00:01
of heart failure particularly related to cardiomyopathy
as a very malignant disease within cardiology.
00:01
Ischemic cardiomyopathy, along with hypertrophic
cardiomyopathy, are the two commonest forms
of cardiomyopathy seen. In the dilated cardiomyopathy
due to ischemic heart disease, very often
the patients will have had symptomatic myocardial
infarcts, usually multiples, and each one
of these damages the left ventricle with the
end result that one ends up with markedly
reduced left ventricular muscle and a dilated
cardiomyopathy. Something that we don’t
understand is that some patients show up for
the first time with heart failure, never having
had a clinical heart attack or myocardial
infarct, never having had angina, and yet
when we do their coronary angiogram as part
of the evaluation, we discover terrible, severe,
advanced coronary disease as the cause. Why
these patients have no symptoms and other
patients have clear-cut symptoms is still
a mystery and is the subject of intense investigation.
00:52
Hypertension, untreated, can also lead to
dilated cardiomyopathy by putting a major
stress on the left ventricle that eventually
causes it to fail and dilate. Valvular heart
disease, longstanding mitral regurgitation,
longstanding aortic regurgitation, untreated,
also eventually can lead to a dilated cardiomyopathy.
The next one listed on your list here, the
anthracyclines, these are drugs used in a
variety of cancers, but particularly for breast
cancer, particularly metastatic breast cancer,
and they can cause heart damage. And so, the
cardiologists are often involved with the
oncologist in carefully monitoring the patient
who’s receiving these drugs and we stop
the treatment as soon as we start to see some
heart injury.
There’s a small number of women who, following
pregnancy, will develop a dilated cardiomyopathy.
Again, there seems to be a genetic predisposition
here. And finally, chronic, heavy use of alcohol
leads to a dilated cardiomyopathy, among other
problems.
Now, let’s talk a little bit about ischemic
dilated cardiomyopathy because again, this
is a very very common form. It seems that
this is the most common form of dilated cardiomyopathy,
although the genetic forms now compete with
it for most common status. It’s, as we’ve
talked about, caused by repeated injuries
from ischemia that can be symptomatic or asymptomatic.
And, in fact, many of these patients come
first to attention when they have a myocardial
infarction that is symptomatic. But others,
as I’ve told you, come to attention when
they’ve never had any symptoms and we discover,
to our surprise, that the patient has severe
coronary artery disease. The prognosis is
not good with the dilated cardiomyopathy,
as I’ve been expressing throughout this section.
02:47
Any form of dilated cardiomyopathy has a poor
prognosis. The ischemic form has the worst
prognosis.
Now, let’s talk for a few moments about
diagnosis. We would, of course, love to diagnose
these patients early in the course of their
cardiomyopathy. Unfortunately, they usually
come to our attention when they develop symptoms
of quite significant heart failure. And, of
course, in the heart failure segment, we’ve
already talked about that. Patients may be
short of breath. They may have peripheral
swelling and edema. Sometimes the ischemic
form, the patient will have had some ischemic
event, and then when we do the echocardiogram
and the catheterization, we discover, to our
surprise, that the left ventricle has been
severely injured, has a markedly reduced ejection
fraction that is a reduced percentage of blood
that it squeezes out with each beat. There
are often electrical abnormalities, both atrial
and ventricular arrhythmias. We’re going
to talk about the arrhythmias in a few moments.
And, of course, there are enla-, there’s
enlargement on the electrocardiogram of the
left atrium and also, often evidence for enlargement
of the left ventricle as well.
On physical exam, it’s the heart failure
exam. The heart may feel enlarged when you
feel the chest. There is often a third heart
sound which is a sign that the ventricle has
been severely damaged. There may be sounds
in the lung that suggest fluid. There may
be edema in the legs, as I’ve already said.
04:25
And one may even have, as I mentioned before,
mitral or tricuspid regurgitation murmurs
from stretching of the valve annulus or ring
in which the valve is contained. The workup
for the diagnosis usually starts, of course,
with the physical exam and a history, followed
by an electrocardiogram. Usually, by then,
we’re starting to have a clue because we
see it's a heart failure patient, that
we’re dealing with a dilated cardiomyopathy.
