The following is from the latest online edition of theheart.org. You have to sign up (free) to read the articles so I thought I'd post it. While percutaneous valve replacements are in their nascent stage, and will have plenty of problems and issues to be resolved, I think a whole new area in non-coronary interventional cardiology is upon us -- to the benefit of patients.
"European cardiologists offer new horizons in percutaneous valve replacements"
"Paris, France - At the Paris Course on Revascularization, cardiologists were presented with a glimpse into several procedures of the future, foremost among them a detailed review of the first-ever percutaneous aortic valve replacement. The procedure was conducted on April 16, 2002 by Dr Alain Cribier (Chief of Cardiology, University of Rouen Hospital, Charles-Nicolle, France), a pioneer in the development of balloon valvuloplasty.
That procedure galvanized particular interest as it is aimed at transforming the treatment of more than 150 000 patients worldwide who currently receive open-heart surgery and possibly several hundred thousand others who are deemed either insufficiently symptomatic or overly high-risk to merit an invasive and expensive valve replacement operation.
Dr Bernhard Meier (Bern, Switzerland) said that the reports, which included a touch-and-go live demonstration of the tenth catheter-delivered pulmonary valve replacement in man, pointed to "a new era in interventional cardiology" and said that "this is about the most incredible session I've ever seen."
Cribier termed the results of his first transcatheter aortic valve implantation case - performed as a 57-year-old patient's cardiac output crashed from cardiogenic shock - "extraordinary and unexpected." He and Dr Martin Leon, (Lenox Hill Hospital, New York, NY) are co-founders of a New Jersey-based company called Percutaneous Valve Technologies (PVT), which has been developing for the last 2.5 years a balloon-expandable stent technology for implanting a prosthetic valve made from biological tissue over failing native valves.
Future applications of the technology could include the treatment of mitral stenosis, aortic regurgitation, and venous insufficiency. Other companies developing various catheter-delivered valve repair, replacement, and annuloplasty systems include St Jude, Evalve, Edwards Lifesciences, Medtronic, Boston Scientific, Sorin Medical, JOMED, and Sulzer Carbomedics. Health Research International sees the transcatheter valve interventions becoming a widespread alternative to surgery by 2005, with sales perhaps reaching $500 million half a decade later.
Baptism by fire
Open ? (Source: Percutaneous Valve Technologies)
Cribier had intended to do his first stent-valve implantation on a calm, elective basis several months later; in fact, he had initially treated the first patient's severely calcific aortic stenosis with valvuloplasty. Even that intervention was risky - three surgical teams had refused to operate because the patient had almost no cardiac output, silicosis and lung cancer from his former work as a coal miner, and subacute ischemia in his right leg following the development of a total occlusion in a prior femoral artery bypass.
Unfortunately, the improvement following valvuloplasty was short-lived. Within 3 days, the patient suffered a second collapse in cardiac output, with his ejection fraction plummeting to between 8 and 10%. The PVT technology, to that point, only used in more than 50 sheep experiments and bench testing (to an equivalent of 150 million human heartbeats), was raced to France in the hope it might be life saving.
The idea is fairly straightforward. The business end of the 9 French catheter folds an outer 14-mm stent around the collapsed prosthetic valve, which in turn squeezes around an inflatable NuMed? delivery balloon and is then advanced into a 24 French introducer sheath. As the balloon is inflated within a failing valve, the stent forces and holds the diseased native stenosis open, while the prosthetic valve is tamped into place over the now distended natural one - if all goes well.
. . . and closed (Source: Percutaneous Valve Technologies)
But the emergency Rouen case was additionally complicated by the fact that femoral artery access was impossible. So Cribier's team had to work through the right femoral vein, and then advance the system retrograde across the septum to the left atrium and ventricle and the approach to the ascending aorta. The initial 0.35 guide wire was then snared and joined with an extra stiff guidewire advanced via the left femoral artery for additional backbone in the face of such tortuous, elliptical access. The moment of truth came when the sheath was removed and the entire system was advanced and inflated across the old valve (whose leaflets are expanded by the stent and left permanently out of the circulation). The heart is totally arrested for as long as the inflation proceeds.
Crossed fingers
"When we crossed the valve, we also crossed our fingers," Cribier acknowledged. "I was a little worried, because we didn't know exactly what would be the consequence. But then the balloon was deflated and the heart immediately started beating normally."
