ReValving – that is, percutaneously implanting a new heart valve over a defective valve instead of cutting it out – has the potential to one day redefine valve replacement surgery, changing it from a very complex surgical procedure to a relatively simple, less invasive one
This potentially breakthrough technology is being developed by CoreValve (Paris) and, according to its co-founder and chief executive officer, Jacques Seguin, MD, PhD, the ReValving technology has the potential to be "the next-generation cath lab therapy for interventional cardiology."
The privately held company last month reported the first successful implant of its self-expanding stented aortic heart valve, dubbed the percutaneous ReValving system, in a cardiac catheterization laboratory of a hospital in Asia. As a result of the procedure, the company said a 62-year-old male patient was able to avoid open-heart surgery to treat his aortic calcified stenosis.
The first-of-its-kind procedure on a human was performed by two interventional cardiologists, the renowned Eberhard Grube, MD, chief of cardiology and angiology at the Heart Center Siegburg (Siegburg, Germany), and Jean-Claude Laborde, MD, an interventional cardiologist at Clinique Pasteur (Toulouse, France), who has had extensive preclinical experience with the system.
"Our patient has a frail heart and had been deemed a high surgical risk because of his deteriorated condition and extensive polyvisceral disease," said Grube. "Given the lack of any other therapeutic solution for this patient, the CoreValve ReValving approach has proved to be a life-saving technology. We are extremely proud to be the world's first interventional cardiologists to use this breakthrough technology successfully in a human, which no doubt represents a whole new frontier for heart valve replacement."
Aortic stenosis is a narrowing of the heart valve that causes the heart to work very hard in order to eject blood from the heart, resulting in shortness of breath and, in advanced cases, fainting and heart failure. Today, symptomatic patients are typically treated by traditional open-heart surgery; about 220,000 patients worldwide have surgery on their heart valves. About 60% of valve replacement surgeries are for the aortic valve. Aortic stenosis occurs predominantly in men and women over 70 years of age.
Seguin, himself a former cardiac surgeon, told Cardiovascular Device Update that he came up with the concept for this percutaneous beating-heart approach to performing valve surgery after performing many "traumatic" open-heart surgeries to excise the valve. The traditional approach, he said, involves opening the chest, opening the heart and arresting the heart. "When I worked with stents on animals and then human cadavers, I noticed that one could easily push the calcified [valve] leaflet aside without creating a major issue on the local anatomy of the coronary ostia."
On top of that important finding, Seguin said that in his experience with cadavers, he discovered that by expanding a balloon in the coronary ostia over a stent or by implanting a stent with a very strong radial force, "one could not only push aside the valve leaflets, but one could also push aside into the tissue the local calcifications." He said that was an important breakthrough "because I understood at that moment that one did not need to take the valve out, but one could implant with a stent a valve on top of a diseased valve."
During the procedure, percutaneous access is made through a peripheral vessel in the groin, and a guidewire is inserted into the left ventricle. The entire procedure is done under angiography and trans-esophageal echocardiography.
CoreValve's universal catheter-based delivery system, containing either a biological or synthetic valve prosthesis in a collapsed position, is pushed over the guidewire and advanced to the implantation site. Positioning relative to the anatomy is done using contrast dye injections. The prosthesis is precisely positioned vis- -vis the valve annulus and the coronary sinuses. The protective sheath is then pulled back, and the prosthesis progressively self-expands.
To ensure attachment of the heart valve prosthesis to the vessel wall, the company has developed techniques designed to ensure that the prosthesis is firmly maintained while engaging the valve annulus to avoid prosthesis migration and para-valvular leaks.
Seguin believes that the eventual perfection of his ReValve technology may cause a major shift in technology. He compared the fledgling valve market to that of coronary stents in the 1980s and 1990s. "Previously, if one had a significant disease on a coronary vessel, one would need a coronary bypass, and now I would say 80% of what was operated [on] in the eighties is now treated by stents."
In essence, he said that the perfection of this technology could have a dramatic economic affect on the realm of the vascular surgeon. "What we are expecting in the next five to eight years [is] a shift of technology from the open-heart surgeons to the [interventional] cardiologists. That means a shift of billions of dollars from one specialty to another."
Seguin said he envisions a new hybrid specialty in medicine that combines both the cardiologist and the surgeon, "who could be able to implant a stent, implant a valve and do minimally invasive surgery if needed."
On top of that shift, the new procedure has the potential to cost significantly less ($10,000 to $25,000 for the ReValve vs. $25,000 to $50,000 for the open-heart approach), take significantly less time to perform (45 minutes vs. three-plus hours) and involve a much shorter recovery time (one to two days in the hospital vs. five to seven days).
Another advantage to the procedure, according to Seguin, is its ability to be used in patients with advanced stages of aortic stenosis, those who are not considered to be good candidates for open-heart surgery. He said that a paper published in a recent issue of the European Journal of Cardiology showed that nearly 30% of valve disease patients are deemed poor candidates for the open-heart approach, patients who he said could potentially benefit from his system.
Seguin noted that Edwards Lifesciences (Irvine, California), via its Percutaneus Valve Technologies (PVT; Fort Lee, New Jersey) purchase in January, also is pursuing a catheter-based approach to replacing heart valves. He said the primary difference between the two products is that the PVT device has a balloon-expandable stent vs. CoreValve's self-expanding stent.
CoreValve is in the process of putting together a feasibility trial that involves 21 patients. It hopes to obtain a CE mark by 2006. As for the U.S. market, Seguin said that there have been no formal discussions with the FDA, but indicated that an investigational device exemption for the system was one possible approach.