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To describe the management of patients with atrial fibrillation (AF) and to study consistency with guidelines on management of AF.Observational study on a random sample of cardiologists from a French national database. Each cardiologist had to recruit the first five patients meeting inclusion criteria (patients diagnosed with AF between January 2004 and one month before inclusion and accepting the collection of their medical data).Between December 2006 and January 2207, 1789 patients aged 71 on average have been recruited by 481 cardiologists. Fifty-one percent were diagnosed with paroxysmal, 15% with persistent and 33% with permanent AF. Restoration of sinus rhythm was preferred in forms considered as paroxysmal or persistent forms whereas control of the ventricular rate was more frequent in AF considered as permanent. Overall, therapeutic guidelines are applied in practice, despite a frequent use of amiodarone in patients with no associated heart disease. Prevention of thromboembolism was observed in 88% of the patients.FACTUEL is the biggest observational study on AF ever conducted in France. The therapeutic strategies used by the cardiologists are consistent with the objectives of preventing thromboembolism and controlling heart rhythm and/or rate. In most cases, the treatment used is consistent with the therapeutic guidelines.

In case of an accessory pathway, children are exposed to severe cardiac events including sudden death. Radiofrequency ablation is a standardized procedure, which can be applied to a significant number of children although complications can still potentially occur. In this context, transesophageal evaluation of the accessory pathway evaluation can be discussed.Among 140 procedures performed in 19 years, 70 were done for accessory pathway evaluation. The preexcitation was overt in 59 children older than 5 years, which form the basis in this study.Anterograde refractory period was determined in 88% cases and was found220 ms in 12 cases justifying an ablation procedure. Conversely, in case of a long refractory period (250 ms), the ablation procedure was not performed in 8 asymptomatic cases and was postponed in 11/20 mildly symptomatic children. Transesophageal electrophysiologic study seems legitimate in asymptomatic or mildly symptomatic children.This technique is probably less useful in case of an overt preexcitation and recurrent reciprocating tachycardia requiring long-term antiarrythmic treatment. In this case, endocavitary electrophysiological study eventually followed by an ablation procedure seems the best option.

The clinical syndromes responsible for sudden death have benefited from spectacular advances in recent years. The authors propose a brief review of the genetic, electrophysiological, physiopathological and clinical characteristics of the long QT syndrome, Brugada's syndrome, adrenergic ventricular tachycardias and the short QT syndrome. The initial concept of one gene responsible for one pathology has uncovered new zones of complexity within diseases considered to be monogenetic in origin. These new findings have impacted on diagnostic and therapeutic strategies of these conditions. However, the assessment of the arrhythmic risk and the choice of treatment in individual cases still remain almost exclusively the domain of clinical judgement. Similarly, the better understanding of the mechanisms of the arrhythmias in these syndromes has opened up new specific therapeutic approaches which require validation by clinical trial.

Arrhythmias in neonates and infants require a specific management due to the particular nature of the rhythm anomalies in children. Accurate diagnosis of the tachycardia is realised mainly by means of ECG recording and vagal manoeuvres. The nature of the tachycardia will determine management, therapy and prognosis. In neonates3 months, supraventricular tachycardia due to Wolff-Parkinson-White syndrome represents 70% of all supraventricular tachycardias, which, after conversion by vagal manoeuvres, requires a preventive treatment by digoxine (10 y/kg/day tid). Neonatal flutter occurs in infants without structural heart disease. It has an excellent prognosis after conversion to sinus rhythm by transoesophageal pacing. Atrial tachycardia is less frequent but can induce a tachymyocardiopathy and often requires combined therapy including amiodarone. Long QT syndrome, clinically and genetically heterogeneous, is characterized by a prolongation of the QT interval (QTc440 ms) and a high risk of syncope and sudden death due to malignant ventricular arrhythmias. Beta-blockers significantly decrease cardiac events during follow-up. Congenital atrio-ventricular block is rare but potentially lethal in the first months of life in the absence of permanent pacing. The morbidity remains high during long term follow-up in unpaced children.

Bidirectional tachycardias are rare arrhythmias. Nevertheless in the sixties and seventies these arrhythmias prompted much work relating to their mechanism. Discussions about the supposed supra-ventricular origin of certain bidirectional tachycardias essentially rested on presumptive arguments based on electrocardiographic analysis. All the electrophysiological investigations which could be performed in tachycardia showed a ventricular origin. The current hypotheses concerning the electrophysiological mechanism favour non-unifocal mechanisms as well as a very diverse aetiology: an automatic focus, or the triggered activities being associated with alternating conduction, or re-entry between the left hemibranches. Although the classic context is of excess digitalis with advanced cardiopathy, readily in atrial fibrillation with a poor prognosis as a corollary, the most recent description of catecholergic ventricular tachycardias with the very characteristic appearance of bidirectional tachycardias justifies updating the understanding of these unusual tachycardias.

