What do we see on EKG?
Well, first of all, we see increased muscle mass.
So there'll be a very prominent QRS
complex, so very high peaked waves.
You will also or you may see atrial fibrillation
due to the dilation of the left atrium,
and leading also potentially
to mural thrombus formation.
Ultimately, ventricular fibrillation that can
cause sudden cardiac death can be one of the
in fact primary manifestations
of hypertrophic cardiomyopathy.
Because the mitral valve is
thickened and it's abnormal,
there's going to be an increased propensity
to developing infectious endocarditis
of the mitral valve.
And of course, because the left ventricle
is not getting adequate forward flow,
and there is regurgitant flow,
patients will present potentially with
congestive heart failure,
shortness of breath, etc.
What does this look like, grossly?
So in this particular case, we're
showing you the left ventricle.
This is the anterior half of the heart.
And there is relatively greater
thickening of the septal muscle
compared to the lateral left ventricular wall,
which is all the way over on the left hand side.
There will be focal scarring, again,
because we're not getting good perfusion.
Out the coronary arteries, we
can get areas of larger fibrosis,
but also we're going to have increased interstitial
fibrosis, because of the pressure volume overload
or the pressure overload
on the cardiac fibroblasts.
This image is showing that plaque
of systolic interior motion.
We have lifted up the anterior leaflet of the
mitral valve and reflected that so you can see
underneath where we're pointing, that's
the left ventricular outflow tract
right behind that leaflet is the aortic valve.
And now we are seeing the evidence of that plaque,
or the anterior leaflet flapping
recurrently up against the septum.
And you can imagine that when that happens, we
closed left ventricular outflow tract prematurely.
And we end up with diminished cardiac output.
Histologically this is the myocyte disarray.
This is a very low power shot but you
get a sense that this is not uniform
kind of lining up in the myocytes, that they
kind of look like a herringbone pattern,
with kind of branches going in various ways.
Individually, the cardiac myocytes are also huge.
So the the nuclei of the cardiac myocytes are
10, 5 to 10 fold greater than the normal size,
saying that these cells individually are huge.
You also see some lighter pink,
in between the cardiac myocytes
and that actually represents
the interstitial fibrosis.
We can accentuate that interstitial
fibrosis by doing special trichrome stains.
Trichrome is a histologic staining
procedure that highlights collagen as blue.
So you can see that all the spaces in between, in
fact are increased interstitial matrix deposition.
And as mentioned previously, we can also get
hypertrophy of the intramyocardial arterioles
and so that wall is markedly thickened,
that's what's in the green circle.
Those are the histologic changes.
The buzzword you want to remember for the boards
is myocyte disarray with
increased interstitial fibrosis.