Multicenter cohort study on duration of antiarrhythmic medication for supraventricular tachycardia in infants.

Antiarrhythmic medication (AM) is commonly used to prevent supraventricular tachycardia (SVT) recurrence in infants. Our aim was to determine whether a shorter duration of AM is sufficient to prevent atrioventricular reentrant tachycardia (AVRT) recurrence and evaluate risk factors for recurrence of SVT after discontinued AM.This multicenter cohort study included all infants diagnosed with SVT in the five university hospitals in Finland between 2005 and 2017. Those diagnosed between 2005 and 2012 received AM for 12 months (group 1), and those diagnosed between 2013 and 2017 received AM for 6 months (group 2). A total of 278 infants presented with AVRT (group 1, n = 181; group 2, n = 97), and the median AM duration was 12.0 months (interquartile range [IQR] 11.4-13.4) and 7.0 months (IQR 6.0-10.2), respectively. Propranolol was the most frequently used first-line AM (92% and 95%). Recurrence-free survival rates were over 88% until 12 months after AM prophylaxis in both groups, without any statistically significant difference between them. Independent risk factors for recurrence of SVT after discontinuation of AM were need of combination AM (HR 2.2, 95% CI 1.14-4.20), Wolff-Parkinson-White (WPW) syndrome (HR 2.4, 95% CI 1.25-4.59), and age over 1 month at admission (HR 2.2, 95% CI 1.12-4.48).    Conclusion: Shortening AM duration in infants from 12 to 6 months does not seem to lead to more frequent SVT recurrence. The risk factors for recurrence of SVT were WPW syndrome, need of combination AM, and age over 1 month.

Indications and management of implantable cardioverter-defibrillator therapy in childhood hypertrophic cardiomyopathy.

Sudden cardiac death is the most common mode of death during childhood and adolescence in hypertrophic cardiomyopathy, and identifying those individuals at highest risk is a major aspect of clinical care. The mainstay of preventative therapy is the implantable cardioverter-defibrillator, which has been shown to be effective at terminating malignant ventricular arrhythmias in children with hypertrophic cardiomyopathy but can be associated with substantial morbidity. Accurate identification of those children at highest risk who would benefit most from implantable cardioverter-defibrillator implantation while minimising the risk of complications is, therefore, essential. This position statement, on behalf of the Association for European Paediatric and Congenital Cardiology (AEPC), reviews the currently available data on established and proposed risk factors for sudden cardiac death in childhood-onset hypertrophic cardiomyopathy and current approaches for risk stratification in this population. It also provides guidance on identification of individuals at risk of sudden cardiac death and optimal management of implantable cardioverter-defibrillators in children and adolescents with hypertrophic cardiomyopathy.

Institutional transition from invasive to non-invasive imaging in children with univentricular heart defects: safety and cost savings.

OBJECTIVES: Patients with univentricular heart defects require lifelong imaging surveillance. Recent advances in non-invasive imaging have enabled replacing these patients' routine catheterisation. Our objective was to describe the safety and cost savings of transition of a tertiary care children's hospital from routine invasive to routine non-invasive imaging of low-risk patients with univentricular heart defects. METHODS: This single-centre cohort study consists of 1) a retrospective analysis of the transition from cardiac catheterisation (n = 21) to CT angiography (n = 20) before bidirectional Glenn operation and 2) a prospective study (n = 89) describing cardiac magnetic resonance before and after the total cavopulmonary connection in low-risk patients with univentricular heart defects. RESULTS: Pre-Glenn: The total length of CT angiography was markedly shorter compared to the catheterisation: 30 min (range: 20-60) and 125 min (range: 70-220), respectively (p < 0.001). Catheterisation used more iodine contrast agents than CT angiography, 19 ± 3.9 ml, and 10 ± 2.4 ml, respectively (p < 0.001). Controlled ventilation was used for all catheterised and 3 (15%) CT angiography patients (p < 0.001). No complications occurred during CT angiography, while they emerged in 19% (4/21) catheterisation cases (p < 0.001). CT angiography and catheterisation showed no significant difference in the radiation exposure. Pre-/post-total cavopulmonary connection: All cardiac magnetic resonance studies were successful, and no complications occurred. In 60% of the cardiac magnetic resonance (53/89), no sedation was performed, and peripheral venous pressure was measured in all cases. Cost analysis suggests that moving to non-invasive imaging yielded cost savings of at least €2500-4000 per patient. CONCLUSION: Transition from routine invasive to routine non-invasive pre-and post-operative imaging is safely achievable with cost savings.

