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Alexandre Laurent

Publications and source records attributed to Alexandre Laurent.

10 recordsLinked to original sources
PubMed2006

Arterial distribution of calibrated tris-acryl gelatin and polyvinyl alcohol microspheres in a sheep kidney model.

OBJECTIVE: The objective of this study was to compare the repartition in the renal arterial vasculature of tris-acryl gelatin microspheres (TGMS) and polyvinyl alcohol microspheres (PVAMS) of 3 calibers (500-700, 700-900, and 900-1200 microm). MATERIALS AND METHODS: Twelve kidneys from 6 adult sheep were embolized and histologically analyzed. The number and size of microspheres and vessels were measured, as well as the deformation of TGMS and PVAMS, and the histologic location according to a classification in 5 zones of the kidney. RESULTS: Two hundred eighty-four vessels were measured. The diameter of the occluded vessels increased when the caliber used for embolization was larger for TGMS and for PVAMS (P < 0.0001, each). The location of TGMS and PVAMS within the vasculature was different for each caliber, because PVAMS blocked significantly more distally than TGMS (P < 0.0001 each). The deformation within the tissue was greater for PVAMS (18.0 +/- 12.3%) than for TGMS (9.0 +/- 8.3%) in general (P < 0.001) and for each caliber of injected microspheres (P < 0.001 each). CONCLUSION: The repartition of a spherical embolic agent in a given vascular network can be influenced by its size and also by its deformation within the vascular bed.

Angiography↗
PubMed2005

Midterm results of uterine artery embolization for symptomatic adenomyosis: initial experience.

PURPOSE: To prospectively evaluate the midterm results of uterine artery embolization for symptomatic adenomyosis. MATERIALS AND METHODS: The study protocol was approved by the institutional review board, and all participants gave written informed consent. Eighteen women (mean age, 44.3 years) with symptomatic adenomyosis were treated with bilateral embolization of the uterine arteries. The diagnosis of diffuse adenomyosis was based on heterogeneous abnormal myometrial echogenicity with myometrial cysts at ultrasonography (US) or on enlarged junctional zone and myometrial cysts at magnetic resonance (MR) imaging. Focal adenomyosis was diagnosed if there was a circumscribed nodular lesion mimicking intramural fibroid. All patients with associated uterine fibroids were excluded. Embolization was offered as an alternative to hysterectomy in all women. Clinical evaluation was made at regular intervals to assess patient outcome. Follow-up US or MR imaging was performed 6 months after embolization to assess uterine volume reduction. RESULTS: Bilateral uterine artery embolization was achieved in all but one woman by using polyvinyl alcohol particles or trisacryl microspheres. All women resumed normal menstruation after the procedure. After 6 months, 15 (94%) of 16 women reported improvement in menorrhagia. Follow-up images at 6 months depicted a slight decrease (mean, 15%) in uterine volume in 17 (94%) of 18 women. After 1 year, 11 (73%) of 15 women had improvement in menorrhagia, and eight (53%) of 15, complete resolution. After 2 years, five (56%) of nine women had complete resolution of menorrhagia. Eight (44%) of 18 women required additional treatment during follow-up for failure or recurrence; five women (28%) underwent hysterectomy. CONCLUSION: Even if short-term results of uterine artery embolization to treat adenomyosis appear encouraging, midterm results are disappointing, with only 55% of treated patients showing clinical improvement after 2 years.

Adult↗
PubMed2005

Partition of calibrated tris-acryl gelatin microspheres in the arterial vasculature of embolized nasopharyngeal angiofibromas and paragangliomas.

