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Biomedical subjects

G Lascault

Publications and source records attributed to G Lascault.

At least 73 records · Page 4Linked to original sources
PubMed1987

[Left ventricular insufficiency in chronic obstructive bronchopneumopathies. A cause to look for: dilated cardiomyopathy].

Dilated cardiomyopathy was observed in 2 patients with chronic obstructive lung disease. This association raises first a diagnostic problem: the low specificity of clinical, radiographic and electrocardiographic signs makes it difficult to diagnose a left ventricular failure in such patients. Echocardiography is useful, but right and left heart catheterization and coronary arteriography are needed to establish the diagnosis of dilated cardiomyopathy and exclude other causes of left cardiac failure. The cause-effect relationship between the 2 diseases is not easy to evaluate. It is studied here in the light of the different mechanisms suggested to explain the repercussions function and notably the interactions between ventilation and right and left ventricular function. However, the association of the 2 diseases seems to be fortuitous. Their reciprocal repercussions, notably in the field of haemodynamics, are unquestionable and make the overall prognosis worse.

Aged↗
PubMed1987

[Factors in sudden and non-sudden death after myocardial infarction].

Attempts at preventing total and sudden cardiac death after myocardial infarction can only succeed if its mechanisms and its contributing of determinant factors are known. It is now well established that sudden deaths account for one-half of mortality cases and that in the vast majority of cases these deaths are due to malignant ventricular arrhythmia. Several sudden death risk factors have been identified, including ventricular dysrhythmias, left ventricular dysfunction and myocardial ischaemia. A number of therapeutic trials on the prevention of post-infarction death have been conducted, but so far only beta-blockers have proved effective in reducing the incidence of total and sudden cardiac death. It is permissible to think, however, that other, discerningly selected treatments might also be effective.

Adrenergic beta-Antagonists↗
PubMed1987

[Cellular effects of electric shock. Definitions, physical principles, cellular electrophysiology and morphological analysis of the shocked areas].

In this experimental study the electrophysiological changes induced by electric discharges such as used clinically in some arrhythmias refractory to the usual treatments were investigated. With energies comprised between 2 and 80 joules profound modifications of the electrophysiological properties of muscle cells and conduction were observed. These modifications included loss of resting potential, inactivation of the fast sodium flux, increase in refractory periods of conduction and disorders of conduction through the shocked areas with, at most, complete block sometimes reversible when low-energy currents were used. With the same amounts of energy these effects were maximal when the current traversed tissues positioned between the electrodes and decreased in all other cases. Usually, with currents of 10 joules or more all electric activity ceased in a radius of about one centimetre around the shocked area.

Animals↗
PubMed1987

[Cellular electrophysiological effects of fulguration by low energy shock].

In spite of the increasing use of catheter ablation in the treatment of refractory ventricular and supraventricular arrhythmias, little information is available on the basic electrophysiological effects of the treatment. Although high-energy shocks are still usually delivered, the current trend is toward lower energies. We studied the electrophysiological effects of non-deflagrating anodic shocks of 2 joules on preparations of sheep ventricular myocardium and Purkinje's fibers. The shocks were delivered by a standard defibrillator between a small-area catheter electrode and a wide-area inert electrode. Action potentials were recorded by the standard microelectrode technique. After the shocks were delivered, the Purkinje's cells that were 5 mm distant from the shocked area on either side were depolarized in the -30 to -40 mV zone, but they progressively reverted to an almost normal resting potential. Recovery was bi-exponential, with time constants of about 1 min and 10 min respectively. Similarly, the conduction block induced by the electric shock in 100% of the cases was reversible in 50%. It must be noted that at the time of conduction recovery the pattern observed was that of electrotonic conduction where the distal action potential conducted was preceded by a pre-potential. This pattern always regressed progressively, with gradual disappearance of the pre-potential in the distal cells, suggesting that the unexcitable area had vanished or become smaller. Although a normal 1/1 conduction and normal action potentials returned in the cells that were 5 mm distant from the shocked area, recordings performed at a distance of 1 to 4 mm from that area disclosed alterations of action potentials that were usually irreversible.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1987

[Echocardiographic diagnosis of plurivalvular prolapse. Apropos of a case].

Sonocardiography, especially bi-dimensional, currently represents an examination of choice in the detection of valvular prolapses. The authors report one case of a triple aorto-mitral-tricuspid valvular prolapse, diagnosed with the ultrasound technique. In light of this report and the data from the literature, the frequency and the distribution of valvular affections are discussed. The technical difficulties of recording and interpreting sonographic images responsible for false positive or false negative diagnostic errors are also studied.

Adult↗
PubMed1986

[Detection by contrast ultrasonography of patent foramen ovale before neurosurgery].

