[Syncopes and brief spells of feeling faint: value of Holter monitoring?]. / Syncopes et malaises brefs: utilité du Holter?

A retrospective study of Holter monitoring of 250 patients referred for syncope and short spells of dizziness suspected of being cardiac in origin was undertaken to assess the diagnostic value of the investigation. The arrhythmias observed were classified in 3 groups, significant, suspect and physiological with respect to their true or potential severity and to previously reported results of Holter monitoring in healthy subjects. The following arrhythmias were classified as significant: supraventricular tachycardia with a ventricular rate greater than or equal to 200 bpm; sustained ventricular tachycardia (greater than 30 s and greater than or equal to 150 bpm), bradycardia (less than bpm), sinus arrest (waking greater than 2 s sleeping greater than or equal to 6 s), complete AV block with wide QRS complexes and pacemaker dysfunction. The following arrhythmias were classified as suspect: paroxysmal supraventricular tachycardia with a ventricular rate less than 200 bpm, salvos of ventricular tachycardia (120 greater than 150 bpm); R/T phenomenon and doublets (greater than or equal to 50/24 hours), sinus arrest of 2 to 6 seconds during sleep, complete AV block with narrow QRS complexes or second degree Mobitz II block. This classification led to a diagnosis of certitude in 20 patients (5.7%) with significant arrhythmias concomitant with syncope or a minor form in only 5 cases, supraventricular tachycardia (4 cases), ventricular tachycardia (4 cases), AV block (5 cases), sinus arrest (3 cases), pacemaker dysfunction (4 cases); a diagnosis of presumption in 74 patients (21.1%) with suspect arrhythmias in the absence of syncope or minor equivalent.(ABSTRACT TRUNCATED AT 250 WORDS)

[Genesis of auricular fibrillation in the Wolff-Parkinson-White syndrome]. / Genèse de la fibrillation auriculaires dans le syndrome de Wolff-Parkinson-White.

Atrial fibrillation seems to be more common in the absence of associated cardiac disease in the Wolff-Parkinson-White syndrome (WPW) than in subjects of the same age without this condition. The aim of this study was to analyse the electrophysiological mechanism of AF and to establish its relationship to the accessory pathway. The series comprises 14 out of 51 patients with WPW undergoing classical endocavitary investigation associating the recording of cardiac potentials from the His bundle, right atrium (RA), left atrium (LA) via the coronary sinus and atrial and ventricular stimulation techniques. Three mechanisms of inducing AF were analysed : - AF triggered by RA stimulation : either by a premature extra stimulus or overdrive atrial pacing. In all cases, the accessory pathway was right sides. - AF triggered by overdrive ventricular pacing : three cases were left sided accessory pathways in which atrial desynchronisation was localised in the LA. - Conversion of reciprocating tachycardia to AF (9 cases). In 2 cases, this was preceded by a progressive acceleration of the heart rate. Of 3 left sided accessory pathways, the atrial desynchronisation was located in the LA in 2 cases. The factors which facilitate AF in THE WPW syndrome are discussed : increased atrial vulnerability, the role of the rapid return of ventricular excitation to the atria through the accessory pathway. Our observations suggest that the accessory pathway plays a role in the genesis of AF in the WPW syndrome.

[Electrophysiological effects of anti-arrhythmia agents in man. Attempt at classification]. / Effets électrophysiologiques des agents antiarythmiaques chez l'homme. Tentative de classification.

The electrophysiological effects of anti-arrhythmic drugs in man may be classified in three groups: -- Group I: comprising drugs whose characteristic action is on the AV node (beta blockers, verapamil, digitalis) The nodal conduction time (A-H interval) and refractory periods are increased. -- Group II: comprising drugs acting on the His-Purkinje system, the AV nodal conduction staying unchanged. This group has two sub-groups. Sub-group A: these drugs delay the His-Prukinje conduction (increased H-V interval). Examples are quinidine, procainamide, disopyramide, ajmaline, chloro-acetyl-ajmaline. In addition these drugs usually increase the atrial refractory periods and those of accessory pathways. Sub-group B: the His-Purkinje conduction is unchanged but the refractory periods are modified: lengthened (bretylium tosylate) or shortened (diphenylhydantoin, lignocaine, mexiletine). -- Group III: which includes amiodarone and aprindine whose effects are mixed: on the one hand AV nodal depression, and on the other, alteration of the His-Purkinje conduction manifested by an increased H-V internal (aprindine) or refractory periods (amiodarone). These preparations also increase the refractory periods of accessory AV pathways and amiodarone increase the refractory periods of the atria. This type of classification could help towards a more rational clinical approach to the use of anti-arrhythmic drugs.

