[Mode of action of purinergic derivatives of adenine on auriculo-ventricular conduction. Experimental study in dogs]. / Mode d'action des substances purinergiques dérivées de l'adénine sur la conduction auriculo-ventriculaire. Etude expérimentale chez le chien.

The effects of three purine derivatives of adenine, adenosine triphosphate (Striadyne), purified adenosine triphosphate and adenosine, on conduction tissue, were studied in closed chest dogs with endocavitary recording catheters. The dogs were anaesthetised with pentobarbital and ventilated, then three bipolar catheters were positioned to allow atrial pacing and recordings of atrial and His bundle potentials. The purines studied were administered by rapid bolus intravenous injection. The dosage was identical based on a predetermined dose-response curve (dose of 2 mg/kg). The study of the effects on atrioventricular conduction was carried out before and after administration of antagonists: atropine, 0.08 mg/kg and aminophylline, 10 mg/kg. Twelve dogs were studied for each purine: 6 with initial premedication with atropine and then aminophylline, and 6 with the inverse sequence. Lengthening of AV conduction was due exclusively to nodal depression. No variation in the HV interval was observed (HV = 35 +/- 4 ms). Lengthening of AH interval was observed very soon after injection of the drugs (5 to 10 seconds) with a peak effect between 20 and 40 seconds. Reversion to the initial value always occurred in under 2 minutes. In the model studied, Striadyne and purified adenosine triphosphate were much more powerful than adenosine, both in intensity and duration; high degree AV block was obtained in 10 out of 12 cases with Striadyne and in 8 out of 12 cases with purified adenosine triphosphate, but in only 2 out of 12 cases with adenosine. The use of specific antagonists demonstrated the different modes of action of the three purines.(ABSTRACT TRUNCATED AT 250 WORDS)

[Treatment by endocavitary fulguration of recurrent ventricular tachycardia caused by right ventricular dysplasia]. / Traitement par électrofulguration endocavitaire d'une tachycardie ventriculaire récidivante par dysplasie ventriculaire droite.

A 27 year old man had recurrent ventricular tachycardia since the age of 16. Different antiarrhythmic drugs were used successively without success (mexiletine, amiodarone, acebutolol, propafenone, sotalol). The diagnosis of VT due to arrhythmogenic right ventricular dysplasia was suggested by the morphology of the tachycardia (left-sided delay), surface ECG appearances (right bundle branch block and potential after the QRS in right precordial leads) and the presence of delayed potentials on right ventricular endocavitary recordings. However, there were no obvious RV changes on echo or angiographic examination. The arrhythmogenic zone was localised in the postero-basal zone of the RV using three electrophysiological criteria: the recording of delayed systolic potential in sinus rhythm which overlapped into diastole during tachycardia, mapping of ventricular depolarisation during VT and results of RV "pacemapping" reproducing the appearances of the spontaneous tachycardia. VT was reproducible on stress testing (non-sustained VT at the beginning of the recovery phase) and on endocavitary stimulation. One 250 joule electric discharge between the endocavitary electrodes and a large dorsal surface electrode prevented any further attacks without antiarrhythmic therapy (follow-up: one year). Control electrophysiological investigation after 4 months showed another potentially arrhythmogenic zone which is quiescent at present.

[Study of flecainide in the treatment of ventricular arrhythmia]. / Etude de la flécaïnide dans le traitement des arythmies ventriculaires.

The effect of flécaïnide (new class I antiarrhythmic) on ventricular rhythm troubles was studied in 24 patients using Holter's method. The following results were obtained. For ventricular tachycardia, two cases of suppression, three cases of distinct reduction in the number and duration of attack and one failure were recorded. For single ventricular extrasystoles, doublets and triplets, nine very good results (80 to 100 per cent reduction of arrhythmia) and four 50 to 80 per cent reductions in ventricular prematurity were obtained. Results were uncertain in two patients as the disappearance of extra-systoles was not followed by relapse after termination of treatment. There were three failures. A twenty-fifth patient was treated with flécaïnide IV followed by oral administration with uncertain results. Undesirable effects are infrequent and are often characterized by sinusal bradycardia. Blurred vision and paraesthesia were encountered. The principal biological parameters remained unchanged.