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B Cauchemez

Publications and source records attributed to B Cauchemez.

At least 19 recordsLinked to original sources
PubMed2005

[New energy sources for ablative methods].

Radiofrequency current is the reference energy source for endocavitary ablation of arrhythmias. It is particularly well adapted for the ablation of focal arrhythmogenic substrates such as accessory pathways or foyers of automatism. Technological advances have made the lesions larger but the extension of the indications of percutaneous ablation to more complex substrates such as atrial fibrillation have justified the evaluation of alternative energies. The production of linear transmural lesions or deeper lesions which respect the parietal myocardial architecture and endocardial structure are a challenge for these energies. The capacity of functional mapping specific to cryogenics has provided this energy source with a clinical application for ablation of high risk structures whereas other energies, despite the chronicity of their experimental evaluation, are still at the stage of preliminary clinical trials with the sophisticated catheters in special indications.

Arrhythmias, Cardiac↗
PubMed2005

[Long-term evaluation of endocavitary cryoablation of nodal reentry].

Radiofrequency ablation is the reference treatment of refractory nodal reentry. Cryoablation has the advantage of having more modulable effects and minimises the risk of permanent atrioventricular block (AVB). Its immediate efficacy seems comparable to that of radiofrequency ablation but the long-term results are not well known. Endocavitary cryoablation of the slow pathway was undertaken in 26 patients (18 women) with an average age of 47.7 +/- 72.8 years with re-entrant nodal tachycardia refractory to medical therapy. The primary success rate was 92% (24 out of 26). On average, 2.6 +/- 2.2 (1 to 10) cryoablations at - 70 degrees C were delivered and were preceded by 6.4 +/- 4.5 (1 to 16) cryomappings to locate the site of the slow pathway. During cryomapping, 8 episodes of AVB were observed in 6 patients (6 second or third degree), all of which were revertible on rewarming. No cases of permanent AVB were observed. An oesophageal stimulation test of inducibility was performed on the 4th day in 21 patients, 16 of which were not reinducible. During follow-up of 355 +/- 194 days, 22 of the 26 patients (85%) had no recurrence of the arrhythmia. Two of the 24 primary successes had a recurrence, in addition to the two primary failures. Two of the four recurrences occurred in a non-sustained form which was less disabilitating for the patient and the recurrences were controlled in the 4 patients by antiarrhythmic therapy. These results suggest that cryoablation may be a reliable and effective long-term treatment of re-entrant nodal tachycardias. If confirmed in larger series in terms of efficacy and safety, cryoablation could become the treatment of choice of re-entrant nodal tachycardia.

Atrioventricular Node↗
PubMed2005

[Characterization of premature ventricular contraction initiating ventricular fibrillation].

UNLABELLED: The aim of this study is to characterize the electrocardiographic features of premature ventricular contractions (PVC) from different anatomical region that trigger ventricular fibrillation (VF). METHODS AND RESULTS: 36 consecutives patients (20 males, 42+/-14 yrs) undergoing VF ablation from 7 centres were studied (22 with idiopathic VF, 4 associated with a long QT syndrome, 3 with Brugada syndrome, 4 with ischaemic cardiomyopathy and 3 associated with other substrate). Mapping of these PVC showed 2 different origins, which were then confirmed by ablation: right ventricular outflow tract (RVOT) (22%) and peripheral Purkinje network (81%). One patient had PVC from both origins (Brugada). RVOT PVC were frequent but had triggered only 5+/-5 episodes of VF for 26+/-33 months. Purkinje PVC were more likely to be present during electrical storm with 18+/-28 episodes of VF for 33+/-45 months. Right Purkinje PVC have a left bundle branch block with superior axis morphology whereas left Purkinje ones have a right bundle branch block. The axis of activation showed variation from inferior to superior depending on the area of origin from the Purkinje network and the exit site to the myocardium. However Purkinje PVC were characterized by short QRS duration (126+/-18 vs 145+/-13ms for RVOT PVC; p=0.05). In addition the coupling interval was significantly shorter compared to RVOT PVC (292+/-45 vs 358+/-37ms respectively; p=0.005). CONCLUSION: PVC initiating VF demonstrate specific electrocardiographic features that facilitate determination of their origin. Ablation of these typical PVC is feasible in order to reduce ICD shock.

