Incidence, risk factors, and mortality of neonatal and late-onset dilated cardiomyopathy associated with cardiac neonatal lupus.

BACKGROUND: Dilated cardiomyopathy (DCM), a well-known complication of cardiac neonatal lupus, is associated with high mortality rate. Its risk factors remain unclear. METHODS: We analyzed occurrence of postnatal DCM among children with high-degree congenital heart block (CHB) and mothers with anti-SSA and/or anti-SSB antibodies. RESULTS: Among 187 neonates with CHB, 35 (18.8%, one missing data) had DCM and 22 (11.8%) died during a median follow-up of 7years [range: birth-36years]. On multivariate analysis, factors associated with postnatal DCM were in utero DCM (P=0.0199; HR=3.13 [95% CI: 1.20-8.16]), non-European origin (P=0.0052; HR=4.10 [95% CI: 1.81-9.28]) and pacemaker implantation (P=0.0013; HR=5.48 [95% CI: 1.94-15.47]). Postnatal DCM could be categorized in two subgroups: neonatal DCM (n=13, diagnosed at a median age of 0day [birth-4days]) and late-onset DCM (n=22, diagnosed at a median age of 15.2months [3.6months-22.8years]). Factors associated with neonatal DCM were in utero DCM, hydrops, endocardial fibroelastosis and pericardial effusion, whereas those associated with late-onset DCM were non-European origin, in utero mitral valve insufficiency, and pacemaker implantation. Fluorinated steroids showed no protective effect against late-onset DCM (P=0.27; HR=1.65 [95% CI: 0.63-4.25]). Probability of survival at 10years was 23.1% for newborns diagnosed neonatally with DCM, 53.9% for those who developed late-onset DCM, and 98.6% for those without DCM. CONCLUSION: Neonatal and late-onset DCM appear to be two different entities. None of the known risk factors associated with neonatal DCM predicted late-onset DCM. Long-term follow-up of cardiac function is warranted in all children with CHB.

Incomplete Timothy syndrome secondary to a mosaic mutation of the CACNA1C gene diagnosed using next-generation sequencing.

Autosomal dominant genetic diseases can occur de novo and in the form of somatic mosaicism, which can give rise to a less severe phenotype, and make diagnosis more difficult given the sensitivity limits of the methods used. We report the case of female child with a history of surgery for syndactyly of the hands and feet, who was admitted at 6 years of age to a pediatric intensive care unit following cardiac arrest. The electrocardiogram (ECG) showed a long QT interval that on occasions reached 500 ms. Despite the absence of facial dysmorphism and the presence of normal psychomotor development, a diagnosis of Timothy syndrome was made given the association of syndactyly and the ECG features. Sanger sequencing of the CACNA1C gene, followed by sequencing of the genes KCNQ1, KCNH2, KCNE1, KCNE2, were negative. The subsequent analysis of a panel of genes responsible for hereditary cardiac rhythm disorders using Haloplex technology revealed a recurrent mosaic p.Gly406Arg missense mutation of the CACNA1C gene in 18% of the cells. This mosaicism can explain the negative Sanger analysis and the less complete phenotype in this patient. Given the other cases in the literature, mosaic mutations in Timothy syndrome appear more common than previously thought. This case demonstrates the importance of using next-generation sequencing to identify mosaic mutations when the clinical picture supports a specific mutation that is not identified using conventional testing. © 2016 Wiley Periodicals, Inc.

Description of 214 cases of autoimmune congenital heart block: Results of the French neonatal lupus syndrome.

