PubMed Health⌕ Search

Biomedical subjects

D Crochet

Publications and source records attributed to D Crochet.

At least 19 recordsLinked to original sources
PubMed2006

[An evaluation of the effectiveness of applying 16-slice computed tomography (CT) to coronary arteries in preoperative aortic valve replacement].

UNLABELLED: An evaluation of the effectiveness of applying 16-slice Computed Tomography (CT) to coronary arteries in preoperative aortic valve replacement. PURPOSE: To evaluate the effectiveness of using 16-slice CT to diagnose a significant stenosis in coronary arteries in patients with severe aortic valve stenosis. MATERIAL AND METHODS: 50 patients were included in the study. After a medium contrast injection, CT images of the arteries were taken using 0.75 mm slices. We paired the images with an ECG. Segments smaller than 1.5 mm were discarded, and the results were compared to those from the coronary angiography. RESULTS: A satisfactory visualization of the coronary network was obtained for 80% (40/50) of the patients. For these 40 patients, 23 of the 29 patients without coronary stenosis were correctly classified but 4 of the 11 patients with coronary lesions were not recognized. The sensitivity of the multi-slice CT in detecting a least one significant coronary stenosis is 63.6%, the specificity 79.3%, positive predictive value 53.8% and negative predictive value 85.2%. CONCLUSION: the 16-slice CT is a relatively effective and minimally invasive tool to highlight before valve replacement significant coronary stenosis in arteries greater than 1.5 mm in diameter in patients with severe aortic valvular stenosis. CT technology is currently insufficient for diagnosis, but we hope that with advances in multi-slice CT engineering, its use will help patients avoid invasive coronary angiographies.

Aged↗
PubMed2005

Spread of Coxiella burnetii infection in a flock of sheep after an episode of Q fever.

In October 1998, two abortions associated with Coxiella burnetii occurred in a group of 34 pregnant ewes in the sheep flock belonging to INRA Tours-Nouzilly. The flock was kept in groups of approximately 40 ewes, which were housed together in the same accommodation. The prevalence of C burnetii infection in the groups was investigated by using ELISA and PCR tests, which revealed a high prevalence of C burnetii. The ewes were treated with oxytetracycline to reduce the shedding of C burnetii and to prevent further abortions. Nevertheless, five abortions attributed to C burnetii occurred in January and March 1999 in three groups of ewes, and 24 of the ewes still shed the bacteria into their vaginal tracts. In addition, a serological study was carried out during the first year of life of the female lambs born in 1999 and 2000; 12 per cent of 113 lambs born in 1999 were seropositive for C burnetii by ELISA, and half of the ELISA-positive lambs were born either to serologically positive ewes or to dams that excreted the pathogen into their vaginal tracts. However, all the 150 lambs born in 2000 were ELISA-negative, suggesting that the preventive measures undertaken had suppressed both the abortions and the shedding of C burnetii, and reduced the transmission of the agent.

Abortion, Veterinary↗
PubMed2005

[Septal alcoholisation of hypertrophic obstructive cardiomyopathy in childhood].

The authors report a case of septal alcoholisation in a 6 year old child with hypertrophic obstructive cardiomyopathy responsible for congestive cardiac failure despite optimal betablocker therapy. The indication was retained in a context of mucoviscidosis complicated by multiresistant bacterial infection. At catheterisation, the dominant septal artery was identified and an alcoholisation was performed by the classic technique described in adults. The immediate result was satisfactory with regression of the signs of cardiac failure and reduction of 70 mmHg of the maximal instantaneous pressure gradient (from 160 to 90 mmHg). However, 10 months later, the signs of right heart failure reappeared with a partial increase in the maximal instantaneous pressure gradient (100 mmHg) leading to surgical myectomy while the patient's condition had considerably improved from the pulmonary point of view. Septal alcoholisation would appear to be a therapeutic alternative in children especially in cases with a temporary or permanent contraindication to conventional surgery.

Cardiac Catheterization↗
PubMed2004

Neointimal hyperplasia after stenting in a human mammary artery organ culture.

