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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Cause, timing, and location of death in the Single Ventricle Reconstruction trial.

OBJECTIVES: The Single Ventricle Reconstruction trial randomized 555 subjects with a single right ventricle undergoing the Norwood procedure at 15 North American centers to receive either a modified Blalock-Taussig shunt or right ventricle-to-pulmonary artery shunt. Results demonstrated a rate of death or cardiac transplantation by 12 months postrandomization of 36% for the modified Blalock-Taussig shunt and 26% for the right ventricle-to-pulmonary artery shunt, consistent with other publications. Despite this high mortality rate, little is known about the circumstances surrounding these deaths. METHODS: There were 164 deaths within 12 months postrandomization. A committee adjudicated all deaths for cause and recorded the timing, location, and other factors for each event. RESULTS: The most common cause of death was cardiovascular (42%), followed by unknown cause (24%) and multisystem organ failure (7%). The median age at death for subjects dying during the 12 months was 1.6 months (interquartile range, 0.6 to 3.7 months), with the highest number of deaths occurring during hospitalization related to the Norwood procedure. The most common location of death was at a Single Ventricle Reconstruction trial hospital (74%), followed by home (13%). There were 29 sudden, unexpected deaths (18%), although in retrospect, 12 were preceded by a prodrome. CONCLUSIONS: In infants with a single right ventricle undergoing staged repair, the majority of deaths within 12 months of the procedure are due to cardiovascular causes, occur in a hospital, and within the first few months of life. Increased understanding of the circumstances surrounding the deaths of these single ventricle patients may reduce the high mortality rate.

Risk factors for hospital morbidity and mortality after the Norwood procedure: A report from the Pediatric Heart Network Single Ventricle Reconstruction trial.

OBJECTIVES: We sought to identify risk factors for mortality and morbidity during the Norwood hospitalization in newborn infants with hypoplastic left heart syndrome and other single right ventricle anomalies enrolled in the Single Ventricle Reconstruction trial. METHODS: Potential predictors for outcome included patient- and procedure-related variables and center volume and surgeon volume. Outcome variables occurring during the Norwood procedure and before hospital discharge or stage II procedure included mortality, end-organ complications, length of ventilation, and hospital length of stay. Univariate and multivariable Cox regression analyses were performed with bootstrapping to estimate reliability for mortality. RESULTS: Analysis included 549 subjects prospectively enrolled from 15 centers; 30-day and hospital mortality were 11.5% (63/549) and 16.0% (88/549), respectively. Independent risk factors for both 30-day and hospital mortality included lower birth weight, genetic abnormality, extracorporeal membrane oxygenation (ECMO) and open sternum on the day of the Norwood procedure. In addition, longer duration of deep hypothermic circulatory arrest was a risk factor for 30-day mortality. Shunt type at the end of the Norwood procedure was not a significant risk factor for 30-day or hospital mortality. Independent risk factors for postoperative renal failure (n = 46), sepsis (n = 93), increased length of ventilation, and hospital length of stay among survivors included genetic abnormality, lower center/surgeon volume, open sternum, and post-Norwood operations. CONCLUSIONS: Innate patient factors, ECMO, open sternum, and lower center/surgeon volume are important risk factors for postoperative mortality and/or morbidity during the Norwood hospitalization.

The effect of NavX on fluoroscopy times in pediatric catheter ablation.

PURPOSE: Catheter ablation is the established curative therapy for pediatric tachyarrhythmias. However, exposure to ionizing radiation from fluoroscopy during the procedure is of concern to both patients and caregivers. We sought to assess the impact of an impedance-based three-dimensional navigation system (NavX(TM), Endocardial Solutions, Inc., St. Paul, MN) on pediatric catheter ablation procedures. METHODS: We retrospectively analyzed procedural data during a 7-year period (2002-2008), which spanned the transition between standard fluoroscopic mapping and adoption of NavX(TM) mapping for catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) and right/left-sided accessory pathways (RAP/LAP). Comparisons of total procedure time, total fluoroscopy time, and ablation fluoroscopy time (from insertion of ablation catheter until completion of procedure) between NavX(TM) and conventional mapping were made. RESULTS: Three hundred eighty-eight patients (aged 1-18 years, M/F 236:183) underwent ablation of AVNRT (n = 101), LAP (n = 130), or RAP (n = 157) using either conventional (n = 70) or NavX(TM) (n = 318) mapping. Overall success rates were similar between the two mapping approaches (95.7% for conventional versus 95.9% for NavX(TM)). NavX(TM) mapping significantly reduced ablation fluoroscopy time (15.9 ± 14.3 versus 11.0 ± 8.9 min for NavX(TM), p < 0.01) with a trend towards a decrease in total fluoroscopy time (26.4 ± 15.6 versus 23.8 ± 11.1 min for NavX(TM), p = 0.095). Total procedure time was not significantly different between the two methods (210.1 ± 66 versus 222.8 ± 61 min for NavX(TM), p = 0.13). When analyzed by arrhythmia substrate, there were significant reductions in ablation fluoroscopy time for both LAP and RAP. CONCLUSIONS: NavX(TM) mapping reduced ablation fluoroscopy times for accessory pathways during pediatric catheter ablation.

"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.

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.

Diagnosis-specific characteristics of ventricular tachycardia in children with structurally normal hearts.

BACKGROUND: Improved mechanistic insights and clinical tools provide increasing diagnostic refinement for ventricular tachycardia in young patients with structurally normal hearts, yielding potentially important prognostic and management implications. OBJECTIVE: The purpose of this study was to survey the clinical characteristics and outcomes of otherwise healthy children with ventricular tachycardia (VT) who were classified according to contemporary diagnostic criteria. METHODS: A single-center retrospective review of patients younger than 18 years of age with VT diagnosed between January 1980 and December 2005 was undertaken. Patients with significant systemic illness or with underlying structural or functional heart disease were excluded. RESULTS: A total of 77 patients met inclusion criteria and were grouped as follows: accelerated idioventricular rhythm (AIVR; n = 19), right ventricular tachycardia (RVT; n = 30), left ventricular tachycardia (LVT; n = 23), and catecholamine sensitive polymorphic VT (CPVT; n = 5). AIVR patients were youngest at diagnosis and had the most benign natural history, while the opposite was true of CPVT patients. Ablation was attempted in 2/30 RVT (50% success) and 10/23 LVT (80% success) patients. Severe cardiac events occurred in 3/23 LVT (no deaths) and 2/5 CPVT (one death) patients. CONCLUSION: The natural history and appropriate management of VT in young patients with structurally normal hearts are highly dependent on the specific diagnosis. LVT and CPVT are associated with significantly greater morbidity and mortality than AIVR and RVT.