The neonatal congenital long QT syndrome (LQTS) is rare and of bad prognosis due to the presence of severe ventricular arrhythmia and conduction abnormalities.we included 24 propositus newborns from our population with LQTS. Genetic study was possible in 19 cases.the diagnosis of LQTS was made according to a QT prolongation associated with a sinusal neonatal bradycardia (n=9) or a 2/1 AV block (n=15). The onset presentation consisted of syncope (n=2), torsades de pointes (n=7), cardiovascular collapse (n=5), cardiac arrest (n=1). The mean QTc was at 550+60 ms. During the neonatal period the treatment consisted of beta-blocking agents in all cases, associated with a definitive pacemaker implantation in 10 cases with 2/1 AV block. Three newborns with a 2/1 AV block died during the first month of life (one case due to a septecemia after implantation of a pacemaker, and two who were waiting for that implantation). All survivors remained asymptomatic during a follow-up period of 7 years. In all cases with a 2/1 AV block we identified mutations in HERG (n=8). Newborns with isolated sinusal bradycardia presented all a mutation in KCNQ1 (n=9).the LTQS with 2/1 AV block is preferably associated with mutation in HERO with a bad initial prognosis.

The Brugada syndrome is characterised clinically by the occurrence of syncope or sudden death due to ventricular arrhythmias in patients with structurally normal hearts and electrocardiographic signs of right bundle branch block and ST elevation in the right precordial leads (V1 to V3). The transmission of the condition is autosomal dominant with variable penetration. Mutations have been identified in a gene coding for the alpha sub-unity of the sodium channel (SCN5A) on chromosome 3 in only 30% of cases. This mutation is responsible for a reduction of the density of the sodium current and explains the aggravation of the electrocardiographic anomalies by antiarrhythmic drugs which block the sodium channels. The prognosis is poor in symptomatic patients and depends on the prevention of sudden death by the implantation of an automatic defibrillator. The therapeutic decision is much more difficult in asymptomatic patients without a family history. The authors propose a decisional algorithm. The management may have to be modified in the months or years to come depending on advances in the understanding of this syndrome.

The congenital long QT syndrome (LQTS) is a variable clinical and genetic entity characterised by prolongation of the QT interval on the ECG associated with the risk of serious ventricular arrhythmias (torsades de pointe, ventricular fibrillation) which may cause syncope and sudden death in patients with otherwise normal hearts. To date, 6 loci have been identified with the genes responsible for the forms LQT1, LQT2, LQT5 and LQT6, coding for the potassium channels (KCNQ1, HERG, KCNE1 and KCNE2, respectively) which, in the heterozygote state, are responsible for the main forms of LQTS without deafness and, in the homozygote state (KCNQ1 and KCNE1) for the recessive forms of LQTS with or without deafness. The gene for the LQT3 form codes for the cardiac sodium channel (SCN5A). The genetic variability observed in the LQTS corresponds to the diversity of cardiac ionic channels implicated in the genesis of the action potential, so making the LQTS a disease of the ionic channels or a "channelopathy". The potential severity of the prognosis justifies testing of subjects with long QT intervals on the ECG and Holter recording. In order to identify subjects with the genetic abnormality who are asymptomatic, these investigations associated with genetic testing should be made in all close members of the family of an affected person. The major problem remains the evaluation of the risk of sudden death in asymptomatic subjects with a genetic abnormality. At present, in the absence of clearly proven prognostic factors and in the knowledge that effective treatment without major secondary effects is available, all patients should be given prophylactic betablocker therapy.

Prone sleep position is obviously the main risk factor for sudden infant death. Other risk factors, such as vagal overactivity particularly in the familial form, are still discussed. We here report 15 families characterized by the coexistence of vagal overactivity and sudden infant death. At least, 1 child for each family had documented [Holter or occulo-cardiac reflex (OCR)] vagal overactivity. In 5 families 2 children were affected; in 2 families 3 children were affected and in 1 family 4 children were affected. Sudden death occurred in the elderly of the family in 8 cases, in the twin in 3 cases, in the 2nd in 3 cases and in the 5th child in 1 case. Within the 15 families, at least 1 parent had experienced vagally-induced fainting or syncope in 10 cases. Familial pattern of vagal overactivity is underlined. Possible links between vagal overactivity, risk factor for suddden death and sudden death are discussed. We suggest an Holter-ECG and OCR follow-up for sudden infant death siblings with history of familial vagal overactivity (3 examinations during the 1st year of life, at 1, 3 and 9 months).

