Aortic Valve Choices

[caro]

Nice to meet someone else with a unicuspid valve (well, I used to have one). Your surgery is a day before my AVR one year anniversary. My AVA was .9 at time of surgery. My results from stress echo made my surgeon opt for surgery (even though I was successfully able to run at top speed at the top incline setting with 20 pounds of wires on me- oh well). My dad got his SJM in 50’s. He’s had it over 15 years now. Valve looks great and no complications. I got an On-X. I keep INR above 2.5. He does too. Both options are great. Wishing you the best. You’ve got this. BTW- Just saw that you had first procedure at Cleveland Clinic. They are wonderful. That is where mine was replaced. Had a mini-thoracotomy.

 

[Unicusp]

I had the On-X placed with conduit 6 years ago, it was what my surgeon recommended. Despite the claim of only needing to keep your INR between 1.5 and 2.0 I still keep it at 2.5 to 3.0. Warfarin has not been a problem for me, easy to self monitor. After researching both valves I felt they were comparative, so I went with the surgeons suggestion.

Thanks for the info.. Do you know what size valve was put in? Where did you have it done and was it a full sternotomy? Thx.

 

[vitdoc]

Go with the valve with the best hemodynamics i.e. the biggest opening.
The rest is hype.

 

[pellicle]

Go with the valve with the best hemodynamics

I think such is a troubled area

1)

Exercise hemodynamics of aortic prostheses: comparison between stentless bioprostheses and mechanical valves - PubMed

Stentless valves behave similarly to normal aortic valves in that there is almost no increase in gradient at exercise. Both mechanical valve groups showed increased gradients at exercise, suggesting that these valves obstruct blood flow. Our data add further evidence that stentless valves are...

pubmed.ncbi.nlm.nih.gov

Our data add further evidence that stentless valves are hemodynamically superior to mechanical valves in the aortic position.​

2)

https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.108.778886

The hemodynamic performance or “EOAbility” of the prosthesis is essentially determined by the size of prosthesis that can fit into the patient’s annulus and by the proportion of the total cross-sectional area of that prosthesis that is actually available for blood flow. To this effect, it should be underlined that the hemodynamic performance is not equivalent for all models of prostheses. Indeed, it is generally superior in newer compared with older generations of prostheses, in mechanical compared with stented bioprosthetic valves, in stentless compared with stented bioprosthetic valves and in supraannular compared with intra-annular stented bioprostheses. A recent meta-analysis18 shows that, compared with stented bioprostheses, stentless valves provide larger EOAs, reduced transprosthetic gradients, and greater left ventricular (LV) mass regression, but at the expense of prolonged cardiopulmonary bypass time.


a wise man said to me that all things being equal a good prosthetic valve was one that lasted 20 years or more.

So assuming that all valves are converging on better performance we get to the point that there are of course other factors which will indicate or contra-indicate. I'd call "a propensity for bleeding" a contra-indication for anticoagulation.

Some posts from Harriet (I hope she's well) on this topic after she agnoised over mechanical vs tissue

Update for -Now or Never Redo

Hello friends Thank you for all the comments and messages on my last post and for the Thoughts and Prayers on the passing of my mom 2 mtg ago today ... I miss her terribly! After my last post l checked into hospital where l spent 2 weeks before they transported me to Calgary whee l remain now...

www.valvereplacement.org

Angiodysplasia / Heyde syndrome

Angiodysplasia / 1) in the jejunum 2) mid sm intestines I couldn't be more upset. . Waiting for surgeon to come and see me as we speak for jejunum procedure . The are making to send me via ambulance to Calgary South Health Campas for a DBE .. Colonoscopy Ballon scope of some sort very invasive...

www.valvereplacement.org

 

[Unicusp]

I think such is a troubled area

1)

Exercise hemodynamics of aortic prostheses: comparison between stentless bioprostheses and mechanical valves - PubMed

Stentless valves behave similarly to normal aortic valves in that there is almost no increase in gradient at exercise. Both mechanical valve groups showed increased gradients at exercise, suggesting that these valves obstruct blood flow. Our data add further evidence that stentless valves are...

pubmed.ncbi.nlm.nih.gov

Our data add further evidence that stentless valves are hemodynamically superior to mechanical valves in the aortic position.​

