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International audience; Introduction: T1-based method is considered as the gold standard for extracellular volume fraction (ECV) mapping. This technique requires at least a 10 min delay after injection to acquire the post injection T1 map. Quantitative analysis of Dynamic Contrast Enhancement (DCE) images could lead to an earlier estimation of an ECV like parameter (2 min). The purpose of this study was to design a quantitative pixel-wise DCE analysis workflow to assess the feasibility of an early estimation of ECV.Methods: Fourteen patients with mitral valve prolapse were included in this study. The MR protocol, performed on a 3 T MR scanner, included MOLLI sequences for T1 maps acquisition and a standard SR-turboFlash sequence for dynamic acquisition. DCE data were acquired for at least 120 s. We implemented a full DCE analysis pipeline with a pre-processing step using an innovative motion correction algorithm (RC-REG algorithm) and a post-processing step using the extended Tofts Model (ECVETM). Estimated ECVETM maps were compared to standard T1-based ECV maps (ECVT1) with both a Pearson correlation analysis and a group-wise analysis.Results: Image and map quality assessment showed systematic improvements using the proposed workflow. Strong correlation was found between ECVETM, and ECVT1 values (r-square = 0.87).Conclusion: A DCE analysis workflow based on RC-REG algorithm and ETM analysis can provide good quality parametric maps. Therefore, it is possible to extract ECV values from a 2 min-long DCE acquisition that are strongly correlated with ECV values from the T1 based method.

Background Sympathetic overactivity is implicated in the initiation and maintenance of electrical storm (ES). Deep sedation has empirically been considered as an efficient therapeutic option to blunt sympathetic tone and control ES. Purpose The aim of this multicenter study was to determine the efficacy of deep sedation in patients presenting intractable ES refractory to anti-arrhythmic drugs. Methods Patients requiring deep sedation for refractory ES from January 1st 2007 to July 31st 2018 were retrospectively included in 13 centers. The primary endpoint was the rate of acute response to sedation, defined as ES termination within 15 minutes after deep sedation. Results Among the 116 patients, 55 (47.4%) had ES termination within 15 minutes and were considered “acute responders” to deep sedation. Clinical signs of congestive heart failure before deep sedation (OR=3.31, 95% CI:1.001–10.97, p=0.049) was the only independent predictor of non-acute response. Twenty-one non-acute responders (34.4%) had an extracorporeal membrane oxygenation (ECMO) implanted. Non-acute responders had a significantly lower in-hospital survival (Log-rank, p=0.010). ECMO implantation did not influence survival in non-acute responders to sedation. Acute response to deep sedation was an independent protector of in-hospital mortality, decreasing by 73% the risk of death (OR 0.27; 95% CI:0.10–0.70, p=0.008). Conclusion To the best of our knowledge, this multicenter study is the first analysis of the efficacy of deep sedation in patients with intractable ES refractory to anti-arrhythmic drugs, and demonstrating the positive impact of “acute response” on in-hospital survival. Funding Acknowledgement Type of funding source: None

Background Epicardial adipose tissue (EAT), through a paracrine secretion of various molecules, seems to be implicated in left atrial (LA) adverse remodelling, promoting persistent atrial fibrillation (PersAF). Computed tomography (CT) density appears to be a marker of EAT secretory activity. Purpose We sought to assess whether EAT density alone or combined with EAT volume is associated with the occurrence of PersAF after a first catheter ablation (CA) procedure. Methods This retrospective study included all consecutive patients undergoing a first CA procedure for PersAF in Nancy University Hospital in 2016 and 2017 with a one-year follow-up. Cardiac CT performed before the ablation allowed quantitative (volume) and qualitative (density) analysis of EAT. Results One hundred and seventy-seven patients were included. After adjustment, determinants of EAT volume were age (β = 0.97, P = 0.014), triglycerides level (β = 10.61, P = 0.002), LA area (β = 4.06, P Conclusion EAT density assessed by cardiac CT seems to be correlated with the risk of recurrence after a first PersAF CA. EAT density might be useful to predict PersAF recurrence after CA and could also become a therapeutic target.

Background Catheter ablation is a well-established therapy for atrial fibrillation. However, some patients are not responders, and there exists currently no method to efficiently select non-responding patients. Purpose The aim of this study is to look for predictive parameters of catheter ablation failure by analyzing the 12-lead surface electrocardiogram (ECG), combined with clinical parameters in patients undergoing the first ablation of persistent atrial fibrillation (PersAF). Methods Two hundred and fifty-eight patients with persistent AF (183 men; mean age 60,1 ± 9,8years) hospitalized for first catheter ablation were retrospectively recruited. A standard 12-lead ECG was acquired before the ablation procedure for each patient. Clinical parameters (CHA2DS2-VASc, LA volume, cardiomyopathy, left common trunk of pulmonary vein) and electrical parameters (f-wave amplitude and frequency) were analyzed and integrated in univariate and multivariate prediction models using a logistic regression technique. Results During an average follow-up of 13.2 ± 4.7 months, 129 patients were in sinus rhythm at 1 year of follow-up after ablation. A feature selection step was performed to select the most informative outcome predictor. A multivariate analysis combining clinical and electrical parameters obtained an AUC of 67.3, with sensitivity of 49.7% and positive predictive value of 52.3%. This model performed better than clinical and electrical parameters analyzed separately. Conclusions Two clinical parameters are associated with failure: LA volume and CHA2DS2-VASc score in univariate analysis. Combination of clinical and electrical parameters allowed for a better selection of non-responding patients. CHA2DS2-VASc score showed a significant correlation with predictive ablation failure, but further studies are needed to confirm that.

Purpose The existence of inter-atrial epicardial connections bridging the two atria at different levels has well been described and their implication in some forms of supraventricular arrhythmias is a known fact. However, up to date, little data exists in the literature showing their role in the mechanisms of focal atrial tachycardias, providing at the same time clear electroanatomical and activation maps using a three-dimensional, non-fluoroscopic mapping system. Patients and methods We present the case of a 29-year-old woman with a focal atrial tachycardia with the origin in a pulmonary vein, manifested as a right atrial origin due to the conduction of the electrical impulse form the right inferior pulmonary vein (RIPV) to the postero-inferior right atrium (RA) via inter-atrial epicardial connections. Using a three-dimensional, non-fluoroscopic mapping system (CARTO, Biosense Webster), an RA activation map was created during tachycardia. Results Radiofrequency (RF) application at the earliest endocardial breakthrough site situated in the postero-inferior RA changed the right atrial depolarization sequence without terminating the arrhythmia. Subsequently, a left atrium activation map was created showing the earliest endocardial breakthrough site at the level of the RIPV ostium and RF application at this level abolished the atrial tachycardia. Conclusion Inter-atrial epicardial connections can be part of the substrate of some forms of supraventricular arrhythmias. Awareness of their existence is important to the electrophysiologist, since a better understanding of transseptal activation can avoid, in some cases, unnecessary RF applications at the level of the postero-septal right atrium, with a subsequent increase in procedural risk.

