RESUMO
A magnetic guidance methodology to rotate a device around the catheter axis is proposed. The specific medical application is to intracranial aneurysms. An endovascular device, the asymmetric stent, has a low porosity region that is rotated to cover the aneurysm neck so as to reduce the blood flow into and hence obliterate the aneurysm. The magnetic guidance system consists of a magnetic device attached to the asymmetric stent and an external homogeneous magnetic field of 0.1 T. This magnetic field puts a torque on the magnetic moment of the magnetic device, thereby rotating the stent for proper orientation. For the magnetic device with the required magnetic moment of 0.001 A m2, a cylindrical neodymium permanent magnet is proposed due to its favorable material characteristics while a coil electromagnet with iron core appears impractical due to demagnetizing effects.
Assuntos
Prótese Vascular , Cateterismo/instrumentação , Cateterismo/métodos , Magnetismo/instrumentação , Magnetismo/uso terapêutico , Implantação de Prótese/métodos , Desenho Assistido por Computador , Desenho de Equipamento , Análise de Falha de EquipamentoRESUMO
[reaction: see text] Bisketenes O=C=CH(CH(2))(n)()CH=C=O (1b,c,d, n = 4, 3, 6) and (E)-O=C=CHCH=CHCH=C=O (E-13) were generated in solution by dehydrochlorination of bis(acyl chlorides) and by photochemical Wolff rearrangements and identified by their characteristic IR signals. The bisketenes react with aminoxyl radicals to give tetraaddition products for 1b and conjugate 1,6-diaddition for E-13.