BACKGROUND: Cardiac neonatal lupus syndrome is due to anti-SSA or SSB antibodies and mainly includes congenital heart block (CHB) and dilated cardiomyopathy (DCM). Its optimal management is still debated. We report a large series of autoimmune high degree CHB. METHODS: Inclusion criteria in this retrospective study were fetuses or neonates with high-degree CHB associated with maternal anti-SSA/SSB antibodies. RESULTS: 214 CHB were included: 202 detected in utero at a median term of 23 weeks' gestation (WG) [range 16 to 39 WG] and 12 neonatal cases diagnosed at a median age of 0 days [range birth to 8 days]. The 214 cases of CHB included 202 (94.4%) third-degree CHB, 8 (3.7%) second-degree CHB, and 4 (1.9%) intermittent CHB. In multivariate analysis, the factors associated with feto-neonatal deaths (15.7%) were hydrops (p<0.001; hazard ratio [HR] 12.4 [95% confidence interval (95%CI) 4.7-32.7]) and prematurity (p=0.002; HR 17.1 [95%CI 2.8-103.1]). During a median follow-up of 7 years [birth to 36 years], 148 of 187 children born alive (79.1%) had a pacemaker, 35 (18.8%, one missing data) had DCM, and 22 (11.8%) died. In multivariate analysis, factors associated with child death were in utero DCM (p=0.0157; HR 6.37 [95%CI: 1.25-32.44]), postnatal DCM (p<0.0001; HR 227.58[95%CI: 24.33-2128.46]) and pacemaker implantation (p=0.0035; HR 0.11[95%CI: 0.02-0.51]). The use of fluorinated steroids was neither associated with survival nor with regression of 2nd degree CHB. CONCLUSION: In this second largest series of CHB, we confirm some of the previous results. We were unable to find data supporting the routine use of in utero fluorinated steroids.

Parental electrocardiographic screening identifies a high degree of inheritance for congenital and childhood nonimmune isolated atrioventricular block.

BACKGROUND: The origin of congenital or childhood nonimmune isolated atrioventricular (AV) block remains unknown. We hypothesized that this conduction abnormality in the young may be a heritable disease. METHODS AND RESULTS: A multicenter retrospective study (13 French referral centers, from 1980-2009) included 141 children with AV block diagnosed in utero, at birth, or before 15 years of age without structural heart abnormalities and without maternal antibodies. Parents and matched control subjects were investigated for family history and for ECG screening. In parents, a family history of sudden death or progressive cardiac conduction defect was found in 1.4% and 11.1%, respectively. Screening ECGs from 130 parents (mean age 42.0 ± 6.8 years, 57 couples) were compared with those of 130 matched healthy control subjects. All parents were asymptomatic and in sinus rhythm, except for 1 with undetected complete AV block. Conduction abnormalities were more frequent in parents than in control subjects, found in 50.8% versus 4.6%, respectively (P<0.001). A long PR interval was found in 18.5% of the parents but never in control subjects (P<0.0001). Complete or incomplete right bundle-branch block was observed in 39.2% of the parents and 1.5% of the control subjects (P<0.0001). Complete or incomplete left bundle-branch block was found in 15.4% of the parents and 3.1% of the control subjects (P<0.0006). Estimated heritability for isolated conduction disturbances was 91% (95% confidence interval, 80%-100%). SCN5A mutation screening identified 2 mutations in 2 patients among 97 children. CONCLUSIONS: ECG screening in parents of children affected by idiopathic AV block revealed a high prevalence of conduction abnormalities. These results support the hypothesis of an inheritable trait in congenital and childhood nonimmune isolated AV block.

Multifocal ectopic Purkinje-related premature contractions: a new SCN5A-related cardiac channelopathy.