Adult↗
PubMed2005

[Value and limitations of programmed ventricular stimulation].

The electrocardiogramme and methods of prolonged ECG recording are sufficient for diagnosing most cardiac arrhythmias. They also provide some prognostic information and allow evaluation and follow-up of treatment. However, in some situations, endocavitary electrophysiological investigations are required when the diagnosis is uncertain, that more prognostic information is required or interventional techniques (endocavitary ablation) are envisaged. The aim of this report is to summarise the value and limitations of programmed ventricular stimulation. Many of its indications have been abandoned in terms of rhythm stratification in the face of more robust parameters, in particular the left ventricular ejection fraction. However, it retains a potential utility in terms of prognosis in arrhythmogenic right ventricular dysplasia, the Brugada syndrome and operated Tetralogy of Fallot. In any event, it is important to remember that studies resulting in diagnostic or therapeutic recommendations were performed with strict protocols of stimulation in selected patients and that these recommendations can only be applied when the evaluation protocols are respected. The indications of programmed ventricular stimulation will increase in the therapeutic field with the development of new techniques of 3D mapping, new systems of catheter guiding which should extend the indications of endocavitary ablation.

Arrhythmias, Cardiac↗
PubMed2005

[Primary anomalies of ventricular repolarisation].

The duration of repolarisation is the main determinant of the refractory period and therefore plays a major electrophysiological role. Ventricular repolarisation can be influenced or modified by very many extrinsic factors responsible for so-called secondary changes or anomalies. On the contrary, primary anomalies of ventricular repolarisation correspond to intrinsic anomalies of ionic conduction which in turn affect repolarisation. Primary anomalies of ventricular repolarisation are the consequences of vascular disease, which is the origin of both electrocardiographic anomalies and rhythm disorders, and which can result in sudden death from ventricular fibrillation. Three clinical syndromes correspond with these definitions: long QT syndrome, short QT syndrome, and Brugada syndrome. Much of the experimental work seems to show that arrhythmogenic action results mostly from an increase in the heterogeneity of the refractory periods, whether this involves a prolonged, short or even normal repolarisation time. The various experimental models also give a better understanding of the repolarisation changes observed on the electrocardiogram. Knowledge of the mechanisms responsible for arrhythmias due to primary anomalies of ventricular repolarisation could provide a model for secondary anomalies.

Action Potentials↗
PubMed2004

[Recent concepts of the Brugada syndrome, the long QT syndrome and adrenergic ventricular tachycardias].

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.

Bundle-Branch Block↗
PubMed2004

[Ventricular extrasystoles].

Ventricular extrasystoles result from premature excitation of the heart from a site beyond the bifurcation of the bundle of His, at the level of the conductive tissue or myocardial cells. In practice they represent a daily problem for cardiologists due to their frequent occurrence. They can be detected in symptomatic patients and also in asymptomatic subjects, for example during routine health checks. It is therefore important to distinguish benign ventricular extrasystoles from those which are potentially serious, so that a useless or even dangerous treatment is not undertaken and severe anxiety is not caused in patients who have become 'medicalised'. The decision about treatment is only made following electrocardiographic and echographic clinical investigation, with the presence of cardiopathy being one of the major deciding factors.

Adrenergic beta-Antagonists↗
PubMed2003

[Brugada syndrome].

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.

Algorithms↗
PubMed2003

[Indications for implantable automatic defibrillators: critical analysis].