Various trials using non-antiarrhythmic drugs, antiarrhythmic agents and implantable-cardioverter defibrillators (ICDs) have been performed in order to decrease the incidence of sudden death and to improve survival in chronic heart failure (CHF). The present review addresses some of the key findings of those trials. First, it addresses the importance of considering the potential electrophysiological effects of non-antiarrhythmic drugs and of using angiotensin-converting enzyme inhibitors, beta-blockers and antialdosterone agents in the optimal management of patients with CHF. Second, it reviews the effects of the antiarrhythmic agent amiodarone on mortality and arrhythmic deaths in patients with depressed left ventricular function. Third, it assesses the evidence that patients with CHF and a history of sustained ventricular arrhythmias or resuscitation may benefit from ICD implantation. Finally, it outlines the growing role of ICD therapy in patients with CHF as a primary indication.

Resume Introduction. – La maladie de Lyme peut se presenter de maniere atypique. Elle doit etre evoquee en zone endemique meme devant des manifestations inaugurales inhabituelles en raison de sa curabilite. Exegese. – Les auteurs rapportent et discutent le cas d’un patient ayant presente une cardiomyopathie dilatee et arythmogene severe suivie de l’apparition d’une panuveite bilaterale, rapportees a une maladie de Lyme apres une enquete infectieuse, immunologique et inflammatoire. La serologie de Lyme etait fortement positive en Elisa et western blott. Le traitement par ceftriaxone et amoxicilline a permis la guerison de l’atteinte ophtalmologique et une regression de l’atteinte cardiaque. Conclusion. – L’observation souligne l'extreme diversite clinique de la maladie de Lyme. Atteintes cardiaque et ophtalmologique doivent etre connues du clinicien.

Resume Le nombre de procedures d’ablation endocavitaire concernant la fibrillation atriale (FA) augmente regulierement dans les pays industrialises, alors que ces interventions restent longues et demeurent compliquees en cas de FA chronique. Les enjeux du futur sont doubles : reduire la duree de chaque procedure et ameliorer le taux de succes pour les formes de FA les plus complexes, tout en garantissant le plus faible risque possible de complications operatoires. Certains progres technologiques peuvent contribuer a atteindre ces objectifs. Les systemes de navigation, de cartographie et de robotique intracardiaque existent deja et font regulierement l’objet d’ameliorations. Ils facilitent le deplacement et le repositionnement des catheters ainsi que la comprehension des circuits d’arythmies et le reperage des zones cibles pour l’ablation ; mais ils integrent egalement des logiciels d’analyse des signaux endocavitaires qui favorisent l’identification des sites qui soutiennent les FA chroniques. On peut egalement imaginer que l’identification du substrat arythmogene des FA chroniques passe par l’imagerie cardiaque, notamment l’IRM, et l’integration des images obtenues dans un systeme de cartographie 3D. Enfin, plusieurs societes ont investi en recherche et developpement sur des catheters d’ablation qui permettent a la fois de reduire les temps de procedure et d’ameliorer la qualite des lesions produites, notamment grâce a des catheters « intelligents » qui permettent de mesurer le contact avec la paroi myocardique. Qu’il s’agisse de catheters epousant la forme des ostia veineux ou utilisant d’autres sources d’energie que la radiofrequence, des progres technologiques sont toutefois necessaires avant d’arriver a l’efficacite attendue.

International audience; An electrophysiologic study (EPS) of children and teenagers with paroxysmal supraventricular tachycardia (SVT) and normal electrocardiography (ECG) in sinus rhythm was evaluated. Generally, EPS is performed only before paroxysmal SVT ablation in these patients. In this study, 140 patients (mean age, 15 ± 3 years) with normal ECG in sinus rhythm were studied for SVT by a transesophageal route in baseline state and after isoproterenol. Idiopathic left or right ventricular tachycardia was diagnosed in four patients (3 %). Anterograde conduction over an atrioventricular (AV) left lateral (n = 10) or septal (n = 9) accessory pathway (AP) was noted in 19 patients (13.5 %) at atrial pacing. Orthodromic AV reentrant tachycardia (AVRT) was induced in these children. Five of the patients had a high rate conducted over AP (>240 bpm in baseline state or >290 bpm after isoproterenol). Two of the patients (a 10-year-old girl with well-tolerated SVT and a 17-year-old with syncope-related SVT) had the criteria for a malignant form with the induction of atrial fibrillation conducted over AP at a rate exceeding 290 bpm in baseline state. Of the 140 patients, 74 (53 %) had typical AV node reentrant tachycardia (AVNRT), nine had atypical AVNRT (6 %), 1 had atrial tachycardia (0.7 %), and 33 (23.5 %) had AVRT related to a concealed AP with only retrograde conduction. Electrophysiologic study is recommended for children with paroxysmal SVT and normal ECG in sinus rhythm. The data are helpful for guiding the treatment. Ventricular tachycardia or atrial tachycardia can be misdiagnosed. Masked preexcitation syndrome with anterograde conduction through AP was present in 13.5 % of the patients, and 1.4 % had a malignant preexcitation syndrome.

International audience; Sex-related differences were not reported for the atrial flutter (AF). The purpose of the study was to look for the influence of gender on indications, clinical data and long-term results of AFl ablation.METHODS:985 patients, [227 females (23%)] were referred for radiofrequency AFl ablation. Clinical history, echocardiography were collected. Patients were followed from 3 months to 10 years.RESULTS:Age of women and men was similar (65.5 ± 12 vs 64 ± 11.5 years). Underlying heart disease (HD) was as frequent in women as men (77.5 vs 77%), but women had more congenital HD (10 vs 2%;p

International audience; Purpose of the study: Typical Atrioventricular (AV) Node Re-entrant Tachycardia (AVNRT) occurs in patients with dual AV nodal pathway, a rapid pathway used for retrograde conduction and a slow pathway used for the anterograde conduction. In sinus rhythm the patients have generally the signs of conduction through the rapid pathway with a normal or short PR interval. The purpose of the study was to evaluate the prevalence of patients with 1st degree AV block and with AVNRT and their clinical characteristics.Methods: 1040 patients, 366 males, 665 females were admitted for typical AVNRT. They were aged from 6 to 90 years (mean age 50±19). Initial ECG and clinical data were collected. Electrophysiological study was systematic.Results: Spontaneous 1st degree AV Block (AVB) was rare and noted in 8 patients. The prevalence of the association 1st degree AV Block and AVNRT was 0.8%. AVB was suprahisian in 7 of 8 and infrahisian in one of them. Five patients complained of AVNRT at exercise. Two patients had an ischemic heart disease. Patients with AVB were significantly older (71.5±16 years) than patients without AVB (50±19) (p