2)

https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.108.778886

The hemodynamic performance or “EOAbility” of the prosthesis is essentially determined by the size of prosthesis that can fit into the patient’s annulus and by the proportion of the total cross-sectional area of that prosthesis that is actually available for blood flow. To this effect, it should be underlined that the hemodynamic performance is not equivalent for all models of prostheses. Indeed, it is generally superior in newer compared with older generations of prostheses, in mechanical compared with stented bioprosthetic valves, in stentless compared with stented bioprosthetic valves and in supraannular compared with intra-annular stented bioprostheses. A recent meta-analysis18 shows that, compared with stented bioprostheses, stentless valves provide larger EOAs, reduced transprosthetic gradients, and greater left ventricular (LV) mass regression, but at the expense of prolonged cardiopulmonary bypass time.


a wise man said to me that all things being equal a good prosthetic valve was one that lasted 20 years or more.

So assuming that all valves are converging on better performance we get to the point that there are of course other factors which will indicate or contra-indicate. I'd call "a propensity for bleeding" a contra-indication for anticoagulation.

Some posts from Harriet (I hope she's well) on this topic after she agnoised over mechanical vs tissue

Update for -Now or Never Redo

Hello friends Thank you for all the comments and messages on my last post and for the Thoughts and Prayers on the passing of my mom 2 mtg ago today ... I miss her terribly! After my last post l checked into hospital where l spent 2 weeks before they transported me to Calgary whee l remain now...

www.valvereplacement.org

Angiodysplasia / Heyde syndrome

Angiodysplasia / 1) in the jejunum 2) mid sm intestines I couldn't be more upset. . Waiting for surgeon to come and see me as we speak for jejunum procedure . The are making to send me via ambulance to Calgary South Health Campas for a DBE .. Colonoscopy Ballon scope of some sort very invasive...

www.valvereplacement.org

Thanks for the detailed information. Appears that this topic can get very deep! So, the data above at the top is 20 years old and aren't they porcine valves with finite lifespan? And even if one lasted 20 years for me, that's not enough time with more dangerous surgery down the road on a much older me. And even TAVR is risky and more risky on older people.
So.....in your extensive research which mechanical valve (or other valve that will last 35 years) has the best hemodynamic performance? Thanks!

 

[pellicle]

your research which mechanical valve (or other valve that will last 35 years) has the best hemodynamic performance? Thanks!

To my knowledge there is no significant difference between the various bileaflet pyrolytic carbon valves.

A point is also their tendency for clotting caused by pressure jets (think of when you occlude the hose with your thumb). There are opening and closing jets.
Some are optimised to minimise opening pressure, others closing some an average.

We're there a real difference we would see that in market dominance as surgeons would lean that way. We don't. I think that's some evidence there.

Best wishes

 

[pellicle]

aren't they porcine valves with finite lifespan

All bioprosthetic valves are quite finite. There have been incremental improvements of durability in situations.

 

[Unicusp]

All bioprosthetic valves are quite finite. There have been incremental improvements of durability in situations.

Thanks. I'm having my red wine right now. Shitty situation, but could always be worse. At least we have some options. It's just very surprising to me that there really has not been any significant improvement in the mechanical valve area in over 20 years. Looks like an opportunity!

 

[pellicle]

Thanks. I'm having my red wine right now.

its difficult, but I hope its something you can bear ;-)

It's just very surprising to me that there really has not been any significant improvement in the mechanical valve area in over 20 years. Looks like an opportunity!

I'm not sure I see it the same way. A **** ton of work has gone into this already and making something ourselves which can better the hundreds of millions of years (sorry creationists) of natural evolution (can you imagine the failures) is going to be hard.

I don't know what you know about the morphology of the actual natural heart valve but its pretty amazing stuff (for a biochemist / biologist).

I'd say that 90% of the hard work in design and materials (limited by materials science) is pretty much done and we're nipping around the very minor edges. Further when you consider that the cost of Research and Development is only going up and the demands of safety and product testing make it even more expensive I just can't imagine how.

Have a look through this:

Mechanical Heart Valves - History

and see what I mean.

However (much like diabetes) the real honing of treatment is now in the realm of putting in the patients hands the tools to monitor their INR themselves and takes us into an area where we have a valve that will outlast us, the tools to monitor anticoagulation AND its all cheap.

