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ABSTRACT: Endovascular neurosurgery is now becoming available as one of strategies for the treatment of cerebro-spinal arterio-venous malformations and aneurysms. For this treatment, a microcatheter is advanced into or close to a lesion and then an embolic material is administered through it to obliterate the lesion. N-butyl-2-cyanoacrylate (NBCA) has preferentially been used as an embolic material in Europe and America. However, its exceptionally strong adhesive force sometimes causes adhesion between the tip of the microcatheter and the artery. In this study, a new non-adhesive cyanoacrylate, isostearyl-2-cyanoacrylate (ISCA), was developed. It carries a long hydrophobic side isostearyl group with lower reactivity and adhesion than other cyanoacrylates. Its polymerization rate is, however, too low to obliterate a vascular lesion with a rapid blood flow. To increase the polymerization rate. ISCA was mixed with NBCA. As a result, the adhesive force of the mixture became extremely low, compared with that of NBCA. The viscosity of the mixture was low enough to allow its' use as an embolic material. Tissue reactions against the mixture was milder than those against NBCA. Radio-angiography became possible by mixing further with Lipiodol. The evaluation of this new embolic material with a rabbit renal artery showed that the obliteration effect of the mixture of ISCA and NBCA was excellent to use as an embolic material for clinical applications.
Biomaterials 06/2000; 21(10):1039-46. · 7.40 Impact Factor
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ABSTRACT: Local drug delivery is an attractive approach to the associated problems of percutaneous transluminal coronary angioplasty (PTCA), including arterial injury. The objective of the present research was to deliver a high concentration of a potent anti-thrombin agent, argatroban (ARG), to the vessel wall in order to reduce arterial injury. Local delivery was accomplished by the ionic attachment of drug particles to a modified balloon surface. Surface graft polymerization of ionic monomers to a high-density poly(ethylene) (PE) substrate was performed utilizing ultra-violet (UV) methods. Acrylic acid (AAc) and 2(dimethylamino) ethyl methacrylate (DMAEMA) were successfully grafted onto PE surfaces. Surface grafting was verified by contact angle, X-ray photoelectron spectroscopy, and zeta potential measurements. The amount of ARG adsorbed onto the modified PE surface was highly dependent on the pH of the drug media for both anionic and cationic grafted monomers. The efficacy of local drug delivery to the arterial wall was analyzed using drug-immobilized PE balloon catheters in the rabbit common carotid artery model. High concentrations of ARG (280 nmol/g tissue) were found within the ballooned arterial segment immediately after angioplasty, followed by a decrease after blood flow was restored.
Biomaterials 06/2000; 21(10):1057-65. · 7.40 Impact Factor
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ABSTRACT: An immediately electrically detachable coil (IEDC) that we previously developed was modified to enhance the reliability in its detachment system. IEDC is detached by applying a monopolar high-frequency electrical current that heat and disrupt a junction between a platinum coil and a delivery wire. The original IEDC immediately detaches only when the junction is just outside the catheter tip and precise positioning of the junction is required. In the modified IEDC, its delivery wire was insulated with poly tetra fluoroethylene (PTFE) to concentrate electrical current to the junction. The modified IEDC was tested in vitro and in animal experiments. Modified IEDC always detached instantaneously even when the junction was far beyond the catheter tip. Insulated delivery wire enabled the electrical current to be concentrated at the PVA junction and produce appropriate heat to disrupt the junction.
Interventional Neuroradiology 11/1999; 5 Suppl 1:215-8. · 0.56 Impact Factor
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ABSTRACT: We have developed a new liquid material for embolisation of arteriovenous malformations: a mixture of methyl and butyl methacrylate, plus dimethylaminoethyl methacrylate copolymer (Eudragit-E) in a solvent consisting of ethanol and iopamidol. Upon contact with aqueous substances, Eudragit-E precipitates rapidly and forms a soft elastic sponge within 3 s, as the ethanol diffuses. In blood, the positively charged Eudragit-E aggregates the negatively charged blood elements. Transcatheter embolisation of 4 canine and 52 rat renal arteries was feasible. Histological studies revealed no acute inflammatory reaction within 1 week, but mild to moderate reactions in the subacute and chronic stages. No recanalisation was seen. Because of its unique properties and excellent thrombogenicity the Eudragit-E, mixture seems a promising embolic material.
Neuroradiology 06/1996; 38 Suppl 1:S151-6. · 2.82 Impact Factor
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ABSTRACT: Embolization of three surgically difficult cerebral aneurysms was performed using our newly developed non-adhesive embolic material, EVAL mixture (ethylene vinyl alcohol copolymer). Conventional embolic materials such as detachable balloons or microcoils were not used because of a large or irregular aneurysmal neck. After temporary occlusion of the parent artery with a superselective balloon catheter, the EVAL mixture was slowly injected through a microcatheter placed in the aneurysm or parent artery. The locations of the aneurysms were anterior communicating artery, basilar artery-posterior cerebral artery and basilar artery-anterior inferior cerebellar artery (BA-AICA). One aneurysmal occlusion and 2 parent artery occlusions were performed. Patients had no persistent deficits. The patient with the BA-AICA aneurysm associated with an arteriovenous malformation died of rupture of the residual AVM due to haemodynamic change 2 weeks after embolization. In selected and limited cases, embolization of surgically difficult cerebral aneurysms using EVAL mixture was more effective and safer than embolization using conventional embolic materials such as balloons and microcoils.
