00:00
We're going to talk here in these series of slides about a
very important cause of heart disease.
00:08
This is going to be one of the major things that ends up
causing morbidity and mortality
for roughly a third to 40% of the population globally.
00:19
So if you are sitting next to two friends, look to the
right, look to the left.
00:24
One of you will probably exit this world via ischemic heart
disease.
00:30
Kind of a scary thought. Alright, with that happy entry,
let's get started.
00:36
Fundamentally, in ischemic heart disease or IHD,
it's a balancing of how much blood supply the heart gets
versus how much it needs in order to maintain itself, to
maintain viability.
00:53
And usually, under most circumstances, we have an excess
supply.
00:58
So blood supply is shown here.
01:00
Perfusion usually exceeds any of our myocardial oxygen and
nutritional demands.
01:05
That is until other diseases supervene.
01:08
If it gets to the point where things are pretty close to
being equal,
then a little bit of extra activity can tip us over
so that the demands of the myocytes exceed the perfusion.
And that will be stable angina.
01:24
Meaning, we'll get a little sense of heart chest pain and
we'll talk about the mechanism shortly.
01:29
But if we stop doing whatever it is we're doing, the scales
come back to even.
01:34
Now, however, if the scales tip completely the other way
where demands far exceed the nutritional supply, the
perfusion.
01:42
Then, we're talking about out and out, ischemia and
infarction.
01:46
Okay. That's a big picture, but that's really all ischemic
heart disease is about.
01:51
It's a big problem. I've already said, a third of us are
going to die as a result of this.
01:58
It's the leading cause of death worldwide.
02:00
Although cancer is catching up, ischemic heart disease
is still the most common way that the grim reaper takes us
off the planet.
02:08
So about 9 million deaths each year are attributable to
this.
02:09
So about 9 million deaths each year are attributable to
this.
02:12
In the United States alone, 700,000 Americans,
In the United States alone, 700,000 Americans,
almost three quarter of a million Americans will experience
a myocardial infarction each year.
02:22
That's what an MI is, a myocardial infarction. So they will
have a heart attack.
02:26
And the lifetime risk of coronary artery disease.
02:31
That's not necessarily to say a heart attack
but the lifetime risk of developing coronary artery disease
which is the major cause of ischemic heart disease is about
50% for men lifetime.
02:43
So half of us, me, maybe, are going to have some coronary
artery disease.
02:49
And in women, the risk over a lifetime is 40%, so it's
substantial.
02:53
As I've already mentioned previously, more than 90% of
ischemic heart disease
is caused by obstructive atherosclerotic vascular disease.
03:03
And we'll talk about this briefly but there is a whole
separate talk elsewhere
that you can listen to my dulcet tones explain how
atherosclerosis develops in greater detail.
03:14
We'll cover it briefly but it's the major cause.
03:17
And then there are 10% of causes of ischemic heart disease
that are other causes,
which we will talk about very briefly.
03:25
Those other causes of ischemic heart disease include
increased demand.
03:31
So remember the scales?
I may have actually, not bad atherosclerotic disease of a
coronary artery,
but I may increase demand so much by increasing heart rate
or increasing blood pressure that I exceed the capacity,
even of those normal coronaries to do their job.
03:50
You can also have diminished blood volume.
03:54
So if you have inadequate blood supply because you've
exsanguinated
that's going to be a cause of ischemic heart disease.
04:01
You may not have serious coronary artery disease
but you don't have enough blood to flow through those
vessels.
04:07
You can have diminished oxygenation.
04:09
So, remember, it's not just providing nutrition to the
myocardium.
04:12
It's providing oxygen because you have to generate ATP.
04:15
So if the lungs are compromised, if we're not getting
adequate oxygenation
due to pneumonia or congestive heart failure,
that's going to be a cause of ischemic heart disease
and if you don't have enough red blood cells or their
oxygen-carrying capacity is diminished,
say, because of carbon monoxide poisoning.
04:34
That's also going to be a cause of ischemic heart disease.
So that's 10%. Let's cover the other 90%.