Bovine vs porcine

[Ray Norsworthy]

My surgeon thinks porcine is best, but I've heard from other people who say bovine lasts longer. I trust my surgeon, Dr. Steven Jones, but I just wanted to hear some other opinions. Would you rather oink or moo?

 

[tprice54]

well, as a good consultant would say,"it depends"!
A porcine is the actual valve from the pig, which then gets fixed so as to not be live tissue.
An Edwards Bovine is made from the pericardial tissue, not the actual valve. The tissue is hand sewn into a valve by people. This assures every bovine valve is exactly correct.

 

[neil]

to be honest there both excellant valves, not a lot in them, i just prefer to oink

 

[Mentu]

Ray, this is a problem for us all. Few of us have the time to become expert in comparing heart valves so in large part we discuss the topic from the position of very interested amateurs. With the changes in tissue valves during the past few years, it is difficult (and probably impossible) to know which is "best". There are other variables that your surgeon may consider and you only know what those issues are by asking. Does he just prefer porcine valves or is there a particular reason he feels that one would be better suited to your needs? There are some things you could do such as check with Cleveland Clinic as to which valve is used more often there. The CC has become sort of the "Gold Standard" for valve replacement in the US. The last I heard, they are using more bovine pericardial valves. You could also seek the opinion of another surgeon with respect to valve selection. Try to remember that the surgeon works for you; getting a second opinion is a normal part of health care today. After all, you are the one who will live with the valve and I think it is important that you feel comfortable with the selection. After surgery, you want to focus on recovery not worrying about the valve itself.

Larry

 

[ElectLive]

Ray - I did not venture down the road of cow versus pig, primarily because of lack of time. I trusted my surgeon and haven't given it much thought since. With that said, if there had been more time, I think I would have tried to learn more, to at least ask better questions anyway. Most likely, you can't really generalize bovine vs porcine...you have to be specific to manufacturer and model. Perhaps one is better, perhaps not. Perhaps it just depends more on surgeon preference, or patient factors than anything else. There are more than a few of both porcine and bovine on this site, so hard to glean too much clarity here. Sadly, there sure are a lot of ties in our world, not too many outright wins.

My surgeon did mention one variable he considers with patients. Between two specific valves he discussed - the Medtronic Mosaic (porcine) and the Edwards Magna (bovine) - he noted that the Edwards valve has a bigger opening for the same size annulus. This was one factor to consider for him given the possibility that percutaneous valves may one day (maybe) be a reasonable "replacement" option. Opening size impacts the viability of percutaneous, particularly the possibility for two percutaneous procedures. Now, percutaneous will likely never come into play in my situation, but perhaps it might in yours, who knows, only time will tell. But, this is one specific variable that might enter into a given surgeon's decision on valve selection.

Also, I do remember one member here (Normofthenorth) who has voiced his opinion on your question not that long ago, perhaps he will see this thread and chime in. If not, you might be able to look through his posts and find.

 

[ElectLive]

I guess we shouldn't forget about equine either...

 

[normofthenorth]

And (TaDa!!) here he is! Several websites and a few people here have claimed in the past that there's better durability from bovine (pericardial) than porcine, but I've never seen that documented in published studies. And the single tissue valve with the best documented durability in published studies seems to be "my" pig valve, the Medtronics Hancock II. There are several studies documenting that, most recently one from "my" center from 2010, entitled "Hancock II Bioprosthesis for Aortic Valve Replacement: The Gold Standard of Bioprosthetic Valves Durability?" by Tirone E. David, MD, Susan Armstrong, MS, Manjula Maganti, MS, in Ann Thorac Surg 2010;90:775-781, abstract at ats.ctsnetjournals.org/cgi/content/abstract/90/3/775? .

