Risky Business

I am always asked – Why do you think the AvA Bypass Graft is a superior off-pump aortic valve procedure compared to stent valve procedures being developed by Edwards LifeScience , CoreValve, and probably a dozen smaller companies?

My short answer:

Superior risk management profile

Now for the longer answer.

When compared to emerging stent valve technologies, I believe our bypass graft device will provide an equivalent less invasive “off pump” aortic valve therapy but with lower short term and long term risks for the patient, the surgeon, and our company.

Prosthetic Heart Valve Risk
In our approach to “off pump” valve surgery, we do not have to accept the historically predictable high development and product liability risks associated with the design, manufacture, and implantation of a new class of heart valves.  One only needs to review the “Shiley Experience” to realize how much risk can be imbedded in a heart valve implant.  Contrary to a defective angioplasty catheter that can be discovered and corrected on the table within a few minutes, a defective heart valve can remain in remission only to emerge years later possibly as a life threatening failure affecting thousands of patients (and implanting physicians) and the financial stability of the valve company.

With our valve bypass graft system, the surgeon will not need to worry about valve quality or valve implantation risks.  Our device employs an already commercially available, already clinically proven heart valve selected by the surgeon at the time of implant.  Our implantable graft device is a low risk design with essentially no chance of peri-valvular leak.  It is composed of well characterized blood compatible materials and has no moving parts.

Implantation Risk
Unlike stent valves, we will not ask our customers to implant a historically unproven valve using a technique outside of their normal surgical skill set.  Based on initial animal studies, we believe all surgeons, not just those fortunate to work in a hybrid OR surrounded by a large support team, can perform our bypass graft procedure off-pump safely with minimal additional training.   With our off-pump approach, through a mini-thoracotomy the surgeon has complete line of sight visual and tactile control of the operation.  If any problem occurs, the surgeon has multiple options to control the situation.  Prior clinical work performed by surgeons around the world has already established  human feasibility of the general procedure, including multi-year follow-ups.

Compare the bypass graft risk scenario with the stent valve procedure (percutaneous or apical) that relies on extensive pre-op work-ups and calculations, a large support staff, real time fluoroscopic and ultrasound vision, remote manipulation, and allows for few bail-out options when, inevitably, a life-threatening mistake is made.  Our device does not rely on “good” stenotic morphology at the implant site for procedure success, does not have a propensity to generate emboli, and will not damage conduction pathways.   Unlike conventional valves where long term durability risk resides exclusively with the manufactuer, stent valve durability relies in large part on the procedure technique.  The implanter must now accept a large portion of the risk for future device failure.  Was the valve damaged during crimping?  Was it placed too high or too low.  Was a native leaflet inverted so that calcific excrescences can wear away a leaflet?  Is the stent so oval that the leaflets do not coapt without exerting undue stress on the tissue?

We all know that in either technology, the patient will benefit short term from a successful “off pump” procedure.  But only with our procedure can the patient benefit long term by knowing that the implanted prosthetic valve (required to open and close 40 million times per year) is an already clinically proven and highly reliable device.   Stent valve supporters openly admit that collapsible stent valves may not be as durable as traditional valves.  They want the patient (and market) to accept the inevitable higher risks associated with a radical new valve design in return for the life saving benefits of an “off pump” procedure.  With our device, this tradeoff is not required.   Patient, surgeon, and Cardious will all sleep well, knowing that the implant will be as safe and reliable as the “gold standard” traditional heart valve because it will contain that same “gold standard” heart valve within a “gold standard” textile graft.

At the End of the Day
In summary, at the end of the day, we believe our customer, the cardiac surgeon, will continue to judge the success of heart valve surgery based on the long term performance of the valve, not the short term convenience of the procedure.  Stent valves have opened the door to allow surgeons to consider “off pump” options for their large pool of “no option” and “high risk surgical” patients.  We believe when we advance our technology into human use,  a proper risk/benefit analysis will drive the market, in particular the cardiac surgeon, to see that our approach is the obvious next step in aortic valve therapy.

What do you think?  I look forward to reader response, especially from surgeons.

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