welcome to another MedCram lecture we're gonna talk about heart
failure today now sometimes this can be a little confusing because there's a lot
of different definitions this was known as congestive heart failure and there's
been some new definitions that have been introduced that have been a little bit
confusing as well and we're gonna go over the basics first here in the first
lecture and tell you a little bit about the definitions and also the path of
physiology behind heart failure now generally speaking if you look at the
heart and we will symbolize that here with actual heart remember the heart is
just a pump and you've got blood going into it and by definition all blood that
goes to the heart must go to the heart via veins and then you have blood coming
out of the heart and by definition those are arteries now of course in the
pulmonic circulation the arteries have deoxygenated blood and the vein has
oxygenated blood and in the systemic circulation all of the arteries have
oxygenated blood and all of the veins have deoxygenated blood and we'll talk
about that a little bit later but as you can see the heart is meant to pump blood
and have it flowing in the correct direction
generally speaking if you have heart failure you're not going to get as much
blood going forward and you're not going to get as much blood going in and so as
a result the two major types of symptoms that you're gonna see in heart failure
is not enough forward flow and because there's not enough forward flow blood
stays in the heart and as a result of that blood which should be entering the
heart is not entering the heart and as a result of that you're going to see
congestion before it okay this is like an accident on the freeway there is no
traffic in front of the accident because there's not enough forward flow but we
certainly know that there's plenty of traffic before the accident and there's
quite a bit of congestion now things would be pretty
simple in this situation if this is all that we had and so we're gonna get into
a little bit more detail but let's look at how these symptoms manifest
themselves not enough forward flow could mean number one kidney function
decreases just think about all of the organs which are all of them that rely
on blood perfusion and if the kidneys are not getting enough blood you're
gonna have kidney function decreasing that of course is going to activate the
reno angiotensin system or the Rast system it will also activate the anti
diuretic hormone system of course this is going to increase the amount of fluid
retention that you have and that could exacerbate your congestive heart failure
number two think about your pulmonary system and think of chain Stokes
respirations okay so not enough carbon dioxide is circulating and therefore you
get chained Stokes ventilation where you breathe fast and then you breathe slow a
lot of the symptoms that you see are on the congestion side and so certainly
when you have congestion the first organ that it goes to is the lung so think of
pulmonary edema but if it keeps backing up you know that the next organ it's
gonna go to is the liver so liver congestion so you could see the ast and
alt go up this is also known as nutmeg liver because if you do a
cross-sectional of the liver it would look like there is nutmeg you would also
get elevated pulmonary artery pressures and also think of pedal edema
so these constellation of symptoms can be divided in problems associated with
poor output and problems associated with poor input or congestion
and in any heart failure you could see both of these types of symptoms now I
want to talk about the heart itself now the heart we set as a pump but it's not
your typical swimming pool pump which you just turn on and just runs
continuously it actually has two very distinct actions it has an action of
active contraction and it also has an action of active relaxation and it's
this active relaxation that is the most misunderstood and so there are two
phases of this pump if you will a two stroke pump where there is one phase
called systole and there is another phase called diastole now systole is
where there is active contraction diastole is when there is active
relaxation if you have a problem with either of these two functions you could
get congestive heart failure systole is when the heart is pumping blood actively
into the aorta and to the systemic circulation and pulmonic circulation
when it relaxes however blood enters from the veins into the heart both the
pulmonic vein and also the inferior vena cava and allows the heart to fill if the
heart can't contract you have something called systolic dysfunction if the heart
can't relax you have something called diastolic dysfunction there is something
that is known as the ejection fraction otherwise known as the e F the ejection
fraction is simply the size of the hearts at end diastole in other words
the size of the heart when it's the largest - the size of the heart at and
systole in other words the size of the heart
after it contracts so in other words what we're looking at here is how much
blood was pumped out of the heart and we divide it by the size of the heart at
the end of diastole so what we're saying here is that the ejection fraction is
the proportion of blood that the heart can pump out in one contraction the
thing I want you to notice is that if the heart has a hard time contracting
this number up here is going to get smaller but this number is going to stay
the same let's review that again if there's a problem with systole if the
heart is too weak to contract then these numbers are going to be very similar and
therefore the difference between them is going to be very low this number will
not change however and so the ejection fraction will go
down in systolic dysfunction however in diastolic dysfunction
remember what the problem is the problem is is that the heart can't relax and as
a result of the heart not being able to relax this number will go down and as a
result when you have a small heart that can't relax there's not a lot of blood
that you can pump out of a small heart and so therefore what happens in this
situation is this will stay about the same or if it goes down this also goes
down and so as a result the ejection fraction in diastolic dysfunction is
about the same it doesn't change and this distinction has been made with the
new classification let's talk about that officially speaking this is the new
terminology there's something called heart failure due to reduced ejection
fraction and then there is heart failure with normal ejection fraction now if you
notice here is the reduced here is the normal that's all you really need to
look at you know that if you have a reduced ejection fraction then you have
systolic dysfunction and the problem here is that blood cannot be ejected out
of the heart blood can't get out as a result of the fact that blood can't get
out then blood can't get in to the heart okay now with a normal ejection fraction
what's the problem here the problem is is that blood can't get into the hearts
because the muscles won't relax when the muscles don't relax
they can't relax enough to allow the blood to come into the heart during
diastole and so here the problem is is the blood can't get in and as a result
of the fact that the blood can't get into the heart the blood can't come out
of the heart the heart can't pump that blood out if it's not getting in blood
can't get out notice you have the same problems in both types of heart failure
but the key is is the why the reason why you have heart failure due to a normal
ejection fraction is because blood can't get in the reason why you have heart
failure in a reduced ejection fraction is because blood can't get out now what
are some of the causes of these things let's talk about reduced ejection
fraction so things that can cause reduced ejection fraction would be
ischemic heart disease so you haven't had enough oxygen going to the heart and
as a result of that tissue has died and it's no longer functional it's weak
if parts of the whole muscle die you can even have aneurysms of the heart muscle
so ischemic heart disease is classic think of this in coronary artery disease
people that have had cabbage people with diabetes okay so what's the problem
in normal each action fraction well remember here is that blood can't get
into the heart and the reason why blood can't get into the heart is because
they've had hypertension for so long that their muscles are so thick that
they can't relax anymore so the big one here is hypertension almost certainly so
think of these in patients with a normal ejection fraction and they've got
thickened myocardium left ventricular hypertrophy these people still benefit
from lasix because remember blood can't get in
therefore blood can't get out and if blood can't get in it's going to congest
into the pulmonary circulation so the key that I want you to remember here is
if you suspect somebody has congestive heart failure and you get an
echocardiogram and the ejection fraction is greater than 40% you really can't say
that this patient doesn't have congestive heart failure
because they very well certainly can they would have heart failure with a
normal age ection fraction we'll talk later about some of the other aspects of
heart failure please join us for our next video thanks for joining us