Mainstream clinical practice in endovascular treatment of intracranial aneurysms has changed little since the 1990's when vasooclusive coil use became widespread. Certainly, improved catheters and other auxiliary devices (e.g., stents) have helped make coiling procedures safer and/or more effective. However, the art in achieving adequate and appropriate aneurysm coil packing is best accomplished by the most highly skilled physicians.
Where practicable, aneurysm exclusion by cover-type devices (e.g., as described in U.S. patent application Ser. No. 12/397,123 to the assignee hereof) may be preferred. Certain other groups are attempting to shift the paradigm away from intra-aneurysm coil packing to achieve embolization via deployment of an extra-aneurysm flow disruptor/diverter stent in the parent vessel. These densely braided devices and/or multiple braid devices layered upon one another are placed in the parent vessel across the neck of an aneurysm with the intent to alter hemodynamics so as to effect embolization.
These WALLSTENT-like devices are best suited for placement across sidewall aneurysms. Yet, terminal aneurysms (e.g., bifurcation aneurysms) are estimated by some to make-up between about 60 and 80% of all aneurysm occurrences. By most optimistic count, only about 40% of intracranial aneurysms can be treated using the referenced stent-like devices.
Numerous other devices have been conceived in effort to address terminal aneurysms. Complicated and/or impracticable deployment is common to many. Others simply serve as adjunctive to coils or liquid embolic agents. In these latter examples, procedures may become even more complicated and require even greater physician skill than a standard coiling procedure.
A simpler, yet promising solution is proposed in PCT/US 2007/0076232 to Dieck, et al. A braided/mesh conical member is described for diverting blood flow from the aneurysm neck. A base of the device is set inside the aneurysm while a flow diverter portion extends into the parent vessel to direct blood flow toward adjacent side branches and away from the aneurysm. The implant may be positioned within the aneurysm as a stand-alone device or be supported by a connected stent-like body.
U.S. Pat. Nos. 6,168,622 and 6,506,204 to Mazzochi, et al. discloses another type of braided flow disruptor set at least partly within an aneurysm. A bulbous portion is adapted to fit within the aneurysm dome and is anchored on the outside by a neck-covering flap. Given the manner in which bifurcation aneurysms often incorporate branch vessel anatomy, such a patch would often interfere with and/or “flap” free raising significant issues of potentially pathological thrombus formation within the parent vessel.
Implants of the present invention address shortcomings of each of the above-referenced devices. As such, the subject implants (as well as their associated delivery systems) offer potential to advance the state of the art in endovascular treatment of vascular malformations, including aneurysms.