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Biomedical subjects

J E Dion

Publications and source records attributed to J E Dion.

At least 19 recordsLinked to original sources
PubMed2001

In vitro effects of transcatheter injection on structure, cell viability, and cell metabolism in fibroblast-impregnated alginate microspheres.

PURPOSE: To determine if microsphere-encapsulated cell preparations can be delivered through a microcatheter without compromising microsphere structure, cell viability, or metabolism. MATERIALS AND METHODS: Fibroblast-impregnated microspheres were fabricated by using 1.0% alginate and rabbit synovial fibroblasts. Fibroblast-impregnated alginate microspheres injected through microcatheters were analyzed in parallel with identical noninjected microspheres. The effects of transcatheter injection on structure and cell viability (percentage of viable cells per microsphere) were correlated with microsphere size. Structural effects were analyzed by using light microscopy, and 7-day percentage (ratio of live cells to dead cells) cell viability was assessed with confocal microscopy and fluorescent staining. In a second series of experiments, the metabolism of small microspheres was studied during a course of 7 days by using a spectrophotometric bioanalyzer. RESULTS: Transcatheter injection caused fracturing and/or fragmentation of large (800-1,000 microm) and medium (500-750 microm) microspheres, while small (250-400 microm) microspheres were structurally unaffected by transcatheter injection. Fracturing and fragmentation were associated with cell release from the alginate matrix. Although transcatheter injection reduced cell viability by 17%-23% in all size categories, it did not cause a detectable alteration in the rate of glucose metabolism. CONCLUSION: Transcatheter injection was physiologically well tolerated by fibroblasts encapsulated in alginate microspheres; however, when microsphere diameter exceeded the catheter diameter, fracturing and fragmentation of microspheres compromised the sequestration function of the microsphere vector.

Alginates↗
PubMed2001

Endoluminal stent placement and coil embolization for the management of carotid artery pseudoaneurysms.

PURPOSE: To present a series of carotid artery pseudoaneurysms treated successfully using an endovascular approach. METHODS: From April 1995 to November 1999, 5 patients with neurological symptoms not explained by computed tomography of the head were identified by carotid angiography as having internal carotid artery (ICA) pseudoaneurysms. Three patients had sustained blunt trauma, and 2 had previous elective carotid endarterectomies for atherosclerotic disease. The time between injury and treatment ranged from 3 days to 10 years. The patients were treated with endovascular stent placement for exclusion of the pseudoaneurysm, followed by filling of the cavity with multiple detachable coils. Patients were maintained on oral antiplatelet agents or anticoagulant therapy after the procedure. RESULTS: Primary technical success was 100%. No patient suffered permanent neurological sequelae. Postprocedure angiography demonstrated a patent ICA in all cases, with complete obliteration of the pseudoaneurysm. At a mean 8.4-month follow-up (range 2-21), all patients remained symptom free; angiograms in 3 patients at a mean 11.7 months demonstrated continued ICA patency. One patient had a 60% focal narrowing of the distal common carotid artery, which was treated successfully with balloon dilation and stenting. CONCLUSIONS: Endovascular treatment of carotid artery pseudoaneurysms is a useful alternative to standard surgical repair. This modality avoids the necessity for surgical exposure at the skull base with its inherent morbidity.

Adult↗
PubMed2001

Bilateral type 1 proatlantal arteries with absence of vertebral arteries.

The persistent proatlantal artery is a well-described communication between the carotid and vertebrobasilar system. However, persistence of bilateral proatlantal arteries is exceptionally rare. Although usually noted as an incidental finding, the presence of a proatlantal artery, particularly when bilateral, may result in unusual symptoms or may have implications for therapy. We report a case of bilateral proatlantal arteries, describe their embryology, and consider potential clinical implications of this finding.

Angiography, Digital Subtraction↗
PubMed2001

Use of abciximab for mediation of thromboembolic complications of endovascular therapy.

We describe four cases in which abciximab was used as a thrombolytic rescue agent in the setting of thrombotic events complicating interventional neuroradiologic procedures. After IV administration of abciximab, the thrombus resolved within 30 min in three cases, whereas no thrombolysis occurred in the fourth case despite the addition of intraarterial tissue plasminogen activator. Further evaluation of glycoprotein IIb-IIIa inhibitors in patients with cerebral thromboembolic events is necessary to prove clinical efficacy.

Abciximab↗
PubMed2000

Adjuvant use of epsilon-aminocaproic acid (Amicar) in the endovascular treatment of cranial arteriovenous fistulae.

