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Biomedical subjects

L Pourcelot

Publications and source records attributed to L Pourcelot.

At least 109 records · Page 6Linked to original sources
PubMed1987

Stroke risk in patients with carotid stenosis.

In 242 neurologically symptomless patients with at least one non-occlusive carotid stenosis on ultrasonography (continuous wave doppler and echotomography-B mode imaging) 171 carotids showed 0-50% stenosis, 150 showed 50-75% stenosis, and 78 showed more than 75% stenosis. The mean follow-up was 29.4 months, with stroke and death as end points. Of the 56 deaths 2 were causally linked to a stroke (crude annual mortality index 9.57%). Of the 10 strokes 7 were judged to be infarctions in carotid territory. 7 out of 20 patients with transient ischaemic attacks (TIA) had ischaemic symptoms definitely related to carotid territory. The crude annual indices of specific stroke or TIA were 0.45% for nonstenotic carotid, 0.23% for 0-50% stenosis, 2.48% for 50-75% stenosis, and 1.71% for 75-99% stenosis. Stenoses of greater than 50% were associated with more ischaemic events than were lesser degrees of narrowing (p less than 0.01).

Aged↗
PubMed1987

A linear array system for deep vessel explorations.

A system for the exploration of deep vessels is proposed. This device is based on a single 300 element linear array in which a "Doppler area" is selected to electronically steer a Doppler beam. Characteristics of the equipment are excellent and it is as easy to handle as a simple linear array scanner. A real-time spectrum analyser is used to process the Doppler signals. The probe and the associated electronics are described and some results are given to illustrate the capabilities of the device such as blood flow estimation and deep vessel studies.

Aorta↗
PubMed1987

Exploration of the fetal cerebral blood flow by duplex Doppler--linear array system in normal and pathological pregnancies.

The umbilical circulation can be investigated by Doppler ultrasound techniques very easily. The Doppler frequency spectrum from the umbilical arteries provides information on the placental circulation. The diastolic flow amplitude is directly related to the vascular resistances of the placenta (Rp). In cases of pathological pregnancies with hypertension the decrease of the diastolic flow and the increase of the resistance index Rp have been correlated with intrauterine fetal growth retardation. Fetal cerebral arteries have also been explored during normal pregnancies (n = 40). The index of cerebral resistance (Rc) as defined by Pourcelot is Rc = S-D/S (with S systolic amplitude and D diastolic amplitude) and shows variations similar to the placental index. During normal pregnancy, the cerebral index is higher than the placental index and the cerebro-placental ratio (Rc/Rp) is greater than 1. This preliminary study of both umbilical and cerebral circulation seems to demonstrate that during pathological pregnancies with hypertension (n = 21), with fetal growth retardation one of the indices, Rc or Rp may be out of the normal range but the cerebro-placental ratio (CPR) is always less than 1. However a larger number of patients should be explored in order to evaluate the clinical usefulness of such an observation.

Cerebral Arteries↗
PubMed1987

[Doppler examination of the umbilical arteries. Its role in the surveillance of pregnancy].

Pregnancies with a high risk of fetal growth retardation are at present watched by using clinical observations and biological parameters including ultrasound and estimation of the fetal heart rate. The Doppler waveform in the umbilical arteries provides information about circulatory resistance in the placenta. An index of resistance "R" is evaluated on the Doppler trace. The purpose of this study is to describe the score (with its possibilities and limitations) for this parameter "R" to follow-up pregnancies with fetal growth retardation and to compare it with ultrasound, biological and clinical parameters that are commonly used. Two groups of pregnancies have been explored: pregnancies with hypertension and pregnancies with idiopathic fetal growth retardation. Abnormal values of "R" correlate well with failure of fetal growth. Furthermore pathological values of "R" do not correspond to the same population as abnormal values of the other parameters. In some cases "R" is disturbed before the others are. In conclusion, this study shows that the index increases the accuracy of detection and the follow-up of chronic fetal growth retardation, particularly in cases of pregnancies with vascular placental pathology.

Birth Weight↗
PubMed1987

[Doppler examination of the umbilical and cerebral arterial circulation of the fetus].

Umbilical circulation can be explored by Doppler ultrasound methods very easily. The umbilical arteries spectrum provides information on the placental circulation. The diastolic flow is directly related to the vascular resistances of the placenta (Rp). In cases of pathological pregnancies with hypertension the decrease in the diastolic flow and the increase in the resistance index Rp have been correlated with intra-uterine fetal growth retardation. The specificity of this index Rp is of 95% but the sensitivity much more lower (approximately 70%). For that reason Doppler assessment of the fetal circulation in other areas has been recently carried out. Fetal cerebral arteries have been explored during normal pregnancies. The index of cerebral resistances as defined by Pourcelot Rc = S-D divided by S (with S systolic amplitude and D diastolic amplitude) show similar variations to the placental index but later in the pregnancy. During the pregnancy the cerebral index is higher than the placental one and the cerebro placental ratio (CPR) superior to 1. During pathological pregnancy (hypertension) with fetal growth retardation one of the index Rc or Rp may be out of the normal range but the cerebro placental ratio CPR is always lower than 1. The follow up of both the umbilical and cerebral circulation increases notably the accuracy of the Doppler method for the detection of intra-uterine fetal growth retardation.

