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Biomedical subjects

C Barnay

Publications and source records attributed to C Barnay.

At least 19 recordsLinked to original sources
PubMed1992

[Effects of disopyramide on normal and pathological atrioventricular conduction].

Disopyramide is a Vaughan-Williams class Ia antiarrhythmic, which is distinguished by its anticholinergic activity, which is due to its active metabolite: mono-N-alkyl disopyramide. In cells with a rapid response, such as those in the His-Purkinje tissue, it depresses conduction. In slow-responding cells (sinus node and Tawara's node) direct depression of conduction and automatism, and anticholinergic stimulation have opposing effects. In terms of clinical electrophysiology, this is a Touboul class IIa compound: and action mainly on the His-Purkinje system involving extension of the conduction time and of the refractory time. Nodal conduction is improved according to measurement of the alternate Wenckebach; according to studies of the denervated heart in transplanted patients, there is a depressant effect on automatism and conduction at all levels, but the vagolytic effect corrects this activity at Tawara's node. Clinical trials have demonstrated the absence of any deterioration, and in some cases and actual improvement of nodal conduction disorders in response to disopyramide and good safety in the presence of non-major intraventricular conduction problems (such as bundle branch block). In practice, these properties mean that moderate nodal conductive disorders and simple bundle branch block do not constitute an obstacle to the use of disopyramide. In junctional tachycardia, it is particularly indicated for use in tachycardia involving an accessory pathway, but is also effective in intranodal tachycardia due to its twofold action.

Arrhythmias, Cardiac↗
PubMed1992

[Cardiology in general hospitals. A cooperative survey on medical teams, technical means and activity].

A national enquiry carried out in 1990 in the departments of cardiology of general and private non-profit making hospitals established the status of these departments and the evolution of their personnel and equipment since their creation. The enquiry involved two thirds of the cardiology departments of the general hospitals (119/180) and showed that most (66%) were established between 1974 and 1988. Implanted in fairly important cities with catchment areas of 100,000 to 400,000 people, they have an average of 32 beds (range 11 to 100) and 7.25 coronary care beds (range 4 to 19); 347 doctors work full (211) or part time (136) in these departments. These two types of work are allowed in the majority of these units (64/119). Specialist certified cardiologists practice in 62 departments (56%). The usual technical equipment is available in 80% of the units (Doppler echocardiography, exercise stress testing, Holter monitoring, right heart catheterisation). Permanent pacing is performed in 65% of these hospitals, more so in the provinces than in the Paris region. Coronary angiography is only available in 21%, radioisotopic investigations in 15% and coronary angioplasty in 12% of these centres. A prospective study performed in 1990 concerning 110 hospitals recruited 1,030 myocardial infarctions, which enabled the total number of infarcts hospitalised in the coronary care units of the general hospitals to be estimated at about 21,000 (60% of French myocardial infarctions).

Angioplasty↗
PubMed1990

[Topographic diagnosis of Kent's bundles using dynamic vectorcardiography. Correlation with the new electrocardiographic criteria proposed by R. Franck].

The topographic diagnoses of Kent's bundles obtained from vectorcardiograms with maximum preexcitation in 33 patients (dynamic VCH) were compared with those obtained using Franck's new algorithm. Only three cases disagreed, and the three anteroseptal topographies were identified a posteriori. This simple method therefore shows very satisfactory sensitivity (82%) and provides worthwhile orientation for later investigations.

Adult↗
PubMed1988

Sino-atrial dissociation: evidence by intracardiac recordings in man and by microelectrode studies on isolated rabbit atrium.

The electrophysiologic mechanisms of sinus dysfunction have recently been determined by direct recordings of the sinus node electrogram. The association of various degrees of abnormalities in the formation of the impulse within the sinus node and of sinoatrial conduction block, represents the pathophysiological substrate of the mechanism of sinus node dysfunction. The purpose of this work is to present clinical and experimental data supporting the concept of sinus node isolation. In our clinical case, the sinus node was probably intact despite aspects of sinus node dysfunction on the surface ECG. Sinus node electrograms were recorded with a sinoatrial conduction time of 100 ms (normal values in our laboratory: 83 ms +/- 38 ms). Atrial mapping demonstrated that the area depolarized by the sinus node involved a 2 cm2 zone surrounding it. This perisinusal activity could not be recorded on the surface ECG. Both exit and entry blocks in the sinus node were demonstrated. Our experimental data showed a total desynchronization between the electrical activity of the sinus node and that of the atrium under hypoxic conditions. Both types of cases demonstrated that an atrial dysrhythmia was coexisting with regular sinus activity. From these data we concluded that a sinus node free from any pathological involvement could be associated with severe symptoms of sinus node dysfunction on the surface ECG.

