Ka-thump.  Ka-thump.  Ka-thump.  These are the sounds of a normal heart.  What if your heart valves don’t close properly (they let blood leak backwards [regurgitation]) or they won’t open completely (thereby restricting blood flow [stenosis])?  Then, those are not the sounds you will hear. If you are an adult, you may need valve replacement, because of deposits that occur over years  that make the valve stiff, rendering closure difficult.  But, now imagine you are told that your infant has that problem… Back years ago, the heart valves had a 10 to 15 year life (tissue valves); the mechanical ones now have some 25 year life expectancies.  So, if an infant has a valve problem- you know there will be yet another traumatic operation, after this one…

But, now,  there’s new hope (for the subsequent operation if an infant needs valve replacement and for almost all adults, who need their first). No longer may open heart surgery be involved.  Just like stents are deployed, these new valves will be able to be inserted via the groin.  At least, that’s what Abbot Laboratories, Medtronic, and Edwards LifeSciences hope to have available, after their approvals from the FDA soon.

There are tradeoffs, though.  It looks like (assuming it’s approved) the Edwards’ entrant will lead to a 4% increase in strokes (1 in 25 subjects).  Abbott’s mitral valve repair may not last as long as the units implanted via open heart surgery.  Medtronic has at least four years of testing to complete before it submits its entrant to the FDA(plus a patent lawsuit with Edwards).

The Edwards’ valve is comprised of cow tissue, encased in a steel frame (kind of like a stent).  It can be threaded via a small catheter into the heart (under general anaesthesia).  Once the valve is in place, a balloon expands it from 8 mm to some 20 mm in diameter (a typical valve size; the total diameter is adjustable).  There’s another caveat- it only works with those aortic valves that have failed due to stenosis.  These the artificial valves use the calcium coating (from the stenosis) as its backbone. (No calcium deposit, no proper valve placement.)  And, that’s why there’s a risk of stroke.  The calcium (or maybe cholesterol plaque) deposits can be shed, only to travel to the brain, thereby causing a stroke. The saving grace- death due to open heart surgery has about the same risk rate as that from stroke risk resulting from the Edwards’ valve. And, Edwards is still developing improvements to the device, based upon this research finding. They have made the valve thinner and are experimenting with cobalt chromium to replace the steel cage.  They are employing a filter (Embrella Embolic Deflector System) that can potentially “catch” the released calcium or cholesterol.  However, unless these improvements solve the problems, one can expect that the devices will only be approved the highest risk patient.

Share this: