Search PubMed⌕ Search

Biomedical subjects

P Peronneau

Publications and source records attributed to P Peronneau.

At least 55 records · Page 3Linked to original sources
PubMed1981

Non-invasive diagnosis of mitral regurgitation by Doppler echocardiography.

The value of Doppler echocardiography for the non-invasive diagnosis of mitral regurgitation was studied blindly in 161 consecutive invasively investigated adult patients. Regurgitation was graded from 0 to 3 at selective left ventricular angiography. The Doppler echocardiographic examination was considered to be positive when a disturbed systolic flow was found within the left atrium behind the aorta or the anterior leaflet of the mitral valve. The test was considered to be negative in the absence of a regurgitant jet. The level of the signal to noise ratio was checked by the recording of the ventricular filling flow. The study was performed in 131 cases from the left side of the sternum and in 101 cases from the apex. There were no false positives and thus the specificity was 100 per cent. The 20 false negatives were all in patients with grade 1 regurgitation. Thus only some (33%) instances of mild regurgitation were misdiagnosed, and the sensitivity for moderate to severe mitral regurgitation was 100 per cent.

Adolescent↗
PubMed1981

Preload changes modify systolic pressure-diameter relations in the conscious dog.

The behavior of the end-systolic ventricular diameter was examined during control state, atrial pacing, and acute volume loading (VL) followed by methoxamine infusion in conscious dogs instrumented with a left ventricular micromanometer and ultrasonic crystals measuring internal diameter and wall thickness. Heart rate and systolic pressure were markedly increased by maximal VL but for moderate VL were minimally modified. Moderate VL increased end-diastolic diameter by 5% and end-systolic diameter by 2.9% with a significant increase of systolic stress. There was no common final pathway of shortening in the force-velocity-length diagram for different preloads. During methoxamine infusion, the end-systolic pressure-diameter points described a linear regression but points obtained during atrial pacing before VL were significantly shorter. We conclude that VL increases the total loading of the heart producing a lengthening of the end-systolic diameter when end-diastolic diameter is increased. This reduces the expression of the Starling mechanism and suggests caution when interpreting end-systolic pressure-diameter relations and derived indices for significantly different end-diastolic diameters.

Animals↗
PubMed1981

[Biomaterials].

Biomaterials--materials used for the elaboration of systems designed for human implantation or organ substitutes--can be classified as metals and alloys, ceramics and polymers. Their uses are largely diversified, for soft and hard tissues replacement. Interactions rise between biological environment and implants, the mechanisms of them not always known: inflammatory response, corrosion and degradation of materials leading to leaching of some constituents possibly toxic and alteration of their mechanical properties. Blood interfacing materials introduce some particular problems of hemocompatibility. The matching of implant to biological medium, in other words, its biocompatibility has to be a priori evaluated, but until now no in vitro or in vivo evaluation method is fully reliable.

Biocompatible Materials↗
PubMed1979

Noninvasive assessment of aortocoronary bypass graft patency using pulsed Doppler echocardiography.

To evaluate noninvasively aortocoronary bypass graft patency, pulsed Doppler echocardiography was performed at the time of postoperative coronary angiography in 120 consecutive patients. Ultrasonic examination of 163 vein grafts was possible. One hundred twenty-seven patent and 14 occluded grafts were correctly identified. Eleven patent grafts could not be recorded, and 11 occluded grafts were falsely diagnosed as patent. The method had an overall sensitivity of 92% and a specificity of 56%. This high sensitivity level may be increased to almost 100% by enhanced technical skill and experience. The low specificity level, although the method must be tested in a larger number of bypass grafts, stresses the importance of correctly identifying other sources of diastolic blood flow. Diastolic flows from the superior vena cava, internal mammary veins, tricuspid valve, mitral valve and right ventricle may be eliminated by careful adjustment of the depth, site and size of the pulsed Doppler electronic sampling gate. Standard echocardiographic landmarks for avoiding confusion with the coronary arteries are also described.

Coronary Artery Bypass↗
PubMed1979

Flow in the thoracic aorta.

