[Atrioventricular block and localized reentry into the trunk of the bundle of His]. / Bloc auriculo-Ventriculaire et ré-entrée localisés au tronc du faisceau de His

In a patient with an AV block and a resulting variable rhythm, the coupled ventricular complexes with dissociated P waves on the standard tracing suggested a reentry into the atrioventricular area. Intracavitary investigation revealed: 1) a complete bidirectional AV block in the upper portion of the bundle of His (there being a proximal His potential with a fixed relationship with the dissociated atrial activity shown on the ventriculogram); 2) escape of the bundle of His low down, or of the beginnings of the branches, preceded by a distal Hispotential; 3) re-entry echos preceded by a third variety of potential in the bundle of His.

[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.

[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%.

[Congenital defects of the aortic system]. / Artériopathies congénitales du système aortique.

The authors give a basic embriological classification of congenital arterial defects. Congenital abnormalities of the arterial system (arising in an embryo of 12 to 30 mm) affect the primary segments, and comprise excessive involution of the antibrachial trunk, of the popliteal artery, of the tibio-peroneal trunk and peroneal artery, abnormal or persistence of the interosseus artery, of the artery of sciatic nerve, and of the peroneal artery, a high axillary origin of the radial or antecubital artery, renal polar arteries arising directly from the aorta, and agenesis of the palmar or plantar arches. In the second generation arteries, they comprise agenesis or hypogenesis of the radial, antecubital or tibial arteries, and gross hypogenesis of the trunk of the renal artery with an immature kidney. Arrested or mal-development in the foetus can give rise to coarctation and stenosis of the thoracic aorta and large vessels, to segmental agenesis with huge collaterals, to imperforate osita, especially in the mesenteric arteries, to sudden variations in diameter of the renal arteries, and to parietal dyplasia and aneurysms in vessels in the residual undifferentiated mesenchymatous tissue, and diffuse dilatation or stenosis. The authors give their experience for a cardiological clinic, adding arterial hypertension and arterioparenchymatous dysplasia of the kidneys, Raynaud's, Takayasbu's and Burger's disease, and intermittent claudication of the lower limbs; they indicate the areas which they are currently studying.