Aortic Sclerosis – Valvular Heart Disease

00:00 Well, since the development of atherosclerosis in the aortic valve is associated with worsening valve function and eventually, severe aortic stenosis, it was early on suggested, let’s put these patients on Statin drugs. You’ll remember from the pharmacology lecture, Statins actually retard the development of atherosclerosis.

00:23 So, there had been a number of studies where statins were tried in a double blind randomized fashion. A very excellent study in the New England Journal, a few years ago, was in Norway and unfortunately, it didn’t work. There was no improvement in the group that got Statins versus the group that got placebo. Most people seem to think that the reason for this is that the Statins were started too late. The process was already far advanced in the aortic valve before the Statins were given. There are now some other trials underway, trying to give Statins much earlier in the course, in an attempt to be preventive or prophylactic, if you will, in terms of development of aortic stenosis, but we don’t have the results of that yet. In any case, many of these patients will have elevated lipids that require Statin therapy anyway and the decision is made not based on the presence of the bicuspid valve or atherosclerotic… early atherosclerotic aortic valve, but much more on the likelihood of developing coronary artery disease.

01:31 A question that often arises is, does the patient with aortic sclerosis, which is extremely common, eventually develop into aortic stenosis? In fact, studies have shown that aortic sclerosis is the beginning of the atherosclerotic process in the aortic valve. You might consider it very, very mild aortic stenosis. And just as atherosclerosis in the coronary arteries and elsewhere in the body can develop and get worse with time, the same thing can happen with the atherosclerosis in the aortic valve. So, when you identify a patient with aortic sclerosis, you have identified a patient with atherosclerosis, probably not only in the aortic valve, but also in the coronary arteries. It correlates with all the risk factors that lead to atherosclerosis. I use it in my clinical practice. When a patient comes in and tells me they're having chest discomfort with exertion and I hear an aortic sclerosis murmur, I’m quite convinced that I’m dealing with atherosclerosis in the coronary arteries because I’m already hearing atherosclerosis in the aortic valve.

02:37 So, it’s important to listen carefully to these patients with the stethoscope to see if you can identify an aortic sclerosis murmur. Aortic sclerosis murmurs are very common in the elderly. And guess what? Atherosclerosis is very common in the elderly. So, the two of them go together. And in fact, there have been a number of studies that have actually looked at this. This is what I’m demonstrating to you. Here, is a study from Seattle, Washington in which 5,000 elderly patients were followed. You can see quite a large percentage had aortic sclerosis and a much smaller percentage actually had gone on to significant clinical aortic stenosis. So, the atherosclerotic aortic valve initially is just producing a very limited little murmur, an atherosclerosis murmur. And then with time, that murmur becomes more prolonged and loud as the patient develops various phases of aortic stenosis. Well, let’s talk for a moment about the risk factors. As you might imagine, since atherosclerotic aortic stenosis is related to the development of atherosclerosis, it is no surprise that it’s related to the presence of risk factors. So, patients who are smokers, patients who have hyperlipidemia, patients who are diabetic and hypertensive are going to be much more likely to develop aortic sclerosis that proceeds to aortic stenosis than individuals who are lacking in those risk factors. So, when you develop a preventive cardiology program and treat these risk factors, you are not only decreasing the likelihood that the patient will develop coronary artery disease, but very likely, you are also decreasing the risk that they will develop atherosclerotic aortic stenosis.

04:33 Many years ago, when we had a patient with severe aortic stenosis that was due to atherosclerotic calcific disease, about 50% of the patients turned out to have associated coronary disease.

04:44 No surprise since atherosclerosis is a diffused disease affecting, in this case the aortic valve, and of course, in about half the patients, it affected the coronary arteries.

04:56 Today, actually 70 to 80% of patients with calcific atherosclerotic aortic valve disease have significant coronary disease. What’s the reason? The patients are a lot older today than they were some years ago when they presented with… when they presented with atherosclerotic calcific aortic stenosis. So, they’ve had much more time to develop coronary artery disease. They're older, they're sicker and they have more co-morbid condition in particular, a greater incidence of significant narrowings in the coronary arteries from atherosclerosis.

05:28 Well, let’s talk about the three symptoms. I mentioned them earlier, the three warning symptoms that say, “This patient really needs to be considered for urgent operative intervention.” The three symptoms are angina, heart failure and syncope.