I'm sure I've posted this before, but:


In the west the median age of AVR is around 70 years old (so you and I are outliers) which means tha the current crop of even tissue prosthetic valves will suit most people.

Its the 3rd world where disease damages heart valves (with still health problems of rheumatic fever and scarlet fever a problem) that you get more people under 50 ... who just get mechanicals and deal with it using the cheap drugs available.

Nobody in India or China is going to pop for a $20,000 dollar valve

There is some light on the horizon for technology development however

http://media.corporate-ir.net/media_files/irol/64/64106/ATS_Forcefield.pdf

and

Non-physiologic closing of bi-leaflet mechanical heart prostheses requires a new tri-leaflet valve design

Mechanical heart valve prostheses are based on older designs without changes during the last 40 years. Today, there is an unmet need for less thrombog…

www.sciencedirect.com

US20100131056A1 - Mechanical prosthetic heart valve - Google Patents

A mechanical prosthetic heart valve, includes an annular support ( 12 ) on which at least two movable flaps ( 18, 20, 22 ) and several articular extensions ( 32, 34, 36 ) are arranged in an articulated manner. Each flap includes a central part ( 38 ) framed by two lateral wings that each...

patents.google.com

 

[pellicle]

At least we have some options.

another one

Foldax valve trials

I have been keeping an eye on the foldax valve over the last several months regarding the start of their human trials, nothing new on their site recently But then I came across this from several days ago and trials have started-...

www.valvereplacement.org

Early Feasibility Study for the Foldax Tria Aortic Heart Valve - Full Text View - ClinicalTrials.gov

Early Feasibility Study for the Foldax Tria Aortic Heart Valve - Full Text View.

clinicaltrials.gov

 

[RealtorRick]

I'll try to keep this brief. I was diagnosed with BAV & ascending aorta aneurism at age 50. Monitored the aorta for 2 years and had replaced by dacron graft at 52 at the Cleveland Clinic. Surgeon inspected the aortic valve and confirmed it to be a unicuspid that was healthy and functioning so he left it alone. Here I am 7.5 years later with severe stenosis and need replacement soon. I'm very healthy, active and asymptomatic. Heck, I walked over 12.5k steps at the Cleveland Clinic the other day walking between the many testing area's. I've pretty much decided that I only want to do this one more time. This second time is difficult enough. I can't see installing a tissue valve with an expiration date of anywhere between 1 and 20 years. Yes, the thought of Coumadin sucks, but I feel it safer than more invasive surgeries down the road. Yes, there is TAVR but that has many potential risks as well.
So, for me it appears to boil down to either the St. Jude Regent or On-X valves. Has anyone directly compared these two valves? They are both made from the same pyrolitic carbon and are very similar in design. But, my surgeon appeared to favor the SJ as it appears a larger SJ can be installed in the same area as a On-X, and he mentioned the On-X is "Bulky" and I guess requires a larger annulus for proper installation. Which valve has better hemodynamics? They both appear to be robust enough and tested to last a "lifetime". Any thoughts/comments/experiences appreciated. I apologize if I am re-visiting an old topic. Thanks everyone! By the way, this is a great site.

I had my bicuspid aortic valve replaced with SJM 9 years ago. Only issue I ever had with Coumadin was after Prostate cancer surgery I had some bleeding g in my bladder, likely due to an improperly placed(kinked) catheter. The good news is that I had a major infection a week after the cancer surgery, resulting in an ER visit from feeling crappy. Turns out my resting heart rate was 204 bpm.
The valve worked flawlessly and it along with Coumadin resulted in zero clots. A year
Later I had radiation therapy for resistant cancer cells. Again, no valve issues. SKM has been proven for many years. Others MIGHT be as good, but I cannot say they are BETTER. Make a decision and accept that it was the best decision at the time you made it. There is no wrong decision. Coumadin is not a big deal to me. You eat what you want, you just eat consistently. I don’t drink so that is a non-issue. For those who feel they cannot live without alcohol, tissue might be the answer.