Les vingt dernieres annees ont ete les temoins d’avancees scientifiques significatives dans le domaine de la rythmologie, et notamment dans la comprehension du mecanisme des arythmies. Ces progres se sont traduits rapidement au niveau des soins offerts aux patients par une augmentation, reguliere et importante, du nombre des ablations endocavitaires realisees pour des troubles du rythme cardiaque. L’exemple de la fibrillation atriale est le plus demonstratif. En effet, en 1990, le traitement curatif par ablation endocavitaire de la fibrillation atriale n’etait que pure chimere alors qu’en 2010 pres d’un quart des patients admis dans un centre de rythmologie interventionnelle en France le sont pour ce motif ! Au cours de ces deux decennies, des progres importants dans le domaine de l’imagerie cardiaque ont egalement favorise l’essor de l’electrophysiologie interventionnelle. En effet, en dehors de l’ablation des troubles du rythme les plus « simples », comme le flutter atrial commun dependant de l’isthme cavotricuspide ou les tachycardies par reentree nodale, les besoins des cardiologues interventionnels ne se limitent plus simplement a l’utilisation de la fluoroscopie et a l’enregistrement des electrogrammes intracardiaques. En effet, avec l’accroissement de la complexite des arythmies traitees dans les centres de rythmologie interventionnelle, l’imagerie cardiaque a pris une place de plus en plus importante pour aider les electrophysiologistes.

We studied the relationship between wall motion abnormalities determined by echocardiography and the signal-averaged electrocardiogram in 82 consecutive patients during the acute phase of a first myocardial infarction. An abnormal signal-averaged electrocardiogram was defined as the presence of two of the following criteria: a QRS durationor = 114 ms, a root mean square voltage (RMS) of the last 40 msor = 25 microV and an amplitude signal lower than 40 microV lastingor = 39 ms. The left ventricle was divided into 13 segments and the contraction pattern divided into akinesia alone (including dyskinesia) (group A), hypokinesia alone (group B) and both hypokinesia and akinesia (group C). An abnormal signal-averaged electrocardiogram was found in 14/82 patients (17%) and was correlated with the persistence of occlusion of the infarct-related vessel (32% vs 9%, P0.02). In patients with a patent vessel, the incidence of an abnormal signal-averaged electrocardiogram was 14% in group A, 9% in group B and 0% in group C (NS). In patients with an occluded vessel an abnormal signal-averaged electrocardiogram was found in 10% of group A patients, in 36% in group B patients and in 75% of group C patients (P = 0.05). Our study suggests that the presence of hypokinetic areas during the acute phase of a first myocardial infarction and an abnormal signal-averaged electrocardiogram indicate an occluded infarct-related vessel.

In industrialized countries, the number of atrial fibrillation (AF) catheter ablation procedures regularly increases every year, but these interventions are still time consuming and complex, especially for chronic AF. The stakes in the future are twofold : to reduce the duration of each ablation procedure and to increase the success rate for the more difficult AF ablation cases (i.e. : chronic AF), but with the lowest possible complications rate. Some technological improvements may contribute to reach these goals. Intracardiac 3D mapping and navigation systems as well as robotic-assisted catheter manipulation are available and these technologies are regularly upgraded. These systems are helpful both in catheter manoeuvring and repositioning as well as in the understanding of arrhythmia circuits and the definition ablation targets. In addition, these systems are equipped with software specially designed for automatic electrogram analysis to identify myocardial areas which may play a role in the maintenance of chronic AF. Cardiac imaging, such as MRI, may also help identifying arrhythmogenic areas in patients with chronic AF, with subsequent MRI 3D images integrated into a 3D mapping / navigation system. Several companies have invested on the research and development of ablation catheters aiming both at the reduction of procedure time as well as the improvement of the quality of the created lesions, especially with 'smart'catheters which can appreciate wall contact quality. Whatever the type of catheter shape or type of energy used, technological improvement is needed before the expected efficacy is reached.

The long QT syndrome is a rare disease. The prevalence is estimated at 1/5 000 to 1/20,000. Numerous drugs are contra-indicated because they can lengthen the QT interval. A case of pollen allergy in an adolescent with LQTS is described. The possibility to prescribe anti-H1 drugs is reviewed since cases of torsades de pointe and even deaths have been reported for terfenadine and astemizole. Diphenhydramine, orphenadrine and hydroxyzine are contra-indicated. No accidents and no effects on the QT interval have been published for ebastine, fexofenadine, desloratadine and levocetirizine. These anti-H1 drugs could be used with great care, without any association with drugs resulting in low serum potassium level. Azelastine eye drops have been authorized and a routine protection by inhaled corticosteroids during the pollinic period has been advised in this adolescent treated by betablockers.

Sudden death during sport is a rare and unexpected event. It essentially affects young males, and a cardiomyopathy that had not been diagnosed during medical examinations is present in the majority of cases. In young subjects, there is generally hypertrophic cardiomyopathy or arhythmogenic right ventricular dysplasia. This is revealed during sporting activity, and sudden death is often the first symptom of the disease. Competitive sport increases the relative risk of sudden death to 2.5 compared to the risk in a non-sporting subject. The prevalence of sudden death during competitive sport is poorly understood. From the rare studies available, it could be estimated at 2.3/100,000 athletes per year. In Europe, it essentially occurs during football matches. However, the prevalence of sudden death during so-called 'recreational' sports is not precisely known. It could be much higher because these activities involve a larger number of people, and take place without supervision and usually without a medical examination beforehand. The participants are older, and coronary pathology is usually implicated.

Brugada syndrome is a recently identified cause of sudden death. Its primary prevention remains controversial, and epidemiology poorly defined.Electrocardiograms (ECG) of 35,309 individuals (mean age = 37.2 years, 47% men) recorded over a 1-year period were reviewed and classified as (1) typical, (2) suspicious, and (3) negative. Subjects whose ECG was suspicious were offered a provocative test with flecainide, 2 mg/kg, i.v., and individuals whose ECG was typical were advised to undergo programmed ventricular stimulation (PVS).In 14 men and 6 women between the ages of 24 and 77 years (mean =47.5), ECGs were typical (n=6) or suspicious (n=14). Among 6 subjects with typical ECGs, 3 underwent PVS, which was positive in 1, who received an implantable cardioverter defibrillator (ICD). Among 14 subjects whose ECGs were suspicious, 5 declined further investigations and 5 developed typical ECG characteristics of Brugada syndrome after flecainide administration. PVS was negative in 4 subjects who consented to the procedure. Overall, among 35,309 individuals screened, 11 had ECG findings consistent with Brugada syndrome and, over a follow-up of 30 months, all had remained free of adverse cardiac event.we estimated a prevalence of Brugada syndrome of 0.3% in Lorraine. A single patient received an ICD for inducible ventricular tachyarrhythmia during PVS, representing a potential 30 per million asymptomatic adult rate of ICD implantation for this indication.

