STS Video Blog #4: “What About Horse (Equine) Tissue For Heart Valve Replacements?” By Dr. Allan Stewart

During the 47th annual Society of Thoracic Surgeons meeting last week, I received a great question from Keith about the use of horse (equine) tissue in heart valve replacement devices. Keith wrote to me, “Adam – What can you share about aortic valve replacement surgery using horse tissue?”

Luckily, I was able to discuss this topic with Dr. Allan Stewart at the convention. Dr. Stewart, who practices in New York City, is one of the most experienced heart valve surgeons with horse valve replacements — like the ATS 3f Aortic Bioprosthesis manufactured by Medtronic.



As several members of our patient and caregiver community are hearing impaired, I have provided a video transcript below.

Adam: Hi, everybody. It’s Adam and I’m here at the STS convention in San Diego. I’m very fortunate to be standing next to Dr. Allan Stewart from Columbia Medical Center, New York Presbyterian and we are answering your questions that you posted at We have a question for Dr. Stewart from Keith Barker. Keith asks, “What can you share about aortic valve replacement surgery with horse tissue?”

Dr. Stewart: Well, why replace a valve with horse tissue? It’s almost become now like an animal farm. There are pigs. There are cows. There are horses available. And people are surprised because it’s less well known, but the transcatheter valve, or the valve without opening your chest, was initially conceived with horse tissue and here’s why. The tissue has got more textile strength and is actually very thin in appearance. Also it lacks — One of the important things that ruins valves, something called phospholipids. They’re very low in concentration in horse tissue — which is why it’s ideal for a valve replacement. Nowadays, it really doesn’t much matter what the tissue is made of but it matters how the valve is designed. The structural engineering of all the newer valves is much more advanced than it was earlier. I believe that this horse valve replacement tissue combined with the valve structure will make it last 15, 20 years.


Horse Valve Replacement Tissue Device
ATS 3f Aortic Bioprosthesis (Horse Valve Replacement By Medtronic)


Adam: Great. You mentioned the cow valves, the pig valves. You mentioned, obviously, the horse valves. In terms of how common a valve replacement is done with the horse tissue valve, is it very common? Because I’m sure a lot of patients, they’re more familiar with pig valves and cow valves.

Dr. Allan Stewart, MD: Well, the pig valves and cow valves have been around for about forty years now. The equine, or horse valve tissue, has only been around for about nine years and, really, our longest experience was in Europe, in Germany and Belgium, who have done a fair bit of implantation. It’s been out that long but, unfortunately, we can’t start with a new product and immediately have twenty-year results. We’ll have to wait and see. All of these valves be it porcine, or pig, or cow, or bovine, have all been tested on the same rapid testing method while which will give a lab results of twenty-year data but, really, we need to wait for twenty-year data from a human being.

Adam: So, in terms of that testing, you’re talking about the valves are actually put into some kind of experience where they’re pressurized and challenged to be very similar to a human heart valve, correct? Is that right?

Doctor Stewart: Exactly, Adam. What occurs is put into something we call a rapid accelerator where the valve is opening and closing several hundred million times to replicate the decades of life in someone but, unfortunately, it’s not subject to the same emotional stresses and blood and changes in doing exercise as a valve would be when it’s sewn into a person.

Adam: Right. Well, thank you very much for your time, Dr. Stewart. Again, this is Dr. Allan Stewart, MD who’s practicing in New York City and you can learn more about him by going to Thank you very much.

Dr. Stewart: Good to see you again!

Keep on tickin!

Adam Pick
Written by Adam Pick

Adam Pick is a patient, author of The Patient's Guide To Heart Valve Surgery and the founder of

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