 

[Unicusp]

I had my bicuspid aortic valve replaced with SJM 9 years ago. Only issue I ever had with Coumadin was after Prostate cancer surgery I had some bleeding g in my bladder, likely due to an improperly placed(kinked) catheter. The good news is that I had a major infection a week after the cancer surgery, resulting in an ER visit from feeling crappy. Turns out my resting heart rate was 204 bpm.
The valve worked flawlessly and it along with Coumadin resulted in zero clots. A year
Later I had radiation therapy for resistant cancer cells. Again, no valve issues. SKM has been proven for many years. Others MIGHT be as good, but I cannot say they are BETTER. Make a decision and accept that it was the best decision at the time you made it. There is no wrong decision. Coumadin is not a big deal to me. You eat what you want, you just eat consistently. I don’t drink so that is a non-issue. For those who feel they cannot live without alcohol, tissue might be the answer.

Excellent. Thanks for the feedback. You must be a big/tall guy as a 31mm is a large valve. Thanks again.

 

[PeterII]

So, for me it appears to boil down to either the St. Jude Regent or On-X valves. Has anyone directly compared these two valves? They are both made from the same pyrolitic carbon and are very similar in design. But, my surgeon appeared to favor the SJ as it appears a larger SJ can be installed in the same area as a On-X, and he mentioned the On-X is "Bulky" and I guess requires a larger annulus for proper installation. Which valve has better hemodynamics? They both appear to be robust enough and tested to last a "lifetime". Any thoughts/comments/experiences appreciated. I apologize if I am re-visiting an old topic. Thanks everyone! By the way, this is a great site.
[/QUOTE]

Hi, there is ONE, main difference between On-X and the other mech valves, and is the fact that the leaves open at 90 degrees and that results in better hemodynamics

Attached see the files i usded 5 years ago to make a decision, they may have some highliting i did for myself, sorry.

The On-X is an improvement on St Jude since it was designed by the same guy that designed St Jude and has 100% pirolitic carbon

I was 62 when the day came, and choose mechanical because dont want to go again to a hospital for this IF i can avoid it, surgeon told me, you can get a tissue that will last you till mid 70s.... , and then.... ? at 73 back to surgery ?, that did not work out "For Me" , there is no right and wrong

Hope this docs help you make a decision

St Jude is as good as On-X, tha later is just an improvement as per design and materials , so it seems...

 

[Superman]

St Jude is as good as On-X, the later is just a change as per design and materials , so it seems...

Is it an improvement? Or just a change? Are On-X patients living longer than their St Jude or ATS peers with fewer events and better quality of life? I don’t know the answer, but it would seem “improvement” would be measurable in some way.

 

[tom in MO]

So, for me it appears to boil down to either the St. Jude Regent or On-X valves. Has anyone directly compared these two valves? They are both made from the same pyrolitic carbon and are very similar in design. But, my surgeon appeared to favor the SJ as it appears a larger SJ can be installed in the same area as a On-X, and he mentioned the On-X is "Bulky" and I guess requires a larger annulus for proper installation. Which valve has better hemodynamics? They both appear to be robust enough and tested to last a "lifetime". Any thoughts/comments/experiences appreciated. I apologize if I am re-visiting an old topic. Thanks everyone! By the way, this is a great site.

Hi, there is ONE, main difference between On-X and the other mech valves, and is the fact that the leaves open at 90 degrees and that results in better hemodynamics

Attached see the files i usded 5 years ago to make a decision, they may have some highliting i did for myself, sorry.

The On-X is an improvement on St Jude since it was designed by the same guy that designed St Jude and has 100% pirolitic carbon

I was 62 when the day came, and choose mechanical because dont want to go again to a hospital for this IF i can avoid it, surgeon told me, you can get a tissue that will last you till mid 70s.... , and then.... ? at 73 back to surgery ?, that did not work out "For Me" , there is no right and wrong

Hope this docs help you make a decision

St Jude is as good as On-X, tha later is just an improvement as per design and materials , so it seems...
[/QUOTE]

Your literature appears to be from the manufacturer. Is it? If so, one would expect it to be presented as the "best thing since sliced bread."