Air embolism may occur during neurosurgery if performed in the seated position. Paradoxical systemic air embolism represents a potentially severe complication in case of patent foramen ovale. Contrast echocardiography detected such a malformation in 10/100 patients, which contra-indicated the sitting position in these 10 patients. No episode of paradoxical air embolism was observed in the 90 remaining patients, although 16 cases of pulmonary air embolism were detected during surgery.

Adult↗
PubMed1986

[A new technic for recording cardiac action potentials. Laser spectrometry].

The new technique described rests on analysis of the fluorescence emitted by a potential-sensitive dye after excitation by a laser light of suitable wavelength. This technique, which requires no physical contact with tissues, should also be applied to the study of surface activation, using more potent pulsed laser rays and video methods.

Action Potentials↗
PubMed1986

Left coronary artery aneurysm and anteroseptal acute myocardial infarction following blunt chest trauma.

After a suicide attempt (fall from the ninth floor) a 28-year-old man presented with a blunt chest trauma. Electrocardiographic and enzymatic changes were characteristic of an acute anteroseptal myocardial infarction. A thallium myocardial scan showed decreased uptake of thallium over the septal area. Coronary angiography performed 6 weeks after the injury demonstrated aneurysmal dilatation of the left anterior descending artery which was patent, intramyocardial haemorrhage in the septum, and septal akinesia. The other left and right coronary arteries were normal. The patient remained asymptomatic 8 months later under medical treatment.

Adult↗
PubMed1986

[Coronary stenosis after radiotherapy. Clinical study of 5 cases and review of the literature].

Coronary artery stenosis is one of the possible complications of radiotherapy to the mediastinum. Although less frequent than pericardial disease, anatomopathological studies have shown it not to be uncommon. Five cases with different clinical presentations are reported and the 30 previously described cases are reviewed. Radiotherapy was performed for Hodgkin's disease in 70% of cases and for carcinoma of the breast in 10% of cases. The average delay before onset of the symptoms was 4 years but in some cases delays of up to 10 years were observed. The most common presentation was an inaugural myocardial infarction (50 to 60% of cases). In other cases, angina of effort or typical spastic angina was observed. The coronary lesions were mainly proximal single artery stenosis affecting especially the left anterior descending artery. The typical histological appearances of the stenosis were intimal and sometimes adventicial fibrosis, occasionally associated with medial hyaline sclerosis. However, atherosclerotic lesions were also commonly present. This observation raises the question of the role of irradiation in the development of precocious atherosclerosis by coronary endothelial damage. This hypothesis is supported by the results of experimental studies and by the fact that several autopsy reports showed that the atheroma only developed in the irradiated zone. In addition, although the most demonstrative cases are those of young patients of 30 to 35 years of age, the responsibility of radiotherapy in the development or coronary pathology of older patients cannot be excluded, especially when none of the classical coronary risk factors are present.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

[In vitro electrophysiological effects of sodium dantrolene on isolated preparations of Purkinje fibers and ventricular myocardium of sheep].

Dantrolene sodium is a drug used in the treatment of spasticity and malignant hyperthermia. It is known to have a myorelaxant effect related to inhibition of the "release" of calcium by the sarcoplasmic reticulum of striated skeletal muscle. A direct cardiac effect which has only recently been suspected was demonstrated in vitro on isolated preparations of sheep Purkinje fibres and ventricular myocardium. Dantrolene caused a spectacular lengthening of the duration of the action potential of Purkinje fibres. This could be due either to an action on the slow calcium current or to stimulation of an ingoing sodium current sensitive to tetrodotoxin (TTX). This effect on the cardiac action potentials could explain the antiarrhythmic properties of dantrolene sodium during attacks of malignant hyperthermia.

Action Potentials↗
PubMed1985

[Familial forms of interauricular communication of the ostium secundum type].

The occurrence of several cases of ASD in the same family is rare. Familial forms of ASD are characterised by the high incidence of associated cardiac lesions in affected patients or in the family, by the frequency of atrioventricular block with prolongation of the PR interval and by the presence of a large defect in the interatrial septum. The condition is thought to be transmitted in an autosomal dominant manner. The authors report the case of a family in which 7 cases of ASD were found, 6 of which were repaired surgically. There were no associated cardiac or extracardiac malformations; AV conduction was normal in 4 of the 6 operated cases--the defects were all large. The study of the genealogical tree with examination of most members of the family suggests autosomal dominant transmission of the condition.

Adolescent↗
PubMed1985

[Electric activation of the heart using laser spectrometry. 1. Study of transmembrane action potentials using optical technics].

The action potentials of the contractile myocardium and conduction cells are usually recorded by intracellular glass microelectrodes but they call also be obtained at a distance and without physical contact by optical techniques. The myocardial fragment must be stained with a dye which, when illuminated by a laser beam, emits a fluorescence whose wave length is related to the transmembrane potential. The responses obtained were checked by microelectrode and optical techniques on several types of preparation (sheep myocardium, sheep Purkinje cells, mouse myocardium). The morphology of the action potential was identical by both methods; the beginning of phase 0 in particular was identical with both methods, eliminating any mechanical activity. Contraction appeared later, during the plateau phase of the action potential with a measurable interval corresponding to the excitation- contraction coupling time. Remote recordings of action potentials without physical contact with the preparation, should enable very accurate myocardium activation mapping using CCD video techniques.