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

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

Population-based single-center outcome for pediatric catheter ablation of common supraventricular tachycardias.

BACKGROUND: Catheter ablation has become the preferred treatment for common supraventricular tachycardia (SVT) in children and adolescents, but long-term follow-up data on pediatric patients remain limited. METHODS: To provide follow-up data, we created a population-based prospective pediatric catheter ablation registry in 1997. All patients underwent clinical follow-up at 1 month and 1 year after the procedure. The follow-up data were completed with a single questionnaire in 2010. RESULTS: Of 318 patients, 289 (91%) required one to three procedures for successful ablation. A total of 211 (66%) patients had an accessory pathway, 97 (31%) atrioventricular nodal reentrant tachycardia, and 10 (3%) atrial tachycardia. Two (0.6%) of the 318 patients had serious complications: the first had a complete atrioventricular block and required a pacemaker, while the second had a hemopericardium, which was treated with drainage. A successful ablation procedure was followed by a recurrence in 18 (6%) patients during childhood. In addition, two patients had atrial fibrillation and one had a focal atrial tachycardia as adults after a successful ablation procedure during childhood. Moreover, 12 (4%) patients, who had undergone a successful ablation, complained of increased heart rate after exercise compared to their status before the procedure. CONCLUSION: In our cohort study of 318 pediatric patients, with a mean follow-up of 5 years, SVT ablation was successful for 91% of the patients. Arrhythmia recurred in 6% of the patients. The increased sinus rate following radiofrequency ablation, observed in 4% of pediatric patients, constitutes a new finding, which warrants attention in other patient series.

[Myocarditis in children--a diagnostic and therapeutic challenge]. / Lasten myokardiitti--diagnostinen ja hoidollinen haaste.

Viral infections are the most common causes of myocarditis in children. Chronic myocardial injury may develop following an immune or autoimmune reaction triggered or maintained by an infection, or can be part of a systemic autoimmune disease. Although many of the children having developed myocarditis are symptomless, initial symptoms may include cardiac insufficiency, arrhythmias and sudden death. The diagnosis requires a clinical suspicion as well as laboratory and imaging studies. Recovery from myocarditises often takes place spontaneously, but some result in the development of dilated cardiomyopathy (DCM).

Pharmacological and non-pharmacological therapy for arrhythmias in the pediatric population: EHRA and AEPC-Arrhythmia Working Group joint consensus statement.

In children with structurally normal hearts, the mechanisms of arrhythmias are usually the same as in the adult patient. Some arrhythmias are particularly associated with young age and very rarely seen in adult patients. Arrhythmias in structural heart disease may be associated either with the underlying abnormality or result from surgical intervention. Chronic haemodynamic stress of congenital heart disease (CHD) might create an electrophysiological and anatomic substrate highly favourable for re-entrant arrhythmias. As a general rule, prescription of antiarrhythmic drugs requires a clear diagnosis with electrocardiographic documentation of a given arrhythmia. Risk-benefit analysis of drug therapy should be considered when facing an arrhythmia in a child. Prophylactic antiarrhythmic drug therapy is given only to protect the child from recurrent supraventricular tachycardia during this time span until the disease will eventually cease spontaneously. In the last decades, radiofrequency catheter ablation is progressively used as curative therapy for tachyarrhythmias in children and patients with or without CHD. Even in young children, procedures can be performed with high success rates and low complication rates as shown by several retrospective and prospective paediatric multi-centre studies. Three-dimensional mapping and non-fluoroscopic navigation techniques and enhanced catheter technology have further improved safety and efficacy even in CHD patients with complex arrhythmias. During last decades, cardiac devices (pacemakers and implantable cardiac defibrillator) have developed rapidly. The pacing generator size has diminished and the pacing leads have become progressively thinner. These developments have made application of cardiac pacing in children easier although no dedicated paediatric pacing systems exist.