 

[pellicle]

Hi, there is ONE, main difference between On-X and the other mech valves, and is the fact that the leaves open at 90 degrees and that results in better hemodynamics

Interesting ... yes the On-X is the only one that says it opens to 90

Measurement of Opening and Closing Angles of Aortic Valve Prostheses In Vivo Using Dual-Source Computed Tomography: Comparison with Those of Manufacturers' in 10 Different Types

The aims of this study were to compare opening and closing angles of normally functioning mechanical aortic valves measured on dual-source computed tomography (CT) with the manufacturers' values and to compare CT-measured opening angles according to valve ...

www.ncbi.nlm.nih.gov

Table 3
CT Measurement for Opening and Closing Angles in Normally Functioning Valves According to Valve Type

​	CT Measurement​	Manufacturers' Value​	P​
Opening angle (degree)​	79.1 (76.5-83.3, n = 86)​	​	​
SJR (n = 23)​	84.1 ± 0.9​	85​	< 0.001​
Carbomedics (n = 15)​	77.1 ± 2.1​	78​	0.121​
ATS (n = 12)​	69.5 ± 2.8​	85​	< 0.001​
On-X (n = 10)​	79.0 ± 2.1​	90​	< 0.001​
Sorin (n = 8)​	79.3 ± 1.5​	80​	0.225​
MIRA (n = 8)​	78.6 ± 0.6​	80​	< 0.001​
Duromedics (n = 5)​	77.0 (76.0-77.1)​	78​	0.063​
SJM (n = 4)​	83.4 (83.1-83.8)​	85​	0.125​
MH (n = 1)​	59.8​	60​	N/A​
Closing angle (degree)​	24.5 (23.0-29.8, n = 84)​	​	​
SJR (n = 23)​	28.6 ± 2.6​	30​	0.016​
Carbomedics (n = 16)​	24.3 ± 1.3​	25​	0.038​
ATS (n = 11)​	24.7 ± 1.3​	25​	0.407​
On-X (n = 10)​	40.3 ± 0.5​	40​	0.108​
Sorin (n = 8)​	21.7 ± 1.1​	20​	0.004​
MIRA (n = 8)​	21.9 ± 1.2​	20​	0.003​
Duromedics (n = 4)​	19.3 (17.9-20.4)​	20​	0.625​
SJM (n = 3)​	29.5 (28.7-30.2)​	30​	0.219​
MH (n = 1)​	0​	0​	N/A​

CT = computed tomography, MH = Medtronic-Hall, SJM = St. Jude Medical, SJR = St. Jude Medical Regent


However I'm not clear that this is an advantage; from:
A turbulence in vitro assessment of On-X and St Jude Medical prostheses

DEFINE_ME

 

[vitdoc]

Nice data Pellicle. Basically the reality is we have a teeedle dee and tweedle dum situation here. Not much if any significant difference in the valves.
Newer is not always better just different. The biggest difference is the ON-X claim for safe lower INR values which most feel are dangerous due to the possibility that a 1.5 INR could easily go lower.
And that looking at the ON-X data concerning low INR showed a tendency towards more embolic events.
So both valves from a functional perspective are very similar and probably need similar anti coagulation to be safe. They have some difference in their profiles which under certain situations might favor one over the other.

 

[Unicusp]

Interesting ... yes the On-X is the only one that says it opens to 90

Measurement of Opening and Closing Angles of Aortic Valve Prostheses In Vivo Using Dual-Source Computed Tomography: Comparison with Those of Manufacturers' in 10 Different Types

The aims of this study were to compare opening and closing angles of normally functioning mechanical aortic valves measured on dual-source computed tomography (CT) with the manufacturers' values and to compare CT-measured opening angles according to valve ...

www.ncbi.nlm.nih.gov

Table 3
CT Measurement for Opening and Closing Angles in Normally Functioning Valves According to Valve Type

​	CT Measurement​	Manufacturers' Value​	P​
Opening angle (degree)​	79.1 (76.5-83.3, n = 86)​	​	​
SJR (n = 23)​	84.1 ± 0.9​	85​	< 0.001​
Carbomedics (n = 15)​	77.1 ± 2.1​	78​	0.121​
ATS (n = 12)​	69.5 ± 2.8​	85​	< 0.001​
On-X (n = 10)​	79.0 ± 2.1​	90​	< 0.001​
Sorin (n = 8)​	79.3 ± 1.5​	80​	0.225​
MIRA (n = 8)​	78.6 ± 0.6​	80​	< 0.001​
Duromedics (n = 5)​	77.0 (76.0-77.1)​	78​	0.063​
SJM (n = 4)​	83.4 (83.1-83.8)​	85​	0.125​
MH (n = 1)​	59.8​	60​	N/A​
Closing angle (degree)​	24.5 (23.0-29.8, n = 84)​	​	​
SJR (n = 23)​	28.6 ± 2.6​	30​	0.016​
Carbomedics (n = 16)​	24.3 ± 1.3​	25​	0.038​
ATS (n = 11)​	24.7 ± 1.3​	25​	0.407​
On-X (n = 10)​	40.3 ± 0.5​	40​	0.108​
Sorin (n = 8)​	21.7 ± 1.1​	20​	0.004​
MIRA (n = 8)​	21.9 ± 1.2​	20​	0.003​
Duromedics (n = 4)​	19.3 (17.9-20.4)​	20​	0.625​
SJM (n = 3)​	29.5 (28.7-30.2)​	30​	0.219​
MH (n = 1)​	0​	0​	N/A​