The electrocardiogram, as much as the clinical examination, is a basic tool for the cardiologist. Technological advances have led to a certain lack of interest in learning to read the electrocardiogram, for which close analysis can allow precise diagnosis, notably in the field of cardiac rhythm disorders. This article concerns the electrocardiogram in ventricular tachycardias with two themes: differential diagnosis of wide QRS complex tachycardias and recognition of the site of origin of a ventricular tachycardia. "Fine" analysis of the electrocardiogram is not an intellectual "game". Actually, careful analysis of the 12 lead ECG allows exact and rapid diagnosis in a large majority of cases, distinguishing a ventricular tachycardia from a supraventricular tachycardia with conduction defect; the appropriate management can be selected without delay. At the same time, close reading of the electrocardiogram also allows the site of origin of a ventricular tachycardia to be recognised. Combining this information with elements of the patient's record can allow the arrhythmia to be related to a known pathology or to prompt a targeted aetiological investigation.

The indications of radiofrequency ablation of arrhythmias have considerably increased since the introduction of the technique in the early 1990s. Interventional rhythmologists now treat arrhythmias which are more and more complex by their mechanism. This requires accurate representation of the ablation catheter position and the integration of spatial and temporal data to identify the arrhythmogenic substrate. The systems of mapping and navigation developed over the last ten years are important tools for interventional rhythmologists. They are very useful for the identification of complex arrhythmogenic substrates which require "individualised" ablations in specific cases. The aim of this article is to review different systems of mapping, and/or navigation currently on the market and their principal characteristics without entering into the details of their use in interventional electrophysiology.

Aim Assessment of a bidirectional conduction block within the cavotricuspid isthmus (CTI) is critical during radiofrequency (RF) atrial flutter (AF) ablation. We investigated the use of bipolar atrial electrogram (BAE) morphology as an additional criterion identifying CTI block and tested it against two recognized criteria: differential pacing and reversal of the right atrial depolarization sequence during coronary sinus (CS) pacing. Methods and results An RF ablation procedure was performed during 600 ms CS pacing in 100 consecutive patients with a common AF. BAE recorded along the CTI were continuously monitored. CTI conduction block was achieved by RF ablation in all patients and a clear change in BAE polarity in the Electrogram recorded by the dipoles located on the CTI and immediately lateral to the intended line of block (RS to QR pattern) associated with a confirmed CTI conduction block was observed in all cases. BAE morphology changes predicted bidirectional CTI conduction blocks with a 100% positive and a 100% negative predictive value. At a mean follow-up of 33 11 months, there was a 5% AF recurrence rate. Conclusions Our study suggests that morphological changes in BAE recorded at sites lateral and adjacent to the target line of block may be used as a unique and robust criterion to validate CTI conduction block during AF ablation procedure.

The implantable automatic defibrillator has proved its superiority over pharmacological treatments for preventing mortality by serious ventricular arrhythmia. We studied the cause of death in a population of 283 consecutive patients implanted between February 1988 and December 2000 (age at implantation: 58 +/- 14.7 years; extremes: 15-78 years, 45 females, ejection fraction: 0.39 +/- 0.15) and followed up over a median of 25 months (extremes = 1 day-163 months).At the end of follow up, 55 patients had died (average age: 62.7 +/- 12.6 years, extremes: 15-79 years, 7 females). All except 2 had a cardiopathy: ischaemic cardiopathy (n = 38, 36 IDDM), dilated cardiomyopathy (n = 14), arrhythmogenic dysplasia of the right ventricle (n = 1). The median interval between implantation and death was 35 months (extremes = 1 day-137 months). The causes of death were the following: cardiac insufficiency (n = 24), refractory arrhythmias (n = 13), other cardiac causes (n = 8), extra-cardiac pathologies (n = 10). The deceased patients had presented an average of 86.6 +/- 23.4 ventricular arrhythmias (extremes = 0-1309) but 18 of them (33%) did not present any during follow up.Cardiac insufficiency is the prime cause of death in refractory arrhythmias; on patient in 4 dies from ventricular arrhythmia, despite the defibrillator and one deceased patient in 3 had no arrhythmia during follow up.

We report the case of a 33-year-old man who presented with headaches and vomiting. Soon after admission he became drowsy and agitated, developed ventricular tachycardia and his neurological state worsened (Glasgow coma score 6). Blood analysis showed respiratory alkalosis, hyperlactacidemia (8 mmol/l), hyperammonemia (390 micro mol/l) and hypoglycaemia (2.4 mmol/l). Subsequently, he developed supraventricular tachycardia, ventricular tachycardia and ultimately ventricular fibrillation resulting in cardiac arrest, which was successfully treated. A CT scan of the head revealed cerebral oedema. Whilst in the intensive care unit, he developed renal failure and rhabdomyolysis. The metabolic abnormalities seen at the time of admission normalised within 48 h with IV glucose infusion. Biological investigations, including urinary organic acids and plasma acylcarnitines, showed results compatible with MCAD deficiency. Mutation analysis revealed the patient was homozygous for the classical mutation A985G. This is one of only a few reports of severe cardiac arrhythmia in an adult due to MCAD deficiency. This condition is probably under-diagnosed in adult patients with acute neurological and/or cardiac presentations.

Cavotricuspid isthmus conduction (CIC) is closely associated with the maintenance and recurrence of common atrial flutter (AFL). This study systematically sought to assess the prevalence and characteristics of acute CIC recovery during AFL ablation and to define its predictors and its relationship with the results of long-term follow-up.A total of 124 consecutive patients (105 men, 19 women, mean age 58 +/- 11 years) who underwent successful AFL ablation were included. The procedure endpoint was defined as complete bi-directional CIC block. During an observation period of 30 min, the incidence of CIC restoration was 34.% in patients and 39.8% in applications. It increased with increasing block time and decreased over time during the observation period. Block time in successful burns followed by persistent block was shorter than in those followed by CIC resumption (12 +/- 6 vs 33 +/- 12 s, P0.0001). A negative correlation between block time and resumption time was found (r = - 0.57, P0.001). Patients with permanent pacemakers had a higher incidence of acute CIC resumption than those without pacemakers (5/7 vs 29/117, P = 0.007). The AFL recurrence rate was 4.8% during a mean follow-up period of 21 +/- 8 months. Our results suggest that acute CIC resumption may be a potential risk for clinical AFL recurrence during long-term follow-up.Acute CIC resumption in common AFL ablation varies in terms of incidence and time course. Block time has a predictive value for acute CIC recovery. Observation time can be shortened if block time is short. With longer block time, it is essential to observe for a longer period in order to minimize CIC resumption.