PURPOSE: To determine the location of calibrated tris-acryl gelatin microspheres (TGMs) in the arterial vasculature of nasopharyngeal angiofibromas (NAFs) and paragangliomas (PGs). MATERIALS AND METHODS: Forty-nine specimens (25 PGs and 24 NAFs) treated operatively after embolization with TGMs of various sizes (100-300 microm to 900-1200 microm) were stained with hematoxylin and eosin saffron and analyzed at an objective magnification of 10 or 20 with a micrometric eyepiece (magnification, x12.5). The diameter of occluded vessels, their localization (intra- or extratumoral), and the number and diameter of TGMs they contained were determined. RESULTS: Embolized vessels (N = 1125) were measured: 440 in PGs and 685 in NAFs. Vessels were 89% intratumoral and 11% extratumoral. The diameter of the occluded vessels increased significantly with the size range of TGMs used for embolization for each tumor type (P < .0001). Intratumoral occluded vessels were significantly smaller than extratumoral vessels (P < .0001). Distribution of TGMs within the vascular network (intratumoral or extratumoral location) were similar for NAFs and PGs. The intratumoral and extratumoral dissemination of TGMs was different when comparing 100-300-microm TGMs versus 500-700-microm TGMs (P = .0006) as well as 300-500-microm TGMs versus 500-700-microm TGMs (P = .0001). CONCLUSIONS: The size of the vessels occluded by TGMs and their intra- or extratumoral location directly depend on the size of the injected TGMs. The vessels located inside the tumors were smaller than those located outside the tumors. A threshold for the intratumoral penetration of TGMs in the vasculature can be proposed from these data. There was no evidence of different behavior of TGMs in NAFs versus PGs.

Acrylic Resins↗
PubMed2005

Uterine fibroid vascularization and clinical relevance to uterine fibroid embolization.

Embolization has become a first-line treatment for symptomatic uterine fibroid tumors. Selective catheterization and embolization of both uterine arteries, which are the predominant source of blood flow to fibroid tumors in most cases, is the cornerstone of treatment. Although embolization for treatment of uterine fibroid tumors is widely accepted, great familiarity with the normal and variant pelvic arterial anatomy is needed to ensure the safety and success of the procedure. The uterine artery classically arises as a first or second branch of the anterior division of the internal iliac artery and is usually dilated in the presence of a uterine fibroid tumor. Angiography is used for comprehensive pretreatment assessment of the pelvic arterial anatomy; for noninvasive evaluation, Doppler ultrasonography, contrast material-enhanced magnetic resonance (MR) imaging, and MR angiography also may be used. After the uterine artery is identified, selective catheterization should be performed distal to its cervicovaginal branch. For targeted embolization of the perifibroid arterial plexus, injection of particles with diameters larger than 500 mum is generally recommended. Excessive embolization may injure normal myometrium, ovaries, or fallopian tubes and lead to uterine necrosis or infection or to ovarian failure. Incomplete treatment or additional blood supply to the tumor (eg, via an ovarian artery) may result in clinical failure. The common postembolization angiographic end point is occlusion of the uterine arterial branches to the fibroid tumor while antegrade flow is maintained in the main uterine artery.

Embolization, Therapeutic↗
PubMed2004

Location of vessel occlusion of calibrated tris-acryl gelatin microspheres for tumor and arteriovenous malformation embolization.

PURPOSE: To evaluate (i). the presence and number of calibrated tris-acryl gelatin microspheres (TGMS) in targeted organs after embolization of tumors or arteriovenous malformations (AVMs) and (ii). the possible correlations among the size of TGMS used for embolization, the size of TGMS found in specimens, and the size of the occluded vessels. MATERIALS AND METHODS: Histologic slides were reviewed of 92 specimens from 80 patients with primarily head and neck tumors or AVMs operatively treated after embolization with TGMS of various sizes (40-120 microm, 100-300 microm, 300-500 microm, 500-700 microm, 700-900 microm, and 900-1200 microm). The diameters of the vessels containing TGMS, the size of TGMS, and the thickness of the inflammatory reactions developed around them were measured, and the location of the microspheres was recorded. RESULTS: TGMS were found in 88% of the specimens; 1985 embolized vessels containing TGMS were analyzed. The median number of TGMS per vessel was one (mean +/- SD, 3.1 +/- 6.9). The diameter of the occluded vessels increased significantly (P <.0001) with increased size of TGMS used for embolization. In tumors, 92% of the occluded vessels were located inside the tumor. CONCLUSION: There is an obvious correspondence between the size of the TGMS used for embolization and the diameter of the occluded vessels. This correlation confirms the possibility that the vessels to be occluded can be precisely targeted with the use of a proper TGMS size range.

Angiography↗
PubMed2003

Limited uterine artery embolization with tris-acryl gelatin microspheres for uterine fibroids.