OBJECTIVES: The aim of this study was to describe a new familial cardiac phenotype and to elucidate the electrophysiological mechanism responsible for the disease. BACKGROUND: Mutations in several genes encoding ion channels, especially SCN5A, have emerged as the basis for a variety of inherited cardiac arrhythmias. METHODS: Three unrelated families comprising 21 individuals affected by multifocal ectopic Purkinje-related premature contractions (MEPPC) characterized by narrow junctional and rare sinus beats competing with numerous premature ventricular contractions with right and/or left bundle branch block patterns were identified. RESULTS: Dilated cardiomyopathy was identified in 6 patients, atrial arrhythmias were detected in 9 patients, and sudden death was reported in 5 individuals. Invasive electrophysiological studies demonstrated that premature ventricular complexes originated from the Purkinje tissue. Hydroquinidine treatment dramatically decreased the number of premature ventricular complexes. It normalized the contractile function in 2 patients. All the affected subjects carried the c.665G>A transition in the SCN5A gene. Patch-clamp studies of resulting p.Arg222Gln (R222Q) Nav1.5 revealed a net gain of function of the sodium channel, leading, in silico, to incomplete repolarization in Purkinje cells responsible for premature ventricular action potentials. In vitro and in silico studies recapitulated the normalization of the ventricular action potentials in the presence of quinidine. CONCLUSIONS: A new SCN5A-related cardiac syndrome, MEPPC, was identified. The SCN5A mutation leads to a gain of function of the sodium channel responsible for hyperexcitability of the fascicular-Purkinje system. The MEPPC syndrome is responsive to hydroquinidine.

Characteristics and long-term outcome of non-immune isolated atrioventricular block diagnosed in utero or early childhood: a multicentre study.

AIMS: The natural history of congenital or childhood non-immune, isolated atrioventricular (AV) block is poorly defined. METHODS AND RESULTS: We retrospectively studied 141 children with isolated, non-immune AV block diagnosed in utero, or up to 15 years of age, at 13 French medical centres, between 1980 and 2009. Patients with structural heart disease or maternal antibodies were excluded. Atrioventricular block was asymptomatic in 119 (84.4%) and complete in 100 (70.9%) patients. There was progression to complete AV block in 29/41 (70.7%) patients with incomplete AV block over 2.8 ± 3.4 years (1-155 months), but all patients with incomplete AV block may not have been included in the study. Narrow QRS complex was present in 18 of 26 patients (69.2%) with congenital, and 106 of 115 (92.2%) with childhood AV block. Pacemakers were implanted in 112 children (79.4%), during the first year of life in 18 (16.1%) and before 10 years of age in 90 (80.4%). The mean interval between diagnosis of AV block and pacemaker implants was 2.6 ± 3.9 years (0-300 months). The pacing indication was prophylactic in 70 children (62.5%). During a mean follow-up of 11.6 ± 6.7 years (1-32 years), no patient died or developed dilated cardiomyopathy (DCM). The long-term follow-up was uncomplicated in 127 children (90.1%). CONCLUSION: In this large multicentre study, the long-term outcome of congenital or childhood non-immune, isolated AV block was favourable, regardless of the patient's age at the time of diagnosis. No patient died or developed DCM, and pacemaker-related complications were few.

A new presentation of neonatal lupus: 5 cases of isolated mild endocardial fibroelastosis associated with maternal Anti-SSA/Ro and Anti-SSB/La antibodies.

OBJECTIVE: Maternal anti-SSA/Ro or anti-SSB/La antibodies are associated with neonatal lupus erythematosus syndrome (NLES), especially congenital heart block (CHB), which may be associated with severe endocardial fibroelastosis (EFE) and dilated cardiomyopathy (DCM). A few reports have described severe EFE without CHB associated with anti-SSA/Ro antibodies, with a poor prognosis. EFE has also been observed in biopsies of DCM that had been considered idiopathic. These points, considered in association with 5 unusual cases of mild EFE, led us to consider the relationship between underrecognized cases of isolated autoantibody-associated EFE and DCM that had been considered idiopathic. METHODS: We analyzed 5 cases of EFE diagnosed in utero (n = 4) or after birth (n = 1). In 3 cases, maternal antibody status was discovered because of the EFE diagnosis. RESULTS: Endomyocardial hyperechogenicity predominated in the left atrium (n = 3) and mitral annulus (n = 3). No left-heart dysfunction was observed. Two mothers were treated with betamethasone. One mother chose to have a therapeutic abortion, and EFE was confirmed at autopsy. Electrocardiograms at birth (n = 4) did not show CHB. Other manifestations of NLES were present in all cases. One child had right ventricular hypoplasia and underwent a partial cavopulmonary anastomosis. At last followup (4-7 yrs), the other 3 children had normal heart function, and echocardiography showed a normal heart (n = 2) or mild persistent EFE (n = 1). CONCLUSION: Middle-term prognosis of isolated autoantibody-associated EFE may be better than previously reported, although the longterm prognosis remains unknown. We hypothesize that a fetal insult can lead to DCM.

