disappearance of AP during the cryomapping phase. The acute success rate for the first ablation was 94% (47/50). RESULTS: Mean fluoroscopy time and number of cryoablations were 28.5 ± 23.3 minutes and 2.6 ± 1.2 seconds, respectively. The time to effect was 8.5 ± 7.1 seconds. The overall recurrence rate was 14.9%, decreasing from 40% in the first 10 cases to 8.1% in the next 37 (P <.02). Multivariate analysis showed that the only independent predictor for recurrence rate was time to effect <10 seconds (P <.001). A high recurrence rate was also associated with concealed APs and ablation during supraventricular tachycardia (P <.03 and P <.05, respectively). The patients who had recurrence underwent a second successful cryoablation. During median follow-up of 59.7 months (range 6-102 months), a long-term success rate of 94% was achieved. No permanent ablation-related complications occurred. CONCLUSION: Cryoablation of parahisian APs has excellent short- and long-term efficacy and safety profile. Increased physician experience is associated with a reduced recurrence rate.

Associations Between Day of Admission and Day of Surgery on Outcome and Resource Utilization in Infants With Hypoplastic Left Heart Syndrome Who Underwent Stage I Palliation (from the Single Ventricle Reconstruction Trial).

Newborns with hypoplastic left heart syndrome and other single right ventricular variants require substantial health care resources. Weekend acute care has been associated with worse outcomes and increased resource use in other populations but has not been studied in patients with single ventricle. Subjects of the Single Ventricle Reconstruction trial were classified by whether they had a weekend admission and by day of the week of Norwood procedure. The primary outcome was hospital length of stay (LOS); secondary outcomes included transplant-free survival, intensive care unit (ICU) LOS, and days of mechanical ventilation. The Student's t test with log transformation and the Wilcoxon rank-sum test were used to analyze associations. Admission day was categorized for 533 of 549 subjects (13% weekend). The day of the Norwood was Thursday/Friday in 39%. There was no difference in median hospital LOS, transplant-free survival, ICU LOS, or days ventilated for weekend versus non-weekend admissions. Day of the Norwood procedure was not associated with a difference in hospital LOS, transplant-free survival, ICU LOS, or days ventilated. Prenatally diagnosed infants born on the weekend had lower mean birth weight, younger gestational age, and were more likely to be intubated but did not have a difference in measured outcomes. In conclusion, in this cohort of patients with single right ventricle, neither weekend admission nor end-of-the-week Norwood procedure was associated with increased use of hospital resources or poorer outcomes. We speculate that the complex postoperative course following the Norwood procedure outweighs any impact that day of admission or operation may have on these outcomes.

Determinants of outcome in isolated ventricular noncompaction in childhood.

Isolated ventricular noncompaction is now recognized as an important cause of pediatric cardiomyopathy; however, predictors of outcome have yet to be detailed. Echocardiographic features at presentation, including increased noncompacted to compacted segment ratio and enlarged left ventricular dimension, were found to be associated with poor outcomes (heart transplantation, transplant listing, or death).

Sudden cardiac death in children and adolescents between 1 and 19 years of age.

BACKGROUND: Understanding pediatric sudden cardiac death (SCD) may inform age-specific prevention strategies. OBJECTIVE: To characterize potential underlying causes of SCD in children and adolescents METHODS: We performed a retrospective population-based study in Ontario, Canada, of all SCD cases in a 5-year period (2005-2009) involving persons aged 1-19 years identified from the comprehensive database of the Office of the Chief Coroner. Of 1204 coroner's cases, 351 potential SCD cases were reviewed. RESULTS: Of 116 cases of adjudicated SCD, there was no identifiable cause of death in 60 (52%). The majority were males (66%), and median age was 12.7 years. The incidence of SCD was greatest between 1 and 2 years (3.14 per 100,000 person-years), decreased, and then increased to 1.01 per 100,000 person-years (15-19 years). Autopsy findings were normal in 29 of 35 (83%) of children younger than 5 years and were more likely to be abnormal in those 10 years and older (odds ratio 9.0; 95% confidence interval 3.3-24.9). In 9%, the pathology findings may be of uncertain significance. Most events occurred in the home (68%). Activity level at the time of the event was associated with both age group (χ(2) = 34.9; P < .001) and autopsy findings (χ(2) = 28.9; P < .001). Events during moderate or vigorous activity were more common in those older than 10 years 16 of 66 (24%), and the majority had abnormal autopsy findings 13 of 18 (72%). DISCUSSION: Death in the very young is often caused by presumed primary arrhythmia syndromes, and death during exertion is typically seen in those with structural heart disease. CONCLUSION: These differences should inform age-specific diagnostic and prevention strategies.

Scope and nature of sudden cardiac death before age 40 in Ontario: a report from the cardiac death advisory committee of the office of the chief coroner.

BACKGROUND: Understanding sudden cardiac death in the young may inform prevention strategies. OBJECTIVE: To determine the scope and nature of sudden death in a geographically defined population. METHODS: We performed a retrospective population-based cohort study in Ontario, Canada, of all sudden cardiac death cases involving persons aged 2-40 years identified from the 2008 comprehensive Coroner database. Of 1741 Coroner's cases, 376 were considered potential sudden cardiac death cases and underwent review. RESULTS: There were 174 cases of adjudicated sudden cardiac death from a population of 6,602,680 persons aged 2-40 years. Structural heart disease was present in 126 cases (72%), 78% of which was unrecognized. There was no identifiable cause of death in 48 cases (28%), representing primary arrhythmia syndromes. The majority of decedents were men (76%) over the age of 18 (90%). The overall incidence of sudden cardiac death increased with age from 0.7/100,000 (2-18 years) to 2.4/100,000 (19-29 years) to 5.3/100,000 (30-40 years) person-years. Persons experiencing sudden cardiac death before age 30 were more likely to have a primary arrhythmia syndrome (odds ratio 2.97; P<.001). The majority of events occurred in the home (72%); 33% of the events in children/adolescents and 9% of the events in adults occurred during reported moderate or vigorous exercise (P = .002). There were no pediatric deaths during organized competitive sports. CONCLUSIONS: The incidence of sudden cardiac death increases with age, typically occurring in a man at rest in the home with unrecognized underlying heart disease or a primary arrhythmia syndrome. Prevention strategies should consider targeting identification of unrecognized structural heart disease and primary arrhythmia syndromes.