Long QT syndrome is characterized by a prolongation of the QT interval on the surface ECG. This clinically and genetically heterogeneous cardiac disease is potentially lethal due to ventricular polymorphic tachyarrhythmias leading to syncope or sudden death. It is transmitted according to different mendelian modes due to mutations in several genes coding for cardiac ion channels. Heterozygous mutations in KCNQ1, HERG, SCN5A, KCNE1 and KCNE2 genes are responsible for the dominant form without deafness whereas homozygous mutations in KCNQ1 and KCNE1 are responsible for the recessive form (Jervell and Lange-Nielsen syndrome) associated with congenital deafness. We report the case of a 5 year-old boy referred for syncope with a prolongation of the QTc interval (526 ms) and a 2/1 Atrio-Ventricular (AVB) block on the surface ECG. Under beta-blocking therapy, the sinus rate decreased and the 2/1 AVB disappeared. Electrophysiological study evidenced an infra-hisian block and a unipolar ventricular endocardial pacemaker was implanted. A V1777M missense mutation was identified in the C-terminal part of SCN5A, cardiac sodium channel gene, at the homozygous state in the proband and at the heterozygous state in both parents and 2 sibblings. Only the proband had a severe phenotype with syncope and AV conduction anomalies. All other genetically affected subjects were asymptomatic. This study provides evidence for the involvement of homozygous LQT3 forms in "functional" AVB.

Atrial fibrillation is not a homogenous entity. Numerous parameters affect its cause, its continuation, and the arrest of an attack. The presence or absence of cardiopathy and left ventricular dysfunction play a major role via the electrophysiological and haemodynamic consequences and the repercussions on the state of the autonomic nervous system, and finally on the effect of anti-arrhythmics themselves. This shows the importance of taking into account all of these parameters together in order to adapt the therapeutic approach. Equally, this underlines the difficulty in interpreting clinical studies comparing pharmacological treatments when the populations treated are poorly defined or very heterogenous. Most often, one drug is not more or less effective than another, it is more or less suited to the patients treated. The frequency of recurrences of AF despite anti-arrhythmic treatment (on average 50% to 60% at one year) means that in paroxysmal AF the goal of anti-arrhythmic treatment is relatively modest: essentially reducing the frequency, duration and severity of AF attacks, allowing an improvement in the quality of life. The consequences in daily practice are clear: one must ensure good patient compliance and minimise the risks of treatment: side effects of and pro-arrhythmic effects of anti-arrhythmics.

The authors report two cases of foetal supraventricular tachycardia in healthy hearts with 1/1 atrioventricular conduction which turned out to be atrial tachycardias in the postnatal period. The first foetus had permanent tachycardia at 190/minute at 34 weeks' amenorrhea with left ventricular dysfunction at 36 weeks. In the postnatal period, treatment with digoxine and amiodarone restored sinus rhythm and normal left ventricular function. Permanent foetal tachycardia, even at a rate of less than 200 beats/minute, should suggest an arrhythmia and may lead to left ventricular dysfunction in utero. The other foetus had an aneurysm of the foramen ovale with paroxysmal tachycardias at 220/minute without cardiac dysfunction. A Holter at 1 month showed paroxysmalatrial tachycardia. Postnatal rhythm monitoring is necessary in paroxysmal foetus tachycardia, especially with prenatal aneurysm of the foramen ovale.

The two genes which code for the potassium channels, KCNQ1 and HERG, are responsible for the most common forms of the long QT syndrome, LQT1 and LQT2. Abnormalities of duration and morphology of the ventricular repolarisation are amongst the diagnostic criteria of this syndrome. The morphology of the T waves was studied by 24 hour Holter monitoring in 190 subjects with a long QT syndrome due to KCNQ1 (LQT1) [N = 133] or HERG (N = 57) and in 100 controls, and it was compared with the ECG T wave. The T wave was characterised according to 3 morphological features: grade 0 (G0) = normal, grade 1 (G) = slight ST depression and grade 2 (G2) = presence of ST elevation of the descending phase of the T wave. The T wave morphology on Holter ECG was normal for most LQT1 and control subjects compared with LQT2 (92%, 96% and 19% respectively, p0.01). Grade 1 appearances were observed more often in LQT2 (18 vs 8% for LQT1 and 4% for controls, p0.01). Grade 2 appearances were only observed in the cases of LQT2 (63%). The predictive factors of G2 were young age and an anti-sense mutation of the transmembrane domaines of HERG. The authors conclude that Holter monitoring improves detection of T wave changes compared with the ECG. Grade 2 changes seem to be a phenotype marker for a HERG mutation, especially those situated in the transmembrane domaines.

