Why are pig valves used?

[alan_delac]

Hi,

Does anyone know what are advantages of pig valves (any generation or model) over bovine pericardial valves? If there were none, pig valves would not be used. Right? Wrong?

Regards

Alan

 

[johnbelloh]

Alan

There is quite a bit of marketing hype being put forth by the manufacturers of both porcine and bovine pericardial valves. Porcine valves have been used for years because a pig?s heart is very similar to a human heart and the valves are almost identical. The latest generation of porcine valve is treated with chemical agents to prevent calcification. Calcification is the enemy of all tissue valves. Bovine pericardial valves are not cow valves but are man made and fabricated from the pericardium ( lining ) of a cows heart. They are also treated with chemical agents to prevent calcification. There are many different variants of both types of valve. They come in stented and stentless versions depending on the required application. Both porcine and bovine valves now have a 20 year track record.

We won?t know how long the newer types will last ( other than manufacturer?s claims ) until we have experience with them.

John

 

[tobagotwo]

As John so aptly said, the porcine valves are actual valves.

Many surgeons tend to pick the natural valve (porcine) over the manufactured one (cow pericardium), as they don't have to triple-check for manufacturing faults, or worry that there might be an invisible flaw in the manufacturing that shows up later inside their patients.

However, the long-term data for the previous generation of valves, the Carpentier Edwards Perimount (bovine) and the Medtronics Freestyle (porcine), seem to show the bovine valves as lasting longer on average.

The newer valves from these companies are the Carpentier Edwards Perimount Magna and the Medtronics Mosaic.

New processes now being used on the porcine valves show some promise to extend the valve's useful life. Medtronics now uses a process they call Physiologic Fixation to prepare the valve leaflets for use without compressing the tissue. This compression of the leaflets is believed to have been one of the reasons for its more rapid failure, as dense tissue attracts more calcium deposits from the body.

Both the porcine valve and the bovine valve are now processed with other new anti-calcification treatments, which should help both to last longer.

 

[Debrinha GT]

valve selection

valve selection

The piece of information I've just read here is very useful and makes me wonder why the Pericardium bovine bioprosthetic cardioprothesis valve I've had for eight years has started to thicken up already. I remember that at the time I made my option in 1995 my surgeon said I would have a rather ormal life for about ten years and three months ago when I got my echo done, my cardio, not the surgeon, said that these valves are likely to start deteriorating after eight or ten years. When I asked him if he had any idea of how long it might still last he said he couldn't really answer it because it depends on how fast or slow it would deteriorate to the point of the need of surgery. I went back to see him a couple of days before Easter and there was no leakage and it was still working fine and my EKG was also OK so, he told me to go back within 2 or3 months. The echo done at the end of January showed my mitral valve was opening to 2,99cm2,GRAD max=14mmhg, GRADmed= 08mmhg. Can you help me understand what it all means in terms of needing a surgery? I also asked him how they know when it's time for someone to go under the knife and he said that the doctor bases himself on the exams and patient's heart history.

 

[Leighanne]

PVR and Tissue valve selection in general

PVR and Tissue valve selection in general

This is part of an email from a surgeon I emailed due to his knowledge of my condition and valve surgery, this is not to be taken as medical knowledge or advice on my part or of the person who sent this to me, In a way many of us I feel are test subjects since we are in a time when cardiac surgery is getting common, and having great results for so many conditions. We are lucky there are so many surgeons, or enough, who can do these things.

both pericardial and porcine have been used in the pulmonary position. There has been a longer track record with the porcine valve, thus more late results available (durability very good - on average, 10-20 years). The early results with the pericardial valve in the pulmonary position have been encouraging. The use of the pericardial valve is quite common in the aortic position and the late results have been very good. Consequently, there has been more enthusiasm to use it in the pulmonary position with the hope that it may be more durable. I believe the late results of the pericardial valve in the pulmonary position will be probably be comparable to the porcine valve - time will tell.

 

[tobagotwo]

Debora - Mitral

Debora - Mitral

You're young, and that decreases the life of tissue valves, especially earlier generations of them. If you also had this valve when you were pregnant, that would further decrease its lifespan, as changes during pregnancy temporarily degrade even an original mitral valve's functioning.

The cheap tour on mitral stenosis, as I understand it:

Mitral stenosis occurs when the mitral valve thickens, due to illness-created injury or congenital issues, and the opening that the blood passes through becomes progressively smaller, and the valve progressively less flexible.

In some cases, balloon valvuloplasty can be used to widen the opening. While there is frequently a tradeoff with regurgitation when that method is used, about 90% of people who have successful BV have a fix that lasts at least ten years. On a replaced valve, BV is an unlikely option.

Replacements can be either tissue or mechanical. In appearance, they seem to be made more like an aortic valve than a native mitral valve. Issues regarding what type of valve to choose are similar to those involved in choosing an aortic valve. In your case, having had multiple surgeries and your desired number of children, you may well lean toward the mechanical option, in hopes of permanency.

The basic issue with mitral stenosis is that it makes the heart work harder to get enough blood through the heart for the body to use. This puts pressure on the heart muscle, usually causing enlargement, and on all of the other valves in the system, which can begin to cause calcification, stenosis, or regurgitation (leakage) in the rest of the otherwise healthy valves. It can even lead to failure of that side of the heart.