Animals↗
PubMed1988

Long-term follow-up of atrioventricular junctional transcatheter electrical ablation.

Complete data concerning long-term results of transcatheter electrical ablation of the atrioventricular junction is not available. At the request of the French Cardiac Arrhythmia Working group we undertook an inquiry in October 1983. All centers potentially able to perform such procedures were asked to report their experience. Eight centers have performed one case or more, over a period of 3 years, for a total of 91 patients. The mean follow-up completed in all patients in April 1986 was 12 +/- 10 months. The procedure was indicated for a supraventricular arrhythmia resistant to a mean of 3.9 +/- 1.3 classes of antiarrhythmic agents. Atrial flutter or fibrillation in 54 (59%) and atrioventricular nodal reentry in 17 (18%) were the most common arrhythmias. A mean of 2.6 +/- 2.3 electrical shocks (range 1-14 shocks) with a stored energy of 130-400 joules was delivered during 1-5 sessions. Complete heart block was obtained in 83 patients and persisted at the time of discharge from the hospital in 46 patients (50.5%). The immediate complication (within 24 hours after the procedure) included ventricular fibrillation successfully converted (one patient) and nonsustained ventricular tachycardia (three patients). Late complications included one death 3 days after the procedure, in a patient in whom sustained ventricular tachycardia was documented, nonsustained ventricular tachycardia in two patients, sepsis in three patients and pericardial effusion in one patient. At the time of the follow-up, there were three additional deaths related to sepsis due to pacemaker pocket infection in one patient and to preexisting congestive heart failure in two patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Long-term efficacy and safety of oral encainide in the treatment of chronic ventricular ectopic activity: relationship to plasma concentrations--a French multicenter trial.

To establish long-term efficacy and safety of encainide, 48 patients with chronic premature ventricular contractions (PVCs) underwent 6 months of therapy with encainide. Twenty-four-hour ambulatory ECGs were obtained at baseline for each daily dosage of 75 mg, 150 mg, and 225 mg of encainide during the in-hospital titration period and at the end of the first and sixth months during the follow-up period. There was a significant reduction in the median hourly total PVC rates from 480.6 at baseline to 2.0 at the end of the titration period with the highest dosage and to 22.1 at the last visit of the chronic dosing period. Nearly total suppression of PVCs was observed in 56% of patients at the end of the titration period and in 30% at the end of the 6-month follow-up period. The most common side effects were vertigo, vision disturbance, and headache. PR, QRS, and QTc intervals showed consistent significant increases from baseline during the various encainide trial periods. Encainide may have worsened ventricular arrhythmia in four patients who received more than 200 mg of encainide daily. Plasma concentrations of encainide and encainide metabolites showed wide interpatient variation, and no relationship was found between antiarrhythmic efficacy and plasma levels of encainide, O-demethyl-encainide, or 3-methoxy-O-demethyl-encainide.

Adolescent↗
PubMed1985

[Anti-arrhythmia effect of long-term encainide in chronic ventricular extrasystole].

The long term efficacy and tolerance of encainide were studied in 48 patients with chronic/ventricular extrasystoles (VES) treated for 6 months. Holter monitoring was performed before treatment and at each dose increment (75 mg/day; 150 mg/day and 225 mg/day) during the first week of titration, and then after 1 month and 6 months of treatment. The dose administered in the long-term study corresponded to the minimum effective dose during the titration phase (the dose which reduced the number of VES/24 hours by at least 75%). The average number of VES/hour decreased significantly from 480.6 before treatment to 2.0 at the end of the study. The frequency of episodes of ventricular tachycardia decreased significantly during treatment. The commonest side effects were vertigo, visual disturbances and headaches. Treatment was interrupted because of side-effects or inefficacy in 6 patients. The surface ECG showed significant lengthening of the PR, QRS and QTc periods and encainide appeared to have aggravated the ventricular arrhythmias of 4 patients receiving 200 mg/day. The plasma concentrations of encainide and its two principal metabolites were measured during the titration phase, at 1 month and after 6 months of treatment. 15.6 per cent of patients were slow and 84.4% of patients were rapid metabolizers. The wide individual variations of plasma concentrations and the absence of correlation between the plasma concentrations of encainide and its metabolites and the antiarrhythmic effect suggest that the compound and its metabolites play a role in the antiarrhythmic effect of the drug.