The end of the article (unfortunately not available in full-text online without paying ~$30, though I've "quoted" several key passages by retyping them into posts on this forum) compares their Hancock II "porcine" results with published results from a number of other tissue valves, including the CEPMagna cow (pericardial) valve. In summary, (a) the Hancock II durability figures are uniformly better than all the others, and (b) the authors explain that some of the other valve-durability publications use misleading measures, especially "freedom from explant" or "freedom from reop", rather than the more meaningful "freedom from structural valve deterioration". (If you're valve is deteriorating BUT you're too sickly to survive OHS, you are counted as a SUCCESS in terms of "freedom from explant" or "freedom from reop"!!)

Before we leave durability, it's important to note that newer valves may well have even better durability than "old standards" like the Hancock II and the CEPM, but they naturally can't prove it yet with actual statistics. The statistical proof that the Hancock II valve has ~20-plus-year durability in 65-plus-year-old patients is based on the analysis of 65-plus-year-old patients that received the valve ~20-plus years before the study was published. A valve developed and approved in 2005 can't demonstrate a successful ~20-plus-year track record, no matter how good it is, or will eventually be shown to be. So there's always going to be some tension between being "the first kid on the block" to get a valve that SEEMS to be better and SHOULD last longer, and getting an older, more established model whose durability has been proven and the proof published. (BTW, for mech valves, I personally believe that the various accelerated-aging tests are probably reasonable proof of the durability of the valve itself -- but I don't think there's any comparably credible proof of the durability of a new tissue valve.)

The other most-often-referenced component of the "best" tissue valve is usually hemodynamics. The idea here is that you'd like to be as far from stenosis post-op as possible, with as large and unobstructed a valve opening as possible, and as small a pressure drop across it as possible. On that scale, I've seen one published article (from 2007), directly comparing the CEPM cow/pericardial valve with the Hancock II pig valve -- http://ats.ctsnetjournals.org/cgi/content/full/83/6/2054#TBL3 -- and it finds that the CEPM has significantly better hemodynamics one week post-op. So, on the face of it, the pigs seem to win on durability, but the cows win on hemodynamics, specifically very early on.

Personal sidebar -- when I expressed disappointment with the (1.6 sq. cm.?) estimated effective area of my not-small (25 mm?) Hancock II from my post-op-discharge echo-cardiogram (~5 days post-op), my surgeon told me to wait for future echo-cardiograms, which would be better. And they have been (1 only, so far), though I don't have any numbers or reports here.

Secondly, I think the hemodynamics of a replacement AV, within reason, are probably irrelevant for the vast majority of patients -- the exceptions being those with "valve-donor mismatch", i.e., patients with unusually small AVs for the size of their bodies. The rest of us seem to be able to achieve high levels of athletic output and achievement relatively regardless of the measured area, flow rate, or pressure drop of our AVs. Indeed, most valve-replacement surgeons (including mine) have lots of stories about patients who competed in marathons and the like with valves that very soon afterwards astounded the surgeon with their terrible condition, and which also demonstrated high levels of stenosis on echo EKGs and other tests. My personal experience also fits in with that pattern, as I was in my 60s and easily keeping up with a bunch of 30-somethings in competitive volleyball (4-on-4 court and beach including 2-on-2!) with AV stenosis around .8 sq. cm., IIRC, and a valve that my surgeon said was "toast", among the worst he'd seen. My disappointing reading 5 days post-AVR had twice that effective area, so it's hard to believe it would hold ANYBODY back athletically, even if it never improved.

As ElectLive suggests above, it's also possible that a valve with better hemodynamics (a wider opening) will be a better candidate for TAVI, or for multiple TAVIs. It sounds logical, though logic doesn't always lead to proof in medicine.

Of course there are other considerations, too, e.g.: Any valve your surgeon is comfortable with is arguably a "better" valve than one that makes him/her nervous! In that regard, my fancy Toronto (Canada) center was an early adopter of the Hancock II, while most US centers seem to have gravitated toward the cow valves, for whatever reasons, good or bad. Even if the reasons don't seem compelling, a patient might reasonably choose a valve that puts your surgeon in the "comfort zone".

