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Biomedical subjects

R Saumont

Publications and source records attributed to R Saumont.

At least 19 recordsLinked to original sources
PubMed1984

Comparison of geometrical models for evaluating left ventricular wall motion from cineangiograms.

Regional wall motion of the left ventricle (LV) has been analyzed from contrast ventriculograms by using 4 methods based on different geometrical frameworks. Two of them utilize moving internal reference systems, the center of mass (CMM) and the long axis (LAM) methods; the two other ones use fixed external reference systems, the area-based (ABM) and the Palo Alto (PAM) methods. The techniques were applied on a set of 81 patients: 42 were normal and composed the group I; 22 had a single vessel obstruction greater than 75% of the left anterior descending coronary artery (group II) with old necrosis or active ischemia of the LV anterior wall; 17 had a single vessel obstruction greater than 75% of the right coronary artery (group III) with old necrosis or active ischemia of the LV inferior wall. ABM and PAM showed the highest specificities and sensitivities on the studied sample. Therefore, we believe these two methods, of the techniques tested, are the best to quantitate wall motion from cineangiograms.

Cineangiography↗
PubMed1983

Circadian changes in heart rate in unanesthetized normotensive and spontaneously hypertensive rats.

Circadian changes in heart rate and heart rate variability were measured in spontaneously hypertensive (SHR) and normotensive (WKY) rats. Electrocardiograms (ECG) were continuously recorded, over a 24 hour period from freely moving conscious rats via three small metallic subcutaneous electrodes which were positioned a week before the recording period. The findings reported here show: 1/ Mean heart rate calculated over 24 hours were lower in both strains than previously reported. This difference probably reflects the lack of anesthesia and minimal stress in the present study. 2/ The timing of the circadian variations in both strains were the same, suggesting that were both entrained to the light-dark cycle. 3/ The 24 hours mean heart rate variability was significantly higher in SHR than in WKY but in each strain it was similar throughout the 24 hours. This suggests that the vagal tone in SHR was higher by a fairly constant amount throughout the light-dark cycle.

Animals↗
PubMed1981

Study of relations between arterial oscillation period and heart rate.

This study was performed to determine the relationship between variations of arterial cross-section and cardiac period. Relative section variations were recorded by impedance rheography. In 176 anesthetized adult mongrel dogs, aortic and femoral rheograms, femoral pressure, and ECG were recorded. The cardiac period (Tc) and the interval between the systolic and the dicrotic wave, i.e., the arterial intrinsic period (Ta), were measured and related to each other (Tc/Ta ratio). In 125 dogs, the dicrotic wave appeared spontaneously. In these cases Tc/Ta 1.98 +/- 0.16. In 51 dogs, no dicrotic wave appeared spontaneously. Lengthening of cardiac period was obtained in 25 of these dogs by vagus stimulation. As related to the cardiac period before vagal stimulation Tc/Ta was then 0.98 +/- 0.08. In the remaining 26 dogs, such a lengthening was obtained by inducing a premature ventricular depolarization. In this group, Tc/Ta was 1.00 +/- 0.03. The results of the present study suggest that a constant adaptation exists between ventricular ejection and arterial dynamics. The physiologic implications are discussed.

Animals↗
PubMed1981

Closed-chest myocardial ischaemia in dog.

Myocardial ischaemia in dog was induced with releasable material in the distal segment of the anterior descending branch of the left coronary artery. Three releasable materials were tested: gel foam, wax microspheres (120-200 micron) and latex balloons, using different methods of introduction. The left carotid route was selected for introduction of a preformed catheter. The gel foam and wax microspheres caused transitory ischaemia, which was proximal for the foam and distal for the microspheres. The balloons made it possible to standardize the ischaemia as its localization and duration could be selected. This material therefore provided a model for stable chronic ischaemia. Nine dogs were observed by means of precordial mapping (36 electrodes) during the phase following ischaemia or for a period of 4 weeks. The results of these experiments are analysed and correlated with histological results for the post-mortem phase.

Animals↗
PubMed1977

Impedance rheography: a new method for recording spontaneous arterial section variation.

The aim of this work is to define, on the basis of impedance rheography, a method to record arterial section variations without either inertia or the production of wall-strain. High frequency current (2 MHz) is employed to measure the impedance variations of the deforming artery. The modulating envelope is representative of arterial section variations. This method permits the recording of arterial section variations by a peri-arterial method or an external method on superficial arteries (without denudation). A comparison between arterial section variations and arterial pressure variations at the same point shows that the arterial wall behaves as a non-linear pressure gauge: Rheogram-pressure curves are similar to volume-arterial pressure curves. The great precision with which this method describes the chronology of arterial deformations is of great interest in defining viscous properties of the arterial wall and following their evolution during pathologic alterations such as atherosclerosis.

Animals↗
PubMed1975

[Interpretation of the limits of survival during circulatory support in the dog].

A total cardiac supplementation through a simple by-pass of the left ventricle was performed on hearts in ventricular fibrillation on 51 dogs not treated with heparin. The right-sided circulation was passive to avoid introducing added disturbing parameters. A bi-valved supple prosthesis was set in motion by a pneumatic pump regulated on the left atrial pressure and the arterial tree proper rate. The 44 cases which survived from 7 to 27 hours were limited by a slow and regular lowering of the blood pressure without notable decrease of the output. This lowered pressure was due to the action of the atrial and pulmonary mechanical receptors responding to a left atrial hypertension, secondary to a mild leak of the inflow valve. The mild haemolysis and the total absence of thrombosis should be related with the rate-regulation of the pump on the arterial tree rate, thus providing a maximal yield.

Animals↗