We report our experience with the use of the antifibrinolytic agent epsilon-aminocaproic acid (EACA), Amicar, as an adjuvant to endovascular treatment of cranial arteriovenous fistulae. We also review applications of antifibrinolytic agents to neurovascular disorders and discuss the mechanism of action, dosing strategy, contraindications, and possible complications associated with the use of EACA. We identified 13 patients with cranial arteriovenous fistulae (five direct carotid cavernous fistulae [CCF], seven dural arteriovenous fistulae [DAVF], and one vein of Galen malformation) who received EACA as an adjunct to endovascular treatment. In all cases embolic coils were the primary embolic agent. We reviewed the modes of initial endovascular therapy and angiographic findings immediately thereafter and the response to EACA. Two direct CCF and two DAVF were completely thrombosed on follow-up angiography, and two DAVF demonstrated diminished flow after EACA therapy. Seven fistulae did not respond to EACA. Four of eight tightly coiled fistulae thrombosed, while none of five loosely coiled fistulae thrombosed. None of four cases with a residual fistula separate from the coil mass underwent thrombosis with EACA, while four of nine cases without a separate fistula thrombosed. There was no morbidity related to EACA therapy. EACA may thus be useful as an adjunct to endovascular treatment of cranial arteriovenous fistulae. Loose or incomplete coil packing of the fistula predicts a poor response to EACA therapy.

Adolescent↗
PubMed2000

Endovascular treatment of intracranial aneurysms with Guglielmi Detachable Coils: emphasis on new techniques.

Endovascular therapy for intracranial aneurysms has evolved since Serbinenko pioneered embolisation with latex balloons in the 1970s. The focus of modern endovascular therapy has shifted to the use of Guglielmi Detachable Coils (GDC; Boston Scientific Corporation, Natick, MA, USA) which are retrievable until the operator is satisfied with placement and they are detached. GDC therapy has been shown to be most efficacious in smaller aneurysms with relatively large dome:neck ratios which allow maximal coil packing within the aneurysm lumen. Wide neck aneurysms with dome:neck ratios of less than 2.0 and large aneurysms have a significantly lower incidence of complete treatment, with higher rates of repeat rupture following GDC therapy. The geometry of wide neck aneurysms is less favourable for retention of coils within the aneurysm lumen, resulting in greater risk of parent vessel compromise from coil herniation and difficulty obtaining maximal coil packing. This chapter will summarise GDC therapy for intracranial aneurysms including newer techniques designed to address the problem of wide neck aneurysms.

Angioplasty, Balloon↗
PubMed2000

Bovine type I collagen as an endovascular stent-graft material: biocompatibility study in rabbits.

PURPOSE: To study the biocompatibility of a bovine type I collagen preparation as a material for small-vessel stent-grafts in rabbits. MATERIALS AND METHODS: A composite nitinol-collagen endovascular stent-graft with a 4-mm inner diameter was deployed in the abdominal aorta in nine rabbits. Angiography was performed, and the rabbits were sacrificed at 1, 2, and 7 days and at 1 and 3 months. The portion of the aorta containing the stent-graft was excised and was histologically evaluated. RESULTS: All stent-grafts were patent at all time points. On days 1, 2, and 7 after implantation, scattered red and white blood cells adhered to the stent-graft. At 1 month, the stent-graft was endothelialized and was infiltrated with fibroblasts that deposited collagen within the interstices of the implanted collagen material. At 3 months, there was additional collagen deposition within the interstices of the stent-graft that did not narrow the lumen of the stent-grafts. CONCLUSION: Type I collagen as a intravascular stent-graft material is biocompatible for at least 3 months in rabbits. It is rapidly endothelialized and does not cause reactive stenosis. As a versatile and biocompatible polymer, collagen is potentially useful in the construction of endovascular stent-grafts for use in human arteries.

Alloys↗
PubMed2000

Arterial dissections complicating cerebral angiography and cerebrovascular interventions.

BACKGROUND AND PURPOSE: Iatrogenic dissections are an uncommon complication of cerebral angiography. We retrospectively reviewed 12 cases of arterial dissections complicating cerebral angiography and cerebrovascular interventions to evaluate the clinical course of these dissections. METHODS: Cases from a large tertiary center performing a large number of neurovascular procedures were collected retrospectively. The patients' medical records and imaging studies were reviewed, with particular attention given to the cause of the dissection, the development of ischemic events resulting from the dissection, and the treatment used. RESULTS: Each of nine dissections affected a vertebral artery, each of two affected an internal carotid artery, and one affected a common carotid artery. The prevalence of iatrogenic dissections was 0.4%. Seven of the dissections were noted at the time of contrast material injection for the filming of cerebral angiograms. The other five dissections occurred during catheter or wire manipulations for interventional neuroradiologic procedures. Five of the patients in our series were treated with IV administered heparin for 24 to 48 hours. The other seven patients had recently suffered acute intracranial hemorrhage or undergone neurosurgery and could not undergo anticoagulant therapy. None of the patients developed symptoms of ischemia, but one was later found to have an asymptomatic infarct in the territory supplied by the dissected artery. CONCLUSION: Arterial dissections are an uncommon complication of cerebral angiography and cerebrovascular interventions and usually have a benign clinical course.

Adult↗
PubMed2000

Abciximab rescue in acute carotid stent thrombosis.

Occlusion of an internal carotid artery stent was identified immediately post placement in a patient who had restenosis after prior angioplasty. An IV dose of abciximab was administered, and serial angiograms were performed. This resulted in partial resolution of the thrombus at 10 minutes and complete resolution at 20 minutes.

Abciximab↗
PubMed2000

Preoperative and palliative embolization of vertebral tumors.

