So now let's look at what
happens when things go wrong.
So congestive heart failure is a progressive
condition in which the cardiac output is so low
that you do not have adequate blood circulation
to your tissues and this is gonna lead to
to further dysfunction in the rest of the body.
Congestive heart failure is a
reflection of a weakened myocardium.
This can be caused by different factors.
First, it can be caused by coronary atherosclerosis.
In this, you have clogged arteries
because of build up of fat in your arteries.
This in turn is going to impair
oxygen delivery to those cardiac cells
and when this happens, the heart becomes hypoxic
and that causes contraction to occur inefficiently.
Because remember, the heart has
an absolute dependence on oxygen,
so any blocking of oxygen to the heart is gonna
have major effects on the heart's ability to do work.
Another factor that can lead to this weakened
myocardium and thus to congestive heart failure
is a persistent high blood pressure.
So if your aortic pressure is
always greater than about 90 mmHg,
this can cause the myocardium to
exert more force and thus if this is chronic,
this increases your end systolic volume and causes
the myocardium to hypertrophy or kind of get bigger
but it's getting bigger but it's also getting weaker,
so this is not a good thing when it's hypertrophy-ing.
Another thing that can lead to a weakened myocardial as
going to be multiple myocardial infarcts or heart attacks.
Each heart attack causes the heart to become weak as your
contractile cells start to be replaced with scar tissue
instead of other contractile cells.
So now, your heart is losing its contractility
because we now have a build up of scarred tissue
in place of those contractile cells that
we need for the pumping of the heart.
And then finally, we have dilated cardiomyopathy.
This is when the ventricle stretch and become
flabby and the myocardium begins to deteriorate.
This is usually caused by drug
toxicity or by chronic inflammation.
So with congestive heart failure,
either side of the heart can be affected.
If the left side of the heart fails, this is
going to resolve in pulmonary congestion
and blood being backed up in the lungs.
Because remember, the lungs feed the left
side of the heart so if there's a failure here,
then the the blood has nowhere to
go and so kind of sits in the lungs.
If the right side of the heart fails, this will
result in what's known as peripheral congestion
where the blood will now pool in your
body's organs causing edema or swelling.
Failure of either side is ultimately gonna
weaken the other side and this is because
the other side is gonna be decompensated
and thus so seriously weakened.
And so the way we treat this is by removal
of fluid and drugs that reduce our afterload
and increase the contractility of our cardiac
muscle cells so that we can maintain a healthy heart
that's able to pump blood efficiently.