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Biomedical subjects

C Sebag

Publications and source records attributed to C Sebag.

53 records · Page 3Linked to original sources
PubMed1981

[Fragmenting of the His potential after atrial stimulation].

Splitting of the His potential (H) in sinus rhythm is generally considered to be pathological but its significance during programmed atrial stimulation is not clear. This phenomenon was observed in 10 out of 53 patients aged between 19 and 45 years (average 31.8 years) not suspected of having paroxysmal intranodal block (asymptomatic, sinus rhythm without bundle branch block). Under basal conditions the H and the HV interval (35 to 50 ms; average 41 ms) were normal. Split H was observed with pacing periods of 680 to 885 ms (average 754 ms) and H1 H2 intervals of 325 to 450 ms (average 395 ms). The maximal interval between the split potentials ranged from 80 to 130 ms (average 100 ms). Splitting disappeared at the shortest periods when variable pacing cycles were used. The response to regular atrial pacing up to 150 bpm (10 cases) and to Ajmaline (1 mg/Kg) (4 cases) was normal. All patients but one were followed up to 10 to 41 months (average 21.4 months); the clinical and ECG parameters remained stable during this period. The presence of fragmented potentials between the atrial and ventricular complexes during programmed atrial stimulation may pose a difficult diagnosis problem, especially with respect to delayed atrial potentials. Splitting of the H is generally attributed to dispersion of the depolarisation wave front in the His bundle due to the persistence of the functional refractory state. Other mechanisms, especially longitudinal dissociation of the His bundle, may be discussed. From a prognostic point of view, this finding does not seem to carry more serious implications than simple lengthening of the HV interval or intranodal conduction delay, phenomena usually considered to be non-pathological.

Adolescent↗
PubMed1981

[Double Wenckebach phenomenon at nodal and His levels. Electrophysiological demonstration in slow and irregular flutter].

The authors describe the analysis of a case of atrial flutter with a slow ventricular response, the block being 9:2 with a first RR interval measuring between 3 and 4 PP intervals and a second RR interval between 5 and 6 PP intervals, the second of the 2 RR intervals being exactly 9 PP intervals. The only possible explanation of this sequence is firstly a 3:1 intranodal block (Wenckebach 3:2 in the central zone N of the node and 2:1 block at the nodo-hisian junction) followed by a 3:2 infra- or intra-hisian Wenckebach phenomenon. The His bundle recordings during flutter confirmed this hypothesis with the recording of a 3:2 block after the H potential. When sinus rhythm was restored at atrial level, the intrahisian conduction defect persisted (2:1 or 3:2 Wenckebach block).

Aged↗
PubMed1981

[Atrioventricular block disclosing an isolated congenital aneurysm of the sinus of Valsalva, extending into the septum and not ruptured].

A case of a congenital aneurysm of the right anterior sinus of Valsalva (ASV) extending into the septum is reported. The patient, a 20 year old male Central-African, presented with syncopal complete atrioventricular block (AVB) or recent onset. There were no clinical or radiological signs of associated cardiac disease. After implantation of a pacemaker, the diagnosis of an ASV extending into the septum was suggested on routine M mode echocardiography. It was confirmed by two-dimensional echocardiography and aortography. These investigations provided data on its size, its relationship to the cardiac chambers and also showed absence of rupture. The neck of the aneurysm was closed by an endo-aortic approach. There was moderate postoperative aortic regurgitation. This case underlines the value of systematic echocardiography in young patients with AVB of recent onset and obscure origin.

Adult↗
PubMed1980

[Bitachycardia].

One or several episodes of bitachycardia (a simultaneous ventricular tachycardia and atrial tachycardia or fibrillation) were observed in 13 patients. An oesophageal or right atrial endocavitary recording is usually necessary to show the atrioventricular dissociation: even then the diagnosis may be difficult in cases of isorhythmic dissociation or when the ventricular tachycardia is irregular. In 5 cases the double tachycardia appeared to be coincidental. In 7 patients the ventricular tachycardia seemed to be dependant on the atrial tachycardia and could be initiated by a simple spontaneous atrial extrasystole in 3 cases. In one patient the ventricular tachycardia, after a phase of retrograde conduction to the atria, initiated the atrial arrhythmia. The therapeutic indications depend in part on the eventual relationship between the two arrhythmias.