Gain-of-function mutations in TRPM4 cause autosomal dominant isolated cardiac conduction disease.

BACKGROUND: Isolated cardiac conduction block is a relatively common condition in young and elderly populations. Genetic predisposing factors have long been suspected because of numerous familial case reports. Deciphering genetic predisposing factors of conduction blocks may give a hint at stratifying conduction block carriers in a more efficient way. METHODS AND RESULTS: One Lebanese family and 2 French families with autosomal dominant isolated cardiac conduction blocks were used for linkage analysis. A maximum combined multipoint lod score of 10.5 was obtained on a genomic interval including more than 300 genes. After screening 12 genes of this interval for mutation, we found a heterozygous missense mutation of the TRPM4 gene in each family (p.Arg164Trp, p.Ala432Thr, and p.Gly844Asp). This gene encodes the TRPM4 channel, a calcium-activated nonselective cation channel of the transient receptor potential melastatin (TRPM) ion channel family. All 3 mutations result in an increased current density. This gain of function is due to an elevated TRPM4 channel density at the cell surface secondary to impaired endocytosis and deregulation of Small Ubiquitin MOdifier conjugation (SUMOylation). Furthermore, we showed by immunohistochemistry that TRPM4 channel signal level is higher in atrial cardiomyocytes than in common ventricular cells, but is highest in Purkinje fibers. Small bundles of highly TRPM4-positive cells were found in the subendocardium and in rare intramural bundles. CONCLUSIONS: the TRPM4 gene is a causative gene in isolated cardiac conduction disease with mutations resulting in a gain of function and TRPM4 channel being highly expressed in cardiac Purkinje fibers.

Incidence and risk factors of arrhythmic events in catecholaminergic polymorphic ventricular tachycardia.

BACKGROUND: The pathophysiological background of catecholaminergic polymorphic ventricular tachycardia is well understood, but the clinical features of this stress-induced arrhythmic disorder, especially the incidence and risk factors of arrhythmic events, have not been fully ascertained. METHODS AND RESULTS: The outcome in 101 catecholaminergic polymorphic ventricular tachycardia patients, including 50 probands, was analyzed. During a mean follow-up of 7.9 years, cardiac events defined as syncope, aborted cardiac arrest, including appropriate discharges from implantable defibrillators, or sudden cardiac death occurred in 27 patients, including 2 mutation carriers with normal exercise tests. The estimated 8-year event rate was 32% in the total population and 27% and 58% in the patients with and without beta-blockers, respectively. Absence of beta-blockers (hazard ratio [HR], 5.48; 95% CI, 1.80 to 16.68) and younger age at diagnosis (HR, 0.54 per decade; 95% CI, 0.33 to 0.89) were independent predictors. Fatal or near-fatal events defined as aborted cardiac arrest or sudden cardiac death occurred in 13 patients, resulting in an estimated 8-year event rate of 13%. Absence of beta-blockers (HR, 5.54; 95% CI, 1.17 to 26.15) and history of aborted cardiac arrest (HR, 13.01; 95% CI, 2.48 to 68.21) were independent predictors. No difference was observed in cardiac and fatal or near-fatal event rates between probands and family members. CONCLUSIONS: Cardiac and fatal or near-fatal events were not rare in both catecholaminergic polymorphic ventricular tachycardia probands and affected family members during the long-term follow-up, even while taking beta-blockers, which was associated with a lower event rate. Further studies evaluating concomitant therapies are necessary to improve outcome in these patients.

Effects of cardiac resynchronization therapy on echocardiographic indices, functional capacity, and clinical outcomes of patients with a systemic right ventricle.