Long-term performance of beat-to-beat automatic ventricular threshold adjustment in infants with congenital atrioventricular block.

BACKGROUND: AutoCapture™ (AC) of St. Jude Medical (SJM; St. Paul, MN, USA) pacemakers provides beat-to-beat ventricular capture verification and allows low-amplitude pacing. There has been concern about evoked response signal (ERS) amplitude decreasing over time, leading to discontinuation of AC. The purpose of this study was to evaluate the long-term performance of AC in infants with epicardial pacing leads. METHODS: Data on 16 newborns with congenital complete atrioventricular block (CCAVB) implanted with a SJM Microny pacemaker between January 1998 and December 2004 were collected. The ERS at discharge, at 12 ± 2 months, and long-term AC performance were analyzed retrospectively. The median follow-up time was 5.3 years (range 0.4-8.6 years), the end point of follow-up being either lead or generator exchange. RESULTS: AC could be activated in all patients at discharge; the median ERS was 9.3 mV (3.7-19.0 mV). At 12 ± 2 months, the median ERS measured 4.6 ± 3.6 mV (n = 13), showing a significant decrease (P = 0.002) and leading to discontinuation of AC in three (23%) of 13 patients. AC use was possible in eight patients and long-term use in six patients. CONCLUSIONS: In epicardially paced CCAVB newborns, the ERS amplitude decreased significantly during the first year. ERS decrease was the most common reason for AC failure. At 1-year follow-up, AC was functional in only 53% of patients, although it could originally be activated in all patients. During the first year of follow-up, special attention to AC parameters is recommended in this subgroup of pediatric pacemaker patients.

[Cryoablation in the treatment of cardiac arrhythmias]. / Kryoablaatio rytmihäiriöiden hoidossa.

Catheter ablation is currently the preferred treatment for various arrhythmias. Radiofrequency ablation has been shown to be efficacious and safe. Cryoablation provides better ablation catheter stability and reduces the risk of an inadvertent atrioventricular (AV) block when treating arrhythmia substrates near the normal conduction system. In our own seven year experience of cryoablation in 157 patients no serious complications occurred. In children and young patients, cryoablation has become the preferred method for AV nodal re-entrant tachycardia. Cryoablation is preferable for all tachycardia substrates near the normal conduction system in children, teenagers and adults.

Intravenous epinephrine infusion test in diagnosis of catecholaminergic polymorphic ventricular tachycardia.

INTRODUCTION: A test involving intravenous infusion of epinephrine has been proposed as a method alternative to exercise stress test in diagnosis of catecholaminergic polymorphic ventricular tachycardia (CPVT). We aimed at estimating the predictive value of intravenous epinephrine administration in CPVT patients with frequent exercise-induced ventricular ectopy. METHODS AND RESULTS: We recruited 81 subjects, including 25 CPVT-linked ryanodine receptor 2 (RYR2) mutation carriers, 11 genetically undefined CPVT patients, and 45 unaffected family members. All subjects underwent a maximal exercise stress test and an intravenous epinephrine infusion test. Exercise stress test was positive in 25 (31%) patients including 14 of 25 (56%) established RYR2-mutation carriers and all 11 (100%) genetically undefined CPVT patients. Epinephrine infusion induced arrhythmias in 3 (12%) RYR2-mutation carriers, 4 (36%) genetically undefined CPVT patients, and 1 (2%) unaffected family member. A total of 18 exercise stress test positive patients did not respond to intravenous epinephrine administration, whereas only 1 epinephrine test responder had a normal exercise stress test. Thus, if exercise stress test is used as a standard, the sensitivity of the epinephrine infusion test is 28% and specificity is 98%. CONCLUSIONS: Intravenous epinephrine infusion has low sensitivity and may not be considered as an alternative method for a maximal exercise stress test in diagnosis of CPVT.