Embolization of vertebral tumors is useful as an adjunct to surgery because it can minimize blood loss. Embolization also may decrease surgical operating time and reduce complications by improving visualization in the operative field. It also is occasionally useful as a palliative measure to relieve pain or neurologic compromise in patients with unresectable tumors. Spinal embolization is a relatively safe procedure when performed with proper technique by experienced operators.

Embolization, Therapeutic↗
PubMed1999

Endovascular creation of an in vivo bifurcation aneurysm model in rabbits.

PURPOSE: To develop a rabbit model of an intracranial bifurcation aneurysm to test new endovascular therapies. MATERIALS AND METHODS: An experimental aneurysm model was created in rabbits by means of endovascular balloon occlusion of the left common carotid artery, which created an aneurysm at the bifurcation formed by the aortic arch and the brachiocephalic trunk. A total of 18 aneurysms were created. In eight rabbits, the aneurysms were incubated with intraluminal elastase to induce degeneration of the elastic laminae. The animals were followed up with angiography for as long as 3 months. The animals were sacrificed at various times, and histologic evaluation of the aneurysm was performed. RESULTS: Ten aneurysms created without elastase infusion were all very small or completely closed at 1-3 months. Six aneurysms created with elastase infusion had long-term patency (two were patent at 1 month and four, at 3 months). The elastase aneurysms had a mean width of 3 mm (range, 2-3.5 mm) and a mean length of 5 mm (range, 3-7 mm). Histologic evaluation revealed destruction of the normal elastin layers, which allowed the artery to become aneurysmal. CONCLUSION: This aneurysm model re-created the hemodynamic forces and size of human cerebral bifurcation aneurysms and maintained the integrity of the endothelium. The creation of the aneurysms was rapid, reliable, and reproducible.

Animals↗
PubMed1999

Risk of cerebral angiography in patients with subarachnoid hemorrhage, cerebral aneurysm, and arteriovenous malformation: a meta-analysis.

BACKGROUND AND PURPOSE: A well-defined complication rate of cerebral angiography in patients with subarachnoid hemorrhage (SAH), cerebral aneurysm, and arteriovenous malformation (AVM) would be useful to physicians making decisions regarding the imaging of these patients. We sought to define a statistically significant complication rate through meta-analysis of prospective studies in the literature. METHODS: Meta-analysis of 3 published prospective studies of complications in cerebral angiography was performed to specifically define the risk of cerebral angiography in patients presenting with SAH, cerebral aneurysm, and AVM. The complication rates for cerebral angiography in patients with SAH and AVM/aneurysm without SAH were compared with the complication rates in patients who underwent cerebral angiography for transient ischemic attack (TIA)/ischemic stroke with use of the Fisher exact test. RESULTS: The combined risk of permanent and transient neurological complication was significantly lower in patients with SAH compared with patients with TIA/stroke (1.8% versus 3.7%; P=0.03). The combined risk of permanent and transient neurological complication was significantly lower in patients with aneurysm/AVM without SAH compared with patients with TIA/stroke (0.3% versus 3.7%; P=0.001). When the patients with SAH and cerebral aneurysm/AVM were combined, the overall risk of permanent and transient neurological complication was significantly lower than for the TIA/stroke patients (0.8% versus 3.0%; P=0.001), as was the risk of permanent neurological complication (0.07% versus 0.7%; P=0.004). CONCLUSIONS: The risk of permanent neurological complication associated with cerebral angiography in patients with SAH, cerebral aneurysm, and AVM is quite low (0.07%). This risk is lower than previously recognized.

Arteriovenous Malformations↗
PubMed1999

Endovascular treatment of ruptured, peripheral cerebral aneurysms: parent artery occlusion with short Guglielmi detachable coils.

We report two cases of distal cerebral aneurysms that were treated by parent artery occlusion with short Guglielmi detachable coils (GDCs). One patient had a presumed mycotic aneurysm of the distal left posterior cerebral artery, and the other had a partially clipped aneurysm of the distal right anterior inferior cerebellar artery that had hemorrhaged. Short GDCs allow controlled, accurate occlusion of the parent artery at the aneurysmal neck.

Aneurysm, Infected↗
PubMed1999

Dural arteriovenous fistula of the cervical spine presenting with subarachnoid hemorrhage.

We describe a case of dural arteriovenous fistula (DAVF) presenting with subarachnoid hemorrhage (SAH). The diagnosis of DAVF was based on spinal angiography. A review of the literature revealed that five of 13 previously reported DAVFs of the cervical spine were accompanied by SAH. SAH has not been observed in DAVFs involving other segments of the spinal canal.

Angiography↗
PubMed1999

Exposure of medical personnel to methylmethacrylate vapor during percutaneous vertebroplasty.

The occupational exposure to methylmethacrylate (MMA) vapor during percutaneous vertebroplasty was determined. During five vertebroplasty procedures, air-sampling pumps were attached to medical personnel. MMA vapor levels in the samples were then quantified using gas chromatography. The samples collected yielded MMA vapor levels of less than five parts per million (ppm). The MMA vapor concentrations measured were well below the recommended maximum exposure of 100 ppm over the course of an 8-hour workday.

Air Pollutants, Occupational↗