Adolescent↗
PubMed1979

[Syncope and transient neurologic deficits of undetermined origin. Clinical and electrophysiological correlations].

A consecutive series of 140 patients who presented either with syncope or transient neurological deficit of undertermined cause underwent electrophysiological investigation. The patients were classified in 3 groups: Group I comprising 55 patients having presented "true syncope"; Group II comprising 42 patients with "false vertigo"; and Group III comprising 43 patients in whom a transient neurological deficit had been observed. Globally, the investigations were positive in 58 patients (41,4%). Paroxysmal atrioventricular block was recorded in 21 cases (15%), sinus node dysfunction in 34 cases (2,1%). Permanent pacing was instituted in 57 patients. The correlation between the results of electrophysiological investigation and the clinical symptomatology showed a highly significant difference between Groups I and II where the results were positive in 57% cases, and Groupe III where 93% of the investigations were negative.

Adolescent↗
PubMed1977

[Sinus dysfunction and nodo-hisian conductive disorders. Indication for definitive cardiac stimulation].

A consecutive series of 80 patients has been the object of intracavitary electrophysiological studies, including a study of sinus function and of node/His conduction, before implantation of a definitive cardiac pacemaker. Investigation of the sinus yielded normal or insignificant results in 32 cases. It revealed certain criteria of "major" sinus dysfunction (TRSC 1000 ms; more than compensatory return cycles where there was SAP) in 39 cases, made up of 18/20 in group I (documented evidence of sinus malfunction), 10/14 in group II (sinus bradycardia less than or equal to 55/mn), 9/44 in group III (A-V conduction defects), and 2/2 in group IV (paroxysmal supraventricular tachycardia); criteria of "minor" sinus dysfunction (TRSC between 550 and 1000 ms, TECASA greater than 210 ms) were found in only 9 cases (group I--1; group II--2, group III--6). The association of sinus malfunction with node/His conduction defects was found in 29 cases, the site of the AV block being nodal in 7 cases, intra-His in 2 cases, infra-His in 10 cases, and a combination of nodal and infra-nodal in 10 cases. In 59 cases, the severity of the AV block (40 cases), of the sinus malfunction (17 cases) or of the sinus bradycardia (2 cases) was already obvious, and investigation of the sinus was not critical in determining the indications for a cardiac pacemaker. In 21 cases, however, this investigation was a determining factor, and most especially in 12 cases from group II. Sinus investigation seems to represent, in addition, a valuable indicator for the decision to install a pacemaker in a certain number of litigious cases.

Arrhythmias, Cardiac↗
PubMed1977

[Auricular fibrillation with ventricular tachycardia. Surgical section of a left lateral bundle of Kent].

The authors report the case of a man of 22 years, with no previous cardiac history, in whom a Wolff-Parkinson-White syndrome was discovered during the course of this first episode of atrial fibrillation with a ventricular rate of 300-350/mn; investigation (vecto-cardiogram, intra-cavitory ECG) showed the presence of a short circuit of the Kent type, with a high permeability, and localised in the left lateral position; this was confirmed by pericardial cartography. After the surgical division of the accessory pathway, the electrical phenomenon of pre-excitation disappeared. The current possibilities of operating on cases of a Wolff-Parkinson-White syndrome justify carrying out a scrupulous electrophysiological study of each case, so that any accessory pathway can be precisely localised, and its refractory period determined; thus a pathway of preexcitation localised in the left lateral position, and having a short refractory period leading to a high ventricular rate under atrial fibrillation conditions, constitutes an indication for operation which may be urgent.

Adult↗
PubMed1977

[Effect of a depressant drug on the recovery time of the sinus. Attempt of application to the diagnosis of sinus dysfunctions].

