Studies of the Neuroform Microstent Using Transparent Human Intracranial Arterial Model

• Main Authors: Shih-Wei Hsu, 許世偉
• Other Authors: Yu-fang Cheng
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/34902647502289523146

碩士 === 長庚大學 === 臨床醫學研究所 === 94 === Combination of endovascular stent and coils embolization in the treatment of intracranial aneurysm is a relatively new therapeutic technique. Most of the stents that used in this method were designed for coronary artery. NeuroformTM Microstent (Target Therapeutic/Boston Scientific) is a newly designed intracranial self-expandable stent and is constructed by nickel-titanium alloy. The stent has been proved by FDA in the treatment of wide neck intracranial aneurysm as the assisted device in the coil embolization. A variety of technical difficulties have been encountered using Neuroform stent, in part because of poor visibility of the stent under fluoroscopy during the procedure. The purpose of this study was to assess the mechanics of the Neuroform Microstent by direct visualization within transparent human intracranial arteries. Eight various segments of human intracranial arteries including vertibrobasilar, carotid artery and cerebral arteries were used. Twelve Neuroform stents, including Neuroform 2 (NF2) were deployed into the arteries. The stented arteries were then dehydrated followed by cleared in Methyl Salicylate to obtain transparent arteries. Morphological situations of Neuroform stents were studied by macro digital photography. The radial force of Neuroform stent was studied by stress-strain curve using deformation compression test. The Neuroform stent exhibited good conformity to arterial segments, however, a few important and potentially adverse properties were seen such as: (A) portions of the crown of Neuroform stent may protrude into larger side branches which was mimic the neck of an aneurysm; (B) the gap between stent crowns could be larger than expected in arterial segments with acute or abrupt angulation; (C) the longitudinal rebounding force exerted by NF stent in acute angulation could straighten the short and small arterial segment. Transparent human intracranial artery is an excellent model for evaluating the physical properties and behaviors of Neuroform stent although some limitations are noted regarding to the physical properties. Proper sizing is important for ensuring good stent conformity within the arterial segments. Neuroform stent deployment in acute angulation could be problematic, resulting in excessive gaps between crown segments and exerting a longitudinal rebounding force against arterial wall. The deformation compression test of NF stent revealed that the stent is a purely elastic deformation stent within 40% of diameter compressed. The radial force at the end of the stent is lesser than at the central portion of the stent with statistically significant.