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Biomedical subjects

G Guglielmi

Publications and source records attributed to G Guglielmi.

At least 73 records · Page 4Linked to original sources
PubMed1996

Endovascular treatment of arteriovenous malformations with selective intranidal occlusion by detachable platinum electrodes: technical feasibility in a swine model.

The technical feasibility of selective intranidal endovascular occlusion of experimental arteriovenous malformations with detachable superfine platinum electrodes was assessed in a swine model. The delivery and release of electrodes were performed within normal carotid retia mirabilia, the faster-flowing nidus (bilateral retia) of a carotid-jugular fistula-type model of an arteriovenous malformation, and a small-caliber H-type direct arteriovenous fistula. Controllable atraumatic placement of the electrodes was possible deep within each rete and in the middle of the fistula. The devices were soft and flexible, allowing them to conform to the tight turns and branches of rete vessels. Marked diminution of flow was achieved by release of multiple devices within each rete. Migration of the electrode occurred when detached within the larger-caliber arteriovenous fistula. The main advantages of this technique appear to be the controlled delivery and assured release of an occlusive radiopaque embolic agent within the nidus.

Animals↗
PubMed1996

Laboratory simulations and training in endovascular embolotherapy with a swine arteriovenous malformation model.

We assessed the suitability of a swine experimental arteriovenous malformation model for laboratory simulations and training in endovascular embolotherapy. Embolizations with liquid glue or particles were performed in 10 animals. The parameters of injection (microcatheter position, concentration and volume of embolic agent, injection rate) were deliberately varied to simulate results that may be observed in clinical practice. A range of successful and less desirable therapeutic outcomes or complications was simulated. In one model, intravascular mean blood pressure in the "terminal feeder" rose after "nidus" embolization, consistent with observations in feeders of cerebral arteriovenous malformations. Experience in the technical aspects of embolotherapy was gained by repeated performances using this model. Simplicity of creation, clear angiographic visibility of feeders, a nidus and a draining vein, and hemodynamic similarities with cerebral arteriovenous malformations make this an attractive in vivo experimental model for learning the principles of embolotherapy, testing new embolic agents, and training/gaining experience in embolization techniques.

Animals↗
PubMed1995

Two concurrent spinal dural arteriovenous fistulae in a patient with rapidly progressive myelopathy. A case report.

A rare case of two separate spinal dural arteriovenous fistulae (DAVFs) occurring concurrently in a patient with a rapidly progressive myelopathy is reported. Although concurrent spinal DAVFs may be "well known," their occurrence has been only anecdotally reported. To the authors' knowledge, this well documented case of a presumably rare variant of spinal DAVFs is the first to appear in the literature and is instructive for reconsidering approaches to optimal diagnosis and evaluation of posttherapeutic efficacy of these lesions.

Angiography↗
PubMed1995

Correlation of the angioarchitectural features of cerebral arteriovenous malformations with clinical presentation of hemorrhage.

Superselective angiography is the most accurate technique in the analysis of brain arteriovenous malformation (AVM) angioarchitecture. Therefore, we reviewed the selective and superselective angiograms of 100 consecutive patients with intracerebral AVMs. Our purpose was to determine which parameters of angioarchitecture were significantly correlated with a clinical presentation of hemorrhage. The vascular characteristics evaluated on the angiograms were the size of the AVM, the location of the AVM, the type of nidus, the type of feeders, the characteristics of venous drainage, and the number and location of aneurysms. The parameters found to correlate with hemorrhage were deep venous drainage (P = 0.01), feeding by perforators (P = 0.01), intranidal aneurysm(s) (P = 0.004), multiple aneurysms (P = 0.001), feeding by the vertebrobasilar system (P = 0.002), and location in the basal ganglia (P = 0.04). Six parameters of AVM angioarchitecture were correlated with a clinical presentation of hemorrhage. Among these parameters, three (feeding by perforators, number of aneurysms, and presence of intranidal aneurysms) were well displayed by superselective angiogram.

Adolescent↗
PubMed1995

Neurosurgical management of cerebral aneurysms following unsuccessful or incomplete endovascular embolization.