AIMS: Surgically (SC) or congenitally corrected (CC) transposition of the great arteries (TGA), associated with a systemic right ventricle (RV), is often complicated by heart failure. This retrospective study assessed the functional and mechanical effects of cardiac resynchronization therapy (CRT) in patients presenting with TGA. METHODS AND RESULTS: Seven patients with SC (n = 5) or CC (n = 2) TGA (mean age 24.6 +/- 12 years), a failing systemic RV, and intraventricular dyssynchrony, underwent implantation of a CRT-P. Permanent pacemakers were previously implanted in five patients. The leads were implanted by a combined transvenous and epicardial approach in the five patients with SC TGA. Echocardiography, including tissue Doppler imaging and cardiopulmonary exercise testing were performed before and during CRT. Since, in all patients, ventricular dyssynchrony was due to delayed septal wall contraction, the interventricular septum and RV free wall were stimulated synchronously, with a view to resynchronize a maximum amount of myocardium. After 19.4 +/- 8.1 months of CRT, mean QRS duration decreased from 160 +/- 31 to 120 +/- 28 ms (P = 0.03), intraventricular delay from 104 +/- 27 to 14 +/- 15 ms (P = 0.01), New York Heart Association functional class from 3.0 to 1.57 (P = 0.01), and peak oxygen consumption increased from 13.8 +/- 2.5 to 22.8 +/- 6.7 mL/kg/min (P = 0.03). One patient died suddenly at 23 months of follow-up. CONCLUSIONS: CRT was technically feasible and associated with improvements in cardiac mechanical function and clinical status in patients with TGA, failing systemic RV, and intraventricular dyssynchrony.

Acute amiodarone-induced pulmonary toxicity: an association of risk factors in a child operated by arterial switch operation.

Amiodarone is an antiarrhythmic benzoflurane drug with an imposing adverse effect profile. Amiodarone pulmonary toxicity is the major complication. It is well described in adults, whereas it is extremely rare in pediatric patients. This is a case of a child with supraventricular tachycardia post repair of transposition of the great vessels who developed amiodarone toxicity.

Indications for pacing in patients with congenital heart disease.

BACKGROUND: Advances in pacing technology have increased indications for antibradycardia pacing and new indications have appeared for treatment of atrial tachycardia and cardiac failure in patients with congenital heart disease (CHD). METHODS AND RESULTS: Implantation of a pacemaker is mandatory for symptomatic children with complete atrio-ventricular block (CAVB). In asymptomatic neonates and infants, prophylactic pacing is indicated when the ventricular rhythm is <55 beats per minute (bpm) or 70 bpm in case of significant cardiac malformations. Beyond one year of age, PM implantation is recommended in children with an average heart rate <50 bpm or long pauses on 24-hour recordings. Post-operative block that persists 7 days after cardiac surgery is a class I indication for pacing. Postoperative heart block may also be transient, but patients with residual conduction abnormalities and a long HV interval have a high risk of late sudden death and should be paced. After cardiac surgery, atrial pacing may also be considered, in patients with severe sinus bradycardia and symptoms, or in those requiring antiarrhythmic drugs for tachy-bradycardia syndrome; in case of failure of antiarrhythmic drugs, antitachycardia atrial pacing now appears to be safe and efficacious. Finally, cardiac resynchronization therapy may apply to children with congenital heart block and cardiomyopathy, as well as to the population with CHD. Methods and results are described in the section dedicated to resynchronization. CONCLUSION: Cardiac pacing indications have extended beyond prevention of sudden death and pacemaker implantation is now indicated to improve quality of life of patients with CHD and as a bridge to cardiac transplantation.

Clinical aspects and prognosis of Brugada syndrome in children.