Cardiac complications are common in adolescent anorexia nervosa and are the cause of a third of deaths. Some workers have reported prolongation of the QT interval and cases of sudden death in these patients. The aim of this study was two-fold: to assess the cardiac complications of anorexic adolescents and to determine the outcome after renutrition in the hospital setting. This was a prospective study of 48 consecutive cases (45 girls) with an average age of 14 +/- 2 years, admitted to the paedopsychiatric unit and fulfilling the DSM-IV criteria of anorexia nervosa. The digitised ECG, Holter ECG and echocardiography were recorded before and after renutrition. Anorexia nervosa was severe with a body mass index14 in 2/3 of cases. Over 2/3 of patients had bradycardia with a heart rate50/min in half the cases but normal chronotropic function on Holter monitoring. Prolongation of the QTc interval was demonstrated (QTc440 ms in 11/44 cases). Echocardiographic abnormalities, in particular left ventricular dysfunction (24/46) and pericardial effusion (12/46) were reversible after renutrition. There were no clinical or biological predictive factors for the occurrence of cardiac complications on admission. The authors confirm that cardiac complications of anorexia nervosa are common, usually benign and always reversible after renutrition in hospital. Therefore, most electrical abnormalities normalise with the heart rate and echocardiographic abnormalities with improvement of conditions of load.

Long QT syndrome (LQTS) is a clinically and genetically heterogenous syndrome characterized by a lengthening of the QT interval on the surface ECG and a propensity to severe ventricular arrhythmias such as torsades de pointes and ventricular fibrillation, leading eventually to syncope and sudden death. This rare syndrome with a mendelian inheritance occurs in subjects with otherwise normal cardiac morphological examination. The potentially severe prognosis justifies a presymptomatic diagnosis. The genetic nature of the disease has been confirmed with the identification of at least six loci and five genes. This syndrome is a perfect illustration of an adrenergic-induced ventricular arrhythmia. The first-line treatment is a beta-blocking agent for all symptomatic patients. In addition, a number of drugs known to lengthen ventricular repolarization must be prohibited. In case of suspicion of LQTS, all family members should be tested both clinically with a surface ECG and genetically in order to diagnose presymptomatic patients.

The identification of patients at high risk of sudden cardiac death is one of the greatest challenges for cardiologists. Non-invasive methods have, characteristically, low predictive sensitivities and specificities. The role of abnormalities of ventricular repolarisation (QT interval) in the genesis of ventricular arrhythmias has been well established by experimental data. For this reason, parameters of ventricular repolarisation on the surface electrocardiogram have been proposed. However, taken in isolation, these markers are limited in terms of arrhythmic risk stratification. This report analyses the value of the different parameters of ventricular repolarisation in the identification of high risk: QT dispersion, QT dynamics and T wave alternans. The dispersion of the QT interval is a marker of unhomogenous ventricular depolarisation. This concept must be applied differently in such pathologically dissimilar diseases such as myocardial infarction, cardiomyopathy or the long QT syndrome. Moreover, methodological problems make the interpretation of many experimental studies very delicate. Frequency dependence of the QT helps select high risk patients after myocardial infarction or with dilated cardiomyopathy. A common feature of pathological ventricular myocardium is the more pronounced frequency-dependency of the QT interval. The predictive value of this new index should be evaluated and compared with other non-invasive risk factors in prospective trials. Studies of T wave alternans in selected high risk populations, essentially patients with coronary artery disease and dilated cardiomyopathy, have shown this parameter to be predictive of arrhythmia. The predictive value requires confirmation in much larger populations at lower levels of risk of arrhythmia and sudden death in prospective trials. A new field of research has opened up in the study of ventricular repolarisation. Many studies have been undertaken on the duration of the QT interval, the morphology of the QT (including T wave alternans and post-pause changes) and, finally, the dynamics of the QT interval. By regrouping, analysing and using these data correctly, we should be able to identify new markers of high arrhythmic risk.

In cases of permanent tachycardia, ante-natal diagnosis of chronic reciprocating rhythms with long RP' intervals or His bundle tachycardias is difficult. The authors report two cases of permanent foetal tachycardia with 1/1 atrioventricular conduction. In one case, the tachycardia rate was 170/min with anasarca treated by amiodarone in view of a family history of His bundle tachycardia. In the other case, the tachycardia rate was 200/min but with no signs of cardiac failure and was, therefore, not treated. The ECG at birth confirmed the diagnosis of His bundle tachycardia in the first case and identified a chronic reciprocating rhythm in the other.

The congenital long QT syndrome is characterised by the presence of syncopes due to torsades de pointe which may degenerate to ventricular fibrillation and cause sudden death. These syncopes occur in young subjects with electrocardiographic abnormalities and prolongation of the QT interval. Patients with the autosomally dominant transmitted Romano-Ward syndrome with normal audition are classically opposed to those with the Jervell and Lange-Nielsen autosomally recessive syndrome who have bilateral total deafness. Our understanding of the congenital long QT syndrome has improved in recent years with respect to the physiopathology, diagnosis and treatment, due to research in the fields of genetics, electrocardiography and electrophysiology. The diagnosis is based on analysis of the phenotype and genotypes. A family enquiry is always necessary to detect unrecognised forms. Five culprit genes have been identified for the Romano-Ward syndrome. All code for subunits of sodium or potassium channels: two a subunits of the potassium channels (QVLQT1 for LQT1, HERG for LQT2), the a subunit of the sodium channel INa (SCN5A for LQT3), and two regulatory subunits of potassium channels (KCNE1 for LQT5 regulating the KvLQT1 channel and MiRP1 regulating HERG). The concept of genetic heterogeneity of the congenital long QT syndrome may thus be understood: different genes may be responsible for the same phenotype. Except for specific cases, the usual treatment is life-long betablocker therapy and the avoidance of a large number of drugs, the list of which is continually updated. A multicentre trial is underway to validate betablocker therapy for the prevention of cardiac events in a LQT1 genotype population. Prospective studies will be necessary to assess gene-specific treatments.