 

[Ray Norsworthy]

Wow, what great answers, every one of you. I appreciate it a great deal. In fact, I'm going to print this out. I've talked to the surgeon twice, but we hadn't settled on a valve for certain, although he voiced preference for the porcine. As big as I am (6' 3", 275, former wrestler, weight-lifter, etc) I have been concerned about the size of the new valve's opening. It seems like when my valve narrowed to around 1.5 cm2 I started to drag a little, & my workouts started to suffer--not a lot, but it was noticeable. But until 2 weeks ago I was still warming up on the bench with 315, curling 170, doing heavy sled squats. (I know what you're thinking: no, I've never done steroids!) Following doctor's orders, I haven't come close to maxing out, though, in over a year. When I saw the surgeon last week I asked how in the heck all my blood could be pumped through that tiny opening. He just shrugged his shoulders & smiled. I should also mention that there hasn't been any hypertrophy in either ventricle. Maybe it's all the Omega 3, Vit. K-2, Vit. D, etc. I've been taking. Sure didn't get rid of the calcium crap, though.

Thanks again, everyone. My surgery is coming up later this month. Don't have a certain date yet, but I'll find out tomorrow or the next day.

 

[neil]

you do realise if you choose porcine theres no more bacon sandwiches dont you?

 

[ElectLive]

you do realise if you choose porcine theres no more bacon sandwiches dont you?

Stuck between a rock and a hard place: honor the cow or indulge in a tasty iron rich food that helps treat surgery related anemia.

 

[epstns]

I don't know. . . I have a bovine valve and every time I eat a steak or a hamburger, a cow's name pops to mind. It is like thinking of family members who have passed on.

One of my friends has a porcine valve and he squeals every time he passes a Bar-B-Que joint.

 

[ElectLive]

You know, I just remembered that animal-sourced insulin led the market way back when I was diagnosed with Type 1 diabetes. So, guess what, I was porcine for a while too. This will make it even harder for me to be respectful.

Ok, moving on, Ray, sorry for derailing your thread. As you've probably guessed, though, humor is one of the better therapies this site has to offer. I would like to get back to the topic at hand, though, so let me start a new post...

 

[ElectLive]

Personal sidebar -- when I expressed disappointment with the (1.6 sq. cm.?) estimated effective area of my not-small (25 mm?) Hancock II from my post-op-discharge echo-cardiogram (~5 days post-op), my surgeon told me to wait for future echo-cardiograms, which would be better. And they have been (1 only, so far), though I don't have any numbers or reports here.

Norm - Did your surgeon say why future echo's would be better and over what period of time the effective area increases?

The reason I ask is that I just looked at my 5 week post op echo, and it measured an aortic valve area of 3.25 cm2. I know what my surgeon said for his specific example, but I wasn't expecting anything that substantial, could our valves really be that different?

For anyone else that has posted above, do you happen to know what your porcine or bovine valve area measured?

 

[normofthenorth]

The surgeon just indicated that the early measurements are usually (or at least "often") much smaller/tighter than later ones. As I recall, my cardiologist told me that he didn't have the exact eff. area from the later (3-month?) echo, but that it was over 2 sq. cm..

I haven't memorized that article I cited/linked above, but I think it gives real numbers for both kinds of valves, a few days post-op, so you can see if your 3.25 cm2 is an outlier (or worthy of Guinness WBOR!).

 

[epstns]

Could it be that the materials the valve leaflets are made from gets "looser" after having been flexed and un-flexed for a while? Much like breaking in a pair of shoes. . .

Or, it could be post-op swelling that makes the area seem smaller than it really is. Maybe the aorta and heart muscle swell due to the insults of surgery and once the swelling goes down fully, the effective valve area can enlarge.

Where are the experts when we have questions? (Of course, I'll bet some will come along soon.)