Cerebrovascular Circulation↗
PubMed1986

Cardiovascular system and microgravity simulation and inflight results.

Main results of cardiovascular investigation, performed with ultrasound methods during the common French/Soviet flight aboard Salyut VII in June 1982, are compared to variations of the same parameters studied during ground-based simulations on the same subject or observed by other investigators during various ground-based experiences. The antiorthostatic bed rest simulation partly reproduces microgravity conditions and seems to be better adaptated to cardiac hemodynamics, despite some differences, and to the cerebral circulation, than to the inferior limb circulation.

Aerospace Medicine↗
PubMed1986

An original method for submacroscopic metastases visualization in cases of cancer minimal residual disease.

Scintigraphic imaging due to its sensitivity is in many cases one of the most powerful techniques for demonstrating metastases. Severe limitations still exist in cancer when it is necessary to detect the presence of a few tumour cells in the residual minimal disease. In preliminary experiments it had been observed that an immunomodulator isolated from Nocardia bacteria (Nocardia Soluble Peptidoglycan Derivative: NSPD) electively bound to a model of activated macrophages. An hypothesis has been put forward that the enhanced detection of macrophages that are usually present in the vicinity or inside tumours should represent a polyspecific test for scintigraphy of a variety of metastases. NSPD radiolabelled with 99mTechnetium is not usable when injected intravenously due to its physiochemical properties. It has therefore been encapsulated into liposomes then administered via the respiratory tract as an aerosol. Amphiphilic properties, as well as its low molecular weight allow a rapid diffusion of NSPD in blood. Scintigraphy of metastases was possible from 1.5 to 6 hours after inhalation. The first stage of the study was carried out on 5 patients bearing known metastases (skin, lymph nodes, bone) from malignant melanoma that all were imaged with 99mTc-NSPD. The test was then applied to patients with a high risk of recurrent cancers (melanoma: 6, breast tumour: 7) based on the detection in their plasmas of high Lipid Associated Sialic Acid (LASA) concentrations. The association of these two sensitive techniques has resulted in the detection of very small metastases that were not seen using conventional scintigraphy; they were then confirmed histologically.

Aged↗
PubMed1985

[Tentative classification of the ultrasound symptomatology of the prostate by an anatomo-ultrasonic comparison of 34 cases].

Ultrasound and histological sections were taken of 34 prostate units removed from fresh cadavers. Ultrasonography seems to raise more problems than it solves; only 73% of the normal prostates were homogeneous under ultrasound. Ultrasonography visualized nodular structures requiring biopsy in 71% of the cases of prostatic adenoma. There were too few cases of malignant tumors in the sample to warrant a conclusion. They were highly evolved. Ultrasonography gave strong grounds for suspicion, but they could be easily diagnosed clinically.

Adenoma↗
PubMed1985

[Non invasive measurement of the cerebral blood flow in infants with hydrocephalus].

The present study was undertaken to verify by a non invasive Doppler technique the effect of ventricular dilatation on cerebral blood flow in infants with hydrocephalus. The measurement of pulsatile flow in cerebral arteries is also a valuable parameter for determination of optimal timing of corrective intervention.

Cerebrovascular Circulation↗
PubMed1985

[Relative values of carotid ultrasonic diagnosis and the Doppler test].

The rapid development of techniques for vascular imaging raises questions as to the hierarchy of exploratory non-invasive investigations of cervical vessels. However, caution is necessary when interpreting data provided by different teams because of the unequal experience in the use of these methods by the teams and the variable quality of the apparatuses used. A general rule should be to avoid dissociating imaging and Doppler. Too many teams give priority to ultrasound because of its simplicity in use and the apparent quality of data supplied. However, errors may arise from the weak reflectivity of soft plaques, particularly recent clots, from an acoustic shadow associated with some calcified plaques and from an unfavorable position of the lesion in relation to possible section planes. These problems increase when the apparatus is poorly adjusted, when resolution is insufficient or when there is a threshold to the detection of echos.

Arteriosclerosis↗
PubMed1985

[Ultrasonic, arteriographic and anatomopathological correlation in 59 cases of carotid atherosclerosis].