The aim of this study was to report the authors' experience of radiofrequency ablation of accessory atrioventricular pathways over a 10 year period (01-91 to 10-00), and the effect of the "learning curve" on the results. The data of 400 patients admitted to primo-ablation of a bundle of Kent was analysed retrospectively. A total of 481 ablations were performed (1.20 per patient). The cumulative global success in the 414 accessory pathways treated was 90.6%. The primary success rate increased from the 1st to the 4th quartile from 68 to 97% (p = 0.0001). The mean duration of fluoroscopy and number of ablation sites decreased from the 1st to the 4th quartile respectively from 47 +/- 27 to 25 +/- 18 minutes (p = 0.0001) and from 8.5 +/- 7.8 to 4.5 +/- 3.8 minutes (p = 0.0001). The average recurrence rate over the four quartiles was 3.6. The overall complication rate was 1.44%. The improved primary success rate from 1991 to 2000 and, in parallel, the reduction of the number of inappropriate ablation sites and fluoroscopy duration are explained not only by the "learning curve" of our centre but also by the benefits of the application of scientific acquisitions (unipolar recordings, criteria for ablation site localisation...) and technical progress (ablation with temperature monitoring...) over this period.

The clinical expression of Lyme disease is highly variable. If a patient presents clinical findings consistent with a systemic Lyme borreliosis, this disease must be considered in an endemic area because of its favorable outcome with adequate treatment.The authors report and discuss the case of a patient with an unusual history of dilated cardiomyopathy and supraventricular fibrillation followed by bilateral panuveitis. Enzyme-linked immunosorbent assay and Western blot were positive for Borrelia burgdorferi antigens. The diagnosis of Lyme disease was made after other infectious, inflammatory and autoimmune disorders were excluded by clinical, instrumental and biological investigations. The treatment by ceftriaxone and amoxicillin resolved the ophthalmologic manifestations and improved the cardiac condition.This report underlines the possibility of an unusual presentation of Lyme disease. Ophthalmologic and cardiac involvement should be known by clinicians.

Hypertrophic cardiomyopathy (HCM) is defined as primary hypertrophy of the heart muscle, usually the left ventricle which is not dilated. HCM is a relatively common disease with a prevalence estimated at about 1 in 500. It is a complex disease with relatively stereotypical anatomical features but a very variable clinical presentation with a major risk of complication. All forms may be observed from almost asymptomatic hypertrophy to severe familial forms with multiple cases of sudden death. Over the last few years, molecular studies of the genetic abnormalities responsible for HCM have improved our understanding of the clinical variability of this disease. Schematically, HCM is caused by mutation of one of 4 genes which code the proteins of the sarcomere: the gene of the heavy chain of beta-myosin, the gene of cardiac T-troponin, the gene of alpha-tropomyosin and the gene of protein C linked to cardiac myosin. The main problem for clinicians is not making the diagnosis, which is relatively simple by echocardiography, but to assess the risk of complications, especially in adolescents and young adults. Patients over 40 to 45 years of age pose fewer problems as their disease is generally associated with a better prognosis since they have already survived to that age. There are many prognostic factors of sudden death, a reflection of the multifactorial character of sudden death in this disease. Four major risk factors have been identified: a family history of sudden death, abnormal blood pressure changes on exercise, a history of syncope and non-sustained ventricular tachycardia on 24 or 48-hour Holter monitoring. In children and adolescents, only the first three factors may be used, knowing that syncope, though rare, carries a very poor prognosis. On the other hand, in adults up to 40, all 4 factors are valid. Unfortunately, their positive predictive value is relatively poor, all the patients with one of these risk factors not automatically experiencing sudden death. On the other hand, their negative predictive value is excellent. Therefore, a patient with none of these factors has an excellent prognosis and should be allowed to lead a normal life. The risk is considered to be high when 2 or 3 of the factors are associated, theoretically justifying aggressive management (amiodarone? defibrillator?). Finally, there is no established management protocol in cases with a single risk factor. The discovery of mutations causing HCM will probably open up new methods of assessing the risk of sudden death in this disease. It would seem to be possible to assess the impact of the genotype on prognosis. However, this "genetic stratification" remains the realm of top research teams and is not yet accessible routinely in clinical practice.

Overproduction of NO by an inducible NO synthase (iNOS) plays a role in the pathophysiology of septic shock. In such situations, NOS inhibition might be of therapeutic value, although detrimental side effects possibly related to inhibition of constitutive NOS have been reported. The use of L-canavanine, a selective inhibitor of iNOS, might be more suitable. The aim of the study was to compare in a rodent endotoxic shock the effects of saline (2 mL/h), N(G)-methyl-L-arginine(L-NMMA) (10 mg/kg/h) and L-canavanine (100 mg/kg/h) on muscle intracellular pH (pHi) and intracellular bioenergetic patterns (ATP, phosphocreatine/inorganic phosphate ratio) using in vivo 31P magnetic resonance spectroscopy (31P MRS). Three groups of anesthetized, mechanically ventilated and paralyzed rats received an intravenous infusion of 15 mg/kg of endotoxin. A fourth time-matched control group (n = 8) received 2 mL/h of saline. Mean arterial pressure, femoral blood flow, arterial blood gases, lactate, nitrate level, and 31P nuclear magnetic resonance (31P MRS) measurements were acquired at onset (T = 0), 90 min (T = 90), and 180 min (T180) after the endotoxin challenge. Femoral oxygen delivery was calculated as the product of femoral blood flow (mL/min) and arterial oxygen content. Endotoxin induced a marked decrease in arterial pressure and femoral oxygen delivery and an increase in lactate level. Intracellular pH and phosphocreatine/inorganic phosphate ratio decreased. ATP level did not change. Both L-NMMA and L-canavanine reversed the endotoxin-induced decrease in arterial pressure. L-NMMA attenuated the decrease in femoral oxygen delivery and the increase in lactate level while these were corrected by L-canavanine. Considering 31P MRS derived bioenergetic indices, the endotoxin-induced decrease in pHi and Pcr/Pi was attenuated by L-NMMA and corrected by L-canavanine. In conclusion, in a rodent model of endotoxinic shock, the continuous infusion of L-canavanine, a selective iNOS inhibitor, improved the systemic hemodynamic parameters and the intracellular bio-energetic patterns estimated by in vivo 31P MRS. To the contrary, the continuous infusion of both constitutive and inducible NOS inhibitor L-NMMA was not followed by the same achievement.

