[The supernormal phase of cardiac conduction. An experimental study in the dog]. / La phase supernormale de conduction cardiaque. Etude expérimentale chez le chien.

The existence of a cardiac phase of supernormal excitability is not fully proved at the cellular level. As far as the whole heart is concerned, the phenomenon of supernormal conduction is still under discussion. Intracardiac conduction has been studied both in the right atrium (13 dogs) and in the right ventricle (14 dogs) by programmed stimulation (extrastimulus technique), while monophasic action potential (MAP) was recorded. The phenomenon of supernormal conduction was noted in 67.7% of cases, starting at 59.0% and ending at 78.0% of the basic cycle, hence occuring shortly after phase 3 of the MAP. In the ventricle, a phase of supernormal conduction was present in 52.4% of cases, starting at 66.1% and ending at 77.9% of the basic cycle. After ajmaline, the supernormal conduction was moved towards the end of the cycle. The mechanism of supernormal conduction, and its implications in the study of arrhythmias are discussed.

[Analysis of the electrophysiological effects of amiodarone using simultaneous recordings of monophasic and bundle-of-his action potentials]. / Analyse des effets électrophysiologiques de l'amiodarone par l'enregistrement simultané des potentiels d'action monophasiques et du faisceau de His

The effects of amiodarone given by rapid intravenous injection at a dosage of 10 mg/kg have been studied in the dog. The peak activity is found between the fifth and the tenth minute. The rate of discharge of the sinus is lowered by 36%. At the atrial level, the duration of the monophasic action potential (MAP) is increased by 9% and its dv/dt is lowered slightly, the total refractory period is increased by 22%, the effective refractory period is increased by 27%, the functional refractory period is increased by 19%, the ratio of the length of the effective period/duration of the MAP becomes slightly greater than unity, conduction facilitation disappears, and the period of slow conduction increases. In the A/V node the AH interval increases by 44% under normal rhythm, while atrial stimulation at 200/min. results in conversion to total AV block in more than half of the cases. The potential of the bundle of His and the HV interval are not altered. At ventricular level the duration of the monophasic action potential increases by 25%, its dv/dt decreases slightly, the total refractory period is increased by 8%, and the effective refractory period is increased by 14%.

[Effects of Bunaphtine on right atrial and ventricular monophasic action potentials in man. Preliminary note (author's transl)]. / L'effetto della Bunaftine sui potenziali d'azione monofasici del miocardio atriale e ventricolare destro nell'uomo. Nota preliminare

Effects of Bunaphtine on right atrial and ventricular monophasic action potentials were investigated in 6 patients using the technique of endocavitary recording with a suction electrode. The authors found that the drug, given intravenously in the usual therapeutic dosages, increases the total duration of MAP both atrial and ventricular, together with quite a proportional ERP prolongation. At ventricular level MAP's increase in correlated to a prevailing and strong increase of phase 3. However, the variations of the MAP's amplitude, its O dv/dt phase and the cardiac specific conduction's alterations (noted only at higher dosages) have been inconstant and poor on the whole. On the basis of these results, the mechanism of the action of the drug is discussed.

[A study of the mechanism of the action of Bunaphtine recording the myocardial monophasic action potentials in man. Conclusive report (author's transl)]. / Studio sul meccanismo d'azione della bunaftine mediante registrazione dei potenziali d'azione monofasici del miocardio nell'uomo. Nota conclusiva

In this paper the authors conclude their study of the mechanism of the action of Bunaphtine. Both atrial and ventricular MAP were recorded by a suction electrode in 13 patients before and after Bunaphtine (1.5-2 and 2.5 mg/Kg i.v.). With the lower dosages, the drug acts specifically on repolarization: it greatly increases the duration of MAP, together with a proportional ERP prolongation; the ERP/MAP ratio is not changed. With the higher dosages, there is a greater effect on the depolarization velocity (decrease of the O dv/dt phase of MAP) and on the conduction, this last being less evident. At the atrial level there is a conspicous ERP prolongation, with a remarkable increase of ERP/MAP ratio. There is full agreement between these results and those obtained experimentally on the dog and in vitro. Bunaphtine has therefore unquestionable antiarrhythmic properties and it can have a double action mechanism; with higher dosages its action-quinidine-like-is predominant at the atrial level.

[1st and 2d degree atrio-ventricular blocks caused by disorders of intra-auricular conduction]. / Blocs auriculo-ventriculaires du premier et deuxième degré par trouble de conduction intra-auriculaire

In three cases collected among subjects with atrial anatomical lesions (two cases of "sinus disease" with partial atrial paralysis and one traumatic lesion of the right atrium in a WPW syndrome), atrial pacing demonstrated a considerable increase of the interval between stimulus and atrial response or intra-atrial Luciani-Wenckebach periods, for slightly increased pacing rates. Conduction changes into the right atrium explain apparently paradoxical variations of the degree of pre-excitation under pacing, in the case of Wolff-Parkinson-White syndrome.

[Abnormalities of the renal arteries in arterial hypertension in adults]. / Les anomalies des artères rénales dans l'hypertension artérielle de l'adulte

Results of arterial surveys on the basis of renal arteriograms in 100 consecutive unselected and hospitalized cases of lone arterial hypertension of the adult. Abnormal polar arteries with direct branching from the aorta were observed in 52 cases, combined with a stenosing or parnechymatous arterial anomaly in 7, quite isolated in 45 cases (61.8 percent of 73 cases). The very great incidence of abnormal polar arteries is a fundamental epidemiological datum of lone arterial hypertension of the adult.

[Study of monophasic action potentials of the myocardium by endocavitary approach. Methodology]. / Etude des potentiels daction monophasiques du myocarde par voie endocavitaire. Méthodologie

The suction electrode makes it possible to record the monophasic action potentials (MAP) of the heart in situ. The technical characteristics of the tripolar electrode which we use are described. The O phase of the MAP is more prolonged than that of the intracellular action potential, but makes it possible to demonstrate the time of arrival of the activation wave in front of the exploring electrode. The phase 1-2 and the phase 3 have their characteristic contour in the right atrium and ventricle. The duration of repolarization makes it possible to assess the refractory period of different parts of the atrial and ventricular myocardium. The relatively simple and harmless method of recording of the monophasic action potentials by the endocardial route, both in the animal and in man, widens our investigation field of electrophysiology applied to the study of arrhythmias, of the repolarization disturbances and of the drug influences on the cell activity.