What is the origin of this arrhythmia?

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.

[Ablation of atrial fibrillation: new technologies and challenges]. / Ablation de la fibrillation atriale: enjeux du futur, progrès technologiques.

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.

[Prevalence of sudden cardiac death during sports activities]. / Prévalence de la mort subite au cours du sport.

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.

[Prevalence of Brugada syndrome among 35,309 inhabitants of Lorraine screened at a preventive medicine centre]. / Prevalence du syndrome de Brugada dans une population de médecine préventive en Lorraine a propos de 35,309 cas.

UNLABELLED: Brugada syndrome is a recently identified cause of sudden death. Its primary prevention remains controversial, and epidemiology poorly defined. PATIENT POPULATION AND METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.

[New systems of mapping and navigation in electrophysiology]. / Nouveaux systèmes de cartographie et de navigation en électrophysiologie.

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.

[The electrocardiogram in ventricular tachycardias]. / Electrocardiogramme des tachycardies ventriculaires.

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.

[Characteristics and causes of death in 283 patients with implanted defibrillators]. / Caractéristiques et causes de décès chez 283 patients implantés d'un défibrillateur automatique.

UNLABELLED: 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). RESULTS: 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. CONCLUSIONS: 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.

Correlation between electrogram morphology and standard criteria to validate bidirectional cavotricuspid block in common atrial flutter ablation.

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.

Acute resumption of conduction in the cavotricuspid isthmus after catheter ablation in patients with common atrial flutter. Real-time evaluation and long-term follow-up.

AIMS: 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. METHODS AND RESULTS: 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, P<0.0001). A negative correlation between block time and resumption time was found (r = - 0.57, P<0.001). 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. CONCLUSIONS: 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.

[Immediate and long-term results of radiofrequency ablation of accessory atrioventricular pathways]. / Résultats immédiats et à long terme de l'ablation par radiofréquence des faisceaux accessoires atrioventriculaires. Rôle de la maturation de la technique.

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.

Cavotricuspid isthmus mapping to assess bidirectional block during common atrial flutter radiofrequency ablation.

BACKGROUND: We sought to compare published methods to an alternative approach ascertaining cavotricuspid isthmus (CTI) block during atrial flutter ablation. METHODS AND RESULTS: In 39 consecutive patients who underwent an atrial flutter ablation procedure, a 24-pole mapping catheter was positioned so that 2 adjacent dipoles were bracketing the targeted CTI line of block (LOB), with proximal dipoles lateral to the LOB and distal dipoles in the coronary sinus. Two pacing sites were lateral (positions A and B) and 2 were septal (positions C and D) to the LOB, with locations A and D closest to the LOB. A resulting CTI block was accepted when 3 criteria were fulfilled: (1) complete reversal of the right atrial depolarization on the 24-pole catheter when pacing in the coronary sinus, (2) conduction delays from A to D greater than from B to D, and (3) conduction delays from D to A greater than from C to A. A successful CTI block was obtained in all patients. Before CTI block was obtained, a progressive CTI conduction delay was observed in 11 patients (28.2%). During the procedure, the 3 criteria defined above were either all present or all absent. CONCLUSIONS: This study establishes that reversal of the atrial depolarization sequence up to the LOB is a definitive and mandatory criteria of successful atrial flutter ablation.

Accuracy and limitations of published algorithms using the twelve-lead electrocardiogram to localize overt atrioventricular accessory pathways.

INTRODUCTION: The purpose of this study was to evaluate the accuracy and limitations of published algorithms using the 12-lead ECG to localize AV accessory pathways (APs). METHODS AND RESULTS: The 11 relevant algorithms found in the literature (MEDLINE database and major scientific sessions) were tested on a series of 266 consecutive patients who successfully underwent radiofrequency catheter ablation of a single overt AV AP. The positive predictive values (PPV) of the algorithms in applicable patients were significantly lower for algorithms with > 6 accessory location sites (40.6% +/- 10.9% vs 61.2% +/- 8.0%; P < 0.03) and show a tendency for algorithms not relying on delta wave polarity but on QRS polarity only (36.6% +/- 11.2% vs 52.3% +/- 13.1%; P = 0.09). The PPV in applicable patients is related to the AP location (P < 0.001) and ranked from the highest to the lowest as follows: left lateral (mean PPV = 86.3%), posteroseptal (mean PPV = 65.2%), right anteroseptal (mean PPV = 45.2%), and right posterolateral (mean PPV = 23.4%). CONCLUSION: Our study suggests that the accuracy of algorithms relying on the 12-lead ECG depends on AP locations as defined in the algorithms and on the number of AP sites. The accuracy tends to be lower when delta wave polarity is not included in the algorithm's architecture. This should be considered when using these algorithms or when building new ones.