Modern endovascular techniques permit treatment of intracranial aneurysms in many circumstances when surgery is associated with significant morbidity. Occasionally, embolization of aneurysms is unsuccessful or incomplete or followed by complications, in which case surgical management is required. Since 1986, 196 patients have undergone embolization of intracranial aneurysms at the authors' institution and 21 (11%) required subsequent surgical treatment. Attempted embolization failed in five patients (Group A). Ten patients (Group B) had only partial occlusion of the aneurysm or demonstrated recanalization on follow-up studies. Eight of these Group B patients underwent embolization with Guglielmi detachable coils (GDCs), representing 5.7% of the 141 GDC-treated patients in this experience. Surgical treatment in these two groups consisted of clipping (eight cases), surgical parent vessel occlusion (one case), and parent vessel occlusion with extracranial-intracranial bypass (six cases). Fourteen (93%) of the 15 patients in these two groups had an excellent or good outcome with complete aneurysm occlusion. Six patients underwent surgery to treat complications related to the endovascular procedure (Group C). Of these, four patients had neurological improvement compared to their preoperative state, and two died. This series of cases demonstrates that surgical treatment of aneurysms is usually possible with good results following incomplete embolization and emphasizes the need for close and continued neurosurgical involvement in the endovascular management of intracranial aneurysms.

Adult↗
PubMed1995

Current methods and advances in bone densitometry.

Bone mass is the primary, although not the only, determinant of fracture. Over the past few years a number of noninvasive techniques have been developed to more sensitively quantitate bone mass. These include single and dual photon absorptiometry (SPA and DPA), single and dual X-ray absorptiometry (SXA and DXA) and quantitative computed tomography (QCT). While differing in anatomic sites measured and in their estimates of precision, accuracy, and fracture discrimination, all of these methods provide clinically useful measurements of skeletal status. It is the intent of this review to discuss the pros and cons of these techniques and to present the new applications of ultrasound (US) and magnetic resonance (MRI) in the detection and management of osteoporosis.

Absorptiometry, Photon↗
PubMed1995

Molecular biology studies on mesothelioma tumor samples: preliminary data on H-ras, p21, and SV40.

The ras gene is one of the oncogenes most commonly detected in human cancers; this protooncogene is converted to active oncogene by point mutations occurring at either codon 12, 13, or 61. SV40 is a DNA-transforming simian virus, a 105 bp sequence of which has been shown recently to be present in a significant fraction of human mesothelioma cells. Eleven human malignant mesotheliomas were examined for H-ras gene mutations at codon 12, 13, and 61 and for the presence of SV40-like sequences. DNA prepared from formalin-fixed and paraffin-embedded tissue was amplified by means of PCR and analyzed using designed restriction fragment length polymorphism. No mutation with respect to H-ras was found in any tumor sample, but the majority of mesothelioma cells contained SV40-like sequences.

Adult↗
PubMed1995

Acute subdural hemorrhage complicating embolization of a cerebral arteriovenous malformation.

We present a case of a young adult in whom acute subdural hemorrhage developed immediately after embolization of a cerebral arteriovenous malformation with glue. Inadvertent venous outlet obstruction with glue was implicated in the production of the hemorrhage. Possible mechanisms of spread of blood to the subdural space are discussed. Awareness of the possibility of iatrogenic subdural hemorrhage is necessary before undertaking embolization procedures.

Adolescent↗
PubMed1995

Collagen microbeads: experimental evaluation of an embolic agent in the rete mirabile of the swine.

PURPOSE: To evaluate the histologic and angiographic effects of collagen microbeads as an embolic agent in the swine rete mirabile. METHODS: Human collagen particles (380 +/- 100 microns) of spheroidal shape and smooth surface were used to embolize the rete mirabile in five swine. Control angiograms and pathologic examinations were obtained immediately and sequentially from 3 to 35 days after embolization. RESULTS: The collagen particles were easy to inject through microcatheters. Embolization was always angiographically complete and persistent for at least 5 weeks. Histologic studies showed occlusion of 25% to 50% of the rete vessels. After 3 and 5 weeks' follow-up, transmural and adventitial chronic inflammation was present. Inflammatory infiltrates included lymphohistiocytic cells and scattered eosinophils. The foreign-body giant-cell reaction was pronounced. No evidence of angionecrosis or focal hemorrhage was shown. CONCLUSIONS: Collagen microbeads are a promising experimental embolic agent, with potential future applications in humans.