Familial Recurrence Patterns in Congenitally Corrected Transposition of the Great Arteries: An International Study.

BACKGROUND: Congenitally corrected transposition of the great arteries (ccTGA) is a rare disease of unknown cause. We aimed to better understand familial recurrence patterns. METHODS: An international, multicentre, retrospective cohort study was conducted in 29 tertiary hospitals in 6 countries between 1990 and 2018, entailing investigation of 1043 unrelated ccTGA probands. RESULTS: Laterality defects and atrioventricular block at diagnosis were observed in 29.9% and 9.3%, respectively. ccTGA was associated with primary ciliary dyskinesia in 11 patients. Parental consanguinity was noted in 3.4% cases. A congenital heart defect was diagnosed in 81 relatives from 69 families, 58% of them being first-degree relatives, including 28 siblings. The most prevalent defects in relatives were dextro-transposition of the great arteries (28.4%), laterality defects (13.6%), and ccTGA (11.1%); 36 new familial clusters were described, including 8 pedigrees with concordant familial aggregation of ccTGA, 19 pedigrees with familial co-segregation of ccTGA and dextro-transposition of the great arteries, and 9 familial co-segregation of ccTGA and laterality defects. In one family co-segregation of ccTGA, dextro-transposition of the great arteries and heterotaxy syndrome in 3 distinct relatives was found. In another family, twins both displayed ccTGA and primary ciliary dyskinesia. CONCLUSIONS: ccTGA is not always a sporadic congenital heart defect. Familial clusters as well as evidence of an association between ccTGA, dextro-transposition of the great arteries, laterality defects and in some cases primary ciliary dyskinesia, strongly suggest a common pathogenetic pathway involving laterality genes in the pathophysiology of ccTGA.

Automatic atrial threshold measurement and adjustment in pediatric patients.

BACKGROUND: Automatic threshold measurement and output adjustment are used as default settings in modern pacemakers. The purpose of the study was to assess Atrial Capture Management (ACM) of Medtronic pacemakers in pediatric patients. METHODS: Forty children were enrolled in two centers. Median age was 9.8 years (range 0.8-17.5 years). Half had undergone surgery for congenital heart defects; 45% of patients had an epicardial atrial lead. The pacing indication was atrioventricular block in 82% of patients and sinus node disease in 18%. Manually determined atrial thresholds and ACM measurements were compared. RESULTS: ACM measurements were within the expected variation in 37/40 (93%) of the patients. In one patient the threshold was 0.625-V lower manually than with ACM. One patient had too high an intrinsic atrial rate for ACM to be able to measure threshold. The mean threshold at 0.4 ms was 0.69 +/- 0.32 V manually and 0.68 +/- 0.35 V with ACM (two-tailed paired t-test, P = 0.52) in all patients. The mean difference was 0.012 V (95% confidence interval: -0.027, 0.053). The mean endocardial threshold was 0.70 +/- 0.36 V manually and 0.69 +/- 0.38 V with ACM; epicardial threshold was 0.67 +/- 0.27 V manually and 0.68 +/- 0.32 V with ACM. The difference between the measurements was 0.012 V for endocardial and 0.014 V for epicardial leads. No atrial arrhythmias due to ACM measurements were observed. CONCLUSIONS: ACM measures atrial thresholds reliably in pediatric patients with both endocardial and epicardial leads, allowing its use in both. Constant high intrinsic atrial rate may prevent automatic threshold measurement in young children.

