Computational fluid dynamics of blood flow in coil-embolized aneurysms: effect of packing density on flow stagnation in
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ORIGINAL ARTICLE
Computational fluid dynamics of blood flow in coil-embolized aneurysms: effect of packing density on flow stagnation in an idealized geometry Tomohiro Otani • Masanori Nakamura • Toshiyuki Fujinaka Masayuki Hirata • Junko Kuroda • Katsuhiko Shibano • Shigeo Wada
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Received: 24 April 2012 / Accepted: 10 March 2013 / Published online: 26 March 2013 Ó International Federation for Medical and Biological Engineering 2013
Abstract Coil embolization is performed to induce flow stagnation in cerebral aneurysms and enhance blood clot formation, thus preventing rupture and further growth. We investigated hemodynamics in differently positioned aneurysms coiled at various packing densities to determine the effective packing density in terms of flow stagnation. As a first step, hemodynamic simulations were conducted for idealized geometries of both terminal- and sidewalltype aneurysms. Porous media modeling was employed to describe blood flow in coil-embolized aneurysms. The stagnant volume ratio (SVR) was analyzed to quantify the efficacy of coil embolization. Regardless of aneurysm type and angle, SVR increased with increasing packing density, but the increase in SVR varied depending on type. For sidewall-type aneurysms, the packing density required to achieve 60 % SVR was 20 %, roughly independent of aneurysm angle; flow stagnation was achieved at low packing density. In contrast, in terminal-type aneurysms, the packing density required to achieve 60 % SVR was highly dependent on aneurysm angle, accomplishing a 20 % packing density only for lower angles. Indications are
T. Otani S. Wada (&) Graduate School of Engineering Science, Osaka University, Machikaneyama-chou 1-3, Toyonaka, Osaka 560-8531, Japan e-mail: [email protected] M. Nakamura Graduate School of Science and Engineering, Saitama University, Shimo-Okubo 255 Sakura-ku, Saitama-shi, Saitama 338-8570, Japan T. Fujinaka M. Hirata J. Kuroda K. Shibano Department of Neurosurgery, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 560-0871, Japan
that a relatively high packing density would be required, particularly when these aneurysms are angled against the parent artery. The packing density required for flow stagnation varies depending on aneurysm type and relative position. Keywords Cerebral aneurysm Computational fluid dynamics Coil embolization Porous media
1 Introduction A cerebral aneurysm is a vascular disease characterized by local ballooning of an intracranial artery. The aneurysm in the brain can compress surrounding nerves and brain tissue resulting in nerve paralysis, headache, and vomiting. The rupture of a cerebral aneurysm usually results in internal bleeding such as a subarachnoid hemorrhage and intracranial hematoma, which often leads to death. Coil embolization is frequently used to treat intracranial aneurysms in patients at high risk after open surgery [2, 9, 20, 21]. In this procedure, metallic coils are delivered to an aneurysm by a catheter that is inserted usually into the femo
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