All About The Aortic Valve

Podcast Transcript

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Welcome to Love Your Heart, brought to you by Cleveland Clinic's Sydell and Arnold Miller Family Heart, Vascular & Thoracic Institute. These podcasts will help you learn more about your heart, thoracic and vascular systems, ways to stay healthy and information about diseases and treatment options. Enjoy!

Lars Svensson, MD, PhD:

I'm Lars Svensson. I'm chairman of the Heart, Vascular and Thoracic Institute, and my interests are valve surgery and aortic surgery. And I wanted to talk to you a bit about the aortic valve today and the aortic root. So the aortic valve is the valve that stops blood flowing from the aorta. In other words, the blood supply to your whole body back into the heart when the heart has stopped squeezing. So it's a valve that typically has three leaflets that sits there. Right above the valve are two what we call ostium openings that supply the coronary arteries to the heart. And those are obviously critical in function of the heart. So the blood supply to the heart is produced during what we call diastole, which is when the heart relaxes, the blood flow occurs to the coronary arteries that supply your heart muscle.

Then, as far as the heart squeezing, when it squeezes these little leaflets, and they are like little cups open up and then allow the blood to flow out to the rest of your body. Now, the problems that occur with the aortic valve can be divided into two. They can either build up calcium, which we call an aortic calcification and stenosis, or they can start leaking. The leaking can occur because the leaflets retract or they've been injured, say, from rheumatic fever, or because the aortic root stretches apart, and then the leaflets cannot oppose each other, and the valve starts leaking. The symptoms that occur with this differ. So with aortic valve stenosis, the buildup or calcification, a narrowing of the valve, produces what we call a gradient. So there's a pressure gradient between the left ventricle and the aorta itself because the blood has to now get squeezed through a tightness in the aortic valve.

And that's very important because flow, and this applies to water or blood, is significantly increased by the fourth power of the radius. So any slight decline in the opening as it gets more and more critical has very big effects on the pressure drop across the valve. So what are the symptoms that occur with aortic valve stenosis? The most common one is chest pain, but that usually is fairly advanced when you start having chest pain from aortic valve stenosis. Early symptoms may be fatigue, some shortness of breath after exercise and it may be subtle. And many people actually can adjust for that over time, particularly if they were born with an abnormal valve, then the heart compensates for that, and it sort of runs a marathon, both for a leaking valve and a stenotic valve as it copes with the increased load it has to cope with.

The other symptom that does occur when the stenosis is pretty advanced is a syncope or dizziness or fainting or losing consciousness. That's usually a pretty bad situation. The problem with aortic valve stenosis is also, based on a study that was done many years ago, about 1% of patients suffer sudden death. In other words, the heart just gives up, and the heart stops functioning, and they drop dead essentially. Unfortunately, also with aortic valve stenosis, when somebody has that event, it's very difficult to resuscitate them. For example, during anesthetic induction for patients with very severe aortic valve stenosis, what we call critical aortic valve stenosis, the anesthesia has to be very gentle so people don't drop their blood pressure.

So what do we do then for patients with aortic valve stenosis? Well, there aren't really many options other than replacing the valve. And so what we do surgically is replace the valve with a new valve, and the choices are a mechanical valve, which requires Coumadin, the blood thinner for the rest of a person's life, or the use of a biological valve. The downside of biological valves is that they wear down over time. We use cow valves here at the Cleveland Clinic because we've shown over the long term that when cow valves deteriorate, it's usually a more slow progress of deterioration, and it's picked up on echocardiograms. And so your cardiologist may say, "Look, your gradients are increasing across your aortic valve, and you may need to have another operation over time." And that may be a sort of early warning that you may be running into trouble with your valve. But we typically would not operate on a valve again until people get symptoms.

Now the other part about this. I mentioned aortic valve stenosis. There are two types of valve that we often operate on. There are the three leaflet valves, which are the normal valves, and then I mentioned people who are born with an abnormal valve. Those are usually called bicuspid valves, or they can be unicuspid, which is more uncommon and very rarely quadricuspid valves. Now, in patients who have bicuspid valves, they usually run into trouble in their 40s and 50s, sometimes a bit older with stenosis of the valve. They build up on calcium. It's an abnormal valve, so, over time, it'll build up calcium.

I'll get back to the question about a leaking bicuspid valve, which tends to occur at a earlier age. So when it comes to the surgical procedure for patients who have no coronary artery disease or any other major problems, and they may have some ascending aortic dilatation or aneurysm, we do those through a [minimally] invasive, what we call J-incision. And so we can replace the aortic valve and the ascending aorta if needed with a small incision that's probably about that size. It depends on your height, what incision length is. Now, the nice thing about that incision is that there are no effects on outcomes. We've shown in multiple studies now that the pain is less, breathing is better after surgery, people recover quicker, they have less blood loss, and especially in patients who have lung disease, is beneficial because we don't open up the whole chest, and we don't interfere with breathing and, for example, diaphragmatic breathing, and so people recover quicker. We also tell people with the minimal invasive approach that they can start driving two, three weeks after surgery if they feel up to it. You might still feel a bit tired because your blood count may be down, but I have patients who go back to work a week after surgery if they're not feeling too tired and they can do a couple of hours a day and then progressively get better.

So for all these operations, whether that's a full sternotomy, in other words, a whole incision for the whole breastbone, or the noninvasive J-incision, it still requires about six weeks to fully recover. As far as your heart, that will take about six months for it to get back to normal. So the thickened heart muscle that has been built up over time because the extra load on it takes about six months to regress and recover.