The objective of this study was to assess the effects of radiofrequency energy application on implanted pacemaker functions. Radiofrequency (RF) catheter ablation may cause pacemaker dysfunction due to electromagnetic interferences. The effects of RF on pacemaker behavior were studied in a series of 38 pacemakers, implanted 18 +/- 26 months prior to a RF procedure using either a right ventricular approach (AV node ablation, n = 35) or a left ventricular approach (left concealed accessory pathway ablation, n = 1; VT ablation, n = 2). The 38 patients (mean age 65 +/- 9 years) included 20 men and 18 women. Before energy applications, the 23 different pacemaker models were programmed to the VVI mode at the lowest available rate. The continuous surface ECG was recorded throughout the procedure. Thorough testing of the devices was performed before and after each RF delivery. Unusual pacemaker responses occurred in 20 of the 38 cases studied (53%). The impact of RF delivery was unpredictable, and variable dysfunctions were observed at different times for a given patient or could vary for a given model. Unusual pacemaker responses included pacemaker inhibition (n = 8), untoggled backup mode (n = 3), electromagnetic interference noise mode (n = 3), temporary RF-induced pacemaker tachycardia (n = 2), erratic behavior (n = 1), oversensing of RF onset and offset (n = 8), and transient loss of ventricular capture, (n = 1). Postablation, most devices automatically toggled back to full functionality. The three devices in the untoggled backup mode had to be reprogrammed to obtain normal operations. At the end of the procedure, pacing thresholds remained unchanged in all but one patient, in whom the increase in ventricular threshold was due to a nicked lead. In conclusion, implanted pacemakers frequently exhibit transient, unpredictable responses to RF energy application. Although all pacemaker functions were restored postablation, some devices had to be reset manually. The anomalies observed during the RF application argue for the simultaneous use of an external pacemaker in pacing-dependent patients.

Determinants of ventricular rate during atrial fibrillation (AF) are controversial. Concealed conduction, summation, rate and irregularity of atrial impulses, pacemaker activity of the AV node, and the electrophysiologic parameters of AV nodal function may all contribute. Findings from series of patients who underwent AV nodal modulation suggest that AV nodal conduction plays some role in the ventricular response to AF. The data are consistent with the presence of dual (or more) atrionodal inputs that play a role in determining AV nodal conduction properties. The data also strongly support the role of summation rather than simple prolongation of refractory periods as a mechanism of ventricular rate control.

Patients with Mahaim fibres form a distinct subgroup of the pre-excitation syndromes (less than 3%). They have episodes of a pre-excitation during sinus rhythm. Originally, Mahaim fibres have been classified into two main groups, nodoventricular and fasciculoventricular fibres. Recent evidence from both surgery and catheter ablation has shown that the substrate for tachycardia arises due to a slowly conducting fright atrioventricular (AV) accessory pathway (AP) with decremental properties. The pre-excited tachycardia (antidromic re-entrant tachycardia) is distinctive with a left bundle branch block (LBBB) pattern, long AV interval (due to the long conduction time over the AP) and short VA interval (over the AV node). The majority of these patients do not have episodes of narrow QRS complex, due to the absence of retrograde conduction of the AP. There are several ECG features that suggest Mahaim tachycardia as a cause of LBBB pattern tachycardia: QRS axis superior or between 0 degrees and 75 degrees, QRS duration of 0.15 s or less and precordial transition in lead V4 or after. Clinically, Ebstein's anomaly is relatively common and multiple APs are also observed with an increased frequency. Small studies and cases reports have demonstrated sensitivity to various classes of AA drugs. Class IA, IC and beta-blocker may be effective in preventing tachycardias. Small surgical series have reported excellent results in patients with accessory AV connections and Mahaim fibres tachycardia. However catheter ablation offers a definitive therapy in such patients with a high success rate and minimal morbidity.

Objectifs Connaitre les performances du scanner multicoupe comme moyen diagnostic du FO permeable (FOP). Materiels et methodes Etude en cours ; inclusion de patients beneficiant d’une procedure electro-physiologique necessitant le franchissement du FO (ablation par radio-frequence des veines pulmonaires par exemple). Protocole : acquisition specifique de type cine-TDM (collimation de 8 × 2,5 mm centre sur le FO lors d’une manœuvre de Valsalva, resolution temporelle : 0,5 s par volume). Analyse des donnees : courbes de densite / temps de chaque cavite. Gold standard : echographique ou catheterisme avec tentative de franchissement du FO. Resultats Preliminaires sur 15 patients (âge moyen : 53,2 ans, SR 1F/3H). Critere diagnostique : rehaussement trop precoce des cavites gauches, avant celui physiologique des veines pulmonaires. Concernant les patients sains, le delai d’opacification moyen apres injection est de 15,47 s pour l’atrium droit et 19,58 s pour l’atrium gauche. Le scanner a permis de diagnostiquer 3 FOP de haut grade, pour lesquels la difference entre les delais d’opacification (AD-AG) etait significative (p Conclusion L’etendue des indications (HTAP, aide aux procedures endo-cavitaires) et l’integration protocolaire aisee de l’acquisition fait du scanner un examen potentiellement interessant dans le diagnostic de FOP severe.

International audience; Introduction: Atrial fibrillation (AF) and atrial flutter (AFL) are frequently associated. The aim of the study was to look for the prevalence of previous history of AF in patients referred for radiofrequency ablation of AFL and the possible causes.Methods: 1061 patients, 819 males, 242 females, mean age 64±12 years were referred for ablation of recurrent or poorly-tolerated typical AFL. Clinical history, previous AF, data of echocardiography, was collected. Patients were followed from 3 months to 10 years (mean 3±3 years). Antiarrhythmic drugs (AAD) were stopped after ablation except in patients with previous AF before ablation.Results: 336 patients had presented at least one episode of sustained AF (>1 min) before AFL ablation (group I). The prevalence of AF in this population was high (32%). These patients were compared to remaining patients without know AF (group II). Ages of group I and II were similar (65±11 vs 64±12 years). They were more frequently females in group I (27%) than in group II (24%) (p

The aim of the study was to compare the value of different modes of endocavitary recordings: unipolar alone, bipolar alone and the association of unipolar and bipolar recordings in radiofrequency ablation of accessory atrioventricular pathways. A retrospective analysis by three independent observers of 135 endocavitary recordings obtained immediately before radiofrequency application in 82 subjects who underwent radiofrequency ablation for symptomatic accessory atrioventricular pathways. In each case, the authors selected the "successful" record which corresponded to the final radiofrequency application and 0.1 or 2 records of "failures". Each initial recording being of 3 types (unipolar, bipolar and association of uni- and bipolar), a total of 390 anonymous and randomised recordings were analysed by the observers who determined whether the appearances indicated successful ablation. Univariate analysis of variants showed a correlation between success with the mode of recording (p = 0.03) and a left lateral position of the accessory pathways. In multivariate analysis, three variables remained correlated with successful ablation: the observer variable (p = 0.001), and two interactions observer - mode (p = 0.005) and observer-stability (p = 0.02). The benefits of the association of unipolar and bipolar recordings with respect to bipolar recording alone, seemed to be important in predicting failure. The results of tests of concordance in the group of failures were confirmatory: concordance between observers was only found between the unipolar mode alone and the association of unipolar and bipolar recordings. The results of this study suggest that the association of unipolar and bipolar endocavitary recordings may reduce the number of unnecessary application of radiofrequency energy by improved identification of recording showing failure.