Aged↗
PubMed1979

[Acute myocarditis simulating myocardial infarct with regressive heart failure].

Two patients were hospitalised with severe heart failure and hypotension thought initially to be due to acute anterior myocardial infarction because of very suggestive electrocardiographic appearances. Heart failure rapidly regressed in both cases. The young age of these two patients, the pyrexia, rapid and total regression of the ECG appearances, the absence of atheromatous lesions at coronary angiography and clinical cure with a follow-up of 10 years in one of the cases, were factors in favour of the diagnosis of acute myocarditis.

Adult↗
PubMed1978

[Biochemistry of myocardium taken at autopsy. Preliminary report].

The findings after biochemical analysis of heart muscle taken at autopsy are given in this preliminary communication. Human myosin is made up of two heavy sub-units and two light sub-units: it is similar to cardiac myosin found in other mammals, but is different in certain characteristics, particularly immunological ones. Tropomyosin is made up of two different sub-units. The normal human heart contains 1 mg of collagen and 130 microgram of desoxyribonucleic acid (DNA) per 100 mg of fresh tissue. The degree of cardiac hypertrophy correlates with the increase total DNA within the heart, and with the lowering of myofibrillary Ca2+ ATPase, the concentration in the collagen remaining unchanged providing there is no ischaemic heart disease. These techniques may be used to quantify several factors, such as the degree of sclerosis or the nuclear mass in ill-understood conditions such as the primary cardiomyopathies.

Actins↗
PubMed1977

Immunochemical evidence for the species-specificity of mammalian cardiac myosin and heavy meromyosin.

Structural differences between various myosins were investigated by means of antibodies to heavy meromyosin, a tryptic subfragment of myosin. Heavy meromyosin was purified from rabbit white skeletal and from pig and human cardiac muscles by gel filtration, and antisera were produced in guinea pigs. Analyses, carried out with the quantitative micro-complement fixation technique, indicated that the antibodies were specific to heavy meromyosin and myosin and not to other contractile proteins. For each muscle type, the corresponding intact myosin reacted, and the degree of dixation was always lower than with heavy meromyosin (50 and 70% fixation respectively). This vertical shift was the same for the three muscle types, indicating that the heavy meromyosin represent corresponding fragments of the myosin molecule from one muscle to the other. Antisera to pig or human cardiac heavy meromyosin clearly distinguished antigens (heavy meromyosins, myosins, or crude extracts) from the ventricles of various heterologous species. Relative to pig, the immunological distances were 50 for the rabbit, 73 for the rat and greater than 100 for human and mice. Relative to human, these values were 20 for the rat, 60 for the rabbit, 72 for the pig. These data provide direct evidence that mammalian cardiac myosin is species-specific.

Adenosine Triphosphatases↗
PubMed1977

Preparation of specific immune sera against rabbit skeletal, pig and human cardiac heavy meromyosins.

Antibodies were produced in guinea-pigs against heavy-meromyosin (HMM) and tested by immunodiffusion and microcomplement fixation (MCF). A similar response was obtained for HMM extracted either from human and pig left ventricles, or from rabbit white skeletal muscles. For each muscle, the antisera cross-react quantitatively with the native intact myosin and are highly specific. Thus, this procedure permits the preparation of muscle type-specific anti myosin antibodies, by a simpler means than those previously published.

Animals↗
PubMedDate not supplied

Experimental cardiac hypertrophy in rabbits after aortic stenosis or incompetence or both.

Four different models of experimental cardiac hypertrophy were compared : abdominal or thoracic aortic stenosis, aortic incompetence and aortic incompetence associated with a thoracic aortic stenosis. After 3 months the ventricular weight of these 4 models reaches +60% +/- 24; +23 +/- 4; +54% +/- 10 and +83% +/- 14. The maximal increase of left ventricular weight (+94% +/- 15) was obtained with the two-step overloading model. Most of the animals had an increase in the right ventricle and lung weights. The DNA content and the protein myofibrillar protein synthesis were both increased in aortic stenosis and were normal in aortic insufficiency. So far the only way to increase the heart weight experimentally more than 60%, is to combine two lesions.

Animals↗