Distal Embolic Protection — Don`t Cause a Stroke Trying to Prevent One!

The article published in this issue of the Journal regarding initial experience with the SPIDER™ Embolic Protection Device (ev3 Inc., Plymouth, Minnesota) provides further evidence of the merit of these newer-generation “gizmos” in reducing complication rates of carotid stenting. The earlier generation protection devices such as the PercuSurge device (Medtronic, Inc., Minneapolis, Minnesota), the Angiogard device (Cordis Corporation, Miami, Florida), and the Accunet™ device (Guidant Corporation, Indianapolis, Indiana) all have inherent advantages and disadvantages. Certainly, those of us who performed early carotid stenting believe distal protection is vital to the procedure. In the “early days” of carotid stenting, transcranial Doppler studies were downright frightening! This, coupled with gross macroscopic evidence of debris retrieval with the early protection devices, was enough evidence for me and many others to abort “bare-back” carotid stenting. Nevertheless, the amazing aspect of early carotid stenting, at most centers, revealed a surprisingly low rate of clinical neurological events despite these disturbing transcranial Doppler findings. Much of this we attribute to the “minimal touch” technique of carotid stenting. In other words, keep catheter manipulations, balloon inflations and wire manipulations to a minimum while still getting the job done. Soon after the introduction of embolic protection devices in U.S. trials, I found myself excessively manipulating the first-generation devices through many typical high-grade angulated lesions. The steerability of the earlier devices was far less than conventional wire technology. Once I did get the wire through, the device would often track only with excessive force or with the use of a “stiff” buddy wire. Next would come an occasional excessively tortuous proximal internal carotid artery. Placing the protection device high enough to allow satisfactory distal stent deployment was a common concern. Frequently, spasm of the internal carotid artery occurred. Nevertheless, as long as the contralateral anterior circulation was patent, this rarely posed a clinical problem. So much for minimal touch with embolic protection devices! The ideal distal protection device should incorporate the following design criteria: 1. The ability to use a state-of-the-art steerable 0.014 inch guidewire the operator prefers. 2. A very soft, hydrophilic transfer catheter with a minimal internal lumen coefficient of friction to allow atraumatic placement of the protection device through the transfer catheter. 3. An embolic protection device that “seals” well inside the internal carotid artery. 4. An embolic protection device that has little potential for movement once in place (monorail technology). 5. A soft, less supportive distal 3 cm of wire with a highly supportive rail on the remainder of the wire. 6. A soft, hydrophilic, steerable multipurpose tipped retrieval catheter (monorail). The authors nicely outline the design advantages of the SPIDER device in this paper. This device includes many, but not all of the optimal design criteria. In the U.S. carotid stent trials, a newer and more user-friendly design of the SPIDER (SPIDER RX) has been evaluated in preliminary trials. It is now commercially available throughout Europe and Asia as these authors mentioned. In any case, the whole point of this editorial is to emphasize the fact that the SPIDER device, in this writer’s opinion, is far and away the safest, most user-friendly distal embolic protection device yet to be investigated. Furthermore, there is still much room for improvement to minimize embolic and ischemic cerebral events in device design. Also, there is still the rare occasion where the benefits of placement of distal embolic protection devices don’t outweigh the inherent risks due to the design of the distal protection device. The SPIDER device clearly improves the merits of distal protection due to its design. Carotid stenting “tools” need to be continually refined to further reduce neurologic events for a procedure that we hope will prevent neurologic events!