The authors have studied the effect of a depressant drug, 71247 or piprofurol, on the recovery time of the sinoatrial node after rapid electrical stimulation of the atrium (CSRT). 72 patients, divided into three groups, underwent the test: 14 patients with documentary evidence of sinus dysfunction; 48 patients in whom a sinus disorder was suspected, and 10 controls. As a general rule, the sinus recovery time was found to be significantly prolonged in the patients as compared with the controls. The authors have applied this test to the diagnosis of latent sinus dysfunction, categorising three different degress of RESA values: normal (less than or equal to 550 ms), average (between 550 and 1,000 ms), and prolonged (greater than 1,000 ms). In 6 patients from group one and seven from group two, the post-stimulatory pause was normal or average before the test, and prolonged after the injection of 71247; on the other hand the test did not give evidence of any prolongation of the pause in the controls. In this way a dynamic pharmacological test of depression brings and interesting slant on the diagnosis of disorders of the sinus.

Anti-Arrhythmia Agents↗
PubMed1976

[Gap phenomenon and supranormal conduction during intermittent left bundle-branch block].

The mechanism of intermittent bundle branch block, whether spontaneous or as a result of vagal stimulation, can be studied by reference to the known facts of atrial stimulation. Three cases with intermittent left bundle branch block were studied by means of an intracavitary electrode, which allowed the potential of the bundle of His to be measured, and was also used for the extrastimulus method of study. In case 1, in which the block was independent of the cardiac rate, a type 1 "Gap" phenomenon (of nodal origin) was demonstrated; the coupling zone in which the extrastimulus overcame the block was situated in two areas, one being late, and the other earlier in a region where the conduction was normal. In case 2, in which the block was dependent upon the heart rate, the "recovery" of the blocked branch after early coupling of the extrastimulus seemed to be associated with the phenomenon of "supra-normal" conduction. In case 3, in which the block was again dependent upon heart rate, the two phenomena of "Gap" and "suppranormality" seemed to act successively when the coupling of the extrastimulus is decreased progressively. These observations allow us to distinguish two types of intermittent left bundle branch block; one, which is not related to heart rate, is characterised by a prolonged refractory period of the left bundle branch, which becomes progressively shorter as the heart rate increases; the other, which is dependent upon tachycardia, is characterised on the one hand by an increased left bundle branch refractory period which does not shorten as the heart rate increases, and on the other by the phenomenon of supranormal conduction.

Bundle of His↗
PubMed1976

[Significance of pharmacodynamics tests in the study of sinus node function].

The evaluation of sinus function in man rests upon atrial stimulation techniques (rapid atrial stimulation, premature atrial stimulation); in a certain number of cases the results are inconclusive. There are various pharmaco-dynamic tests which can be used in such cases, the aim being to stimulate or depress the function of the sinus, or alternatively to modify the action of the extrinsic nerve supply. A study was carried out of sinus function in a series of 120 patients; pharmaco-dynamic tests were carried out using atropine in 43 cases, glucagon in 9 cases, isoproterinol in 9 cases, ajmaline in 9 cases, and piprofurol in 10 cases. The authors conclude from this study that it is worth adding the atropine test (which suppresses vagal tone), the glucagon test (which causes direct and limited stimulation of the sinus) and a test with an agent with a depressant action on the sinus coupled with a sympathetic-blocking action (such as piprofurol) to the conventional atrial stimulation tests.

Ajmaline↗
PubMed1975

[Study of sinus node function. Preliminary results].

Direct exploration of the sinus node remains experimental. Indirect techniques have been put forward to assess the sinus function in man: high frequency atrial pacing; premature atrial pacing; pharmacodynamic tests using atropin and isoproterenol injection. 68 patients were so explored: in 10 of them were ECG signs suggestive of "sinus disease" or "atrium disease" (group I); 14 subjects had only a sinus bradycardia with a rate of 55/mn or below (group II); in 16 cases, the ECG tracing was normal, but there was the notion of paroxysmal tachycardia or various disturbances (group IIIa); finally, in 28 cases the ECG demonstrated atrio-ventricular or inter-ventricular conduction disturbances (group IIIb). The preliminary results reported here should be interpreted carefully; nevertheless, correlation of the data obtained by the various techniques used, seems to be able to allow a correct assessment of sinus automatism, and of sino-atrial conduction.

Adult↗