None of the devices tested completely prevented embolization. Overall, Spider RX had the best performance and is conjectured to have the best wall apposition of the devices tested. Vascular resistance should be considered a key filter design parameter for performance testing since it represents a quantitative estimation of the "slow-flow phenomenon." Our findings should be extrapolated cautiously to help interventionists choose the best device.

Several complications related to apposition of the filter basket on the vessel wall and device retrieval were detected in all the devices. It is inferred that the adaptability of the filter basket to conform to the vessel cross section at the site of deployment is the primary design variable responsible for distal embolization during CAS with cerebral protection.

This investigation, unique for examining the effects of physiologically realistic pulsatile flow on DPF performance, can aid in the development of future generations of novel DPFs.

Purpose-To assess in vitro performance of four embolic protection filters (EPFs) with a varying mass of injected particles. Evaluation is based on capture efficiency, pressure gradient, flow rate, and vascular resistance.Materials and Methods-A bench-top flow apparatus was used for in vitro testing of four devices (Spider RX, FilterWire EZ, RX Accunet, and Emboshield). A silicone phantom with average human carotid artery dimensions and a 70% symmetric internal carotid artery (ICA) stenosis was used to model the carotid bifurcation. A blood-mimicking solution (glycerol/ deionized water) was circulated at the time-averaged mean peak velocity for the common carotid artery. Five and 10 mg of 200-or 300-μm-diameter microspheres were injected into the ICA to evaluate the capture efficiency of the devices. The normalized pressure gradient, flow rate, and vascular resistance in the ICA were calculated from measured values of pressure and flow rate. Results-TheSpider RX captured the most particles (99.9% for 5 mg, 98.4% for 10 mg) and was associated with the slightest increase in pressure gradient (+8%, +15%) for both masses of microspheres injected. The Spider RX and FilterWire EZ were associated with the slightest decreases in flow rate (Spider RX, −1.9% and −12.1%; FilterWire EZ, −3.5% and −8.2%) and the slightest increases in vascular resistance (Spider RX, +10.1% and +33.0%; FilterWire EZ, +20.5% and +32.7%). The device-specific porosity was calculated, and the Spider RX was found to have the greatest at 50.4%; the Emboshield had the lowest at 2.2%. Conclusions-TheSpider RX and FilterWire EZ had the best overall performances. Design features such as porosity and pore density are important parameters for improving the effectiveness of EPFs. Vascular resistance in the ICA is a flow-derived variable indicative of device performance and affected by the filter design features.A narrowing of the carotid artery resulting from atherosclerotic plaque accounts for 20%-30% of all cases of stroke, the third leading cause of death in the United States. Carotid artery stenting (CAS), a relatively new minimally invasive procedure, is quickly becoming a prominent alternative treatment for patients with a severely stenosed carotid artery. However, there is skepticism regarding the efficacy of CAS because of the possibility of periprocedural distal plaque embolization. The widespread acceptance of CAS is dependent Address correspondence to E.A.F., Institute for Complex Engineered Systems, Carnegie Mellon University, Hamburg Hall 1205, 5000 Forbes Ave., Pittsburgh, PA 15213; finole@cmu.edu. M.H.W. serves as a consultant to Cordis (Miami Lakes, Florida), Abbott/Guidant (North Chicago, Il-linois), Medrad (Indianola, Pennsylvania), Boston Scientific (Natick, Massachusetts), Edwards Life Sciences (Irvine, California), and Mallinckrodt Medical (St. Louis, Missouri). E.A.F. has received grant/research funding from the Pennsylvania Infrastructure Technology Alliance (PITA), a partnership of Carnegie Mellon University, Lehigh Universi...

¤ ¤Carotid artery stenting has gained popularity due to its minimally invasive approach. However, several design concerns preclude the successful use of carotid stents. ¤ ¤Balloon-expandable closed-cell stents for carotid artery stenting (CAS) were first introduced in 1995. At that time, the cell structure of these stents was intended to support tissue and plaque against the vessel wall ( Fig. 1) and restore the vessel to its normal dimension (Fig. 2). Unfortunately, there was a 2% incidence of carotid stent collapse: the stainless steel stent, when placed lower than the level of the mandible, could be externally compressed. 1 Consequently, the use of the balloon-expandable stent for carotid artery occlusive disease was largely abandoned. However, several valuable lessons were learned from these early studies. Not only were radial rigidity and scaffolding important features in stent design, but having a range of stent expansion rates became a necessity. The early designs lacked articulations, and their inflexibility and high profile prevented easy trackability. To improve the flexibility and trackability of the stent, a connecting bridge between two stents was integrated into the design (Fig. 3); however, plaque prolapse was seen at this site (depending on the length of the bridge), a critical observation for future generations of stent designs.When the non-collapsible memory alloy nickel titanium (nitinol) stent was introduced, there were several established design requirements for the delivery system: flexibility, device profile, fixation, and trackability. Moreover, stent designers took into consideration factors such as vessel conformability, scaffolding, side branch preservation, stent visibility, and recoil control to minimize migration and foreshortening (length contraction during stent expansion).