Ischemic Heart Disease: Etiology and Epidemiology
Ischemic Heart Disease: Etiology and Epidemiology
► Learn more about ischemic heart disease with Dr. Richard Mitchell, Educator at Lecturio and Professor of Pathology and Health Sciences and Technology at Harvard Medical School. Test yourself and list possible causes of ischemic heart disease in the comments!
► Check out the rest of our Cardiovascular Pathology Playlist here: http://lectur.io/cardiovascularpathology
► LEARNING OBJECTIVES:
- Describe the relationship between blood supply and oxygen demand in cases of angina and infarction
- Describe the epidemiology of ischemic heart disease
- List possible causes of ischemic heart disease
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Content
0 -> We're going to talk here in these series of slides about a
very important cause of heart disease.
7.96 -> This is going to be one of the major things that ends up
causing morbidity and mortality
13.8 -> for roughly a third to 40% of the population globally.
19.48 -> So if you are sitting next to two friends, look to the
right, look to the left.
24.199 -> One of you will probably exit this world via ischemic heart
disease.
29.679 -> Kind of a scary thought. Alright, with that happy entry,
let's get started.
35.56 -> Fundamentally, in ischemic heart disease or IHD,
39.399 -> it's a balancing of how much blood supply the heart gets
46.119 -> versus how much it needs in order to maintain itself, to
maintain viability.
52.56 -> And usually, under most circumstances, we have an excess
supply.
58.359 -> So blood supply is shown here.
59.96 -> Perfusion usually exceeds any of our myocardial oxygen and
nutritional demands.
65.2 -> That is until other diseases supervene.
68.28 -> If it gets to the point where things are pretty close to
being equal,
72.56 -> then a little bit of extra activity can tip us over
76.959 -> so that the demands of the myocytes exceed the perfusion.
And that will be stable angina.
83.76 -> Meaning, we'll get a little sense of heart chest pain and
we'll talk about the mechanism shortly.
88.599 -> But if we stop doing whatever it is we're doing, the scales
come back to even.
93.68 -> Now, however, if the scales tip completely the other way
97.12 -> where demands far exceed the nutritional supply, the
perfusion.
101.56 -> Then, we're talking about out and out, ischemia and
infarction.
106.239 -> Okay. That's a big picture, but that's really all ischemic
heart disease is about.
111.12 -> It's a big problem. I've already said, a third of us are
going to die as a result of this.
117.56 -> It's the leading cause of death worldwide.
120.239 -> Although cancer is catching up, ischemic heart disease
124 -> is still the most common way that the grim reaper takes us
off the planet.
128.199 -> So about 9 million deaths each year are attributable to
this.
128.84 -> So about 9 million deaths each year are attributable to
this.
132.12 -> In the United States alone, 700,000 Americans,
134.12 -> In the United States alone, 700,000 Americans,
136.039 -> almost three quarter of a million Americans will experience
a myocardial infarction each year.
141.719 -> That's what an MI is, a myocardial infarction. So they will
have a heart attack.
145.8 -> And the lifetime risk of coronary artery disease.
150.599 -> That's not necessarily to say a heart attack
153.719 -> but the lifetime risk of developing coronary artery disease
156.039 -> which is the major cause of ischemic heart disease is about
50% for men lifetime.
162.96 -> So half of us, me, maybe, are going to have some coronary
artery disease.
169.24 -> And in women, the risk over a lifetime is 40%, so it's
substantial.
173.08 -> As I've already mentioned previously, more than 90% of
ischemic heart disease
178.639 -> is caused by obstructive atherosclerotic vascular disease.
182.56 -> And we'll talk about this briefly but there is a whole
separate talk elsewhere
188.439 -> that you can listen to my dulcet tones explain how
atherosclerosis develops in greater detail.
194.479 -> We'll cover it briefly but it's the major cause.
197.199 -> And then there are 10% of causes of ischemic heart disease
that are other causes,
201.879 -> which we will talk about very briefly.
205.319 -> Those other causes of ischemic heart disease include
increased demand.
210.8 -> So remember the scales?
212.12 -> I may have actually, not bad atherosclerotic disease of a
coronary artery,
216.879 -> but I may increase demand so much by increasing heart rate
221.479 -> or increasing blood pressure that I exceed the capacity,
226.84 -> even though there's normal coronaries to do their job.
230.08 -> You can also have diminished blood volume.
234.36 -> So if you have inadequate blood supply because you've
exsanguinated
239.08 -> that's going to be a cause of ischemic heart disease.
241.08 -> You may not have serious coronary artery disease
243.319 -> but you don't have enough blood to flow through those
vessels.
246.879 -> You can have diminished oxygenation.
248.8 -> So, remember, it's not just providing nutrition to the
myocardium.
252.319 -> It's providing oxygen because you have to generate ATP.
255.199 -> So if the lungs are compromised, if we're not getting
adequate oxygenation
261.6 -> due to pneumonia or congestive heart failure,
264.319 -> that's going to be a cause of ischemic heart disease
266.439 -> and if you don't have enough red blood cells or their
oxygen-carrying capacity is diminished,
272.079 -> say, because of carbon monoxide poisoning.
274.079 -> That's also going to be a cause of ischemic heart disease.
So that's 10%. Let's cover the other 90%.
Source: https://www.youtube.com/watch?v=AtVg09ZrXXk