When mitral stenosis becomes severe enough, possible resultant issues like thrombosis (blood clots) or atrial fibrillation become considerations. At some point before it becomes this severe, some form of anticoagulant therapy is usually introduced, anything from aspirin to Coumadin.

The normal area of the mitral valve orifice is 4-6 cm. Yours is about 3 cm. The pressure gradient is how much pressure or force is required to push the proper amount of blood through the valve in a single heartbeat. Results for this include a max (peak) pressure and an average pressure.

When a mitral valve is to be replaced (as yours is), it is usually deemed critical at about 1.4 cm, or with a maximum pressure gradient greater than 60 mmHG (millimeters of mercury - a measurement based on how high a column of mercury the pressure would create). If you showed other symptoms, such as shortness of breath (SOB) or atrial fibrillation (Afib), the critical pressure point might be set at 50mmHG.

Usually, the pressure doesn't really start to rise until your valve opening is down to 2 cm. At 1 cm, the pressure is generally around 25 mmHG, and by the time you would hit .5 cm, surgery will likely have already been performed.

Of course, you know that I am neither a doctor nor an expert. This is only my understanding of what I have read, and it contains generalizations. Note: Anyone spotting errors or omissions please step in. I am always open to learning more about all valve issues, and would be very unhappy to have misinformed and not been corrected.

Debora, you realize that certainly, individual heart histories affect the point at which a cardiologist or surgeon will say, "enough!" You have a long, interesting, and somewhat terrifying heart history, so much said here about criticality may be thrown out the window, based on your cardiologist's experienced view of your particular situation.

I don't know how much time you have left on your valve, but generally, valve stenosis progresses more rapidly over time. In other words: the worse it gets, the faster it gets worse. Your cardiologist may be able to make a "time remaining" judgement call, based on the rate at which the valve opening has narrowed over your last few echoes.

I hope yours is moving very slowly.

Best wishes,

 

[Debrinha GT]

I've beaten the odds

I've beaten the odds

Hi Bob, first of all, I want to thank you for your very long but considerably honest reply. I've never fully understood what all those echo result numbers meant except for the opening of the valve itself and I'm so happy to have someone in this forum who can help me decipher it. I've actually asked my doctor how long I still have left before I have to go into surgery yet again and he said he didn't know. Would you risk taking a guess judging by my echo results and heart history? You see, one minute I think I'm feeling some of the symptoms but the next, when I'm not paying much attention to what I'm doing, I realize I didn't really feel anything. I guess that being too aware of my situation doesn't really allow me to tell the difference between my imagination playing tricks on me and the valve problem making itself evident. When I went to see my cardio just before Easter, I asked him about the symptoms and he said that for the moment I shouldn't really be feeling anything yet but again, that was over a month ago. Regarding the duration of tissue valves, I must've beaten the odds with my second valve because although I was only 15 when I got it put in, it lasted for nearly 16 years when it was totally worn out as described by the surgeon on opening my heart up.

 

[tobagotwo]

Debora, I wouldn't know where to begin. A guess like that takes experience that I don't have. And I certainly couldn't guess what your cardiologist would consider a proper stopping point for you. I'm sorry.

I would think your cardio could hazard a rough guess by looking at your last three echoes and extrapolating a little. He just may be unwilling to give you an answer, if he is concerned that you might take as gospel, rather than as an estimate. Or perhaps a surgeon may have more direct experience for hazarding a guess.

As far as symptoms, once you're in the middle of it, it's so hard to be objective about yourself. Especially since most of the symptoms are just extensions of what are really normal events. People do get SOB from running up the stairs (when I was at my worst, I still did less huffing and puffing after two flights than the college recruits who trailed after me). Your heart does sound loud after sudden exercise, or even a tense movie scene. Once in a while, everyone stands up a little too fast. That's why it can be hard to tell if things are really symptoms, and also why it's unfortunately easy to ignore real symptoms when they do occur.

Angina is real, and definitely a symptom. However, even with that, you need to know (which you likely do) how angina feels to you. Everyone seems to experience it a little differently. To me, if felt like the slight tightness at the top of your lungs when you breath in too much cold air. Except it was August, which is summer in this hemisphere.

Unless you show other danger signs, it doesn't sound like this year, anyway. That would be pretty quick to drop more than a cm. However, your cardiologist knows your history, and has to factor in at what point he feels there may be danger to your heart's other parts. Push him a little harder. Remind him how much stress it can be to live in the shadow of upcoming surgery - and how that can have a negative affect on your heart rhythms.

Best wishes,

 

[Debrinha GT]

Very kind

Very kind

Thank you again for taking your time to answer. You've given me some really important information and great advice which I'll follow as I feel the need. You see, I remember that in July 1995 I was walking up a hilly street with my mum when I felt I was gasping for breath and I even told her that I thought it would soon be time for my next surgery. I was trying to get pregnant then and when I went for my echo and the cardio asked me if I was feeling OK, I knew right away what he was trying to say and he never hid anything from me. I started crying because I really wanted to have a baby and he assured me that I could still carry on with my plans and my life quite normally. A few months later, I had a chance to go to Scotland for a holiday and we even bought the tickets to go on January 2nd since the doctor had told me the surgery might still be over a year away. In the end of November I went to see him again just to be sure and the echo showed that my valve was in pretty bad shape so I couldn't go on a plane and the operation would have to be within a couple of weeks. I couldn't believe it and until today I remember every single emotion I went throgh on that day. In a way I dread something of that sort happening again!