The implantable automatic defibrillator (IAD), invented in 1980, has revolutionised the management of patients with malignant ventricular arrhythmias resistant to medical treatment or ablation procedures. The number of devices implanted continues to increase in the industrialised countries and, based on the results of clinical trials, the indications for IAD are now well codified and increase as new clinical studies are published. However, the absolute number of implantations in France remains low (about 1200 to 2000, about 20 per million population) for a number of reasons: cost of IAD, absence of reimbursement by the health service which has restrained the implantation to public hospitals, and information of cardiologists for whom IAD may seem to be reserved for a few exceptional cases. Several factors suggest that the number of implantations will increase in the near future. First of all, the procedures of implantation have become much more simple due mainly to technical improvements. Then, the results of recent studies have validated prophylactic implantations of these devices in primary prevention in the post-infarction period (MADIT, MUSTT, MADIT II studies) and have demonstrated the superiority of IAD over antiarrhythmic drug therapy in terms of global survival in patients with severe ventricular arrhythmias (AVID, CIDS, CASH studies).

Arrhythmias, Cardiac↗
PubMed2003

[Bidirectional ventricular tachycardias].

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.

Electrocardiography↗
PubMed2002

[Endocavitary ablation for arrhythmias. New modalities of radiofrequency applications. New energy types].

Radiofrequency remains the reference energy type for catheter ablation of rhythm disorders. In the classic indications, which are atrial flutter or tachycardia, nodal re-entry and Wolff-Parkinson-White syndrome, this energy source has the best cost-efficiency-safety ratio, subject to strict conditions of use. Some new modalities of application have further improved performance, especially active irrigation of the electrode which allows induction of deeper lesions which is very useful for the ablation of difficult atrial flutters, epicardial fascicles of Kent and ischaemic ventricular tachycardias. The only emerging alternative energy type, in the framework of classical ablation, is cold, for which the principal advantages are the homogenous and slightly thrombogenic character for the lesion involved, and the possibility of reversible applications tests which are especially useful in the ablation of structures at risk. The situation is more open-ended concerning research on ablation for atrial fibrillation or the so-called new energy types, such as ultrasound and laser, whilst recognising a renewal in interest, especially for circumferential ablation of the pulmonary veins to isolate the ectopic venous foci. Mechanical energy such as luminous energy is emitted across a catheter balloon deployed at the orifice of the vein, perpendicular to its axis, aiming to reach a continuous circumferential lesion with a minimum of applications. Equally radiofrequency has been undergoing significant evolution for this application, such as by the development of porous catheter balloons with a liquid electrode, as well as by the development of deployable circumferential catheters. Ablation is use for atrial fibrillation, by endocavity atrial segmentation remains a field of research in which radiofrequency retains an important place. It is delivered via multi-electrode catheters according to the new application modalities, either pulsed or by phase interval, which secure better efficacy by better continuity of the line of block. Research is equally underway on the use of microwaves and cold in this application.

Atrial Fibrillation↗
PubMed2002

[Role of antiarrhythmics in the treatment of paroxysmal atrial fibrillation].

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.

Anti-Arrhythmia Agents↗
PubMed2002

[Homozygotous mutation of the SCN5A gene responsible for congenital long QT syndrome with 2/1 atrioventricular block].

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.

Amino Acid Sequence↗
PubMed2001

Homozygous SCN5A mutation in long-QT syndrome with functional two-to-one atrioventricular block.

