Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Embolic Protection Devices to Prevent Stroke during Percutaneous Angioplasty and Stenting
The use of a cerebral protection device during carotid angioplasty and stenting (CAS) has been a component of most trials demonstrating the safety and efficacy of CAS, thereby suggesting that use of cerebral protection devices is standard practice. Currently, there are two basic mechanisms to provide cerebral embolic protection: interpose a distal protection device between the lesion and the cerebral vasculature to interrupt embolic debris dislodged during angioplasty and institute proximal cessation or reversal of flow in the internal carotid artery. The disadvantage of a filter protection device is that it requires crossing the atherosclerotic lesion without protection. The major advantage of filters, however, is that they preserve antegrade flow and perfusion to the brain. This chapter focuses on the use of the distal embolic protection, including the microporous filter and temporary occlusion balloon, during carotid angioplasty and stenting.
Device Characteristics
Microporous filters are designed to catch embolic debris that is liberated during CAS before it reaches the cerebral circulation. A delivery sheath constrains the filter until it is positioned in a nondiseased segment of the internal carotid artery distal to the area to be stented. Once the filter is deployed, antegrade cerebral perfusion is maintained through the filter throughout the procedure. Embolic material dislodged during balloon angioplasty becomes trapped within the filter and is removed when the filter is reconstrained at the completion of the procedure ( Figure 1 ). Pore sizes for filters range from 100 to 165 μm, allowing capture of particulate debris larger than the pore size yet preserving blood flow through the filter.
A variety of filters are now FDA approved for clinical use in the United States and are delivered either with the filter as a component of the angiographic wire or with separate delivery over an angiographic wire already positioned into the distal internal carotid artery. Filters that are delivered attached to a fixed wire include the Angioguard XP (Cordis, Johnson & Johnson, Miami Lakes, FL), FilterWire EZ (Boston Scientific, Natick, MA), and Accunet (Abbott Laboratories, Abbott Park, IL). Emboshield NAV6 (Abbott Laboratories) and SpiderFx (EV3, Plymouth, MN) are delivered using a wire positioned independently from the filter.
The PercuSurge GuardWire (Medtronic) is a temporary occlusion balloon originally developed for use in the treatment of saphenous vein coronary artery bypass grafts. It has been adapted for use in CAS, where it prevents distal embolization by occluding blood flow in the internal carotid artery distal to the lesion. The balloon is a component of an angiographic wire and is inflated through the hypotube within the core of the wire. Similar to filter devices, the balloon is inflated in a normal segment of the internal carotid artery after passage through the lesion. An Export Catheter (Medtronic) is used to aspirate the debris and standing column of blood in the internal carotid artery between the angioplasty site and the occlusion balloon. An advantage of this device is the lower device-crossing profile and greater flexibility compared to filters; however, of necessity, cerebral perfusion is temporarily interrupted during the procedure.
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here