Normal growth and intravascular volume status with good metabolic control during peritoneal dialysis in infancy.

The most demanding patient population on peritoneal dialysis (PD) consists of children under 2 years of age. Their growth is inferior to that of older children and maintaining euvolemia is difficult, especially in anuric patients. In this prospective study reported here, we enrolled 21 patients <2 years of age (mean 0.59 years) at onset of PD and monitored their uremia parameters and evaluated their nutrition. Since no good instrument currently exists for estimating intravascular volume status, we used traditional blood pressure measurements, echocardiography, and N-terminal atrial natriuretic peptide measurements. Growth was compared with midparental height. Metabolic control was good. Long-term hypertension was seen in 43% of the patients, but left ventricular hypertrophy decreased during the study period. Mean weekly urea Kt/V was 3.38 +/- 0.66 and creatinine clearance was 49 +/- 20 L/week per 1.73 m(2). Catch-up growth was documented in 57% of the patients during PD. However, these children did not attain their midparental height at the end of PD at a mean age of 1.71 years. Although favorable metabolic control and good growth were achieved during PD, these children lagged in term of their midparental height. We conclude that several instruments are needed for determining the management of intravascular volume status and that the control of calcium-phosphorus status is demanding.

Atresia of proximal coronary arteries in pulmonary atresia with intact ventricular septum - fetal and neonatal findings.

Pulmonary atresia with intact ventricular septum (PA+IVS) is a rare congenital cardiac malformation which is associated with ventriculocoronary arterial communications from the right ventricle. We present a case of PA+IVS with a bilateral atresia of the coronary ostia, and thus, a completely right ventricular-dependent coronary circulation followed up by fetal echocardiography. Eventually the infant died of myocardial infarction at 2 days of age.

Long-term outcome after treatment of pulmonary atresia with ventricular septal defect: nationwide study of 109 patients born in 1970-2007.

OBJECTIVES: Treatment of pulmonary atresia with ventricular septal defect (PA + VSD) has evolved during recent decades, but it still remains challenging. This study evaluated 41-year experience of outcome, survival and treatment of PA + VSD patients. METHODS: Patient records and angiograms of 109 patients with PA + VSD born in Finland between 1970 and 2007, and treated at the Children's Hospital, Helsinki University Central Hospital, were retrospectively analysed in this nationwide study. RESULTS: Of the 109 patients, 66 (61%) had simple PA + VSD without major aortopulmonary collateral arteries (MAPCAs). Although we observed no difference in overall survival between those with or without MAPCAs, the patients without MAPCAs had better probability to achieve repair (64 vs 28%, P < 0.0003). Only 3 patients were treated by compassionate care. Overall survival was affected by the size of true central pulmonary arteries on the first angiogram (P = 0.001) and whether repair was achieved (P < 0.0001). After successful repair, the survival rate was 93% at 1 year, 91% from the second year, and functional capacity as assessed by New York Heart Association (NYHA) I-II remained in 85% of patients alive at the end of follow-up. Palliated patients at 1, 5, 10 and 20 years of age had Kaplan-Meier estimated survival rates of 55, 42, 34 and 20%, respectively. Patients who underwent repair attempts but were left palliated with right ventricle (RV)-pulmonary artery connection and septal fenestration had better survival than the rest of the palliated patients (P = 0.001). Further, the McGoon index improved after implementation of a systemic-pulmonary artery shunt in the overall PA + VSD population (P < 0.0001). CONCLUSIONS: These findings show that achievement of repair and initial size of true central pulmonary arteries affect survival of patients with PA + VSD. Although the overall survival of patients with MAPCAs showed no difference compared with simple PA + VSD patients, they had a higher risk of remaining palliated. However, palliative surgery may have a role in treatment of PA + VSD because the size of pulmonary arteries increased after placement of systemic-pulmonary artery shunt. In addition, subtotal repair by a RV-pulmonary artery connection and septal fenestration improved survival over extracardiac palliation.