Radiofrequency catheter ablation has become the treatment of choice of arrhythmias related to accessory atrioventricular pathways. The reported success rate is well over 90%, irrespective of the localisation of the accessory pathway, and serious complications are rare. A basic principle of the technique is the limitation of the number of applications of radiofrequency energy during a session of ablation and this requires mapping to determine the ideal site using various electrographic parameters. With regards to bipolar recordings, they include: the atrioventricular conduction time, localisation of the ventricular pole of the accessory pathway, recording the accessory pathway potential, the atrial pole of the accessory pathway, and stability of the catheter position. However, the parameters are not readily reproducible and the positive predictive value for successful ablation is low. The use of unipolar electrograms could therefore represent a fundamental step in improving the localisation of accessory pathways and thereby reducing the number of useless applications of radiofrequency energy.

Objectifs L’ablation endocavitaire par radiofrequence (RF) est une nouvelle technique prometteuse dans le traitement des troubles du rythme refractaires d’origine atriale. Le scanner volumique permet d’apporter une information anatomique fiable, necessaire a la planification du geste therapeutique. Materiels et methodes Etude preliminaire incluant 197 examens tomodensitometriques cardiaques en synchronisation ECG (LIGHTS-PEED ULTRA) : 54 patients inclus pour troubles du rythme supraventriculaires (68,4 % ayant eu un controle post-procedure et 16,6 % plusieurs ablations) et 60 patients temoins (Coro-CT, pontages coronariens, anevrismes aortiques). L’etude anatomique comporte une analyse qualitative (variations anatomiques, complications) et quantitative complete (diametres maximum et minimum des ostias, distances interveines, volume atrial, epaisseur du ligament de Marshall, angulation des axes veineux…) pour tous les examens. Resultats Les auteurs se proposent de rappeler la procedure d’ablation endocavitaire par radiofrequence, de detailler et illustrer les principales variations anatomiques en nombre, taille et distribution des veines pulmonaires constatees, d’eventuellement montrer une disposition anatomique statistiquement associee aux patients arythmiques. Les differentes contre-indications et complications ainsi que les voies de developpement futures de la technique seront exposees.

The aim of this study was to search for the presence of atrial vulnerability by programmed atrial stimulation in patients with unexplained ischaemic cerebrovascular strokes and to evaluate the effects of intravenous flecainide acetate on the electrophysiological parameters and on the induction of atrial arrhythmias. Thirty-eight patients (20 men, 18 women) with a mean age of 38.4 +/- 11 years were investigated. Programmed atrial pacing triggered a sustained (1 min) atrial arrhythmia with 1 or 2 extrastimuli in 23 of the 38 patients (61%), in these patients, there was a significant shortening of the effective refractory periods (ERP: 193 +/- 23 vs 218 +/- 30 ms; p0.02) and of the functional refractory periods (FRP: 228 +/- 25 vs 253 +/- 27 ms; p0.01) with lengthening of the A2 auriculogramme (99.7 +/- 22 vs 76.1 +/- 16 ms; p0.05). A combined study of the refractory periods and conduction defects provides a means of calculating an index of latent vulnerability which is greatly shortened when an atrial arrhythmia is induced (2 +/- 0.5 cm vs 3 +/- 0.6 cm; p0.001). Atrial arrhythmias could not be initiated after intravenous 3 mg/kg of flecainide acetate in 4 subjects (17%) with initially positive atrial stimulation tests. This study confirms the high frequency of atrial vulnerability in patients with unexplained ischaemic cerebrovascular strokes. In their population, the authors observed a low efficacy of flecainide acetate in the prevention of reinduction of atrial arrhythmias. The indication of long-term antiarrhythmic drugs in these patients are questionnable and should be assessed by a prospective long-term multicentre trial.

A lot of acquired data concerning the prognostic factors of post-infarction mortality dates from the pre-thrombolysis era. This mortality has considerably decreased since the active management of the acute phase of myocardial infarction. This has made it more complex to evaluate the post-infarction electrical risk and may have reduced the need. However, it is not less true that the assessment of the post-infarction risk necessitates a study of each factor predisposing to severe ventricular arrhythmias and sudden death: myocardial ischaemia, left ventricular dysfunction and electrical instability. The latter parameter may be assessed by non-invasive (ventricular extrasystoles, late ventricular potentials, heart rate variability, the baroreflex and the QT interval) and invasive methods (programmed ventricular stimulation). The association of these results has an excellent negative predictive value, and also improves the positive predictive value which, nevertheless, remains insufficient for expensive prophylactic measures associated with a certain morbidity, for example the implantation of a defibrillator device, to be taken.

This retrospective study reports the immediate and long-term results of percutaneous ablation of atrioventricular conduction. Between July 1983 and January 1992, 85 consecutive patients (51 men, age 64 +/- 10 years, range 43-84 years) presenting with supraventricular arrhythmias (atrial fibrillation n = 53; atrial flutter n = 50; atrial tachycardia n = 17; junctional tachycardia n = 6) resistant to antiarrhythmic therapy (number of drugs used: 4 +/- 1.3, range 1-6) underwent interruption of atrioventricular conduction by fulguration (n = 65) or radiofrequency energy (n = 13) or by an association of the two methods (n = 7). The 75 pacemakers implanted (10 patients had pacemakers before the procedure) comprised 55 VVIR, 11 VVI, 5 DDD and 4 DDDR units. The immediate results included two sudden deaths at the 4th and 7th day in patients undergoing fulguration and three complications with a favourable outcome (staphylococcal septicaemia, pulmonary embolism and haematoma at the site of implantation of the pacemaker). None of the patients was lost to follow-up and the average follow-up was 31 +/- 18 months (range 2-108 months). During follow-up, 15 patients died and there was a recurrence of symptoms in 11 patients after 1 to 9 months requiring a repeat procedure. In the 68 survivors, the follow-up is now 38 +/- 18 months (range 12-108 months). Sixty one patients have 2nd (2) or 3rd (59) degree atrioventricular block, giving 90% good electrocardiographic results.(ABSTRACT TRUNCATED AT 250 WORDS)