The congenital long QT syndrome (QTL) is a heterogenic clinical and genetic entity characterised by prolongation of the QT interval which may be complicated by syncope and sudden death. Four genes have been identified for the cardiac potassium (KCNQ1, HERG and KCNE1) and sodium (SCN5A). The aim of this study was to assess the prognosis of the disease by the site of mutation identified on the morbid gene. Thirty-two genotyped families participated to this study. Each subject gave a clinical history, an ECG and a search for genetic mutation. Eighteen mutations in the transmembrane domains of KCNQ1 were identified in 25 families and 2 mutations in the C-terminal part were found in 4 families. The phenotype was less severe in C-terminal part mutations: less syncopes and sudden deaths (22 vs 55%, p0.001) and a shorter QTc (458 +/- 31 ms vs 479 +/- 31 ms, p = 0.0003). Three mutations were detected in the C-terminal part of HERG in 3 different families. Their phenotype was less severe with syncoped related to hypokalemia. The authors also report the case of a family in which two subjects who were the most severely affected had two mutations, one in HERG and the other in KCNQ1. This study confirms the value of a genetic research in assessing the severity of the congenital long QT syndrome.

Tachycardias arise from an arrhythmogenic substrate and a trigger factor, an extrasystole, the two factors being under the influence of the autonomic nervous system. The study of the mechanisms of spontaneous initiation of arrhythmias must, therefore, take these three factors and their interactions into account. The frequency dependency of an arrhythmia and the sensitivity of the substrate to the adrenergic system varies with time in a given subject and from one patient to another according to the presence and type of cardiac disease. The mode of initiation of most ventricular tachycardias and the therapeutic consequences may be understood: in some forms of cardiac disease, such as arrhythmogenic right ventricular dysplasia, the increase in heart rate which usually precedes sustained ventricular arrhythmias is only perceptible in mild or recent forms, unlike the more chronic dysplasias. This suggests that the arrhythmogenic substrate becomes more sensitive to catecholamines with time, and therefore requires smaller changes in sympathetic tone in order to be expressed (adrenergic paradox). Heart rate changes accompany modifications of sinus variability. Holter monitoring has shown, and this has been confirmed by recordings obtained from patients with implanted automatic defibrillators, that global sinus variability decreases before the initiation of a ventricular arrhythmia. Studies of the dynamics of ventricular repolarisation should also confirm the changes of QT frequency-dependency. The analysis of the initiation of arrhythmias would only have an academic interest if this was limited to a purely descriptive exercise. It is one of the best means of understanding arrhythmias and their therapeutic implications. The development of computerised methods of analysis of Holter monitoring should lead to further progress in this field.

SEVERAL FORMS: Congenital long QT syndrome is a clinically (with and without deafness) and genetically (recessive or dominant autosomal inheritance) heterogeneous entity characterized by a long QT interval on the ECG associated with the risk of severe ventricular arrhythmia (torsade de pointes, ventricular fibrillation) and subsequent syncope or sudden death.This rare familial syndrome is transmitted by different modes of inheritance and occurs in subjects with a morphologically normal heart. The severity of the prognosis justifies screening tests. The genetic origin of the disease has been confirmed and at least 5 loci and 4 genes have been identified, giving a perfect illustration of adrenergic ventricular rhythm disorders. Beta-blockers are used as first line treatment in symptomatic patients.All drugs favoring QT interval lengthening are contraindicated in all subjects with a genetic anomaly. All members of the direct family must have a Holter recording and genotype in order to identify mutation carriers or asymptomatic patients.

The genetics of the long QT syndrome are now better understood. However, there is much heterogeneity as three different genes have already been identified affecting the function of sodium and potassium channels. The aim of these recommendations is to draw up a list of drugs which are contraindicated or not recommended in patients with congenital long QT syndromes. The conraindicated drugs are those with which torsades de pointe have already been described. Drugs not recommended are substances which are not electrohysiologically neutral and for which, in view of their modes of action, their metabolism or belonging to a particular therapeutic class, make them very difficult to use in those patients. It is therefore better not to prescribe them whenever possible in this condition. These substances belong mainly to cardiovascular (especially antiarrhythmic), psychotropic, anti-infectious and antiallergic groups of drugs.