Reproducibility of bipolar endocavitary electrogram measurements at sites of radiofrequency energy delivery in patients with the Wolff-Parkinson-White syndrome.

BACKGROUND: Radiofrequency ablation of atrioventricular accessory pathway is widely used to cure patients with the Wolff-Parkinson-White syndrome. The site of successful ablation is determined using electrophysiological parameters, endocavitary bipolar electrogram measurements being the most commonly used. Interobserver reproducibility of these measurements may limit the reliability of ablation criteria based upon bipolar measurements only but, to our knowledge, this reproducibility has not been evaluated so far. Such was the aim of this study. METHODS: Three independent observers reviewed the bipolar electrograms recorded at sites were radiofrequency energy was delivered (successfully or not) in 28 consecutive patients with the Wolff-Parkinson-White syndrome. In each tracing, 4 intervals were measured: (1) A0V0 (onset of the atrial electrogram to onset of the ventricular electrogram), (2) AaVa (activation time of the atrial electrogram to activation time of the ventricular electrogram), (3) V0-QRS (onset of the ventricular electrogram to onset of delta wave on the surface ECG) and (4) Va-QRS (activation time of the ventricular electrogram to onset of delta wave on the surface ECG). RESULTS: The interobserver reproducibility was low since only 50% of A0V0 intervals were measured with an interobserver difference lower than 10 ms and up to 43% of Va-QRS intervals were measured with an interobserver difference greater than 30 ms. The reproducibility of interval measurement was graded from the highest to the lowest as follows: A0V0, AaVa, V0-QRS and Va-QRS (Chi-square statistic, chi 2 = 71.72, p < 0.0001). Kappa values were lower than 0.40, indicating a poor interobserver reproducibility. CONCLUSIONS: Our study suggests that interobserver reproducibility of only bipolar electrograms interval measurements at sites of radiofrequency ablation of atrioventricular accessory pathway is poor, which limits the reliability of bipolar criteria to predict a successful ablation site.

Prognostic value of thrombolysis, coronary artery patency, signal-averaged electrocardiography, left ventricular ejection fraction, and Holter electrocardiographic monitoring for life-threatening ventricular arrhythmias after a first acute myocardial infarction.

Prognostic studies after acute myocardial infarction (AMI) have mainly been performed in the prethrombolytic era. Despite the fact that modern management of AMI has reduced mortality rates, the occurrence of malignant ventricular arrhythmias in the late phase of AMI remains an important issue. We prospectively studied 244 consecutive patients (97 treated with thrombolytics) who survived a first AMI. All patients underwent time domain signal-averaged electrocardiography (vector magnitude: measurements of total QRS duration, terminal low [<40 microV] amplitude signal duration, and root-mean-square voltage of the last 40 ms of the QRS complex), Holter electrocardiographic monitoring, and cardiac catheterization. Late life-threatening ventricular arrhythmias were recorded. Eighteen arrhythmic events occurred during a mean follow-up period of 57 +/- 18 months. Three independent factors were associated with a higher risk of arrhythmic events: (1) left ventricular ejection fraction (odds ratio 1.9/0.10 decrease), (2) terminal low-amplitude signal duration (odds ratio 1.5/5 ms increase), and (3) absence of thrombolytic therapy (odds ratio 3.9). Low-amplitude signal duration sensitivity for sudden cardiac death was low (30%). Left ventricular ejection fraction had the highest positive predictive value for sudden cardiac death (10%). Thus, thrombolysis decreases both the incidence of ventricular tachycardia and sudden cardiac death with a higher reopening rate of the infarct-related vessel. Signal averaging predicts the occurrence of ventricular tachycardia and an impaired left ventricular ejection fraction predicts the occurrence of sudden cardiac death.

[Value of unipolar and bipolar recordings in radiofrequency ablation of accessory atrioventricular pathways]. / Valeur de l'enregistrement unipolaire et bipolaire dans l'ablation par radiofréqunce des faisceaux accessoires auriculo-ventriculaires.

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 ablation of the atrioventricular accessory pathways. Value of unipolar and bipolar recordings]. / Ablation par radiofréquence des voies accessoires auriculo-ventriculaires. Intérêt des enregistrements unipolaire et bipolaire.

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.

[Which patients at risk of sudden death after myocardial infarction? Critical study of prognostic factors]. / Quels sont les patients à risque de mort subite après un infarctus dumyocarde? Etude critique des facteurs pronostiques.

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.