Although the use of stents has limited the incidence of restenosis, in-stent restenosis remains an important problem. In-stent restenosis is the result of a healing process that induced neointimal hyperplasia through mechanisms that are still not understood. The aim of this study was to analyze the histological consequences of the healing process following stent implantation. Internal mammary arteries from atheroslerotic patients undergoing coronary artery bypass surgery were stented and maintained in culture for 0-28 days. Stent implantation after predilatation induced an extensive loss of endothelial cells whereas direct stenting preserved endothelium between the struts. Morphometric analysis shows that stent placement induced neointimal thickening. Smooth muscle alpha-actin labeling indicates that neo-intimal formation was mainly due to proliferation and migration of smooth muscle cells. Smooth muscle cell proliferation, assessed by MIB-1 staining, was maximal at day 14 after stent insertion. Human mammary artery organ culture thus provides valuable information on histological consequences of stent implantation with or without predilatation regarding endothelial cell disappearance and neointimal hyperplasia. These data also demonstrate that neointimal thickening induced by stent implantation comprises an intrinsic component resulting from the vessel wall response to stent insertion and suggest that blood factors could play an amplifying but not necessary role.

Cell Division↗
PubMed2004

[Cardiac tumors].

Metastases are the most frequent tumors of the heart even though they seldom are recognized. Most primary cardiac tumors are benign. The main role of imaging is to differentiate a cardiac tumor from thrombus and rare pseudotumors: tuberculoma, hydatid cyst. Echocardiography is the fist line imaging technique to detect cardiac tumors, but CT and MRI are useful for further characterization and differential diagnosis. Myxoma of the left atrium is the most frequent benign cardiac tumor. It usually is pedunculated and sometimes calcified. Sarcoma is the most frequent primary malignant tumor and usually presents as a sessile infiltrative tumor. Lymphoma and metastases are usually recognized by the presence of known tumor elsewhere of by characteristic direct contiguous involvement. Diagnosing primary and secondary pericardial tumors often is difficult. Imaging is valuable for diagnosis, characterization, presurgical evaluation and follow-up.

Adult↗
PubMed2004

[MR imaging and arrhythmogenic right ventricular dysplasia (ARVD)].

Arrhythmogenic right ventricular dysplasia (ARVD) is a cardiomyopathy of unknown etiology responsible for 20% of cases of sudden death in young adults secondary to arrhythmia. It is characterized histologically by fatty or fibro-fatty infiltration of the right ventricular myocardium. Diagnostic criteria have been proposed for diagnosing ARVD. Imaging, especially MRI, plays an important role. MR imaging must be performed using cardiac gating, and should include both cine-MR sequences for evaluation of segmental and global right ventricular function or any morphological change of the right ventricular shape, and anatomic sequences to detect fatty or fibro-fatty infiltration of the right ventricular myocardium.

Adult↗
PubMed2001

Relationships between the shedding of Coxiella burnetii, clinical signs and serological responses of 34 sheep.

Two abortions associated with Coxiella burnetii occurred in a group of 34 pregnant ewes. The seroprevalence of C. burnetii infection was studied by using an ELISA and the immunofluorescence (IF) assay was applied to the contents of vaginal swabs. In addition, a PCR assay, with primers based on a transposon-like repetitive region of the C. burnetii genome (trans-PcR), was used for the highly sensitive and specific detection of C. burnetii in vaginal swabs, milk and faeces. Of the 34 animals tested at parturition, eight (24 per cent) were positive by ELISA, 11 (32 per cent) were positive by IF, and 15 (44 per cent) were positive when the vaginal swab extract was subjected to the trans-PCR assay. C. burnetii was therefore detected by PCR in the vaginal swabs of seven seronegative ewes. However, five weeks after lambing, 16 (47 per cent) of the animals tested were ELISA positive but only two animals (6 per cent) were positive by PCR. Among the ELISA- and PCR-positive animals, eight (25 per cent) shed coxiella in their milk and six (18 per cent) did so in their faeces.