PURPOSE: To evaluate the midterm results of limited embolization of the uterine arteries in the management of symptomatic uterine fibroids and to evaluate the efficacy and safety of limited uterine artery embolization (UAE) with use of calibrated tris-acryl gelatin microspheres in the management of symptomatic uterine fibroids. MATERIALS AND METHODS: Twenty women (mean age, 43 years) with symptomatic uterine fibroids underwent bilateral embolization of the uterine arteries with use of calibrated microspheres. Devascularization of the fibroids was achieved and the main uterine artery was left patent in all women. Embolization was offered as an alternative to surgery in all women who had been treated unsuccessfully with medical therapy. RESULTS: All procedures were technically successful. Microspheres 700-900 micro m in diameter were used in 14 women (70%). After a mean follow-up duration of 30.2 months (range, 24-48 mo), all women reported improvement in their symptoms, with 85% reporting complete resolution of menorrhagia at the most recent follow-up. One woman with multiple fibroids required a second embolization procedure because of persisting symptoms at 6 months. She is currently symptom-free after 48 months. In two women with submucosal fibroids, expulsion of necrotic fibroids occurred 2 and 7 months after the procedure, respectively. All women resumed normal menstruation after the procedure. One woman had a successful full-term pregnancy after embolization. CONCLUSION: Early experience with UAE with use of calibrated tris-acryl gelatin microspheres indicates that it is safe and efficacious in controlling menorrhagia.

Adult↗
PubMed2002

Complement activation by substituted polyacrylamide hydrogels for embolisation and implantation.

An inflammatory reaction has always been observed in vivo around particles used for therapeutic embolisation. Hydrogel microspheres based on Trisacryl, prepared by polymerisation of N-acryloyl-2-amino-2-(hydroxymethyl)-1,3-propanediol in the presence of a crosslinking agent, are amongst the best materials for such a purpose. The aim of this work was to evaluate in vitro the complement-activating capacity of the OH-bearing Trisacryl particles either microporous, or macroporous, or partially substituted with carboxylate, or diethylaminoethyl, or sulphonate groups, in order to be able to decrease the inflammatory reaction in vivo. Complement was activated in the presence of Trisacryl, but about seven times less than in the presence of Sephadex, despite a quasi-similar density in OH groups, and more than two times less than in the presence of hydroxymethylated polystyrene despite a higher OH density. This demonstrates that not only OH density, but also other features linked to the type of polymeric backbone, are involved in complement activation by OH-bearing polymeric surfaces. The microporous and macroporous particles activated complement at a similar level when crushed and a slight increase was observed on the rough surface of the macroporous microspheres, but the presence of the macropores did not increase complement activation. Concerning the effects of substituting groups on Trisacryl, a clear decrease in the complement activation has been found only in the presence of sulphonate groups.

Acrylic Resins↗
PubMed2002

Uterine artery embolization in sheep: comparison of acute effects with polyvinyl alcohol particles and calibrated microspheres.

PURPOSE: To compare the effects on the myometrium of polyvinyl alcohol (PVA) particles and calibrated microspheres (MS) in embolization of the uterine arteries in sheep. MATERIALS AND METHODS: Superselective and bilateral embolization of the uterine arteries was performed with PVA particles and calibrated MS within 24 hours after artificial ovulation in 26 adult nonpregnant sheep. PVA particles of four diameters, 150-250, 250-400, 400-600, and 600-1,000 microm, were compared with calibrated MS of similar diameters, 100-300, 300-500, 500-700, and 700-900 microm, in eight groups of sheep. Evaluation was based on histopathologic study of uterus, ovaries, and vascular pedicles after sacrifice 5 days after embolization. The scores of necrosis, the diameter of occluded arteries, and the number of particles were determined. The scores of uterine necrosis were compared by using nonparametric tests (Mann-Whitney U and Kruskal-Wallis). Spearman rank test was used for correlations. RESULTS: PVA particles clumped more readily than did MS. Small particles had a higher score (P =.02) of uterine necrosis than did large particles. PVA particles produced more necrosis than did MS. Size of MS and diameter of occluded arteries showed significant correlation (rho = 0.762, P <.001). Size of PVA particles and diameter of occluded arteries showed no correlation. PVA particles occluded vessels of a wider range of size than did calibrated MS. CONCLUSION: PVA particles are associated with intense uterine necrosis and extensive arterial occlusion regardless of size. Calibrated MS, which are associated with less uterine necrosis, permit a segmental arterial occlusion correlated with size.

Angiography↗