Welcome to lecture 8 in the series, “Introduction
to Cardiology”. In this series, we are going
to consider one of the most serious problems
that faces a cardiologist, a patient with
Heart failure is very common and increasingly
common these days. It’s because it is a
common complication of older individuals and
of course, the older population is increasing
throughout North America and Western Europe
as well as Asia. Heart failure is defined
differently in different circumstances by
different cardiologists. But basically, it’s
an inability of the heart to pump enough blood
to meet the demands of the body.
In other words, if one exercises, one requires
an increase in blood flow to the body and
if you can’t do that, you may develop the
symptoms of heart failure. As we're going
to see, there are a number of compensatory
mechanisms that get set off in heart failure
and some of them actually work to increase
symptoms in these patients.
The major issue here is that the heart has
an inadequate or decreased cardiac output.
Remember cardiac output, that’s stroke volume
times heart rate, that is the amount of blood
the heart puts out each beat times the heart
rate. And in this setting, what you see is
that the patient has an increase in blood
volume because of compensatory mechanisms
that work to correct the heart failure state.
Unfortunately, this leads to fluid accumulation
in the body and even edema, that is swelling
in the body.
This can also be associated with circulatory
congestion, for example, in the lungs. So,
you have increased fluid in the lungs, so
the patients are short of breath and in addition,
you may see patients being markedly fatigued
because they’re not getting adequate heart
pumping. As I said before, it’s a very common
problem. There are more than three million
patients in the United States with heart failure.
There’s a number of new patients presenting
every year and unfortunately, heart failure
has a very poor prognosis. Often, a prognosis
just as bad as many forms of cancer.
Heart failure is more common in African-Americans
and it’s interesting that these patients
seem to do better briefly, when they’re
admitted to the hospital, but their long term
outlook is worse, some of this may be because
of lower socio-economic conditions in many
The heart failure frequency in the US has
been increasing with an increasing population.
A statistic I like to quote is that in the
United States, in every 24 hour period, more
people will become age 85 than will be born.
So, you can imagine, if heart failure is a
very common problem in the elderly, just as
atrial fibrillation is a common problem in
the elderly, both of these are what I call
“growth industries”. And again, women
tend to be a little less frequently affected
by heart failure, men is a little more common
early on, but once we get into the geriatric
population - above 65 to 70, the amount is about
There are a number of factors that are referred
to when we talk about heart failure and you’ll
remember some of these factors from the basic
lectures on heart function.
Remember preload? Preload is filling of the
heart so that it’s a manifestation of the
size of the ventricle when it fills up. When
you have increased blood volume, you increase
the preload, that is the amount of volume that
the heart has to squeeze out. This happens
with some of the compensatory mechanisms that
increase the blood volume and consequently,
preload may be increased in the heart and what
increased preload leads to is increased filling
pressures in the ventricle during diastole -
during the rest period. This leads to increased
pressures in the ventricle during diastole
and those increased pressures are transmitted
back to the lungs and even back to the rest
of the body leading to fluid accumulation
in the tissues of the lung and the rest of
Afterload is the work of the heart, it’s
the resistance the ventricle feels when it
is pumping out. This is usually due to resistance
in the vascular system. You’ll remember
that from the basic lecture in cardiology.
Increased peripheral vascular resistance leads
to increased afterload, increased work of
the heart. You can imagine, that’s not good
in heart failure. And in fact, here’s a
clue. When we talk about therapy of heart
failure, one of the things is to decrease
afterload, to decrease the work of the ventricle
and hope that it will recover from its depressed
There are two forms of heart failure - systolic
and diastolic. In other words, sometimes…
let’s take diastolic first. The ventricle
squeezes alright, but it fails to relax normally.
It relaxes slowly or in a stiffened manner
leading to increased pressure in there that
gets transmitted throughout the circulation
and leads to collection of fluid, as we talked
about before - edema.
Systolic heart failure is when the ventricle
fails to squeeze well. That can happen, of
course, with the patient who's had heart
attacks, happens to patients with cardiomyopathy -
heart muscle disease, and often, systolic heart
failure is associated also with diastolic.
So, most patients with heart failure have
both systolic and diastolic, but there’s
a whole group of patients, minorities you
can see from the circle diagram here, who
have pure diastolic heart failure.
Interestingly, the long term prognosis for
diastolic heart failure is just as bad as
for systolic heart failure. Diastolic heart
failure tends to occur in older individuals,
often with thickened heart muscle.
Now, there are a number of compensatory mechanisms