Action Potentials↗
PubMed1984

[Thoracic pain and arteriovenous fistula of the spinal cord].

A 58 year old man was admitted with a pseudo-coronary pain. Cardiological investigations (ECG, chest X-ray, enzymes) were normal. Pain however was exacerbated by movement, coughing and pressure over T4 to T10 vertebrae. On the 4th day, the patient developed a weakness of the right lower limb which worsened 15 days later. On examination there were in the right lower limb a combination of central (Babinski sign) and peripheral signs (diminished deep reflexes, loss of sensation to all modalities ipsilateral to the paralysis). Metrizamide myelography was within normal limits. Spinal angiography revealed a dural arteriovenous fistula draining into spinal veins, at the level of T5. Following the removal of the fistula, the pain disappeared and the other symptoms and signs improved.

Arteriovenous Fistula↗
PubMed1983

[Torsades de pointes initiated by slow ventricular stimulation].

The authors report a case of isolated and probably congenital complete heart block with spontaneous torsades de pointes preceded by an increase in the QT interval. During positioning of a temporary pacing catheter mechanically induced extrasystoles were observed, which seem to favor ventricular extrasystoles and unsustained runs of torsades de pointes. When the basal rhythm showed no extrasystoles, electrical stimulation delivered late in diastole captured the ventricle normally and was then followed in reproducible fashion by episodes of torsades de pointes or minor equivalents. The mechanism of this phenomenon is thought to be related to a concealed phase 4 intramyocardial block. It may have important practical consequences in paced patients predisposed to torsades de pointes. If the pacemaker is programmed at too slow a rate, with stimulation falling late in diastole, torsades de pointes could occur, some attacks of which are known to degenerate to true ventricular fibrillation.

Cardiac Pacing, Artificial↗
PubMedDate not supplied

[Electrocardiographic effects and antiarrhythmic action of 1200 mg of oral amiodarone per day].

The authors administered 1 200 mg of amiodarone orally to 30 patients with paroxysmal supraventricular and ventricular arrhythmias for a period of 6 days. They evaluated the electrocardiographic modifications induced on the surface ECG as well as the anti-arrhythmic action which was assessed by continuous Holter ECG monitoring and endocavitary electrophysiological investigations. They found that the sinus rhythm was slowed by 22%, that the PR interval was prolonged by 22%, that the QTc interval was increased by 13.5% and that there were alterations in ventricular repolarisation in 48% of cases. These ECG modifications were maximal between the 5th and 7th days. The amiodarone controlled the arrhythmia in 57% of cases. Independent of the nature of the arrhythmia, the anti-arrhythmic effect appeared after a mean of 3.9 +/- 1.8 days. There was no significant relationship between the electrocardiographic modifications and the anti-arrhythmic effect. In three cases (10%), major side effects were observed, related to depression of sinus automatism. They only appeared after the 6th day. Thus, a loading dose of 1 200 mg/day of amiodarone p.o. can be administered without fear of major side effects for 4 to 5 days. Such treatment will control about 60% of cases of severe paroxysmal arrhythmias after 4 days.

Administration, Oral↗
PubMedDate not supplied

[Fulguration of extrasystolic ventricular focus].

A case is presented of symptomatic premature ventricular contractions refractory to drug therapy with right bundle branch block QRS morphology and left axis deviation in a 68-year-old female without structural heart disease. Endocardial mapping localized the extrasystolic focus at meso-inferoapical region of the left ventricular septum suggesting an origin from the Purkinje network of the left posterior fascicle. Catheter ablation with direct-current energy abolished extrasystolic complexes, without complications. The patient remained asymptomatic over a follow-up of 3 months.

Aged↗
PubMedDate not supplied

[Radiofrequency ablation in ventricular tachycardia: initial experience and evaluation of its limitations].

The purpose of this paper is to report our initial experience with radiofrequency catheter ablation in 21 patients with ventricular tachycardia of different etiologies and to evaluate the causes which play a role in its limitation. The results show a low rate of effectiveness: total clinical success of 43%. Nevertheless there was a high success rate in a specific subsets of patients. The results depends on several factors: the electrophysiologic mechanisms and substrates of the tachycardia, the criteria to localize the critical area perpetuating the arrhythmia and the biophysical aspects of radiofrequency energy. Its usefulness is manifested in ventricular tachycardia with structurally normal heart and it has a limited success in cases with organic heart disease. Improvement of technical aspects and better understanding of the mechanisms of the tachycardia and characteristics of the target site will enhance the results of radiofrequency catheter ablation in ventricular tachycardia.

Adult↗