Pulsed ultrasonic Doppler velocimetry and theoretical flow analysis have been combined to improve the knowledge and understanding of aortic velocity profiles and wall shear. From the theoretical point of view, particular aspects of the flow were developed, concerning the vorticity in the aorta, the interior velocity distribution, the boundary layer, the flow after separation and the effects of the branches. The experimental approach was performed on dogs, using pulsed ultrasonic Doppler velocimeter providing real-time acquisition of the instantaneous velocity distribution along vascular diameters and perivascular probes designed for bidimensional measurement of velocity distribution. The good agreement found between theory and the experimental velocity profiles has led to comparison of the assessments of axial shear. The peak of the measured shear agrees well with the calculated one; the largest observed shear, obtained at the level of the initial part of the descending thoracic aorta, varies from 4.5 Pa to 7.5 Pa depending on the cardiac output. Finally initial attempts have been made to correlate atheromatous wall lesion localisation with the flow and shear variation.

Animals↗
PubMed1979

[Blood vessel sutures with absorbable suture material: roentgenological, hemodynamic, light and electron microscopy findings. I].

Simple end-to-end anastomoses were performed in the common carotid and femoral arteries and in the jugular and femoral veins of dogs. In other dogs, lateral sutures (running) consisting of absorbable material made from polyglycolic acid were inserted. No occlusions, aneurysms, or infections occurred in the arteries. Without heparin, the patency rate after up to 234 days was 98%. In veins, the observation period was 60 days and a patency rate of 83% was found. All vessels were studied by angiography and by light and electron microscopy. Additionally, an original method of hemodynamic assessment was used (Turbulence Index). The alternating effect of morphological variations in the vessel wall and the degree of blood flow disturbance was evident.

Angiography↗
PubMed1977

[Non-invasive study of the patency of aortocoronary bypass with pulsed Doppler technic. Preliminary studies].

The pulsed Doppler effect is a non-invasive investigation technique based on the fact that the blood cells moving in a vessel on which ultrasound is incident cause a rebound of different frequency, according to their rate. This technique allows us to measure flow in a "measuring volume", whose size and depth are regulable. It is also possible to collect the signal from one or several aorto-coronary grafts, and to distinguish these from the sorrounding vasculature by their diastolic perfusion. This preliminary study (11 cases) is an attempt to formulate strict procedural criteria by comparison with follow-up arteriography of the grafts. The ease of performance of this investigation should, eventually, make it unnecessary to have to carry out repeated arteriography.

Blood Flow Velocity↗
PubMedDate not supplied

Animal evaluation of the prototype omnicath atherectomy catheter.

A prototype directional atherectomy catheter (Omnicath) was evaluated in four Yucatan microswines. Atherectomy was performed on iliac or aortic target lesions. After control angiography, the animals were sacrificed and the target arteries were examined histologically. Atherectomy resulted in arterial ruptures in three cases, and the track of the blade was measured to be of an average depth of 0.38 mm. Maneuverability was satisfactory but aspiration was not efficient. Precise localization of the atherectomy window was difficult. We conclude that modification of the catheter seems mandatory before use in humans.

Animals↗
PubMedDate not supplied

Visualization of the parietal mass transfer by using immobilized peroxidase.

A new method is developed for direct visualization of the local mass transfer at solid liquid interfaces involving the chemiluminescent oxidation of luminol by H2O2 catalyzed by immobilized peroxidase. At low concentration of H2O2 (C less than 5 x 10(-5) M) this reaction is controlled by diffusion and it is possible to characterize the diffusion convection of H2O2 at each point of the tube as a function of the local hydrodynamic properties. These properties are characterized by pulsed Doppler ultrasound velocimetry. 1) The rate of light emission depends on Re1/3 for the laminar case and decreases when going downstream in accordance with the known theories of diffusion convection along tubes. 2)Downstream to a stenosis, a maximum of light appears which depends on the input Reynolds number in a manner similar to the reattachment point of the flow. This constitutes the first experimental confirmation of calculations on diffusion convection downstream to stenoses. These first experiments show the capacity of the method to detect the local properties of the parietal mass transfer phenomenon as a function of the geometry of the wall and the hydrodynamic properties of the flow.

Blood Flow Velocity↗