Biomedical subjects
P Puech
Publications and source records attributed to P Puech.
[Automatic activity of the pre-excitation pathways].
The possibility of preexcitation pathways exhibiting automatic activity was demonstrated in 3 cases: in two cases electrophysiological studies supported this diagnosis which was confirmed in the third case by histological examination of the preexcitation pathway. During sinus node dysfunction, spontaneous or induced (by rapid right atrial pacing or by a reciprocating tachycardia), the substitute rhythm arose from the Kent Bundle either transiently or for a longer period: rhythms arising from the Kent Bundle can only be diagnosed after eliminating the possibility of an atrioventricular junctional rhythm conducted to the ventricles by Mahaïm fibres.
[1st degree and 2nd degree blocks (Wenckebach type) during right ventricular stimulation in the course of Prinzmetal's angina].
Right axial deviation and delay between stimulation and ventricular response was observed during pacing of the apex of the right ventricle in Prinzmetal angina. The degree of deformation of the ventricular complex and the length of this delay appear to be related to the severity of the anginan, the length of the preceding diastolic period and the amplitude of stimulation. This observation demonstrates the presence of conduction defects at the heart of ischaemic myocardium and may explain the failure of prophylactic pacing in Prinzmetal angina complicated by paroxysmal atrioventricular block.
[Improvement and normalisation of the QRS complex by stimulation of the bundle of His in complete left branch block].
The asynchronism of ventricular activation resulting from a major degree of left bundle branch block (QRS greater than or equal to 0.12 s) may be suppressed by stimulation of the distal portion of the His Bundle, whether the block be intermittent (3 cases) or permanent (17 cases). The selective stimulation of the His Bundle normalises ventricular depolarisation whilst non-selective stimulation narrows the QRS complex by the fusion of the activation wave fronts from the His Bundle and the interventricular septum. The reestablishment of synchronous ventricular conduction by His Bundle stimulation is generally interpreted as a sign of longitudinal dissociation in the proximal portion of the His Bundle. This results does not, however, exclude the possibility of a very localised lesion at the origin of the left bundle, responsible for a conduction delay, and suppressed by stimulation carried out close to the zone of block (summation effect, electrotonic influence).
[Spontaneous blocks by intra-atrial conduction disorders of reciprocating atrioventricular rates using a Kent's bundle].
Paroxysmal tachycardia in Type A Wolff-Parkinson-White syndrome was due to a reciprocating rhythm involving a left lateral Kent Bundle in the retrograde direction. Spontaneous interruption of the reentry resulted not from block in the normal or accessory atrioventricular pathways but from an intraatrial conduction defect: delay in conduction between the left and right atria on intraatrial reentry terminated the tachycardia.
[Abnormal communications between coronary arteris and peripheral branches of pulmonary arteries. About two cases (author's transl)].
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Indirect recording of left atrial activation in the main pulmonary trunk.
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[Isolated electrical alternation of the T wave. Experimental study].
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Endocardial and His bundle electrocardiograms.
Endocardial electrocardiograms permit the analysis of auricular depolarization and contribute to the study of ventricular activation. Direct recording of auriculograms from the right atrium and indirect recording of the left auriculograms through the coronary sinus and pulmonary artery, show the different auricular activation pathways in common atrial flutter, atrial tachycardia and in case of retrograde atrial depolarization (via the AV node, septal or parietal accessory pathway). His bundle electrograms obtained via the femoral vein or, less easy, via the brachial vein, has introduced an essential mark in the analysis of intracardiac activation enabling us to precisely locate lesions of the AV conduction system, making easier differential diagnosis between aberrant ventricular conduction and ventricular ectopic rhythms and contributing to the study of ventricular preexcitation. Endocavitary stimulation at increasing rate and by the single extrastimulus technique is the complement of intracardiac electrocardiography in evaluating sinus node function, conduction times and refractory periods at different levels, electrophysiological properties of accessory pathways and studies of the antiarrhythmic drugs. Programmed stimulation allows the recognition of reentry as the mechanism of many tachyarrhythmias. The recording of monophasic action potential by the suction--electrode technique is another step in the intracavitary electrophysiological investigation.
[The heart and digitalis poisoning].
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[The supernormal phase of cardiac conduction. An experimental study in the dog].
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.
The dependence of T wave alternans on diastolic resting period duration.
The dependence of T-wave alternans on diastolic resting period duration as well as on regional differences in monophasic action potential duration was studied in the in situ dog heart. T-wave alternans was elicited when diastolic resting period shortened to values less than 41 +/- 6% of the cardiac cycle. This could be attained either by increasing the driving rate, or lengthening action potential duration by inducing hypocalcemia. During T-wave alternans, monophasic action potentials recorded from anterior and posterior left ventricular surface showed an alternation in duration; the degree in alternation in both regions differed and related to T-wave polarity.
[Negative retrograde P wave in D1, sign of left postero-lateral Kent bundle].
A negative P wave in D1 with a mean atrial vector which is horizontal or descending in the frontal plane, occurring during paroxysmal tachycardial due to reciprocal rhythm or after ventricular stimulation suggests atrial depolarisation which starts in the left auricle at some distance from the A-V node and near the pulmonary veins. In the absence of an external anterograde ventricular pre-excitation, such P waves may indicate the presence of a hidden bundle of Kent posterolaterally on the left, allowing retrograde conduction during the tachycardia by a reciprocal rhythm.
[Corrected transposition of the great vessels and preexcitation syndrome (apropos of 2 cases)].
Two cases with treated transposition of the great vessels and incompetence of the left atrioventricular valve showed a type B preexcitation syndrome. In one case, this consisted of a typical W.P.W. syndrome in which the second PR interval was not shortened, but rather consisted of a delta wave and a widened QRS complex. Post mortem examination showed an abnormal connection between the bundle of His and the ventricular septum, and a low insertion of the inverted tricuspid valve. The published cases of W.P.W. syndrome in cases with treated transposition are reviewed, and the mechanism of preexciation discussed in the light of the anatomical peculiarities of the malformation and of the abnormalities which are a feature of Ebstein's syndrome.
[Electrophysiological cardiac properties of fenoxedil. An experimental study on dogs (author's transl)].
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[Analysis of the electrophysiological effects of amiodarone using simultaneous recordings of monophasic and bundle-of-his action potentials].
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%.
[Right branch of the bundle of His. From morphology to its function].
A histological study of serial sections of 71 right branches of the bundle of His has enabled us to confirm the classical findings, but also lay emphasis on certain facts which are not so well known: --the presence or early collateral branches; --the concept of a septal nerve ending; --variations in its course associated with abnormalities in the relationship of the conus with the inferior part of the septum. Certain embryological and functional implications of these facts are noted.