Follow-up of 316 molecularly defined pediatric long-QT syndrome patients: clinical course, treatments, and side effects.

BACKGROUND: Inherited long-QT syndrome (LQTS) is associated with risk of sudden death. We assessed the clinical course and the fulfillment of current treatment strategies in molecularly defined pediatric LQTS type 1 and (LQT1) and type 2 (LQT2) patients. METHODS AND RESULTS: Follow-up data covering a mean of 12 years were collected for 316 genotyped LQT1 and LQT2 patients aged 0 to 18 years. No arrhythmic deaths occurred during the follow-up. Finnish KCNQ1 and KCNH2 founder mutations were associated with fewer cardiac events than other KCNQ1 and KCNH2 mutations (hazard ratio [HR], 0.33; P=0.03 and HR, 0.16; P=0.01, respectively). QTc interval ≥500 ms increased the risk of cardiac events compared with QTc <470 ms (HR, 3.32; P=0.001). Treatment with ß-blocker medication was associated with reduced risk of first cardiac event (HR, 0.23; P=0.001). Noncompliant LQT2 patients were more often symptomatic than compliant LQT2 patients (18% and 0%, respectively; P=0.03). Treatment with implantable cardioverter defibrillator was rare (3%) and resulted in reinterventions in 44% of cases. CONCLUSIONS: Severe cardiac events are uncommon in molecularly defined and appropriately treated pediatric LQTS mutation carriers. ß-Blocker medication reduces the risk of cardiac events and is generally well tolerated in this age group of LQTS patients.

Increased QT dispersion and loss of sinus rhythm as risk factors for late sudden death after Mustard or Senning procedures for transposition of the great arteries.

Increased QT dispersion and loss of sinus rhythm were both associated with sudden cardiac death in patients with transposition of the great arteries after Mustard and Senning operations at the early and late postoperative periods. A combination of increased QT dispersion with loss of sinus rhythm increases the positive predictive value for sudden cardiac death in patients with transposition of the great arteries after Mustard and Senning procedures.

Junctional ectopic tachycardia after surgery for congenital heart disease: incidence, risk factors and outcome.

OBJECTIVES: Junctional ectopic tachycardia (JET) is a serious, haemodynamically compromising tachyarrhythmia associated with paediatric cardiac surgery, with a reported mortality up to 14%. The incidence, risk factors and outcome of this tachyarrhythmia were evaluated in this population-based, case-control patient cohort. METHODS: A total of 1001 children, who underwent open-heart surgery during a 5-year period, were retrospectively analysed. The patients with haemodynamically significant tachycardia were identified, and their postoperative electrocardiograms were analysed. Three controls matched with the same type of surgery were selected for each patient with JET. RESULTS: JET was diagnosed in 51 patients (5.0%). These patients had longer cardiopulmonary bypass time (138 vs 119 min, p=0.002), higher body temperature (38.0 vs 37.4 °C, p=0.013) and higher level of postoperative troponin-T (3.7 vs 2.1 µg l(-1), p<0.001) compared with controls. They also needed longer ventilatory support (3 vs 2 days, p=0.004) and intensive care stay (7 vs 5 days, p<0.001) as well as use of noradrenaline (23/51 vs 35/130, p=0.019). Ventricular septal defect (VSD) closure was part of the surgery in 33/51 (64.7%) of these patients. The mortality was 8% in the JET group and 5% in the controls (p=0.066). In the logistic regression model, JET was not an independent risk factor for death (p=0.557). CONCLUSIONS: The incidence of JET was 5.0% in this large paediatric open-heart surgery patient group. Compared with controls, these patients had longer cardiopulmonary bypass time and higher level of troponin-T, possibly reflecting the extent of surgical trauma. However, the tachycardia was not an independent risk factor for death.