Alright, now let’s talk for a few moments
about mitral stenosis. This used to be the
commonest form of valvular heart disease when
I was in training many years ago. But, because
of the decrease in acute rheumatic fever,
we don’t see mitral stenosis very much anymore.
Why does the valve get stenotic in a patient
who has acute rheumatic fever as a child?
It’s an unfortunate event. When the body
builds antibodies against the streptococcal
germ which is the cause in many children of
a strep throat, of a severe strep… infection in
the throat, the antibodies that are developed
actually cross react with the surface elements
in the aortic and the mitral valves.
Consequently, there is a small amount of injury
to the mitral and aortic valves during the
bout of acute rheumatic fever. And this small
injury builds up over the years as the valve
continues to open and close, open and close.
So, eventually, you end up with a highly scarred
valve like you see here.
The mitral valve normally has two nice thin
leaflets and here you can barely make out
which leaflet is which because of the severe
thickening and calcification that has resulted
from many, many years of use of the valve
after its initial injury during acute rheumatic
These days, actually, before you have to replace
the valve, we can often open it if it isn’t
too scarred with a balloon procedure, that
is a catheter is snaked across the mitral
valve with a deflated balloon. The balloon
is inflated and it cracks the valve open.
And you can see the results here from one
series, three years after the procedure, the
gradient that is a… which is a measure of
obstruction has not increased very much and
actually, the valve area hasn’t changed
much. And actually, after the balloon procedure,
most patients do well for somewhere between
five, seven, eight years.
And in fact, the nice thing about the balloon
is you can do it again. Usually, the patients
don’t do quite so well, but they gain another
three or four years. Now, with two balloon
procedures, you’ve pushed the patients
out 10, 12 years before they need a valve
replacement, which is a good thing.
That’s all I’m going to say about mitral
stenosis. We don’t see it a lot, when I
see it in my home state of Arizona, it’s
almost always in an individual who’s lived
south of the border, in Mexico, Central America
or Latin America and where they didn’t have
good pediatric care that is they didn’t
get penicillin when they developed a streptococcal
sore throat and so, they did have acute rheumatic
fever. As I said before, North America, Western
Europe, it’s much, much, much less common.
There’s just an occasional case of rheumatic
fever and these patients are treated very
quickly and usually, put on penicillin for
a long time to prevent recurrences with the
end result that they do very well.
Well, let’s talk about mitral regurgitation.
We talked about aortic stenosis and aortic
regurgitation, talked about mitral stenosis,
now we’ll talk about mitral regurgitation.
The commonest causes of mitral regurgitation
are congenital and coronary artery disease.
Here in this picture, we see a patient…
from... an autopsy picture of a patient with
congenital myxomatous degeneration. That is
in which there’s a lot of extraneous material
that gets into the mitral valve. It’s a
congenital inherited condition and you can
see that the valve might function very abnormally
because it’s all thickened and filled with
this mucinous, mucus like material which renders
the valve abnormal.
The valve leaks and as I’m going to show
you, most patients with this do pretty well.
They're at increased risk for germ infections -
for endocarditis, but in fact, relatively
few need to go on to valve replacement. In
this patient, valve replacement should have
been done because you can see the little
cords that hold the valve to the myocardium,
one of them has ruptured resulting in acute
Acute mitral regurgitation is just like acute
aortic regurgitation. It is poorly tolerated
whereas chronic mitral regurgitation, the
heart is able to compensate and many of these
patients can go for decades without needing
a replacement or a repair of the mitral valve.
In these patients… some of these patients
with myxomatous degeneration, the valve can
be repaired and doesn’t have to be replaced.
Here is an echocardiogram showing you the
valve prolapsing, that is the myxomatous valve
falling back into the left atrium. You can
see the little arrow. The valve should be
straight across there not falling back into
the left atrium, labeled LA from the left
ventricle during ventricular systole.
Now, it turns out that when one of these little
cords that holds the mitral valve to the ventricular
muscle breaks and the patient develops acute
mitral regurgitation, medical therapy does
not work. Again, no surprise, the acute load
on the ventricle really requires a valve either
repair or replacement and you can see here
in a series from the Mayo Clinic, patients
who underwent surgery did far better in the
longer term follow up than patients who did
not undergo surgery and only had medical therapy.
So, this brings us to the end of mitral regurgitation.
Couple of points ought to be made again.
First of all, when a patient, for example,
with myxomatous valve disease has a ruptured
cord, the acute mitral regurgitation is poorly
tolerated compared to the very well tolerated
chronic mitral regurgitation.
Secondly, mitral valve repair is possible
in patients with myxomatous degeneration and
younger patients do better with mitral valve
repair than with mitral valve replacement.
Rheumatic heart disease, mitral regurgitation
usually is not amenable to surgical repair
because the valve is too damaged.
In elderly patients, when you replace the
mitral valve either for repair… with repair
or replace the valve, it doesn’t make much
difference in terms of the outcome. It’s
just in younger patients that repair works
better than valve replacement.
So, let’s go on now and speak about what
chance the patient with myxomatous degeneration
actually need surgery. Here’s a series from
Australia where a large number of patients
were followed in a special mitral valve prolapse
or mitral valve myxomatous degeneration clinic
and you can see, it’s only a few percent.
But interestingly enough, a little more common
in men than women and the replacement indication
was, of course, the development of heart failure
or acute mitral regurgitation with a ruptured
cord. But even so, you can see over many years,
it was still a very small percentage that
actually needed valve replacement. And again,
just to point out the statistics, why patients
with severe acute mitral regurgitation do
better with surgery and do better with repair
than with replacement, particularly when the
individuals are in middle life as opposed
to quite elderly.
The major indication for surgery and patients
with mitral regurgitation is the symptoms
of heart failure. And again, we talked about
acute heart failure from a ruptured cord is
a strong indication for urgent valve, either
repair or replacement.