 

[ElectLive]

The surgeon just indicated that the early measurements are usually (or at least "often") much smaller/tighter than later ones. As I recall, my cardiologist told me that he didn't have the exact eff. area from the later (3-month?) echo, but that it was over 2 sq. cm..

I haven't memorized that article I cited/linked above, but I think it gives real numbers for both kinds of valves, a few days post-op, so you can see if your 3.25 cm2 is an outlier (or worthy of Guinness WBOR!).

This is all very interesting. Based on the chart in that article, you actually have superb results. My 3.25cm2 is at 5 weeks, not 1 week, so not apples to apples, but it's definitely way off that particular chart, even at 27mm. Perhaps I should wait until my 18 month echo, though, before petitioning Guinness.

It seems a little odd how most of the averages in the chart would still be considered moderately stenotic (based on the ACC guidelines). But if they all "break in" in a similar fashion to yours, maybe that's not the case further down the road.

 

[epstns]

EL - Early on I thought of the point that most of the valves would be considered mildly restricted and came to the conclusion that it is all relative. If our native valves had only become restricted to the size of the prosthetic valves, would we ever have felt bad enough to seek surgery? I'd bet not. When my stenosis was in the mild and moderate stages, I never knew I had it. It wasn't until mine was graded "moderately severe" that I started to notice energy decline, so many patients will probably feel "as good as new" with artificial valves, even if their ultimate AVA is less than a "fully normal" valve.

 

[Mentu]

I think Steve has the essence of this issue. Regardless of the type or size of the new device, the central point of AVR is restore normal heart function so you can live your life without thinking about your heart valve. No doubt, our natural valves varied with respect to valve area but most of us didn't have symptoms until the area dropped below 1.5 cm2. What we all want is a valve that serves us well and allows us to be ourselves. There is of course also a problem with a valve being too large as well as a number of variables that our surgeons must balance. If they do their jobs well we can get on with our lives.

Larry

 

[normofthenorth]

And another +1 to what Steve said, and even for keen or aggressive athletes, too! My stenosis was well into the "severe" range, well under 1.0 cm2, before I finally felt ANY symptoms. All of this not only makes me content with my 2-point-something cm2 current AVA with the pig valve, it also makes me think that the attention given to tissue-valve hemodynamics is a distraction -- except for the (5-ish%?) of patients who have significant "valve-donor mismatch", i.e., very small AVs for their body size.

If you think of blood flow through your heart in terms of traffic on a highway, we can often tolerate moderate road narrowing with absolutely no delay. E.g., it's nice to have a shoulder to the road, but most of us very seldom use it, and if it's blocked, we don't usually have to slow down. There comes a point -- a combo of how great the narrowing is, and how heavy the traffic is -- where the "road stenosis" DOES slow down the flow, but until that point is reached, it has no "symptoms".

Blood is a bit different from auto traffic because it's incompressible, but I think that just makes the point stronger. I.e., while a highway can have many "bottlenecks" that slow the flow and cause delays, I think there would usually be only ONE significant "bottleneck" in each heart (maybe two), which limits the average and/or max flow through the whole heart. If your AV is NOT the significant "bottleneck" in your heart, then decreasing its size a bit has NO effect on that flow. At some point (which would vary from heart to heart), the AV stenosis becomes severe enough that the AV becomes the heart's significant "bottleneck", and the AV's effective area dictates the whole flow (and AV stenosis starts driving CV symptoms). Patients with "valve-donor mismatch" would get there very quickly, while some of us barely got there at all, even with AVs that had turned to junk.

 

[ElectLive]

I'm with you all...very good points.

My comment on the "oddness" of the replacement opening sizes had more to do with the potential shock value, not the actual improvement to patient experience. Take a 23 mm (a pretty "average" size) Hancock valve for example. If I had a 1 week echo that measured 1.2 cm2, as that chart Norm linked to indicates, I probably would have asked my surgeon "Are you sure you remembered to replace my valve or did you just fix the aneurysm then take an early lunch?"

Good to be aware of these things.