00:01
Let's talk about the causes. There are a variety
of causes—so-called risk factors—often
working together that set off this atherosclerotic
process. One of the most important is abnormal
cholesterol and other lipids (for example,
triglycerides) in the bloodstream. These,
then, get in under the small endothelial inner
layer. They get into the wall of the artery,
and they set off a huge inflammation reaction
with scarring and lots of white blood cells
coming in to try and slow down the inflammation.
But unfortunately, it just gets worse and
worse and worse. It's related… A risk factor
that can be measured in the laboratory is
your total cholesterol level. Your so-called
LDL cholesterol (we're going to talk about
that more in a moment): That's the bad cholesterol.
That's the one that really sets off the trouble.
00:56
High-density lipoprotein cholesterol (HDL
cholesterol) actually helps take some of the
LDL out of the wall and protects against this
disease. We've already mentioned triglycerides,
which—particularly in diabetics—further
the atherosclerotic process. And then there
are other entities, such as hypertension and
cigarette smoking, that also speed along the
development of atherosclerosis.
I mentioned before that there's a good form
of cholesterol and a bad form. The bad form
is the so-called low-density lipoprotein (LDL)
cholesterol. This often gets oxidized—in
a sense, rusted—by oxygen in the bloodstream,
gets inside the artery wall, sets off the
huge inflammatory reaction that results in
atherosclerosis. High-density lipoprotein
actually helps to reduce the risk for this
disease. So if you have a very good high HDL
level, you are at least partly protected.
01:58
Of course, if you're a heavy cigarette smoker,
even a high HDL may not protect you from atherosclerosis.
02:07
The aging process is very important, because
this process starts usually actually in early
childhood and gradually develops over the
years. So the older you are, the more atherosclerosis
you're likely to have. The heart and blood
vessels, over time, become less resilient
with age. The elastic arteries are less able
to withstand the forces from the pulsating
blood coming out of the heart. Systolic blood
pressure often increases. And what can even
happen that's quite dangerous is that part
of the arterial wall can thin and balloon
out and develop into an aneurysm. And when
you have an aneurysm, there's a chance that
this area of the thinned wall may rupture,
can cause massive bleeding and death. And
we're going to talk about aneurysms in subsequent
advanced lectures.
03:02
The risk factors that are most commonly known
to accelerate and cause the atherosclerotic
process: Some, there's not much you can do
about, such as advancing age. This is a very
common disease in people over the age of 65
and 70. Diabetes mellitus is a major risk
factor for this disease as are, for example,
birth control pills. They also increase blood
clotting and can cause advancing atherosclerosis,
and so one has to be very careful with the
use of these pills in patients who have a
family history of atherosclerosis and physical
inactivity (sitting around and not doing regular
exercise). It's more common in men (at least
at younger ages), but women catch up at the
older ages. Obesity often leads to high levels
of cholesterol in the blood and hypertension
and diabetic tendencies, so they all work
in favor of atherosclerosis. Certain types
of personalities: Very aggressive, hostile
personality patients are known to be at increased
risk for atherosclerosis. And of course, if
there's a history in your family of this disease,
you're more likely to get it as well.