Cisapride is frequently used in the newborn and infant for treatment of gastroesophageal reflux. Twisting-spikes have been reported in adults due to overdosage or therapeutic interaction. We report seven cases of QT prolongation in infants treated with cisapride.Seven children (one full-term, two mature preterms, four preterm babies), aged (mean, range) 41.8 +/- 21 days (14-79) weighing 2.1 +/- 1.1 kg (1.2-4), free from any cardiac abnormality, except one patent ductus arteriosus, have been studied by ECG and Holter monitoring. They received cisapride at a mean dose of 1.31 +/- 0.2 mg/kg/d (between 1 and 1.7 mg/kg/d).The corrected QT (QTc: N450 ms) was increased to 486 ms (450-540) with a notched T-wave pattern. No arrhythmia was detected. In five cases, cisapride was stopped and changed to metoclopramide. Cisapride dosage was reduced to 0.8 mg/kg/d in the two others. No other therapeutic modification was done. A control ECG performed 48 hours after therapeutic changes showed a QTc shortening of 74 +/- 18 ms (45-90) and the disappearance of the notches independent of any heart rate changes, leading to normal QTc values: 413 +/- 21 ms (390-440).High cisapride dosage in preterm, newborns and infants seems to favor QT prolongation which is reversible when dosage is reduced or drug is stopped. The use of cisapride in combination with other drugs known to increase QT should be done with extreme caution.

Extensively described since Gallvardin's reports, the electrical features of salves of ventricular tachycardia in an apparently healthy heart are now well known. The usual benign nature of this arrhythmia is acknowledged, seldom contradicted by isolated clinical cases. Although chronicity is the rule in young adults, there have been a few publications concerning the natural history of these tachycardias in the paediatric age group. The authors report three cases of episodic sustained ventricular tachycardia in older children, presenting at an average of 7 years of age (range 5 to 9 years) and followed up for an average of 7 years (range: 5.5 to 9 years). These three children were treated for an average of 4.5 years (range: 3 to 5.5 years). All treatment was finally withdrawn when stable permanent sinus rhythm without ventricular extrasystoles was restored and confirmed over an average period of 2 years (range 10 months to 3.5 years), an average of 4 (range 3 to 7) successive normal Holter recordings at several months' interval. The outcome in children to spontaneous regression after several years would seem to make radiofrequency ablation more dangerous than useful given the benign nature of the arrhythmia and its good response to pharmacological intervention.

The clinical value of assessing the QT interval is obvious as it is a marker of ventricular depolarisation and repolarisation and it allows identification of clinical situations carrying a high risk of ventricular fibrillation and sudden death. Until the last few years, analysis of ventricular repolarisation was based on analysis of conventional surface electrocardiography. Technical difficulties explain the limits of our knowledge of the dynamics of ventricular repolarisation. This situation is beginning to change rapidly by computerised analysis of Holter monitoring, opening up a particularly complex and important field of research. The duration of the QT interval depends on different factors, especially changes in electrolyte balance, effects of certain drugs, and changes in heart rate and autonomic nervous system tone. The difficulty resides in selecting the pertinent data in order to study separately the effects of heart rate and those of the autonomic nervous system. The initial results show that this analysis provides important information for diagnosis and probably prognosis, on the status of the myocardium and the action of the autonomous nervous system. They require confirmation and validation on larger series of patients with different pathological conditions.

The authors report 5 cases of the long QT syndrome. The patients had malaises and syncopes triggered by exercise or emotional stress, occurring before 10 years of age. The diagnosis was delayed by an average of 38 months (range: 2 to 72 months) from the first symptom and systematic familial study which was positive in 4 of the 5 cases. The corrected QT intervals varied from 0.46 to 0.56 second. All patients were prescribed the betablocker nadolol, resulting in total regression of symptoms with no deaths during an average follow-up period of 40 months (range: 26 to 64 months). The long QT syndrome is a rare hereditary disorder comprising several entities. Recent genetic advances have improved our understanding of the condition. All have an idiopathic prolongation of the QT interval (0.44 second) in common with a predisposition to syncope due to torsades de pointes which may cause sudden death. The spontaneous arrhythmic mortality, which was early and high, has been remarkably decreased by betablocker therapy, from 73% to 6% at 10 years. The authors find nadolol to be extremely reliable and well tolerated, and recommend it as the drug of choice in this indication.

