Today's lecture will deal with one of the commonest cardiovascular diseases in the world today,
high blood pressure or the medical term that we use is hypertension.
You will remember when we talked about lifestyle and drugs
for preventing or treating the commonest heart disease that ischemic heart disease,
heart disease of narrowing of the blood vessels in the heart with atherosclerosis,
we talked about lifestyle changes, for example, stopping smoking, reducing weight,
exercising regularly and so forth,
but we also talked about a number of drugs
that were proven in large randomized double blind controlled trials
to be very effective at making patients with these diseases live longer
and have a decreased risk for heart attack.
It turns out that many of these drugs are also used for treating hypertension.
And why should we treat hypertension?
Because hypertension is one of the major factors that leads to atherosclerosis
and a number of other complications.
So, the drugs that we're going to be talking about here in this section
are drugs for controlling blood pressure,
and they include ACE inhibitors and beta blockers and diuretics,
and I'll be talking about each of these as we go through the lecture today.
So, let's talk a little bit about what causes high blood pressure.
It turns out that it's a very simple relationship in the body between blood pressure,
the amount of blood that's pumped by the heart, the cardiac output,
and the resistance of the small vessels, the small blood vessels throughout the body.
In fact, it's the same relationship that we use in electricity.
In electricity, we say that the voltage is equal to the current times the resistance in the wire.
Well, in the cardiovascular system, it's the same thing.
The blood pressure is equal to the cardiac output.
That is the amount of blood that the heart pumps out times the resistance in the small blood vessels.
It turns out that most patients with high blood pressure have an increased resistance
in their small blood vessels throughout the body.
We call it increased peripheral vascular resistance
and when you pump blood against this resistance,
it of course, increases the blood pressure.
It turns out that in the United States,
approximately one-third of the population have a blood pressure that's too high.
Think about that for a moment.
The United States has a population of about 320,000,000 people.
That means there's something like 106 or 7,000,000 people in the United States
whose blood pressure is too high.
And what are the complications of high blood pressure?
They are very serious.
First of all, hypertension or high blood pressure is the number one risk factor for stroke,
one of the most dreaded diseases.
Also, hypertension is a risk factor for an increased likelihood
of having a heart attack, a myocardial infarction.
Hypertension also increases the risk that you will develop heart failure and kidney failure,
and dementia, that is lack of intellectual capacity.
It also is a risk factor for the development of atrial fibrillation
and it markedly decreases life expectancy if untreated.
So, clearly, hypertension needs to be identified and it needs to be treated.
And of course, it's treated with lifestyle changes.
We'll be talking about that.
Things like restricting amount of sodium you're taking,
the amount of salt you're taking in your diet,
as well as regular exercise and weight loss alongside of drugs to help lower the blood pressure.
Let's talk about what happens when you don't treat blood pressure.
I'm gonna give you a case history of a very, very famous patient
who died of a brain hemorrhage because of untreated hypertension.
What you see here plotted out in green is the blood pressure of this very famous individual,
I'm gonna tell you who he was in a moment, over a number of years.
You'll notice on the left hand part of the slide,
the blood pressure was normal early on back in the 1930s and early '40s,
but as time progressed, you can see the blood pressure in this individual
got higher and higher and higher, until they had a major stroke, a brain hemorrhage.
Who was this individual?
It was President Franklin D. Roosevelt
who was president during the Second World War in the United States
and of course, was under intense pressure because of the world war
and because at that time, there were no good drugs for treating high blood pressure.
And as you can see from the newspaper headline here, his doctors were surprised.
How come he had this brain hemorrhage?
This was back in 1945.
It was before we really understood all of the implications of high blood pressure.
So, here was a very famous individual who died relatively young
because of untreated high blood pressure.