CT = computed tomography, MH = Medtronic-Hall, SJM = St. Jude Medical, SJR = St. Jude Medical Regent


However I'm not clear that this is an advantage; from:
A turbulence in vitro assessment of On-X and St Jude Medical prostheses

DEFINE_ME

Very interesting data. The On-X can theoretically (and is designed to) open to 90 degrees but on actual CT measurement opens to a max of 81. Why?? Whereas, the SJR is designed to open to 85, and does in fact open to 85 degrees. To me, that points to the structural design and resultant oscillation and turbulence which determines opening. In my opinion, this would also lead to smoother laminar flow with the SJR.
Another thought; maybe that is how/why On-X can make lower INR claims. Due to higher turbulence, the incidence of clots forming is lower. Mere speculation on my part. Very interesting. Thanks Data King.

 

[pellicle]

Why??

I suggest manufacturing on that ... perhaps even a revision of the facts due to the observations of "wobble" ... dunno ... perhaps in meeting other tolerances (diameters, clearances) that the opening was "revised" in production?

dunno ... email them and ask?

maybe that is how/why On-X can make lower INR claims. Due to higher turbulence, the incidence of clots forming is lower.

no, I think that On-X can make that claim because they undertook FDA approval and the others didn't We already know that the INR levels set in the past were too conservative (quite a number of studies back that) and its just that the other various makers do not see any point in pushing that barrow?

To my mind the frantic obsession with 1.7 min vs 2.0 min is meaningless and has no basis in anything except psychology. I again draw attention to this post:

Failure of Onx valve and problems with lowering INR

Hi all - I need the help of the smarty pants like Ross. I apologize I cannot remember everyone's name. Not sure if you all remember me. I was actively on this forum and 2010 and part of 2011. I will briefly summarize my history. In June 2010 I was diagnosed with a bicuspid aortic valve. Of...

www.valvereplacement.org

which shows that for some patients such a min is dangerous. Perhaps more than we hear about, for I seriously doubt that every On-X patient is on this forum. I encourage you to read that and the ensuing discussion with a clear and analytical eye towards the following points:

• concomitant use of aspirin
• frequency of testing
• INR ranges

Best Wishes

 

[Shiv]

So, for me it appears to boil down to either the St. Jude Regent or On-X valves. Has anyone directly compared these two valves? They are both made from the same pyrolitic carbon and are very similar in design. But, my surgeon appeared to favor the SJ as it appears a larger SJ can be installed in the same area as a On-X, and he mentioned the On-X is "Bulky" and I guess requires a larger annulus for proper installation. Which valve has better hemodynamics? They both appear to be robust enough and tested to last a "lifetime". Any thoughts/comments/experiences appreciated. I apologize if I am re-visiting an old topic. Thanks everyone! By the way, this is a great site.

Hi, there is ONE, main difference between On-X and the other mech valves, and is the fact that the leaves open at 90 degrees and that results in better hemodynamics

Attached see the files i usded 5 years ago to make a decision, they may have some highliting i did for myself, sorry.

The On-X is an improvement on St Jude since it was designed by the same guy that designed St Jude and has 100% pirolitic carbon

I was 62 when the day came, and choose mechanical because dont want to go again to a hospital for this IF i can avoid it, surgeon told me, you can get a tissue that will last you till mid 70s.... , and then.... ? at 73 back to surgery ?, that did not work out "For Me" , there is no right and wrong

Hope this docs help you make a decision

St Jude is as good as On-X, tha later is just an improvement as per design and materials , so it seems...
[/QUOTE]
Perfect.