The French cardiologist said he was relieved to find no evidence of aortic regurgitation at the completion of the 90-minute procedure - although there was a slight amount around the mitral valve - and that aortic pressure had in fact increased to 100 mm Hg systolic from 50 to 60 mm Hg prior to the procedure. "This was the first time in the recent life of this patient that he was reaching this level, and his ejection fraction reached 25%." Echocardiogaphy showed that the prosthetic valve orifice area had reached 1.7 cm2 and that the tricuspid leaflets were opening and closing "beautifully."
Dr Alain Cribier (left) with the patient (center), 2 hours postprocedure (Source: Percutaneous Valve Technologies)
Two hours later, the patient was alert enough to sip champagne with Dr. Cribier. He soon was well enough to be interviewed by French journalists, sit up for 6 hours, and eat at a table. "In all my experience of valvuloplasty and aortic valve disease I have never seen such unbelievable improvement," Cribier said. In mid-May, 2-D echo showed the synthetic valve to be still working perfectly, he added, although the patient will have to undergo an amputation for his peripheral vascular disease.
Cribier sees one potential use of the transcatheter valve implantation technique as a short-term bridge to surgical reconstruction. A series of further procedures are expected to begin in July with the Rouen group joined by Drs Antonio Columbo and Patrick Serruys in Milan and Rotterdam, with later US collaboration from Drs Donald Baim, William O'Neill and Martin Leon.
One emergency valve implantation in man obviously does not a new era make, nor does it say anything about the long-term durability of such devices, the short-term major adverse event rates that can be expected, or what the impact and incidence of restenosis in such prostheses will be. But PVT has its sights set on a variety of other potential applications for this type of technology, and has entered a joint development agreement with VenPro Corporation (Irvine, CA) to develop catheter-delivered leg valve systems for the treatment of chronic venous insufficiency, a condition affecting as many as 4 million patients in the US, Europe, and Japan.
The Cribier insight into treating aortic stenosis. Windows Media Player only. (Source: Percutaneous Valve Technologies)
Interventions on pulmonary valves
In another forward-looking presentation, Dr Philipp Bonhoeffer (Massy, France) performed a live demonstration of his group's 10th human implantation of a similar, but cruder looking, biologically harvested, balloon-expandable pulmonary valve. "Obviously pulmonary valve implantation is much easier because we don't have the problem of the coronary arteries and secondly, we don't need to stretch the valve quite as much because we are working in a lower pressure circulation," Bonhoeffer observed as the procedure began with bright hopes. However, it soon turned into a demonstration of what uncharted waters may lie ahead for interventions of this kind.
The patient in this case was a 37-year-old man who had surgical aortic valvuloplasty in 1995, only to develop a severe valve stenosis in the right ventricle to the pulmonary artery. The terrain in question may have theoretically been more forgiving than that negotiated by Cribier, but the live procedure's rough moments began shortly after a tourniquet-like hand crimping technique was started to ready the VenPro stent-valve system for its delivery sheath. The valve in this case is a homograph developed from harvested bovine jugular veins with valves and is implanted by a NuMed double-balloon system expanded fore and aft of the stenosis - if all goes well.
However, difficulties in delivering sufficient contrast for visualization were followed by a startling rupture of an implantation balloon once it was inflated at the valve site. The tip of the delivery system then disconnected from the catheter as it was withdrawn from the circulation, requiring a snare to be advanced to get the errant tip out of the artery, while the puncture site for the bulky equipment bled freely all the while.
We are really moving into the future of noncoronary interventional cardiology.
The Massy team managed to persevere ably, despite the failure of the first of two snares and subsequent problems with advancing the persistently kinking guide wire. Once back in position, they employed an indeflator to control the inflation of the replacement 18-mm Z-Med? balloon, in order to prevent a repeat rupture while the patient's cardiac output was arrested. The determined operators succeeded in carrying out their stent-homograph valve implantation, achieving a systolic gradient of 10 mm Hg with no evidence of regurgitation or pulmonary insufficiency. Bonhoeffer noted that, in the event of valve restenosis, a second homograph could be implanted, while acknowledging that surgery could become indicated from that point on.
In the August 15, 2000 issue of Circulation, the same group had predicted that the new pulmonary valve procedure would scarcely differ from "routine stent implantation."[1] Although this particular case didn't appear to be routine, the results were ultimately successful, prompting Dr Marie-Claude Maurice (Massy, France) to state, "We are really moving into the future of noncoronary interventional cardiology."
An earlier presentation in the session featured a successful percutaneous transcatheter closure of a left atrial appendage by a Frankfurt group headed by Dr Horst Sievert and a catheter-based PFO closure by Dr Stephan Windecker of Bern."