Animals↗
PubMed1995

High-flow, small-hole arteriovenous fistulas: treatment with electrodetachable coils.

We present one case of carotid-cavernous fistula caused by percutaneous treatment of trigeminal neuralgia and one case of vertebrovertebral fistula caused by percutaneous internal jugular vein cannulation. Each fistula had a small arteriovenous communication that prevented the use of detachable balloons. Endovascular transarterial treatment of these two iatrogenic fistulas with electrically detachable platinum coils was performed. Both fistulas were occluded with preservation of the parent artery, and the patients have fully recovered.

Aged↗
PubMed1995

Epilepsy associated with cerebral arteriovenous malformations: a multivariate analysis of angioarchitectural characteristics.

PURPOSE: To identify the morphological vascular characteristics of cerebral arteriovenous malformations (AVMs) that predict a clinical presentation of epilepsy. METHOD: Fifteen angioarchitectural characteristics of brain AVMs were selected for assessment in 100 consecutive patients referred to our institution for endovascular treatment. In this population, 47% of the AVMs were diagnosed as a consequence of epilepsy. The angioarchitectural characteristics and population demographics were statistically analyzed by means of multivariate analysis. RESULTS: The following six parameters were found to be the most predictive of epilepsy: cortical location of the AVM, feeding by the middle cerebral artery, cortical location of the feeder, absence of aneurysms, presence of varix/varices in the venous drainage, and association of varix and absence of intranidal aneurysms. Three factors were not among the most predictive factors of epilepsy but were significantly associated with the onset of seizures: AVM feeding by the external carotid artery, a temporal cortical location, and a parietal cortical location. CONCLUSION: Detailed analysis of the angioarchitecture of intracranial AVMs has helped us identify features that strongly correlate with epilepsy. This may aid in future understanding of the physiopathologic mechanisms in epilepsy associated with AVMs, and in identifying goals of treatment for epileptogenic AVMs.

Adolescent↗
PubMed1994

Dual x-ray absorptiometry forearm software: accuracy and intermachine relationship.

An ash study was performed to analyze the accuracy of forearm measurements at the one-third site of three dual x-ray absorptiometry (DXA) systems using 20 cadavers. A Hologic QDR-2000, a Hologic QDR-1000/W, and a Lunar DPX-L system were used. The correlations between ash weight and DXA BMC were excellent for the three instruments (r > 0.97, p < 0.001), with accuracy errors < 5.2%. To perform a forearm cross-calibration of bone mineral content (BMC) and density (BMD) between the scanners, 10 healthy volunteers were additionally scanned at the distal one-third radius. The correlations among the DXA machines were excellent (r > 0.95); the absolute BMC and BMD values were significantly different between the two Hologics and the Lunar machine. The slope and intercept of both the BMC and BMD between the two Hologic systems were close to unity. In conclusion, the DXA forearm software packages provide accurate methods for assessing bone mineral content and density. The conversion of data among different manufacturers should be performed by careful cross-calibration measurements.

Absorptiometry, Photon↗
PubMed1994

Experimental saccular aneurysms. I. Review of surgically-constructed models and their laboratory applications.

Experimental models of intracranial saccular aneurysms are a useful contribution to our basic understanding of these lesions. Currently, the commonest in use are those constructed surgically in laboratory animals. We review the numerous surgical techniques available since the 1950s, and the research applications and uses of experimental aneurysms. Further development and use of such models is greatly encouraged in future pathophysiological, hemodynamic, and therapeutic investigations of intracranial saccular aneurysms.

Animals↗
PubMed1994

Experimental saccular aneurysms. II. A new model in swine.

