Medical Device Daily Associate
While the lion’s share of the focus at this year’s EuroPCR meeting in Paris last month was on the drug-eluting stent market, other interesting areas in the interventional cardiology field also were discussed, including the up-and-coming valve replacement and repair sector.
Speaking on the many new innovations in this potentially lucrative sector was Carlos Ruiz, MD, PhD, professor and director of the division of pediatric cardiology at the University of Illinois at Chicago.
He acknowledged that this sector traditionally has been the turf of the cardiovascular surgeon but said that ultimately, as has already been seen in other areas, interventional cardiologists “almost certainly” will win out when furnished with the needed technological advances.
“It’s obvious to every one of us who are here that the less-invasive procedure will always be preferred for as long as there is an equivalent safety and efficacy in that procedure and patients will always like that,” he said.
Adding to that assertion Ruiz hypothesized that “if transcatheter valve replacement and repair can be done safer than surgery with an equivalent efficiency, it may supplant, not all, but some of the current surgical methods for the current options.”
Better yet, he noted that patients who currently are considered bad candidates for surgery and are being managed with medication could have “better outcomes and better possibilities” with new minimally invasive valve technology.
Ruiz described some of the latest developments for transcatheter valve repair. He noted that many of the described devices are still in the animal model stage, but a few have had limited clinical trials. He noted that the valves are either mechanical or biological, with most of the work being done in biologicals.
One exciting new mechanical valve he mentioned involves nanotechnology. Using vacuum deposition, Steve Bailey, MD, of the Janey Briscoe Center for Cardiovascular Research at the University of Texas Health Sciences Center (San Antonio, Texas), can produce 4 micron-thin nitinol to make the Nitinol Membrane PercValve. This device has been used in a small series of animal models.
On the biological side, there are a number of entries. Edwards Life Sciences (Irvine, California) has, according to Ruiz, made a major leap with the PVT valve. There is an ongoing human trial. “This valve is constructed from equine pericardium on a very strong stent and results have been spectacular,” he said. Edwards acquired Percutaneous Valve Technologies (PVT; Fort Lee, New Jersey) early in 2004 (Medical Device Daily, Jan. 29, 2004).
Also on the biological side, he described the Paniagua valve, developed by David Paniagua of the Texas Heart Institute (Houston). He said that device wasn’t exciting so much for the valve itself but rather for the tissue, which he described as a propriety composition of porcine pericardium. “After eight months of implant in the sheep model . . . those pericardial valves have not developed any calcifications,” he said.
Another interesting valve Ruiz mentioned is the CoreValve, from CoreValve (Irvine, California), a bovine pericardial device being developed with a self-expandable, high-radial force nitinol stent. This valve already has been used in several patients with excellent results, he said, though adding that better imaging techniques are needed to utilize the potential of the technology.
Other biological valves he cited include the NuMED Valve from NuMED (Hopkinton, New York) and the Cook SIS valve from Cook Biotech (West Lafayette, Indiana). Using submucosa from pig intestine, the SIS collagen base material includes growth factors. Pig studies show a remodeling process that occurs long-term.
While he said that progress has been made, Ruiz noted that the “ideal transcatheter valve” is not yet available. He said the requirements for the ideal valve include issues of delivery, scaffold, material and design. For delivery, the valve needs to be low profile, reliable for orientation and easily placed. “The scaffold of the valve must be flexible, and stentless is better,” Ruiz said. As to material for the valve, it must be nonthrombogenic, noninflammatory and would be best if it could sustain somatic growth. It should also be readily available off the shelf, with no preparation needed.
Ruiz also described another valvular problem area: mitral valve regurgitation. This occurs when the mitral valve doesn’t hold a good seal. Ruiz said that interventional cardiologists have invented a number of potential devices to treat this problem with transcatheter approaches.
One interesting company attempting to fix this problem is Evalve (Redwood City, California). The company’s technique involves threading a dime-sized clip into the heart via a catheter. The catheter is guided by a small echocardiography probe in the patient’s throat, as well as an ordinary echocardiography transducer placed on the chest.
Edwards Lifesciences has the Milano II LifeStitch, a device using stitches that are applied to the valve, and a nitinol anchor used to tighten the knots.
Cardiac Dimensions (Seattle) is developing an implant using the superior vena cava as its entry point. Guided by echocardiogram, traction is placed on the valve leaflets.
A device from Viacor (Wilmington, Massachusetts) uses nitinol covered with surgical-grade Teflon. The device uses radio frequency to create burns on top of the mitral annulus that cause constriction of the mitral annulus at the selected target.
Another company trying to solve the regurgitation problem mentioned by Ruiz is Mitralign (Salem, New Hampshire). Combining surgical precision with interventional therapy, that company is developing a catheter-based mitral valve repair system
The Mitralign system resembles surgical annuloplasty, during which a dysfunctional, dilated mitral valve opening is reduced or cinched down to a functional size. Catheters are percutaneously guided to the mitral valve using the company’s MitraLock Guidance System. Once positioned in the left ventricle, the physician performs an annuloplasty via the catheters utilizing standard imaging techniques.
Ruiz noted: “No one single device will fix all the varieties of valvular disease, and I wonder how the regulatory agencies will compare the products to traditional surgery.”
Speaking about the valve repair and replacement field, he was unabashedly enthusiastic. “I think it is definitely one of the most exciting fields today in intervention and we’ll see that this is going to be quite explosive.”
That being said, Ruiz cautioned that perhaps one of the only real handicaps to further advancing interventional technology in this field is a lack of good imaging techniques. “We don’t have a good, reliable online imaging that allows us to do safely many of these procedures,” he said.
To that end, Ruiz challenged the device industry to come up with solutions. “I think the imaging companies need to step up to the plate and help us to employ and use those devices in a safe[r] manner.”