04:52
And then the echocardiogram shows us the picture
that really confirms it. We usually do a coronary
angiogram to distinguish the ischemic form
from the forms that are not ischemic, for
example, the genetic or alcoholic ones or
other etiologies. Occasionally, we’ll do
a magnetic resonance image because it gives
us an idea about what is the underlying structure
of the myocardium. There might be a clue,
“Oh, this is ischemic,” or “No, this
is secondary to a chemical that’s being
used for treatment of cancer,” or could
be from alcohol. These days, we’re doing
more MRIs because they give us a lot of information
about the structure of the myocardium in patients
with dilated cardiomyopathy. And again, coronary
angiography to make sure we’re not dealing
with ischemic cardiomyopathy. In some, not
very many, individuals with dilated cardiomyopathy,
when we do coronary bypass and give new blood
flow to the heart muscle, some of the heart
muscle recovers. And so, there’s partial
recovery of the ischemic cardiomyopathic patient,
but usually, that doesn’t happen. Usually,
the ventricle is too damaged and scarred to
recover and after medical therapy fails
to work, these patients are often candidates
for heart transplant. But, we’ll talk about
that in a few minutes.
So, the therapy, of course, is the same therapy
we talked about for heart failure. Beta Blockers
often improve the situation by decreasing
the work of the heart. ACE inhibitors or angiotensin
receptor blockers that block the renin-angiotensin
system, decrease the blood pressure, improve
vascular function and often help. Sometimes
the patients need small and sometimes large
doses of diuretics and sometimes these are
combined with mineralocorticoid diuretics
such as Aldactone that help to decrease the
edema tendency in these patients. We, of course,
try and reduce salt in their diet. Sometimes
regular exercise helps. We have to pay attention
to electrical abnormalities - arrhythmias.
07:04
And in a small number of patients, sometimes
a special pacemaker can re-coordinate the
electrical activation of the ventricle and
improve the contractility a bit. So, there’s
a whole variety of therapies usually starting
with drugs and watching out how much sodium
is in the diet and some exercise and then
progressing to more aggressive things, special
pacemaker therapies and finally heart transplant
in the end.
07:32
Hypertrophic cardiomyopathy is the other very
common form of cardiomyopathy in the population.
07:38
It occurs in about a hundred out of a hundred
thousand people, and as I’ve said before,
most of these individuals have the disease
in a completely benign form. They live long
lives and they have no problems. The disease
is genetic. It’s an autosomal-dominant inheritance
and there have now been discovered more than
1,000 different mutations that lead to hypertrophic
cardiomyopathy. What happens is that the heart
muscle cells develop in an abnormal fashion
so that instead of being lined up and parallel,
they are in a random order and they pull against
each other in abnormal fashion so that there
is a marked tendency for individual cells
to hypertrophy that is to increase in size
and volume and this, of course, then results
eventually in a marked increase in size and
volume of the left ventricle. There are a
variety of different forms of hypertrophic
cardiomyopathy. The commonest one involves
marked hypertrophy of the septum, but there
can be forms in which the apex is hypertrophied,
the base is hypertrophied, and even, sometimes,
the hypertrophy extends into the right ventricle.
08:48
When the disease was first described in the
1960s, it was thought to be a horrible thing.
08:52
Why? Because we only saw patients who were
hospitalized with complications. Well, about
20 years ago, the Italians did a whole community
survey where they went into a community and
they did echocardiograms on everybody in the
community. And what they discovered was large
numbers of patients with hypertrophic cardiomyopathy
who were living normal lives... expectancies,
who got to old age and in fact, I’ve seen
patients well into their 90s with hypertrophic
cardiomyopathy. It turns out the vast majority
of patients with hypertrophic cardiomyopathy
do just fine. However, there is a small sub-group
that has malignant ventricular arrhythmias
and as I said before, the commonest cause
of death in young athletes who are involved
in sports, particularly in high-competition
sports - basketball, football, soccer and
so forth. These individuals can develop malignant
arrhythmias and have cardiac arrest on the
playing field. Again, genetic disease, quite
common, but in the main, quite benign. And
here you see some statistics for how common
in the population. Not that common, certainly
nowhere near as common as coronary artery
disease, but nevertheless, more common, a
little more common, than the dilated cardiomyopathy,
at least in some series. Although in other
series, the two are almost equivalent.
So, let’s take a look again at the genetic
underlying factor. I think I told you already,
it has to do with abnormalities in the DNA
that lead to abnormalities in the contraction
machinery of the heart and that there’s
a thousand different mutations that lead to
this disease. And there’s a variety of forms
and we’ll take a little look at that.
All right, so here’s a diagram. Again, the