A new technique for surgical construction of experimental lateral saccular aneurysms on the common carotid artery of swine is described. It involves end-to-side suturing of an isolated segment of vein to an artery. During a short period of parent artery clamping, an elliptical arteriotomy is fashioned through the open-ended vein graft, the open end of which is subsequently tied and clamps are removed to form an aneurysmal vein pouch. The principal advantage of this technique is the short period of vascular clamping necessary to isolate a segment of the parent artery. This prevents severe endothelial injury and prolonged postoperative vasospasm, both of which may promote intra-aneurysmal thrombosis. Narrow- or wide-necked aneurysms can be created. Steps in the surgical construction of this model are detailed, and specific advantages of using swine are highlighted.

Animals↗
PubMed1994

Saccular aneurysms in moyamoya disease: endovascular treatment using electrically detachable coils.

Moyamoya disease (MMD) often presents with subarachnoid hemorrhage due to rupture of saccular aneurysms. We describe three patients with cerebrovascular features of MMD in whom four aneurysms of the posterior circulation were endovascularly occluded by electrothrombosis using the recently developed Guglielmi electrically detachable coils (GDC). Near total occlusion was achieved in three aneurysms. Subtotal occlusion was achieved in one aneurysm. This patient developed complications related to the neuroleptic anesthesia administered for the procedure. The particular hazards of anesthesia and aneurysmal surgery in MMD are discussed, and comparison is made with the benefits of using the GDC. Initial experience suggests that this endovascular approach is safe and effective in the treatment of saccular aneurysms in MMD. However, follow-up is necessary to assess long-term persistence of aneurysm obliteration.

Adult↗
PubMed1994

Osteoporosis: diagnosis with lateral and posteroanterior dual x-ray absorptiometry compared with quantitative CT.

PURPOSE: To compare the diagnostic sensitivity of posteroanterior and lateral dual x-ray absorptiometry (PA-DXA, L-DXA, respectively) and quantitative computed tomography (CT). MATERIALS AND METHODS: Among 108 women undergoing lumbar spine bone mineral density assessment, 66 were healthy (mean age, 52.9 years +/- 1.2 [standard error of mean]) and 42 had osteoporosis (mean age, 66.9 years +/- 1.2). RESULTS: Although both L-DXA and PA-DXA correlated well with quantitative CT (r = .73 and .72, respectively; P < .0001), L-DXA correlated better than PA-DXA with age (r = -.69 and -.50, respectively; P < .0001). Women with osteoporosis showed higher bone loss with quantitative CT (1.33% per year) and L-DXA (0.3% per year) than with PA-DXA (0.07% per year). Logistic regression analysis indicated that quantitative CT and L-DXA but not PA-DXA are significant predictors of osteoporotic fractures. Receiver-operating-characteristic curve analyses showed L-DXA to have a sensitivity and specificity closer to those of quantitative CT than did PA-DXA. CONCLUSION: Performance of L-DXA helped discriminate better than PA-DXA between healthy subjects and those with osteoporosis.

Absorptiometry, Photon↗
PubMed1994

Radiographic absorptiometry for bone mineral measurement of the phalanges: precision and accuracy study.

PURPOSE: To evaluate the accuracy and precision of a radiographic absorptiometry (RA) method for assessment of bone mineral of the middle phalanges. MATERIALS AND METHODS: Nineteen cadaveric hands were radiographed with an aluminum wedge, once at 50 kVp and 400 mA and once at 60 kVp and 300 mA. Bone mineral content (BMC) and bone mineral density (BMD) of the second to fourth middle phalanges, expressed in arbitrary units (BMC-AU and BMD-AU), were analyzed and averaged in each hand. RESULTS: The precision error of this method was 1.0% for BMC-AU and 0.6% for BMD-AU. A 2.0%-2.4% reduction in BMD-AU seen on radiographs obtained through ethanol thicknesses of 5 and 6 mm compared with that seen on controls was statistically significant (P < .01). The correlation between BMC-AU and forearm BMC determined with dual x-ray absorptiometry was good (r = .887), and that between BMC-AU and ash weight in the phalanges was excellent (r = .983). CONCLUSION: The RA method is precise and accurate for bone mineral assessment of the peripheral appendicular skeleton.

Absorptiometry, Photon↗