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Biomedical subjects

P Puech

Publications and source records attributed to P Puech.

At least 73 records · Page 4Linked to original sources
PubMed1978

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.

Action Potentials↗
PubMed1978

[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.

Action Potentials↗
PubMed1978

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.

Action Potentials↗
PubMed1977

[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.

Electrocardiography↗
PubMed1977

[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.

Child↗
PubMed1976

Intra-His bundle blocks (102 cases).

Some intra-His bundle (intra-HB) blocks escape the routine exploration of the His bundle and are confused with supra- or infrahisian blocks. We believe that a more accurate exploration (recording of His bundle activity successively at the proximal end and the distal end of the His bundle, dynamic tests and drug injection) is needed to detect some concealed cases, mostly paroxysmal intra-HB blocks. In this series of 102 cases of intra-HB blocks, 20% had no criteria of AV block on the surface electrocardiogram, and only 4% had an intact conduction pattern (normal PR interval and normal QRS complexes.) A first degree intra-HB block was found in 35% (15 cases with a normal PR interval), a second degree intra-HB block in 23% and a thired degree intra-HB block in 42% of the cases (unidirectional in 4 cases). Of the 43% having an isolated intra-HB block, most were elderly women with a chronic third degree AV block.

Adolescent↗
PubMed1976

[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%.

Action Potentials↗
PubMed1976

[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.

Bundle of His↗
PubMed1976

[Atrioventricular block and localized reentry into the trunk of the bundle of 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.

Bundle of His↗