Abortion, Veterinary↗
PubMed2001

Evaluation of the LGM Vena-Tech infrarenal vena cava filter in an ovine venous thromboembolism model.

PURPOSE: To validate a new percutaneous model of venous thrombosis in sheep and evaluate the use of the LGM Vena-Tech vena cava filter with use of this model. MATERIALS AND METHODS: After implantation of a LGM Vena-Tech filter in the infrarenal vena cava (IVC), thrombus was obtained by blocking the iliac vein with an inflated balloon (Wedge catheter) for 15 minutes and simultaneously injecting 20 mL of fresh thrombus into the femoral vein. Clot migration of the thrombus was induced by balloon deflation and injection of contrast medium. Migration and capture of the thrombus by the filter were filmed under fluoroscopy at 1 frame/sec. Euthanasia followed by pathologic examination of the IVC, heart, and lungs was performed immediately after the procedure in five sheep (group 1). Sheep in groups 2, 3, and 4, (five in each group), were killed at 2, 4, and 8 weeks, respectively, after vena cavography. Histologic examination was performed to analyze the evolution of the thrombus captured, the incorporation of the filter in the caval wall, and the physical and mechanical effects of captured thrombi on the filter. RESULTS: The Vena-Tech filter captured a large amount of thrombus in all cases except one, in which the filter captured a small strand of thrombus, related to incomplete occlusion of the iliac vein during the clot formation procedure. In the 15 animals in which follow-up was performed, fibrous evolution of the thrombus was observed at gross examination in 14, leading to the formation of fibrous webs between the filter and the IVC wall in eight. These observations were not related to the incidence of filter retraction (n = 4), caudal migration (n = 2), tilt (n = 2), or caval perforation (n = 1). Heart and lung thrombi were present in six animals. Histologic results confirmed the fibrous evolution of the thrombus and its organization during follow-up. Neointima increases significantly (P <.02) during follow-up, from 135.7 microm +/- 13.4 at 2 weeks to 192.2 microm +/- 125.7 at 4 weeks and 334.2 microm +/- 144.1 at 8 weeks. CONCLUSION: The model used is suitable for the formation of a large amount of venous thrombus and analysis of its migration and capture by the LGM Vena-Tech filter. Fibrous evolution of the thrombus, including development of webs and changes in filter shape and position, were the main outcomes observed.

Angiography↗
PubMed2001

[Can one die of sorrow?].

The authors report the case of a 49 year old woman who, on two occasions four years apart, presented with cardiogenic shock following the same type of intense emotional stress. Acute left ventricular systolic dysfunction in the initial phase regressed completely with drugs. A diagnostic investigation excluded atheromatous coronary artery disease, myocarditis and pheochromocytoma. Two hypotheses remained: prolonged coronary spasm causing myocardial stunning or acute catecholaminergic cardiomyopathy secondary to the stress.

Cardiomyopathies↗
PubMed1999

[Quantitative angiography: update for peripheral vascular applications].

Visual estimation of vessel diameter is unreliable and observer-dependent. With digital angiography, software for accurate quantification of arterial diameter are available. They allow: (1) selection of equipment of appropriate size (balloons, stents, etc) during revascularization procedures, (2) objective evaluation of the results of such procedures, (3) comparison between follow-up measurements and initial measurements and (4) provide reproducible data in the case of multicenter studies. The widespread availability of digital systems has been accompanied by a dramatic increase in the number of software packages for quantification. The present article reviews some of the currently available methods for quantification, presents the advantages and pitfalls of each system, and outlines their limits.

Angiography↗
PubMed1998

[Morphometric study of the wall of the caudal vena cava after the implantation of a filter in the sheep].