This study was carried out on 49 patients who underwent an ultrasound study by continuous Doppler and echotomography B real-time, an angiography of supra-aortic arteries, and a carotid endarterectomy. Thirteen had had transient ischemic attacks and 20 a stroke. A quantification of the carotid stenosis in 4 stages was established for each method. For detection of lesion an excellent correlation was observed between the results of echotomography and pathology. For the quantification of lesion the correlation between echotomography and pathology was excellent also in 79,7 p. 100 of the cases, discordant in 20,3 p. 100. It was similar to the correlation between arteriography and pathology (excellent in 83 p. 100 of the cases). The correlation with pathology enabled to distinguish for stages of atherosclerotic lesions, to clarify their type of complications, and to evaluate their functional significance, particularly those with a high risk of embolism.

Adult↗
PubMed1985

[Functional evaluation of temporo-sylvian anastomoses by ultrasonic transcutaneous flow measurement].

The intra-extracranial bypass using the superficial temporal artery remains a matter of controversy about its usefulness and indications. The improvement in ultrasonic technics allows henceforward to measure the blood flow inside this anastomosis with a good precision. In that purpose, we use a duplex Doppler system and a vascular echotomograph. This system brings us the necessary informations to calculate the blood flow: the Doppler frequency shift, the internal diameter of the vessel, and the incidence of the Doppler beam. The spectral analysis of the Doppler signals not only gives us informations concerning the local circulation but also the distal circulatory resistance. An intra-extracranial operation and this examination have been performed in thirty seven patients. The blood flow inside this anastomosis ranges between ten and 360 ml/minute. Patients presenting a blood flow superior to 40 ml/minute seem to improve more frequently. Otherwise there is also an excellent correlation between the blood flow inside the anastomosed temporal artery and its diameter. The evaluation of the cerebral circulatory index of resistance is a good criteria to predict the becoming of the anastomosis and the expected clinical improvement. The functional study of the temporo to middle cerebral artery anastomosis using the duplex echography-Doppler provides essential data to test their efficacy. The expected progress in ultrasonic technics will allow to know, the value of the cerebral circulatory resistances before the operation and so to predict the possible gain for the patient.

Cerebral Revascularization↗
PubMed1985

[Medium-term results of 200 consecutive systematic operations for revascularization of the anterior interventricular artery by the internal mammary artery].

This study presents the preliminary results of systematic revascularisation of the left anterior descending (LAD) by the internal mammary (IM) artery. Between 1981 and 1983, 200 IM bypass procedures were performed (88.5% of bypassed LAD arteries during the same period). With experience, the contraindications of IM bypass surgery progressively decreased (none in the latter 100 cases). The IM bypass grafting was an isolated procedure in 35% of cases and associated with one or more saphenous vein (SV) bypass grafts in 64.5% of cases with an average of 1.9 grafts per patient. The surgical results were better than those of SV bypass grafting alone in the period 1978-1980 with a mortality of 2.5% and a perioperative infarction rate of 2.5% compared to 4.3% and 7% respectively. The medium term results (average follow up 2.5 years) show that more patients undergoing IM bypass surgery were asymptomatic (75%) than those undergoing SV bypass (46%). However, the patients operated more recently by IM bypass benefitted from the latest technical advances in bypass surgery. An unselected sample of 55 volunteers (out of 90 recalled patients) underwent angiography at 1 year. The patency rate was 93% with a very satisfactory angiographic appearance of the graft in nearly all patients suggesting the likelihood of a good long term result. It was possible to demonstrate graft patency by Doppler ultrasound and digitised intravenous angiography in some cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1985

[Circulatory and hormonal changes induced by microgravity].

The absence (or decrease) of the hydrostatic pressure during space flights (microgravity state) or simulations of weightlessness (by immersion, bed rest or head-down tilt) result in a body fluid shift and an engorgement of the central circulation where mechanoreceptors involved in plasma volume regulation are located. Their activation induces the initial (first hours) hormonal response with a decrease in plasma vasopressin, renin and aldosterone and probably an increase in a natriuretic factor (Gauer reflex). Prolonged exposure to microgravity leads to more complex and often hypothetical responses: cardiovascular deconditioning, modifications in secretion and circadian rhythms of above cited hormones. After 24 years of studies on approximately 200 astronauts our knowledge of cardiovascular and hormonal adaptation to space flight is still at the beginning.

Adaptation, Physiological↗
PubMed1984

[Sympathetic paraganglioma. Scintigraphic detection using a new labeled molecule, meta-iodobenzylguanidine].

Two cases of sympathetic paraganglioma are reported: one, benign, in a 20-years old woman with arterial hypertension and attacks of excessive sweating; the other, malignant and with bone metastases, in a 44-years old woman. Both were diagnosed by scintigraphy, using meta-iodobenzylguanidine as radionuclide. This new radiopharmaceutic agent has recently been introduced for the detection of phaeochromocytomas, but it seems to be a general tissue marker of catecholamine uptake and storage. Its use as a therapeutic compound may also be envisaged.

3-Iodobenzylguanidine↗