[Electrophysiological study on mexiletine in man with reference to dose-response relation]. / Etude électrophysiologique de la méxilétine chez l'homme avec référence à la relation dose-effet.

The electrophysiological properties of Mexiletine were investigated by endocavitary His Bundle recording and programmed electrical stimulation of the heart in 30 patients. Differing dosage (2, 2.7 and 3.4 mg/kg) were given intravenously in 3 groups of 10 patients. The effects on the length of the sinus cycle, conduction intervals and cardiac refractory periods were observed and the following results obtained : 1. Sinus rhythm increased at all dosages but this effect was much more pronounced with 3.4 mg/kg dosage (--12.8% +/- 2.81% : : % shortening of sinus cycle with respect to the basal cycle +/- SD, p less than 0.005); 2. Atrioventricular nodal conduction time (A-H interval) decreased, the effect being more marked with the larger dose regimes; 3.His-Pirkinje conduction time (H-V interval) unaltered except in 3 cases where it increased by 5 ms after injection of 2.7 mg/kg; 4. Relative refractory period of His-Parkinje system shortened, this effect also being more pronounced with the larger doses ( --3.75 +/- 0.25% :2.7 mg/kg, p less than 0,001; -- 7 +/- 1.46% 3.4 mg/kg, p less than 0.005). In conclusion, the changes observed in the His-Purkinje system after mexiletine were similar to those of Lignocaine and Diphenylhydantoin. The drug also appears to have a marked vagal inhibitory effect as shown by the acceleration of the sinus rhythm and reduced atrioventricular conduction times.

[Electrophysiological effects of chloroacetyl ajmaline in Wolff-Parkinson-White syndrome]. / Etude des effets électrophysiologiques de la chloro-acétyl-ajmaline dans le syndrome de Wolff-Parkinson-White.

The electrophysiological effects of chloro-acetyl-ajmaline in the Wolff-Parkinson-White syndrome have been studied in 7 patients after an intravenous dose of 1.5 mg/kg of the drug. Preexcitation was abolished in 3 cases, while 3 other subjects showed a slight increase in effective refractory period of the abnormal route of excitation (a mean of 13 ms). The possibility of bringing about a reciprocal rhythm was removed in one case out of two. During tachycardia, chloro-acetyl-ajmaline produced significant lengthening of the ventriculo-atrial conduction time (p less than 0.05). These results show the usefulness of chloro-acetyl-ajmaline in the control of the arrhythmias associated with the Wolff-Parkinson-White syndrome.

Re-entry via Mahaim fibres as a possible basis for tachycardia.

Paroxysmal tachycardia with widened QRS complexes was recorded in a 21-year-old man. In sinus rhythm there was no evidence of pre-excitation. His bundle studies revealed an abnormally short HV interval of 30 ms. Premature atrial stimuli produced an increased PR interval. At short coupling intervals the His bundle activity became incorporated within the QRS complex. Concurrently, a left bundle-branch block pattern appeared identical to that seen during tachycardia. Closely coupled ventricular extrastimuli initiated a tachycardia identical to the initial episode. A re-entry mechanism via anterograde Mahaim fibres and retrograde His bundle -AV node pathway is postulated.

[Action of chloro-acetyl-ajmaline on the electrical properties of the human heart]. / Action de la chloro-acétyl-ajmaline sur les propriétés électriques du coeur humain.

The electrophysiological changes caused by the intra-atrial injection of 1.5 mg/kg of chloro-acetyl-ajmaline were studied in 23 patients by recording the His potential and by the stimulustest method. The length of the basal cycle being kept constant by atrial stimulation, measurements were made before and after the injection, on the one hand of the -VA node conduction time (A-H interval) and the infra-His conduction time (H-V interval) and on the other of the refractory periods of the right auricle, A-V node, and the His-Purkinje system. The effective refarctory period of the right ventricle was determined under pace-making of the ventricle. Finally, the variability of the sinus rate was measured. The results were as follows: 1. The sinus cycle was significantly shortened after administration of the drug (p 0.001); 2. The conduction time and refractory periods of the A-V node were not influenced by this substance; 3. The H-V interval was increased in 20 patients by an average of 11 ms (p less than 0.001). The relative refractory period of the His-Purkinje system was reduced in 4 cases out of 7 by 21 ms (p less than 0.05); the effective refractory period in one case showed a reduction of more than 45 ms. These findings will serve as a base line for assessing the anti-arrhythmic action of chloro-acetyl-ajmaline.