The rapidity of technological progress has now made available a device which was only a dream a few years ago, a nearly ideal implantable defibrillator. Despite the persistence of a number of technical and clinical problems, the fourth generation defibrillators are multiprogrammable, with antitachycardia and antibradycardia functions, implantable by the endocavitary approach in most cases thanks to the introduction of biphasic shocks, fitted with constantly improving systems of telemetry, and are progressively smaller in size. The selection of a defibrillator device requires consideration of the patient's needs and the technical characteristics of the defibrillator. Apart from special situations in which the indications of the implantable defibrillator are generally accepted, it is only possible in the absence of results of prospective clinical trials, to use data accumulated on the place of defibrillation compared with other forms of management of severe ventricular arrhythmias. As there is a wide choice of treatment of these ventricular arrhythmias, the role of each must be defined for each individual patient. With regards to the implantable defibrillator, it is essential to take into consideration a number of clinical and paraclinical factors such as the clinical preservation of the arrhythmia, the underlying cardiac disease, left ventricular function and the type of arrhythmia induced by programmed ventricular stimulation.

Although interruption of atrioventricular conduction has been widely used over the last decade in patients with supraventricular arrhythmias and rapid conduction resistant to antiarrhythmic therapy, the incidence of atrioventricular block obtained by delivering the energy at the tricuspid ring ranges from 45 to 92%. Failure of this technique is usually related to the inhability to record endocavitary electrogrammes compatible with probable success by the right-sided approach. The authors report four cases of interruption of atrioventricular conduction in 4 men (average age 61.5 +/- 10 years) by the retrograde arterial catheterisation after one or more (1 to 3) failures by the right-sided approach. After arterial puncture, the ablation catheter is positioned against the interventricular septum below the aortic cusps to record the His bundle electrogram. His bundle ablation was obtained after an average of 2 radio frequency energy applications (range 1 to 3). At the time of effective application, the average amplitude of the endocavitary electrogram was as follows: auriculogram 0.09 mV (range 0.05 to 0.2 mV), His bundle electrogram 0.19 mV (0.15-0.22 mV), ventriculogram 1.36 mV (1.0 to 1.7 mV). No complications were observed. After an average follow-up of 4 months, the 4 patients were still in complete atrioventricular block. This preliminary series shows that left-sided interruption of atrioventricular conduction is effective and safe. It may be proposed after failure of a right-sided attempt.

The authors report their experience of implantable defibrillators over a 5 year period. Between February 1988 and July 1992, 36 patients (25 men, 11 women, average age 51 +/- 11 years, range 18 +/- 71 years) underwent implantation of an automatic defibrillator with epicardial (n = 13, Group I) or endocardial leads (n = 23, Group II) without patch electrodes (n = 7), with subcutaneous patch electrodes (n = 12) or epicardial patch electrodes (n = 4). Three serious early complications were observed: 2 cardiogenic shocks in Group I, one of which died on Day 1 and one case of infection which required explanation of the defibrillator on Day 23 in Group II. Late complications in Group I included one case of disactivation of the defibrillator, 2 losses of output, one of which required replacement of the defibrillator and 2 increases of threshold treated by implantation of an endocardial lead. In Group II, 2 patients had inappropriate shocks due to overdetection (n = 1) and double counting (n = 1). During an average follow-up period of 28.5 +/- 9 months in group I and 13 +/- 6 months in Group II, 4 patients died, 2 from sudden death. Ninety seven shocks were delivered in 19 patients (56%), 5.1 shocks per patient. In the 17 patients with an antitachycardia function, 14 (82%) developed 947 episodes of VT treated successfully by antitachycardia pacing in 917 cases. This retrospective study confirms the efficacy of implantable defibrillators in the treatment of malignant ventricular arrhythmias. The efficacy of endocardial and epicardial leads seems to be the same but there seems to be a lower immediate mortality and morbidity with the endocardial system.

The presence of late ventricular potentials and the induction of sustained ventricular tachycardia (SVT) by programmed ventricular stimulation (PVS) after myocardial infarction are markers of the risk of serious ventricular arrhythmias. The authors studied the value of signal averaged electrocardiography (SAECG) compared with induction of SVT by PVS in 118 consecutive patients 4 to 8 weeks after myocardial infarction. In addition to this study population, a control group of 22 patients with spontaneous SVT after myocardial infarction was also considered. Three parameters were measured after averaging 200 QRS complexes: the duration of the filtered QRS complex (QRSd), the duration of signals not exceeding 40 microV (LAS) and the root mean square of the voltage of the last 40 milliseconds (RMS). Abnormal values were defined as: QRSdor = 120 ms, LASor = 39 ms, RMSor = 20 microV. Patients in the study population were subdivided into 3 groups: Group I (n = 17) inducible SVT; Group II (n = 72) no inducible arrhythmias; Group III (n = 29) induction of sustained ventricular flutter or primary ventricular fibrillation requiring immediate cardioversion. The results showed a good correlation between SAECG and induction of SVT. The sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV) were as follows: 1) QRSd120 ms: Se = 82%, Sp = 80%, PPV = 41%, NPV = 96%; 2) LAS39 ms: Se = 59%, Sp = 85%, PPV = 38%, NPV = 92%; 3) RMS20 V: Se = 59%, Sp = 88%, PPV = 43%, NPV = 93%.(ABSTRACT TRUNCATED AT 250 WORDS)

The initiation of cardiac impulse is located in the sinus node, in the upper anterior part of the right atrium. The importance of the atrium is not only linked to the regulation of heart rate, but also to its haemodynamic function. Indeed, atrial depolarization leads to atrial contraction which can be responsible for up to 30% of cardiac output by way of ventricular filling. Supraventricular arrhythmias are related to one of the following mechanisms: abnormal automaticity, triggered activity, and reentry. Most of supraventricular tachycardias are due to a reentrant phenomenon (intranodal reentrant tachycardia, orthodromic circusmovement tachycardia, atrial flutter and atrial fibrillation). At the onset of a supraventricular tachycardia, the loss of efficacious atrial contraction as well as the increased heart rate may abruptly decrease ventricular filling. As a consequence, stroke volume is reduced, leading to a decrease in cardiac output and in arterial blood pressure, explaining that the patient may experience syncope. Usually, blood pressure reduction resumes within 30 seconds after activation of the autonomic adrenergic nervous system. In case of an underlying heart disease, the supraventricular tachycardia may lead to acute cardiac failure. When reentry is concerned, the tachycardia is going around a specific circuit. The existence of such a circuit in most of supraventricular tachycardias has led to the development of ablation therapy, the goal of which is to destroy a critical portion of the circuit hence making the recurrence of reentrant tachycardia impossible.