05:45 First, let’s talk about angina. In fact, the patients can have angina even with normal coronaries because the thickened ventricle is doing so much increased work because it’s trying to push the blood thorough the stenotic aortic valve that it demands a great deal of oxygen and nutrients, sometimes more than it can get at a time when the person is exerting themselves and heart rate goes up and blood pressure goes up. So, consequently, angina can occur with coronary disease or without, but it’s a signal that the patient is coming into an accelerated phase of aortic stenosis and needs to be intervened, needs to have a new valve. The second symptom is heart failure that is the patient notices unusual shortness of breath with moderate exertion or even some shortness of breath at night or wakes up at night short of breath. That’s even a more severe warning symptom than angina and the patient again, urgently needs to have an aortic valve replacement.

06:46 Finally, there is the patient who faints. That is the most severe symptom and in that setting, we push patients very very quickly to surgical intervention.

06:58 Okay, what are the various surgical interventions that you can have? Well, first of all, most patients, particularly if they're young and reasonably healthy and can withstand surgery, most patients will go on to… to receive a valve. They can either receive a tissue valve, made either from the pericardium of a cow, bovine pericardium or actually, an aortic valve from a pig; they are specially raised and harvested for their aortic valve.

07:28 The advantage of the tissue valve is that you don’t need to take warfarin. Remember the anti-coagulant, the anti-thrombotic that we talked about in the Clinical Pharmacology lecture? Patients with a prosthetic valve, plastic and steel, need to be on that drug.

07:43 Patients who receive tissue valves, usually do not need to be on that drug and therefore, don’t have the risk of hemorrhage that the patients who are on warfarin have.

07:52 Secondly, there’s a procedure called Ross procedure in which the pulmonic valve is... in a patient, is transplanted into the aortic area and a prosthetic valve is put into the pulmonic area. This operation requires great surgical skill and is only done by a few people. And of course, finally, one can actually, these days, replace the aortic valve with a catheter procedure. This is only done usually in very elderly, frail, infirm individuals who we think will not survive the operation of a surgical aortic valve replacement. The surgical aortic valve replacement results in a valve that’s a little bigger than the catheter one and consequently, the results are slightly better. Although they are remarkably good in a very elderly and frail population when we do the catheter valve procedure. After aortic valve replacement, even in very elderly patients, here you see all individuals who underwent valve replacement. These were surgical valve replacements over age 80 and you can see that even at 10 years, there’s about a 50% survival and many of these patients do not die of heart failure or of their valve disease, they die of other things. Any elderly population is going to die from multiple other things, cancer and heart… disease, heart failure from atherosclerosis and so forth, many other things. But in fact, a substantial portion of these people are still alive even many years after their aortic valve replacement.

09:27 Just very briefly to talk about the diagnostic procedures that we do, once as I’ve shown you a few moments ago, you hear the murmurs that suggest aortic stenosis, you get an electrocardiogram.

09:38 What this electrocardiogram demonstrates is a lot of high voltage. You can see the upstrokes here are very, very large and that is a suggestion that the left ventricle has become hypertrophied, that is thickened in response to the increased work load that it has to face with the stenotic aortic valve. The chest x-ray can be surprisingly normal, but as you can see in the drawing on the right hand side, there’s a little hint of a dilated ascending aorta which is dilated because of the high speed jet coming across the stenotic aortic valve. This is an echocardiogram, two-dimensional echocardiogram. You can see between the LV - the left ventricle and the AO - the aorta, that there’s a very calcified aortic valve. If we saw this as a movie, you would see that the valve is moving very poorly and hardly opening at all. And we can actually estimate the severity of the aortic stenosis from the two-dimensional echo.

10:38 So, in conclusion then with aortic stenosis, valvular heart disease these days is much more either the result of a bicuspid valve or atherosclerosis that is not what we had many years ago when we had a lot of rheumatic fever. Patients who were developing chronic rheumatic heart disease, that there are a number of other complications that it can occur in these patients because of other diseases because the atherosclerotic folks are often very elderly and have a lot of other problems, lung, possibly and kidney disease. The calcific atherosclerotic aortic stenosis when patients develop symptoms, it requires that one consider valve replacement, particularly if they develop one of the symptoms - angina, heart failure or syncope.