Carbomedics 29mm. Sorry, can't think what the model name is just now, but it isn't the supra anular Top hat. Just the regular old style in the anulus.
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Mechanical Valve for an Oversized Aortic Annulus
- Thread starter chaconne
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Carbomedics 29mm. Sorry, can't think what the model name is just now, but it isn't the supra anular Top hat. Just the regular old style in the anulus.
chaconne
Well-known member
Lynlw said:Do you have the measurements of your valve area since surgery?
No, I still need to get the surgery report and I will ask my cardio about my 2 post-op echos this Thursday. I'll post it if I find out anything new or interesting.
chaconne
Well-known member
I spoke at length to Catherine Burnett at On-X today and she sent me a few new data sheets. She says that the reason On-X does not have an aortic valve size as big as the St Jude, is because too big a valve can cause cavitation (air bubbles), and the big leaflets are also noisier. She said that the valve I have is large enough for anyone and will not restrict my performance.
I spoke at length to Catherine Burnett at On-X today and she sent me a few new data sheets. She says that the reason On-X does not have an aortic valve size as big as the St Jude, is because too big a valve can cause cavitation (air bubbles), and the big leaflets are also noisier. She said that the valve I have is large enough for anyone and will not restrict my performance.
Did catherine give any links to studies proving what she claimed about larger valves causing air bubbles . or noisier? beside anything her company did? Also there is a big difference as far as i know between a valve tht is "too big" AND a large person with a large heart needing a large valve that is the correct size.. Why she would talk about using a valve that is 'too big' doesn't make sense in this case and only muddies the water as far as im concerned.
chaconne
Well-known member
I certainly can't answer your questions. I guess you would need to talk to them directly. I was more interested in getting their perspective on my situation. She did mention some studies and she sent me data sheets summarizing some result from an FDA study on gradient.
normofthenorth
Well-known member
FWIW, my understanding of cavitation -- though I know more about boat propellors than mechanical heart valves! -- is that it's caused when mechanical forces "part" a liquid, essentially tearing it apart, so that gaps are left. I don't think those gaps are usually filled with air, unless this all happens right near the surface of a water body -- i.e., if there's air "handy". I wouldn't expect there to be a bunch of air near anybody's Aortic valve, ready to slide into a gap in the circulating blood. (No, I don't think this clarification adds anything to the questions you want answered, chaconne.)
chaconne
Well-known member
normofthenorth said:FWIW, my understanding of cavitation -- though I know more about boat propellors than mechanical heart valves! -- is that it's caused when mechanical forces "part" a liquid, essentially tearing it apart, so that gaps are left. I don't think those gaps are usually filled with air, unless this all happens right near the surface of a water body -- i.e., if there's air "handy". I wouldn't expect there to be a bunch of air near anybody's Aortic valve, ready to slide into a gap in the circulating blood. (No, I don't think this clarification adds anything to the questions you want answered, chaconne.)
Apparently, cavitation in mechanical heart valves is not some imagined effect. I found several articles on the web, 3 of which are below. It seems that in the 80's failures of some Edwards Durometics valves led to the idea that it could have been caused by cavitation. From some of what I've read, it seems that this is more likely to happen at heart rates much higher than normal, with large valves in the mitral position.
http://www.expert-reviews.com/doi/pdf/10.1586/17434440.1.1.95
http://www.icr-heart.com/journal/content/2004/jul/pdfs/12585_Lin_2172_r1.pdf
http://www.ncbi.nlm.nih.gov/pubmed/8061867
From my talk with Katherine, it seems that On-X has made some design decisions and they are willing to discuss them and tell why they think theirs is best. From all the information I've received, I feel like I've been given a satisfactory answer to my question. I still may end up calling and talking to Dr. Bokros (the designer of all modern bi-leaflet valves, an co-worker of Katherine) himself and asking these same questions.
Will the On-X actually perform as they claim it will? I don't know and I may never find out. All I really care about, at this point, is that it works well for me.
bradvo
Well-known member
I was relieved when I got my echo done for a baseline, but the bang for the buck for me was hearing everything looked good.
I had a 23mm installed.
I had a 23mm installed.
chaconne
Well-known member
Just talked to Dr. Jack Bokros
Just talked to Dr. Jack Bokros
I just spend about 30min on the phone with Dr. Jack Bokros. For any who don't know who he is, he's a material scientist who pioneered the techniques for making heart valves out of pyrolitic carbon. He might be considered as the Father of bi-leaflet mechanical valve technology. He's currently the president of the company that makes the On-X valve.
Some interesting things he said/claimed:
- If a valve is too large, too much blood will regurgitate during leaflet closure (the law of diminishing returns)
- Valves that open/close too fast are at greater risk for noise, fracture and cavitation
- The pure pyrolitic carbon in the On-X valve increases toughness (ability to be stressed w/out fracture) by 50%, which is why the inlet flare is possible on the On-X
- The PROACT trial should demonstrate that lower ACT levels are safe, with the On-X, in about a year (after 500 patent years are done)
Whether the last one proves to be true, time will tell!
Just talked to Dr. Jack Bokros
I just spend about 30min on the phone with Dr. Jack Bokros. For any who don't know who he is, he's a material scientist who pioneered the techniques for making heart valves out of pyrolitic carbon. He might be considered as the Father of bi-leaflet mechanical valve technology. He's currently the president of the company that makes the On-X valve.
Some interesting things he said/claimed:
- If a valve is too large, too much blood will regurgitate during leaflet closure (the law of diminishing returns)
- Valves that open/close too fast are at greater risk for noise, fracture and cavitation
- The pure pyrolitic carbon in the On-X valve increases toughness (ability to be stressed w/out fracture) by 50%, which is why the inlet flare is possible on the On-X
- The PROACT trial should demonstrate that lower ACT levels are safe, with the On-X, in about a year (after 500 patent years are done)
Whether the last one proves to be true, time will tell!