BACKGROUND: Brugada syndrome is an arrhythmogenic disease characterized by an ECG pattern of ST-segment elevation in the right precordial leads and augmented risk of sudden cardiac death. Little is known about the clinical presentation and prognosis of this disease in children. METHODS AND RESULTS: Thirty children affected by Brugada syndrome who were <16 years of age (mean, 8+/-4 years) were included. All patients displayed a type I ECG pattern before or after drug provocation challenge. Diagnosis of Brugada syndrome was made under the following circumstances: aborted sudden death (n=1), syncope of unexplained origin (n=10), symptomatic supraventricular tachycardia (n=1), suspicious ECG (n=1), and family screening for Brugada syndrome (n=17). Syncope was precipitated by fever in 5 cases. Ten of 11 symptomatic patients displayed a spontaneous type I ECG. An implantable cardioverter-defibrillator was implanted in 5 children; 4 children were treated with hydroquinidine; and 1 child received a pacemaker because of symptomatic sick sinus syndrome. During a mean follow-up of 37+/-23 months, 1 child experienced sudden cardiac death, and 2 children received an appropriate implantable cardioverter-defibrillator shock; all of them were symptomatic and had manifested a type I ECG spontaneously. One child had a cardioverter-defibrillator infection that required explantation of the defibrillator. CONCLUSIONS: In the largest population of children affected by Brugada syndrome described to date, fever represented the most important precipitating factor for arrhythmic events, and as in the adult population, the risk of arrhythmic events was higher in previously symptomatic patients and in those displaying a spontaneous type I ECG.

Presentation and prognosis of complete atrioventricular block in childhood, according to maternal antibody status.

OBJECTIVES: We sought to determine whether the presentation and prognosis of children with complete atrioventricular block (CAVB) were related to maternal antibody status. BACKGROUND: Comparative studies related to the presence or absence of maternal antibodies anti-SSB/La and anti-SSA/Ro are lacking in children with isolated complete CAVB. METHODS: From 1980 to 2004, we screened for maternal antibodies in 111 children <15 years old with CAVB. According to the presence (Ab+) or absence (Ab-) of antibodies, 2 groups of patients were retrospectively compared. RESULTS: The study group included 56 Ab+ and 55 Ab- patients with equal gender distribution. A total of 96% Ab+ patients were diagnosed in utero or within the first month, compared with 24% Ab- patients. Progression from incomplete to complete block was shown in 23 Ab- and 2 Ab+ patients. Echocardiography showed normal heart structures in Ab- patients, but 8 Ab+ patients had ostium secundum or ductus arteriosus. Pacemaker implantation was performed in 105 patients, and age at implantation was younger in the Ab+ group. At follow-up (age 9.7 +/- 6 years), all Ab- patients were alive with normal left ventricular function; dilated cardiomyopathy was diagnosed at diagnosis or during follow-up in 16 Ab+ patients, and 6 of 16 have died. CONCLUSIONS: Patients with antibody-mediated CAVB were diagnosed and underwent pacing earlier in life and had a more severe prognosis than Ab- patients because of a high risk of dilated cardiomyopathy. The absence of antibody suggests a different pathologic mechanism than autoimmunity, and the term congenital may be not appropriate in these cases.

Radiation dose and long term risk of cardiac pathology following radiotherapy and anthracyclin for a childhood cancer.

PURPOSE: To determine the cardiac status in children 15 years (yrs) or more after a solid tumour treatment. PATIENTS AND METHODS: Of the 447 patients, 229 were fully studied and 218 were not. The following cardiac evaluation was proposed to all the 447 consecutive patients: (1) cardiac Doppler US by one of two expert cardiologists; (2) cardiac rhythm and conduction abnormalities including 24-h holter ECG; (3) (131)I-mIBG myocardial scintigraphy; (4) serum brain natriuretic peptide levels at rest; (5) an exercise test with VO(2)max measurement. The radiation dose delivered to 7 points in the heart was estimated for all patients who had received radiotherapy. RESULTS: Cardiac disorder was diagnosed in 89 evaluated patients (39%) including 24 heart failures and 65 other asymptomatic cardiac diseases. When adjusting on potential confounders, cardiac disorder and cardiac failure risks were respectively linear (ERR at 1 Gy: 26%) and linear-quadratic (ERR at 1 Gy: 19%) functions of the average radiation dose received to the heart. No interaction between cumulative dose of adriamycin and average radiation dose was evidenced for cardiac disorders, but the ERR/Gy of cardiac failure was higher for patients receiving less than 350 mg/m(2) of Adriamycin. CONCLUSION: Long term heart pathologies are probably one of the major iatrogenic risks encored by patients who survived a childhood cancer. This study strongly emphasizes the need to limit the heart irradiation during radiotherapy, particularly, for patients who also received or were susceptible to later received adriamycin.

