valve size question

[Jen]

Hi all,

Question.. What is the average AV opening after surgery?? Is that even a question to ask? I mean, as long as it is larger than what was there pre-surgery right?

 

[epstns]

You know, that's something I was not told, nor did I hear the statistic in anyone's conversation. I'll have to ask my friendly cardio the next time I see him. . .

 

[Jen]

I was just kind of curious...Don't know if it makes a "real" difference or not.
Thanks!!

 

[camgough]

I'm pretty sure it depends on the diameter of your aortic root and aorta itself.

 

[ALCapshaw2]

YES, there are several different size valves, selected to 'fit your plumbing'.

and YES, it is hopefully larger than the reduced opening of a stenotic natural valve

'AL Capshaw'

 

[normofthenorth]

Yes, it "depends" on many things including the overall size of the valve. My "pig" valve's effective area was measured in an Echo Cardiogram before I was discharged from the hospital. That measured area was disappointingly small to my mind (~1.6 cm2, IIRC), but I was told not to worry, that it would increase as everything settled in and relaxed. By the time my Cardiologist measured it again, I think he said it was over 2.0, which is a bit more like it. Whatever it is, I don't think it's been holding me back -- but then, my original valve didn't, either, even when it was measuring 1.0 or even 0.9 cm2(!). YMMV. People with small Aortas (and AVs) might care more about effective area, because it's more likely to be the "weak link" or the "key bottleneck" in their overall CV fitness than in those of us with average-sized or larger AVs.

 

[bdryer]

Hi Jen

I read somewhere that when it comes to mechanical aortic valves, 23 mm is the most common valve size implanted. I was implanted with a 23 mm On-X MHV and its effective opening is 2 ± 0.6 cm2. The popular St Jude 23 mm MHV has an effective opening of 1.6 ± 0.43 cm2.

 

[normofthenorth]

I'm shocked that the two mech valves of a single size have such a big "±" variation in effective opening sizes. Maybe that includes some narrowing upstream or downstream? Otherwise, I'd expect them to be "mechanically" consistent!

It's well known that valve manufacturers (tissue AND mech) use very different systems to assign valve sizes to their valves, so it's always misleading to compare two different (say) 23mm valves as if they're interchangeable. The good studies on comparative valve hemodynamics correct for that inconsistency.

 

[bdryer]

http://www.echopedia.org/wiki/Normal_measurements_of_aortic_valve_protheses

Hi Norm and Jen

Click on the above link. You will wind a chart showing most of the modern valves [even some older] with their specs. It's very interesting. Enjoy!

 

[epstns]

Link won't work for me. . .

 

[jklump]

My Edwards Lifesciences 25mm measured 1.2 after it was implanted. I was disappointed that it was not larger, but cardio said everthing was fine and quit worrying about a number. I am 14 wks post op and feel like I never had surgery.

John

 

[normofthenorth]

My Edwards Lifesciences 25mm measured 1.2 after it was implanted. I was disappointed that it was not larger, but cardio said everthing was fine and quit worrying about a number. I am 14 wks post op and feel like I never had surgery.

John

But you're SURE you HAD the surgery, right?

But seriously, I've been posting for a while that I think AV effective area, pressure drop, and all the other related hemodynamic calculations, are over-rated and often meaningless in terms of post-op CV fitness, even for keen athletes. I've used the analogies of a "weak link" and a "bottleneck" to try to explain the difference between a change in AV hemodynamics that would MATTER, vs. a change that wouldn't matter.

Recently, while sitting at my computer, I just thought of another analogy: Most of us have considered (or made) upgrades to our computers. Maybe I should add RAM, or a faster HDD, or pay for a faster CPU or a Dual-Core CPU, etc., etc. And we've probably heard that some of these upgrades will speed up our computers (usually by a small %), and others won't speed them up at all, because THAT component is NOT the one that's slowing your computer down. THAT's what I'm talkin' about!! If your AV effective area is really what's slowing down the (max) flow through your heart, then it matters; if not, then it doesn't matter. (So don't buy that "upgrade"! )

 

[epstns]

Or another way to look at it. . . If I was asymptomatic and quite happy with an aortic valve area of 1.4 cm2, then it narrowed to 0.8 cm2, then I had surgery to replace it and now my (hypothetical) ava is about 1.6 or 1.8 cm2, I don't really care if "normal" is 2.3 cm2 as long as I'm back to being asymptomatic and can expect to remain so for a decent length of time.

Thus, I don't have any idea what the area of my new valve is, and I won't really care what it is, as long as I can return to what life was like before it started going south. In a few months I'll be able to let you know if I can get all the way back, but initial indications are good!

 

[bdryer]

Hey Steve

Try googling, "Normal measurements of aortic valve protheses".

"Holy Norm" your computer correlation is great. It puts to light the flu virus I'm just getting over, which set me on my rear and a computer virus. Both slow the system down. Beauty Eh!

 

[epstns]

Just did -- Interesting chart. Now what we don't know is how large a valve area we each need to have "normal" functionality. In other words, given the ability of the heart to compensate (as it did during the early stages of stenosis), will our prosthetic valves give us enough area to have 100% performance? How large is large enough? Only the Shadow knows. . .

 

[Lynlw]

Just did -- Interesting chart. Now what we don't know is how large a valve area we each need to have "normal" functionality. In other words, given the ability of the heart to compensate (as it did during the early stages of stenosis), will our prosthetic valves give us enough area to have 100% performance? How large is large enough? Only the Shadow knows. . .

There is alot involved and as Norm said earlier, different manufacturers, have different measurements. It isn't if you got a 23 in On-x you would get a 23 in even another mech valve, I think for example if someone needed a 21 On-x they would get a 23 Carbomedics, because of how different valves are seated. Also in Mech (at least as far as I know) the "name" for example 23 mm, is the outer sewing ring measurement, not the valve opening, but for at least the Perimount tissue the "Name" number is the inner opening, so it isn't as easy as comparing a 19, to 19 to 19.

So prettty much that chart is handy for knowing if a valve in someone falls in the "normal" opening for THAT brand/type valve in that specific size, but not really helpful in comparing 1 valve to another.

As for what is the average valve size the average size person gets, my guess would be somewhere in the middle, (from pretty much 19mm-29 mm) FWIW Justin's bovine perimount is a 29, I DO think a smaller valve, might be a problem in something like pannus, where a small amount of extra tissue would take up more room in a smaller valve than that same amount of tissue would fill in a larger opening, or a case of prosthetic mismatch, But otherwise as long as your heart is functoning well, and better than it was that is all that matter.