Exercise testing may be used to assess symptoms occurring on effort, to search for and evaluate arrhythmias or conduction defects, antiarrhythmic drugs, pacemakers or implantable cardioverter defibrillators. Interpretation of exercise testing is difficult because of the complexity of the factors in play. Exercise itself induces changes in myocardial metabolism and the autonomic nervous system, the nature and importance of which are influenced by the underlying cardiac disease and the presence of cardiac failure or myocardial ischaemia. This is particularly true when studying the behaviour of arrhythmias on effort, which depends on many parameters, in that they may appear or disappear during exercise, irrespective of their relationship to autonomic nervous system activation. The main problem lies in the interpretation of changes in the heart rate before the onset of an arrhythmia. The sinus rhythm is both a passive indicator of the vago-sympathetic equilibrium and one of the determining factor of the arrhythmia (relationship to the rate), but it is, itself, dependent on the presence of myocardial dysfunction, a source of arrhythmias, and its changes then become difficult to interpret. These reasons explain why exercise testing is certainly a valuable tool in assessing arrhythmias but the poor reproducibility, especially in the evaluation of ventricular arrhythmias, advises prudence in the interpretation of results.

Primary ventricular arrhythmias are rarely seen in children. Some of them have a poor prognosis; they should be diagnosed because adequate treatment can prevent sudden death.Twenty children (11 male, nine female), aged 3 to 16 years (mean: 7.7 +/- 4), with apparently normal hearts and normal QTc intervals were referred for stress or emotion-induced syncope. Primary ventricular arrhythmia, consisting of isolated polymorphic ventricular extrasystoles followed by salvos eventually degenerating into ventricular fibrillation, was reproducibly induced by physical exertion. The syncopal events and "torsades de pointe" disappeared with beta-blocking therapy. A total of four syncopal events and two sudden deaths occurred during a mean follow-up of 8 years, probably due to discontinuation of treatment.Fifty-four-cases of stress-induced severe polymorphous ventricular arrhythmia have been reported in the literature. There were four sudden deaths in 37 patients on beta-blocking therapy, and ten sudden deaths in 21 untreated patients.Clinically close to the congenital long QT syndrome, this primary ventricular arrhythmia must be looked for in cases of stress or emotion-induced syncope. The diagnosis relies on Holter monitoring and a stress test. Life-long beta blocker therapy is required.

The results of a multicentre inquiry started in 1988 in reference centres of sudden infant death are presented. This study concerns the sudden and unexplained mortality of infants under 1 year of age who were treated with atropinics for an alleged risk of sudden death. The 7,851 infants involved were divided into 2,605 siblings, 1,067 premature babies and 4,179 infants who experienced malaises. Only one of the 2,034 infants treated with atropinics (385 siblings, 435 prematures, 1,214 with malaise) died, as opposed to 27 deaths among the 5,817 infants who where not treated (10 deaths among 2,220 siblings, 6 among 632 premature and 11 among 2,965 infants with malaise); P = 0.005. These results are encouraging, but they suffer from the limitations and biases inherent in all large inquiries. They certainly do not allow us to conclude without reservation that vagal hyperreflectivity is the mechanism responsible for sudden infant death and that atropinics must be systematically given to all infants at risk. Wide and randomized prospective studies are highly desirable in this particular field.

Signal-averaged electrocardiography was performed in 132 subjects with various ventricular arrhythmias without clinically apparent heart disease and compared with the results obtained in a series of 45 normal subjects. The latter enabled definition of the following criteria of normality: QRS duration after averaging113 ms; Simson vector of the last 40 ms (RMS40)or = 17 microV; low amplitude signal duration over 40 microV38 ms for a high pass bidirectional filter of 40-300 Hz. Complementary investigations (echo or angiography), performed in all cases, showed underlying abnormalities in 26 patients: 13 right ventricular dysplasias, 7 cardiomyopathies, 3 mitral valve prolapses and 3 minor congenital heart defects. These investigations were normal in the remaining 106 subjects. Of the 26 patients with cardiac disease, 15 had 3 criteria of positivity for late ventricular potentials, 6 had 2 criteria and the other 5 had no criteria of late ventricular potentials. Therefore, 81% of cases with cardiac disease had at least 2 diagnostic criteria of late ventricular potentials whereas only 4% of those without cardiac disease, and in the control group, had criteria of positivity (p0.001). Using these criteria, the predictive value of signal-averaged electrocardiography for the detection of underlying cardiac disease was good when 2 criteria are required for diagnosis of late ventricular potentials: sensitivity 81%, specificity 96%; predictive value of a positive test 78%, predictive value of a negative test 97%. Signal-averaged electrocardiography is therefore a good non-invasive method of diagnosing underlying cardiac disease in patients with ventricular arrhythmias without clinically apparent heart disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of actuarial cardiac mortality of 295 patients after a first attack of sustained monomorphic ventricular tachycardia followed up for an average of 5.1 years showed that: the aetiology was the main prognostic factor. Patients with a normal left ventricle had a zero 5 year mortality rate (normal heart) or 3% (arrhythmogenic right ventricular dysplasia) compared with 24% in patients with cardiomyopathy and 40% with myocardial infarction: p less than 0.01. Similar results were obtained if sudden death was considered; in patients with left-ventricular disease, the role of pump function assessed by the ejection fraction was essential: the 5 year mortality was 14.5% (cardiomyopathy) and 30% (myocardial infarction) if this was greater than 0.3 compared to 43% and 51% respectively when less than 0.3 (p less than 0.01); the heart rate of spontaneous ventricular tachycardia and that of tachycardia induced during endocavitary investigation had no influence on the mortality. However, the mortality following a first tachycardia with syncope was higher than that following a well tolerated tachycardia (p less than 0.5 if the ejection fraction less than or equal to 0.3 and p less than 0.001 if greater than 0.3).(ABSTRACT TRUNCATED AT 250 WORDS)

