So, just going to highlight these things again. Left ventricular hypertrophy in the absence
of other cardiovascular pathology is hypertensive heart disease. We will find in other
tissues evidence of hypertension. So, we can see glomerulosclerosis; we can see
arteriolosclerosis; and that’s what’s being represented there on that trichrome stain.
The vessel wall becomes markedly thickened, with more extracellular matrix. So, we can
have evidence of hypertension in other organs as well. So, that’s systemic left-sided
hypertensive heart disease. How do we define hypertension? We’ve talked about this
previously. It’s 120/80, is upper limits of normal. Anything above that is considered
hypertension. And it’s a continuous variable. So, if you have 130/90 that’s modest
degree of hypertension but it’s still hypertension. If you have 180/120, now we’re
worried about very aggressive malignant hypertension, but anything greater than
120/80 is going to be something that we should be concerned about and try to reduce.
It’s very, very prevalent. So, in the age group where many of you are currently sitting,
about a quarter of you will have some evidence of hypertension even now as you aged
because the vessels get stiffer and there is a cumulative amount of small little insults
that will lead to accumulation of hypertensive kind of insults. 55% of patients will have
hypertension and hypertensive heart disease by the time they’re in their mid-50s.
And, 75% will have hypertension and hypertensive heart disease by the time that their
age is 60 and older. It doesn’t necessarily mean you’re going to progress to heart
failure, so only about a third of patients with the typical levels of hypertension that
we see in the population will develop heart failure due to the fibrosis and then the
pulmonary edema, etc. But, there is a three-fold increased risk of heart failure relative
to patients who have normal pressures, so there’s a significant risk associated. Again,
normal ventricle should have myocytes that look like what you see there, with
longstanding hypertension, increased pressures against which the ventricle must pump,
then you get hypertrophy. And, again, you don’t get concomitant increases in the
capillary vasculature. So, we’re going to have large cells with the same number and
density of capillaries and they’re going to be relatively ischemic in the middle. We’re also
going to have increased fibrosis. Again, the fibroblasts that sit in between the cardiac
myocytes are going to respond to that higher pressure differential by making more
extracellular matrix. So, what are the signs and symptoms of hypertensive heart disease?
Well, in fact, the vast majority of patients can be completely asymptomatic, sometimes
until it’s too late. But, if we were to do an EKG or an electrocardiogram or an ECG,
what we would see is very high voltages in many of the limb leads and also across the
precordial leads. And that’s due to the increased muscle mass that’s present in this left
ventricle. So, you see very high peaked QRS complexes and you see it there in 1,
we can also see it in V1, we can also see it as well in AVL which is what's shown,
and also you get nonspecific STT wave changes so you can get an abnormal depolarization,
again presumably because of the increased muscle mass. So, there are changes that
you can see on an ECG. So, what are the outcomes from hypertensive heart disease?
Well, one, is that you’ll live as long as you’re going to live otherwise then you die of
unrelated causes, you fall underneath the bus, whatever, something else happens.
Two, is that you can develop ischemic heart disease. Hypertension is a major risk factor
for atherosclerotic disease. But we’re also going to have microvascular ischemia
because, again, these individual cardiac myocytes are getting so big and the diffusion
distances increasing from the nearby capillaries. So you can have ischemic heart disease.
You can have renal damage or cerebrovascular stroke, and again, remember,
hypertension is going to damage those vascular beds, and with high blood pressure,
you can rupture cerebral vessels or you can have progressive heart failure due to the
mechanisms that we talked about, interstitial fibrosis with diastolic dysfunction,
regurgitant flow through the mitral valve, pulmonary edema, atrial fibrillation.
So, there are a variety of outcomes. That’s left-sided hypertensive heart disease.