Anti-SSA/Ro antibodies and the heart: more than complete congenital heart block? A review of electrocardiographic and myocardial abnormalities and of treatment options.

Apart from complete and incomplete congenital heart block (CHB), new cardiac manifestations related to anti-SSA/Ro antibodies have been reported in children born to mothers bearing these antibodies. These manifestations include transient fetal first-degree heart block, prolongation of corrected QT (QTc) interval, sinus bradycardia, late-onset cardiomyopathy, endocardial fibroelastosis and cardiac malformations. Anti-SSA/Ro antibodies are not considered pathogenic to the adult heart, but a prolongation of the QTc interval has recently been reported in adult patients and is still a matter of debate. Treatment of CHB is not well established and needs to be assessed carefully. The risks and benefits of prenatal fluorinated steroids are discussed.

Redundant pacing in a child.

A 4-year-old boy with congenital complete atrioventricular block (CCAVB) and pacemaker (PM) dependency, received a redundant pacemaker. Two separate leads were implanted in the right ventricle, and connected to a dual chamber PM. The two pacing channels were both programmed so that each lead could compensate for the other in case of threshold elevation. The follow-up was uneventful despite exit block on one of the leads.

Long QT syndrome in neonates: conduction disorders associated with HERG mutations and sinus bradycardia with KCNQ1 mutations.

OBJECTIVES: We hypothesized that neonatal long QT syndrome (LQTS) with 2:1 atrioventricular block (AVB) could be related to HERG mutations. BACKGROUND: Early onset of LQTS is rare but carries a high risk of life-threatening events such as ventricular arrhythmias and conduction disorders. There are no data on possible gene specificity. METHODS: We analyzed the characteristics and outcomes of 23 neonate probands from our LQTS population. Samples of DNA were available in 18 cases. RESULTS: Long QT syndrome was diagnosed because of corrected QT interval (QTc) prolongation (mean QTc of 558 +/- 62 ms) and neonatal bradycardia attributable to sinus bradycardia (n = 8) or 2:1 AVB (n = 15). Symptoms included syncope (n = 2), torsades de pointes (n = 7), and hemodynamic failure (n = 6). Three infants with 2:1 AVB died during the first month of life. During the neonatal period, all living patients received beta-blockers (BB) and 13 had a combination of BB and permanent cardiac pacing. Under treatment, patients remained asymptomatic, with a mean follow-up of seven years. Mutations were identified in HERG (n = 8) and KCNQ1 (n = 8), and one child had three mutations (HERG, KCNQ1, and SCN5A). Conduction disorders were associated with LQT2, whereas sinus bradycardia was associated with LQT1. CONCLUSIONS: Two-to-one AVB seems preferentially associated with HERG mutations, either isolated or combined. Long QT syndrome with relative bradycardia attributable to 2:1 AVB has a poor prognosis during the first month of life. In contrast, sinus bradycardia seems to be associated with KCNQ1 mutations, with a good short-term prognosis under BB therapy.

Emergency trans-oesophageal ventricular pacing in a child.

We report our experience with an 8-year-old boy with complete atrioventricular block and syncopal bradycardia who required urgent pacing. Each attempt to cross the tricuspid valve with a femoral lead triggered ventricular standstill, followed by fibrillation, and pacing through the coronary sinus failed. Successful ventricular pacing was finally achieved through the oesophagus, allowing subsequent implantation of a transvenous pacemaker.