 So let's talk about the leaking aortic valves. So the leakage is mainly because, whether it's a three-leafed valve or two-leafed valve, the leaflets do not come together properly, and so they leak. And the leaflets have to come together to brace each other. In other words, they interact with each other, and there's this area of apposition that the leaflets come together and stop blood flow into the heart.

So when it comes to the bicuspid valves, usually what happens, it occurs early in age in aortic valve stenosis. The leaflets are incomplete, and they're often prolapsing. Now, in the bicuspid valves, if there's no calcium, we have a very high success rate of repairing those valves. Around 90% of them, if we see on the echo that there's no calcium and it's a bicuspid valve, we can repair those. The advantages of repairing the bicuspid valves are, firstly, it's mainly in young people, so you don't have to have a mechanical valve or replacement, and over the long term, you have a less risk of stroke and infection, and you don't have to be on a blood thinner. We've also shown that in our data, long-term survival parallels that are of a matched US population for sex and gender or gender, sex, and age. So long-term, the life expectancy is normal.

And even though we've had to re-operate on some patients who have had bicuspid valve repairs, the risk of the second operation's very low because it's a pretty straightforward procedure. We've also shown that, on average, 91% of those valves are still working 10 years after surgery, and at 20 years, it'll probably be in the region of 85% of those repairs are still working. We find that the repairs usually fail in the first 18 months or so, but if they hold up until then, the long-term results are better than having, say, a biological valve because the biological valves fail over time. It is still an abnormal valve. So two decades later, maybe even three decades later, it will probably fail. So in other words, if you take a hundred patients, about nine of those patients will need another operation within 10 years of a bicuspid valve repair.

For the three leaflet valves, as long as the aortic root is a bit enlarged, we have very good results for repairing and keeping those valves. The operation we do is a reimplantation operation. So what we do is we take the valve, and we carve it out from the surrounding heart muscle and structures. We free up the two coronary arteries, and then what I do is I take that valve, and I put it in a new plastic dacron polyester tube. And it so implanted within that dacron tube and then the two coronary arteries attached to the side of that, and then we replace as much as we need of the aorta that's enlarged. Now, that shows really good results. We've got what we call a 95% freedom from reoperation at 15 years for that. So in other words, five of a hundred patients will need another operation for that procedure within 15 years of surgery. We've also had great outcomes with that, and the risk of death is very low. There are only three surgeons who do that on a regular basis, and here at the clinic, we've had really great results for the surgeons who do this type of operation.

So that's a great option for a leaking three-leaflet valve, and we talked about the bicuspid valve repairs that are leaking. Let me talk a bit then about the biological valves. So the ideal biological valve does not exist. In other words, a valve that you've got to take no medications for, and it lasts forever. And so when it comes to surgery, we have a lot of options of biological valves available to us, and we have them on the shelves here, and we use the ones that we believe have the best long-term results. We've done a study of this. And for example, one of our studies, we have 19,500 patients in a study analyzing one of the type of valves that we use. So the way we choose a valve for a biological setup valve is dependent on age, what the annulus looks like, if it's a re-operation.

And we also take into account TAVR. So TAVR stands for transcatheter aortic valve replacement, and what that involves is putting in a new valve through the groin and seating it within the valve that has aortic valve stenosis. We don't have a good valve for a leaking valve. And from my point of view, you're much better having a repaired valve if you otherwise don't have severe comorbid disease or problems. So for TAVR, we generally recommend that in older patients who have potential risk factors for surgery. In our hands, the results are very good, and the risks are low, but it also deteriorates, and we don't have long-term data on how it's going to hold up. In one of the studies that just was published in the New England Journal of Medicine, the study looked at the outcomes over time for patients who had TAVR and compared them with the aortic valves that are put in open, and most of them hopefully through a noninvasive approach.

What is important to note in that study that after three years, the risk of death increases in the patients who had the TAVR versus those who had open aortic valve replacement. And the risk of stroke is approaching about similar rates, and looks like those are also going to cross. And then the other problem with the TAVRs is that they build up clot on them. Now, we don't know what the long-term implications for that will be. But the general thinking is that over time, that will calcify, scar up and result in gradients across the valve and result in people needing another procedure, whether that's what we call a valve-in-valve or open heart operation to remove the TAVR and then have a biological valve, say, put in, or for that matter, mechanical valve. We are seeing a lot more patients, particularly young patients who've had TAVRs. And so we don't encourage young people having TAVRs, especially if they've got bicuspid valves. So in patients with bicuspid valves, their anatomy is not as suitable for a TAVR, and so more problems occur in that population.

 So most patients, after a minimal invasive operation on hospital, sometimes two days, but three to four days, if they have atrial fibrillation, then they usually need some time to get over that, and we treat them with medications to control the atrial fibrillation before they go. Go at a discharge, that is. So here at the Cleveland Clinic, two days after discharge, you then also get checked by the nurses in our outpatient area, and the checking is for if you have any fever if you're happy with your medications, are you having any pain, are you healing up okay.

If you're cleared at that point, then you can fly home, or if you'll live more locally, drive home. If you have any problems or anything, then your nurse will call typically one of the surgeons to check you out or your own surgeon if he's not busy operating. Most of us operate every day and so may not immediately be available for any questions. We also encourage you to make appointments with your doctors back home within about seven to 10 days of leaving the Cleveland area. So I hope you find this review of what we do helpful. Thank you for listening.

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