The long stabilizers of the VT-LGM filter rest on large areas of the vascular wall. The morphometric study of the layers of the vascular wall, after implantation of filter in 15 ewes, divided into 3 groups of follow-up (2, 4 or 8 weeks) of 5 animals, was made at 3 levels opposite the filter and 1 level outside of it. Changes are seen for all the layers. Filter produces intimal hyperplasia. Stabilizers are quickly isolated from the blood flow. The thickness of the intimal hyperplasia grows for 4 weeks. It is more important at the base of the filter than at its head. There is also hyperplasia of the media with no change according to the follow-up or the level opposite the filter. The adventitia becomes thinner without variation of time or level of the filter. Smooth muscle cells of the adventitia become less frequent and smaller. Their density in front of the stabilizers, is the smallest by 4 week follow-up and remains the same along the stabilizer. The full thickness of the wall is bigger opposite the stabilizers than between them. The filter produces changes that are limited in time and in space. The most important changes are seen at 4 weeks after insertion and opposite the stabilizers.

Animals↗
PubMed1996

Risks of reusing coronary angioplasty catheters: results of an experimental study.

This experimental study was conducted to evaluate the microbiological and mechanical risks of reusing angioplasty catheters after decontamination and resterilization. The catheters studied were decontaminated in an ultrasound chamber, rinsed, dried, wrapped, and resterilized at 25 or 35 Kgray. Sterility checks performed on catheters cut into three segments concerned bacteria, mushrooms, yeasts, and pyrogens. The surface condition of the balloons was studied by scanning electron microscopy. The mechanical properties analyzed were balloon diameter and bursting pressure and the mean resistance of the catheter body to breakage. Seventy angioplasty catheters of three different types (rapid exchange, coaxial, and on-wire balloon catheter) were tested. Decontamination proved insufficient owing to the persistence of cellular elements on the balloon surface and the presence of pyrogens. Sterility of the material was not ensured with an irradiation of 25 Kgray. It was probable but not certain with 35 Kgray, since an inhibitory effect on micro-organism growth was noted. Mechanical properties were not modified significantly. Our results do not favor the reuse of coronary angioplasty catheters. Better decontamination is desirable but difficult to obtain because of the adhesion of cellular elements to the polymers composing the catheters. Although our results are not necessarily applicable to all resterilization protocols, they indicate that teams desiring to reuse angioplasty material should first test the validity of their procedure for decontamination and resterilization.

Angioplasty, Balloon, Coronary↗
PubMed1996

[Combination of true and false left ventricular aneurysm. Cine-MRI diagnosis].

The authors report a case of a 68-year-old man with a history of postero-lateral myocardial infarction complicated by a true and a pseudo-aneurysm of the left ventricle, a chance finding during investigation of a systemic embolism. This is a rare association which is clinically difficult to diagnose. The authors describe the different complementary investigations available to make the diagnosis and underline the value of cine-MRI which was particularly useful in this case. Surgery may be indicated in cases of true aneurysm in cases with left ventricular failure but is mandatory in all cases of pseudo-aneurysm irrespective of the clinical presentation.

Aged↗
PubMed1996

[Value of plain abdominal radiography for evaluating the patency of LGM caval filters].

OBJECTIVES: To evaluate the value of plain abdominal X-Ray to detect vena Tech LGM filter occlusion or patency during follow-up. METHODS: Eighty-nine patients were followed in a prospective study for 2 to 6 years after vena Tech LGM filter implantation. The control examination consisted in a clinical examination, a plain abdominal X-Ray (to measure expansion index = diameter/height of the filter and to detect migration and angulation) and a Doppler ultrasonography and/or a cavography to appreciate filter patency. RESULTS: 175 plain abdominal X-Ray, 172 Doppler ultrasonographies and 28 cavographies were done. Sensitivity and specificity of retraction to suspect a filter obstruction were respectively: 82.3% and 86.1%; if expansion index was lower or equal to 0.34 its sensitivity and specificity were 100% and 92.1%. The negative predictive values of retraction and of the association retraction-migration to exclude a filter obstruction were 85.1% and 96%. CONCLUSION: Absence of migration or retraction on plain abdominal X-Ray during the follow-up is highly predictive of filter patency. This limits the use of Doppler ultrasonography and cavography.

Adult↗