麻豆传媒

WASHINGTON -- Cardiovascular interventionalists got a sneak preview of new devices being readied to help patients deal with an expected explosion in minimally-invasive heart structure procedures, particularly transcatheter aortic valve implantation.

At the annual Transcatheter Cardiovascular Therapeutics symposium here, researchers presented preliminary work on:

• Devices to protect the brain from strokes that might be caused by debris released when interventionalists fix their patients' hearts
• Devices that can help rapidly and easily close the arterial access points required by the use of large-bore catheters
• Devices that make it easier to fix heart valves, including the oft-neglected tricuspid valve

"All these devices need to have further tests before they will be available," said Mathew R. Williams, MD, assistant professor in surgery and medicine at Columbia University, New York City, and moderator of the TCT-sponsored session on innovative technology.

"I think the brain protection devices are the ones we are going to be most interested in," Williams told 麻豆传媒. "The closure devices may be less important because we are moving to smaller devices anyway."

"The tricuspid valve device is interesting, but we need to see a lot more work, including clinical trials with that device," added co-moderator Susheel Kodali, MD, co-director of the transcatheter aortic valve program at Columbia.

Among the devices discussed was the Embrella Embolic Deflector (Embrella Cardiovascular, Wayne, Penn.), designed to prevent calcified debris from entering the carotid arteries -- but instead of capturing the debris, the porous membrane deflects these potentially stroke-causing materials to other arterial branches in the arch of the aorta, where it is hoped they will cause less damage than if they occlude a blood vessel in the heart.

In a clinical feasibility trial involving 20 patients, John G. Webb, MD, professor of valvular heart disease intervention at the University of British Columbia and director of cardiac catheterization and interventional cardiology research at St. Paul's Hospital, Vancouver, said two device-related adverse events occurred. One was a cerebrovascular accident that resolved at discharge -- most likely caused by improper positioning of the nitinol-framed deflector -- and another was a report by a patient of blurred vision, although it could not be determined if the device was at fault. In other institutions another 18 patients have been treated with the device, Webb said.

"The Embrella system appears technically feasible and safe during transcatheter aorta valve implementation," he said. Overall, the total clinical experience in 38 cases has not resulted in any changes in the National Institutes of Health Stroke Assessment, and there were no procedural deaths, heart attacks, renal failure events, limb ischemia events, or major bleeding episodes.

Another device temporarily places emboli-catching baskets in both the brachiocephalic and left common carotid artery branches off the aorta, again in attempts to prevent debris from valve procedures from moving upstream into the brain and causing strokes.

Eberhard Grube, MD, chief of cardiology and angiology at the Heart Center Siegburg (Germany) and consulting professor of medicine at Stanford University, said that the positioning of the Claret Dual Filter Device (Claret Medical, Santa Rosa, Calif.) was improved by using an over-the-wire technique rather than director positioning.

In the five cases in which the device was directly placed, technical success was achieved in all cases in the brachiocephalic artery but only in three of the five common carotid arteries. Over-the-wire technique filters were successfully placed in both arteries in all three cases attempted in the pilot studies -- and the time required to place the filters was reduced from 19 minutes to 9 minutes with the over-the-wire procedure.

"Stroke protection devices for transcatheter aortic valve implantation are helpful and are needed to facilitate and improve outcomes," Grube said. "Clinical trials are needed to confirm the use of these devices and their utility."

Pre-clinical experiments indicate that the Millipede Device (Millipede, Ann Arbor, Mich.) may be able to change the irregular shape of a faulty tricuspid valve into a circular form that is held in place by a nitinol ring with multiple attachments.

Experiments in animals indicate that once the ring is implanted, it appears to stay in place -- even if all the attachments fail to lock into place, said Jason H. Rogers, MD, director of interventional cardiology at the University of California Davis Medical Center. The tricuspid -- and also mitral valve -- annular rings appear to be self-sizing, self-centering and self-attaching, making the implantation of the devices relatively simple, he suggested.

"Prototypes for clinical use have been fabricated for feasibility testing," Rogers said. "A delivery system is under development."

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