00:00
Let’s look briefly at right-sided pulmonary hypertensive
heart disease. The normal
pulmonary pressures are about five to ten folds less than
what you see in the systemic
circulation. So, the normal pulmonary artery pressure should
be somewhere between
8 and 20 mmHg at rest and goes up ever so slightly if you
have increased activity.
00:25
But, at rest, if you have pulmonary arterial blood pressure
in excess of 25 mmHg,
that is indicative of pulmonary hypertension and as a result
as you see there, now
you’re going to have the right ventricle responding to the
higher pressure load by
undergoing hypertrophy. When we get heart failure in this
setting because of pulmonary
hypertension, we give it a special name of cor pulmonale.
The cor means heart
pulmonale means the lungs, cor pulmonale means heart failure
due to pulmonary
hypertension. Okay. So, left-sided heart disease can be a
cause of right-sided heart
disease. You already know that the most common cause of
right heart failure is left
heart failure. So, if the left ventricle has become stiff
with hypertrophy and now you’re
getting flow that’s going regurgitant into the lungs, that
pressure can be translated
into the pulmonary circulation and you can have right-sided
pulmonary hypertension.
01:29
So that’s going to be a common cause of pulmonary
hypertension. Emphysema and things
that damage the lung architecture including fibrosis of the
lungs will give rise to a
situation where you have less vasculature with the same
volume of blood trying
to go through it. If I damaged the lung and I’d lose vessels
in various areas, emphysema,
fibrosis, whatever, now the right heart is still pumping the
same volume but there are
fewer vessels to accommodate it and that will cause
pulmonary hypertension. And if
you have recurrent pulmonary emboli, so you have small
emboli that block a little vessel
may be relatively asymptomatic, but over a period of time,
you collect a lot of those
vessels being blocked, we now functionally have the same
volume of blood from the right
ventricle trying to go through fewer vessels because they
are all blocked by pulmonary
emboli. So, these are kind of the three main bins that we
can think about in terms
of causes of right-sided pulmonary hypertension. So,
etiology, includes everything
that we talked about. You can have primary pulmonary
hypertension too. So, there is a
disease where the patients, for reasons that are not
completely understood, develop
increased pulmonary tone, so primary pulmonary hypertension.
There is also obstructive
sleep apnea, typically happens in the obese population. As a
result of not breathing well
during sleep, you get a relatively hypoxic environment. The
way that the lung responds
to hypoxia is to reduce the circulation to a hypoxic area.
If the entire lung is relatively
hypoxic because you’re snoring and you’re not breathing on a
regular basis, then you
will have the entire lung try to clamp down on the blood. As
a result, you get pulmonary
hypertension due to that. So, obstructive sleep apnea,
particularly in the obesity
epidemic that is sweeping the world is a major cause of
pulmonary hypertension.
03:36
So, when there is dysfunction during systole when the right
heart fails, so systolic
dysfunction, you’re going to be hypoxic, you’re not going to
be pumping blood through
the lungs, you’re not going to be well oxygenated. And,
because you don’t have the
right heart pumping to get over to the left heart, you will
have systemic hypotension.
03:56
So, those are the kind of the major manifestations of
systolic dysfunction. When you
have diastolic dysfunction and right-sided pulmonary
hypertensive heart disease,
now you’re going to see retrograde vasoengorgement of the
venous circulation.
04:12
As a result of that higher pressure, this is going to cause
peripheral edema, you will
have increased edema, if you will, into the liver. As a
result of that, there are fibrogenic
cytokines that will be elaborated and you will get a cardiac
cirrhosis. You can get
the same cirrhosis that you can get from alcoholic liver
disease by having right heart
failure, and with the same manifestations including abnormal
flow through the liver,
abnormal synthetic function and portosystemic shunts. And
with that, we’ve covered
left-sided hypertensive heart disease, right-sided
hypertensive heart disease, and
hopefully, you haven’t raised your blood pressure as a
result of listening to me.