Heterozygous mutations in genes encoding cardiac ionic channel subunits KCNQ1, HERG, SCN5A, KCNE1, and KCNE2 are causally involved in the dominant form of long-QT syndrome (LQTS) while homozygous mutations in KCNQ1 and KCNE1 cause LQTS with or without congenital deafness. In addition, two homozygous HERG mutations have been associated with severe LQTS with functional atrioventricular conduction anomalies in young children. A 2:1 atrioventricular block (AVB) with a major QTc prolongation (526 ms) was evidenced in a 5-year-old boy referred for syncope and seizure. LQTS was diagnosed and beta-blocking therapy initiated leading to normal atrioventricular conduction. Electrophysiological study provided support that location of the AVB was infra-Hisian. DNA analysis was performed in the proband and in asymptomatic family members. A novel missense mutation, V1777M, in the early C-terminal domain of SCN5A was identified. The proband was homozygous while the parents and two siblings were heterozygous carriers. Homozygote and heterozygote expression of the mutant channels in tsA201 mammalian cells resulted in a persistent inward sodium current of 3.96+/-0.83% and 1.49+/-0.47% at -30 mV, respectively, which was dramatically reduced in the presence of tetrodotoxin. This study provides the first evidence for a homozygous missense mutation in SCN5A and suggests that LQTS with functional 2:1 AVB in young children, a severe phenotype associated with bad prognosis, may be caused by homozygous or heterozygous compound mutations not only in HERG but also in SCN5A. The full text of this article is available at http://www.circresaha.org.

Amino Acid Sequence↗
PubMed1999

Simultaneous surgical treatment of atrial septal defect and atrial flutter using a simple modification of the atrial incision.

The reentrant circuit of common atrial flutter is known to be located in the right atrium between two anatomical barriers. Recent electrophysiologic studies have defined the tricuspid annulus as the anterior barrier, and the terminal crest and its continuation as the eustachian ridge as the posterior barrier. Construction of a bidirectional block to conduction between these two barriers by means of lesions created with radiofrequency current have been shown to be effective in ablating the flutter. We now find that surgical creation of such a block to conduction between the barriers by a simple modification of the atrial incision line is equally effective. In a 6-year-old boy, who was admitted to our hospital for closure of an atrial septal defect and treatment of sustained atrial flutter, the atriotomy was performed perpendicular to the terminal groove and extended towards the tricuspid annulus, placing some cryothermal lesions between the end of the incision and the annulus. The septal defect was closed using a Dacron patch. The child was free of arrhythmia both during the postoperative stay and over the initial three months of follow-up. We conclude that this simple modification of the atrial incision line provides cure of atrial flutter in children who require atriotomy for repair of congenital cardiac anomalies. It may also be beneficial in preventing 'incisional' reentrant tachycardia.

Atrial Flutter↗
PubMed1999

[Mechanism of spontaneous occurrence of tachycardia].

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.

Cardiomegaly↗
PubMed1996

Electrophysiological effects of catheter ablation of inferior vena cava-tricuspid annulus isthmus in common atrial flutter.

BACKGROUND: The electrophysiological mechanisms for successful catheter ablation of atrial flutter (AFI) targeting the inferior vena cava-tricuspid annulus (IVC-TA) isthmus have not been determined. METHODS AND RESULTS: Twenty patients with common AFI were studied. All had inducible common AFI, and 8 of them had both common and reverse AFI. Right atrial (RA) activation sequences were investigated during pacing from sites proximal (low lateral RA) and distal (proximal coronary sinus) to the IVC-TA isthmus both during entrainment of common or reverse AFI and during pacing in sinus rhythm. This was repeated after ablation. During pacing in sinus rhythm from the low lateral RA, the septum was activated by caudocranial and craniocaudal wave fronts. Similarly, during pacing from the proximal coronary sinus, the lateral RA was activated by two wave fronts. Catheter ablation of the IVC-TA isthmus induced dramatic changes in mapping due to the loss of caudocranial wave front in all but 1 patient. The septum and the lateral RA were activated by a single craniocaudal front as during entrainment of reverse or common AFI, respectively. After a follow-up of 8 +/- 2 months, common or reverse AFI occurred in 4 patients. Two had no or only unidirectional changes in the isthmus conduction induced by ablation. The other 2 had a late recovery of conduction. CONCLUSIONS: The present study provides evidence that the mechanism of successful AFI ablation targeting the IVC-TA isthmus is local bidirectional conduction block. This change can be used as a new and complementary electrophysiological end point for the procedure. AFI recurrences are associated with failure to achieve a permanent block.

Aged↗