Thirty-five patients aged 6 days to 18 years (average 7.5 +/- 5.2 years) were treated for an average period of 16 months (range 8 days to 50 months) with flecainide acetate at an average dose of 4.8 +/- 1.4 mg/kg (2.9 to 10 mg/kg) or 130 +/- 30.5 mg/m2 administered twice daily. The cardiac arrhythmia was a resistant paroxysmal junctional tachycardia due to a Wolff-Parkinson-White syndrome in 27 cases, intranodal reentry in 6 cases and a chronic reciprocating rhythm in 2 cases. Treatment was successful with complete suppression of the tachycardia in 24 cases. Partial success with a good clinical result was obtained in 4 cases and there were 7 failures, 6 due to inefficacy of the drug, and 1 because of an extracardiac secondary effect. One case of incessant junctional tachycardia was observed in a 9 month old child in whom the preexcitation disappeared. Atrioventricular preexcitation persisted in 20 out of 24 cases. The duration of the non-preexcited QRS complexes increased significantly from 73.6 +/- 13.8 to 82.2 +/- 15.2 ms; n = 14, p less than 0.01. The minimal effective plasma concentration was 347 +/- 147 ng/ml. The plasma concentration/dose ratio of children over 4 years of age was the same as in adults. It was significantly higher in babies and infants suggesting a progressive acquisition of the capacity to metabolise flecainide during the first year of life. In conclusion, flecainide acetate was easy to use with respect to administration and follow-up, and seems to be a drug of choice for the treatment of junctional tachycardia in children.

The authors report on their experience in investigating late potentials (LPs) in arrhythmogenic right ventricular dysplasia (ARVD), by comparing 35 patients with ARVD with 40 control subjects. The values of QRS and RMS40 and the duration of the LP showed a marked difference between the control group and the ARVDs, particularly if sustained VT was present. In this case, 68 per cent of patients were found to have LPs (with at least 2 out of 3 parameters abnormal) versus 50 per cent in the ARVDs without sustained VT and 5 per cent in the controls. There was a difference between the diffuse forms (10 per cent) and the localized forms (25 per cent) of ARVD: the LPs were markedly more obvious in the diffuse forms. Likewise, there was a clear relationship between age and the criteria for LPs in ARVD with sustained VT. This is an argument in favour of the evolutive character of the disease, which could be observed directly in a few cases in which the examinations were repeated over the course of time.

The authors report their experience of signal-averaged electrocardiography (SAE) in arrhythmogenic right ventricular dysplasia (ARVD) in a study comparing the results in 40 control subjects, 21 patients with ARVD with episodes of sustained monomorphic ventricular tachycardia (VT) (Group I), 7 patients with ARVD without sustained VT (Group II) and 10 asymptomatic members of the families of patients in Group I (Group III). There were significant differences in the results of SAE in the time domain between the control group and Group I, patients with "classical" ARVD. The RMS 40 (root mean square of the last 40 ms of the QRS complex) was the most sensitive parameter but the specificity was less than the averaged QRS width and the low amplitude signal duration. The results in Group II were more varied, some patients having clearly abnormal SAE and others strictly normal recordings. In Group III, the investigation was normal. Spectral analysis after Fourier transformation did not show significant differences between the 3 groups. A difference was observed between the diffuse and localised forms of ARVD in Groups I and II: the localised forms had a shorter QRS width and low amplitude signal duration than the diffuse forms. Also, there was a relationship in Group I between age and duration of QRS and delayed potential which increased and with the RMS 40 or 50 which decreased. This is an argument in favour of the progressive nature of ARVD with respect to time.

On the occasion of a preliminary series of 38 cases, the authors review the esophageal pacing technique and its main indications. On the therapeutic level, the esophageal lead may be successfully used to decrease supraventricular tachycardias due to reentry (typical or atypical flutter, reciprocating nodal tachycardia with or without WPW). As a means of investigation, esophageal pacing is overall useful to diagnose undocumented paroxysmal tachycardia fits (palpitations), to evaluate the refractory stage of an accessory pathway (WPW) or to assess the refractory stage of antiarrhythmia medications. This investigation may also be used to assess the sinusal function, the atrioventricular conduction (Wenckebach point) and the spontaneous rhythm of atrioventricular blocks after pacemaker insertion. Due to the technical improvements achieved, esophageal pacing may be used presently in pediatric units taking care of children with arrhythmias.