Acta Neurochirurgica 02/1996; 138(3):294-300. · 1.52 Impact Factor
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ABSTRACT: To determine physical characteristics of mixtures of ethylene vinyl alcohol copolymer (EVAL) and metrizamide dissolved in dimethyl sulfoxide, liquid materials developed for embolization of arteriovenous malformations.
EVAL and dimethyl sulfoxide were mixed in various proportions and sterilized. The viscosity and density of each mixture was measured. Precipitation times were determined by dropping the mixtures into saline or human blood. The mixtures were filtered and the filtrates weighed.
Densities and viscosities of the various mixtures differed significantly, proportionally to the concentration of EVAL. Precipitation times also differed significantly, in inverse proportion to the concentration of EVAL. Temperature and aqueous solution did not affect precipitation times significantly. The weight of the filtrate significantly increased with time but was constant for each precipitation time. Temperature significantly affected filtrate weight; aqueous solution did not.
Because of their different physical properties, the various EVAL mixtures are suited to embolizing different types of arteriovenous malformations.
American Journal of Neuroradiology 07/1994; 15(6):1103-5. · 2.93 Impact Factor
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ABSTRACT: An eighteen year-old boy presented sudden loss of consciousness and tetraparesis. Radiological examinations revealed a ruptured midbrain arteriovenous malformation (AVM) at the right quadrigeminal plate. The patient recovered from symptoms by conservative treatment over 6 months with residual right hemisensory disturbance and mild diplopia during bilateral horizontal gaze. One year later, he was admitted to our institute for radical treatment of the AVM. On the angiography, the AVM was fed by two branches of the right long circumferential artery and a left paramedian penetrating artery of the posterior cerebral artery (PCA), and drained into the straight sinus via a dilated quadrigeminal vein. After much discussion on several strategies, endovascular surgery was chosen as a radical treatment. In the initial session, a medial branch of the right long circumferential artery was catheterized with Tracker-18, and embolized with 1.0 ml of ethylene vinyl alcohol copolymer (EVAL) without any deficits after negative provocative tests using Amytal and Xylocaine. Then, a lateral branch of the same artery was embolized with 0.8 ml of EVAL in the same way without any deficits. In the second session, catheterization into the left paramedian artery was difficult because of its small diameter and steep branching angle, and only a 3 mm hooked tip of Tracker-18 could be canulated into the feeding pedicle. Left oculomotor palsy was induced by provocative Xylocaine test. However, angiographic cure of the AVM was expected to be made possible by the occlusion of this pedicle, and the procedure was continued due to the request of the patient and his family.(ABSTRACT TRUNCATED AT 250 WORDS)
No shinkei geka. Neurological surgery 02/1993; 21(1):67-72. · 0.13 Impact Factor
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ABSTRACT: Three patients presented with rare giant posterior cerebral artery aneurysms, clinically manifesting as cerebral ischemia, mass effect, and subarachnoid hemorrhage. All aneurysms were partially thrombosed, originated at the P2 segment, and possessed broad necks. Surgical neck clipping was difficult but proximal occlusion of the parent artery was feasible. Aneurysm occlusion sparing the parent artery was attempted in all cases, but failed because the detachable balloon did not successfully block the aneurysmal neck. All patients tolerated test occlusion at the P2 segment, so the parent artery was occluded proximally with detachable balloons, leaving the important perforating arteries unaffected. Two transient ischemic attacks were associated with the procedure. Where surgical treatment is unusually difficult, and proximal ligation or trapping just feasible, embolization with detachable balloons is an acceptable substitute.
Neurologia medico-chirurgica 09/1992; 32(9):679-83. · 0.61 Impact Factor
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ABSTRACT: Between April, 1989, and January, 1991, a total of 19 cases of giant aneurysm were treated by the endovascular approach. The patients included seven males and 12 females aged 15 to 72 years. Detachable balloons, occlusion coils, and ethylene vinyl alcohol copolymer liquid were used as embolic materials. In seven cases, thrombosis of the aneurysmal sac and/or base was achieved while sparing the parent arterial flow, complete obliteration of the aneurysm was achieved in four of these. Of these four patients, the thrombotic material was a detachable balloon in two, a combination of a detachable balloon and coils in one, and occlusion liquid in one. In the other three cases, complete occlusion was not achieved; one aneurysm was occluded with a detachable balloon and two with coils. In 11 patients, the parent artery was occluded either by trapping or by proximal arterial occlusion, and all patients showed complete occlusion of the aneurysms. In one patient, a combined bypass procedure and parent artery occlusion was performed. Among the 19 cases in this series there were four transient ischemic attacks, one reversible ischemic neurological deficit, and one death due to aneurysmal rupture during the procedure. Two patients died in the follow-up period, one from pneumonia 2 months postoperatively and the other from acute cardiac failure 2 weeks following surgery. Both deaths were unrelated to the endovascular procedure. It is concluded that the endovascular treatment of giant aneurysms remains difficult because of the large and irregular shape of the aneurysmal base and thrombus in the aneurysmal sac. The proper selection and combination of the available endovascular techniques is therefore of critical importance.
Journal of Neurosurgery 08/1992; 77(1):37-42. · 2.96 Impact Factor
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ABSTRACT: We report a case with a giant PCA aneurysm successfully treated using the detachable balloon technique. The case was a 52 year-old man with episodes of minor stroke probably due to the giant aneurysm. The aneurysm was located in the P2 segment of the right PCA and was broad-based. Clipping of the neck was considered to be impossible and proximal clipping was the alternative treatment. Instead of surgery, proximal occlusion of the PCA was performed with the use of a detachable balloon.
No shinkei geka. Neurological surgery 08/1992; 20(7):787-91. · 0.13 Impact Factor
