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December 3, 2019

– Hey guys, my name is Atif Shahnawaz. I’m an internal medicine doctor, and I make videos going
over medical topics explaining them in layman’s terms. So if that’s something you’re into, please go ahead and
subscribe to the channel. Today, we’re gonna be talking about the causes of heart failure. But before I get into the nitty gritty, let’s quickly make sure
that we’re on the same page about what heart failure is. Think of the heart as a simple pump. The job of the pump is well,
to pump blood around the body. And when this pumping action
is not working quite right, heart failure occurs. And this is pretty simple,
yet accurate definition of heart failure. And in case you’re curious,
I made another video linked here where I go over
the symptoms of heart failure and why they occur. So check that out if you haven’t already. Now as complex as the heart
is, there are actually many ways and many mechanisms through which the pump
stops being effective, and they can all lead to heart failure. But today, we’re going to be going over five of the most common
reasons that the pump fails, and all together, I would say that these five causes account
for the vast majority of all heart failure cases. So chances are whenever
I encounter a patient with a heart failure,
they will very likely fall into one of these five categories. So let’s get started. (upbeat music) The number one cause
of heart failure by far is due to something called
ischemic cardiomyopathy. Now let’s break down what that means. Ischemia is a general medical term that means a poor blood supply. So if you have ischemia of the gut, we call that mesenteric ischemia, a blockage of an artery that
supplies an arm of a leg is called an ischemic limb, and so on. Cardiomyopathy basically
means that something is wrong with the muscle of the heart. So ischemic cardiomyopathy
refers to a heart that is not working right
because it is not getting the blood supply that
it needs to do its job. Now let’s be clear about what we mean when we say a poor blood
supply to the heart. Because the heart has a
lot of large blood vessels associated with it. You have the inferior
and superior vena cava that deliver blood to
the heart from the veins above and below the body. You have the pulmonary arteries and veins that move blood between
the heart and lungs, and you have the aorta,
which is a huge artery that goes on to supply
oxygen-enriched blood to the entire body. Almost every artery that
you have heard the name of is actually a branch of
this artery, the aorta. Two of the very first branches
that the aorta give out are the right and the
left coronary arteries. And when we’re talking
about a poor blood supply to the heart, it is the coronaries
that we’re talking about. In the face of chronic inflammation, the coronaries get stiff
and they get narrow, making blood harder to move through them. Less oxygen is delivered
to the heart muscles and as a result, the heart
doesn’t beat effectively, potentially resulting in heart failure. Now chronic inflammation
happens to all of us. The question is really one of degrees. Healthy people with good
genes and lifestyles will have very little
inflammation over the years and they can live long healthy lives without any of this
inflammation ever having a significant impact on their coronaries. However, smoking as well
as diseases like diabetes, high blood pressure, the use of drugs, especially the stimulant
kind like meth and cocaine, as well as bad genes, will
speed this inflammation up and increase the chances
of clinically significant coronary artery disease. So another way of putting
this is as follows. That the most common
cause of heart failure which is ischemic
cardiomyopathy is in itself caused by years of poorly
controlled diabetes, high blood pressure, smoking,
drug abuse and bad genes. (upbeat music) Now another common cause of
heart failure is drug related. The United States, as you may
know, has a serious problem with methamphetamine abuse
with over a million Americans using the drug at least once a year. The excessive stimulant effect
of meth causes the heart to wear out and in time it
stops pumping as effectively as it used to. Now I’ll tell you that
meth can also accelerate the chronic inflammation
of coronary artery disease that we just talked about,
so it can cause heart failure by that route as well. But methamphetamine is also
directly toxic to heart tissue and it can weaken the heart
just by acting like a poison. Cocaine, by the way, has this exact same kind of effect but it’s not
as commonly used as meth. Now besides meth and cocaine,
another very common drug that causes heart failure is alcohol. And just to be clear, we’re
talking about alcohol abuse, which is heavy drinking
every day or nearly every day for months or years. Heart failure does not
occur from the occasional glass of wine or weekend trips to the bar. We’re unclear about the exact mechanism through which alcohol causes heart failure but we suspect some
kind of direct toxicity of alcohol to the heart tissue itself. Now it’s not uncommon in patients who developed heart failure
from stimulant drugs or alcohol for the heart muscle to recover once these substances are stopped. Although I have personally
seen deaths caused by severe heart failure in
meth users and alcoholics, because they’re addiction
beat them unfortunately before they could beat their addiction. (upbeat music) Diastolic heart failure is
another type of heart failure that I see all the time. The term comes from the word diastole, which is a fancy word
that refers to relaxation phase of the heart beat. So diastolic heart failure
refers to some abnormality with respect to the way
that the heart is behaving between its beats. By the time a person is 65 years old, the heart has beat a total
of about three billion times. And for many people, the
heart can continue to function just fine as they get older. But in some, the heart begins
to show signs of aging. And one of these signs is a
stiffening of the heart muscle. See the heart muscle needs
to be somewhat elastic. And the reason is when
a heart finishes a beat, it has to be able to relax
enough to allow blood to fill it back up again. In a healthy, perfectly elastic heart, the blood floods inside and
fills it up really nicely. So when the heart is ready to beat again, it has plenty of blood inside to pump out. But imagine what would
happen if the heart muscle didn’t relax enough. If it didn’t relax
enough, it wouldn’t allow enough blood to come in. And if there’s less blood coming in, there’s less blood going out. Which ultimately leads
to the same problem, which is heart failure. I usually only see diastolic heart failure in older patients, usually over 65 years of age. Although it can definitely
happen in somewhat younger patients as well. Now stiffening of heart
tissue is more or less a natural part of aging. So a 90 year old will definitely
have a less elastic heart than a 20 year old, but many elderly folks won’t have any symptoms at all because the heart isn’t so stiff that symptoms necessarily develop. Now obviously, the worse the stiffness is the more the chances are that it will lead to heart failure and
factors that we’ve noticed that could potentially
worsen the stiffness in elderly people are poorly controlled high blood pressure, smoking, obesity, and a sedentary lifestyle. But in my practice, I’ve
seen diastolic heart failure in patients without any of these issues. And I do suspect that it’s probably also a genetic component at play here. (upbeat music) Next up are issues with bad valves. Now the heart and the
large vessels leading in and out of it have valves. And like all valves,
everywhere, they function to keep fluid moving
in a certain direction. And if these valves aren’t working right, the food dynamics within
the heart is altered, meaning that blood is
moving through the system in an efficient way. Now there’s a bunch of
valves in the system and they can all fail, and they do. But by far the most
common valvular condition that we see is something
called aortic stenosis. Now remember that aorta
that I talked about earlier, that large blood vessel
that delivers blood to the whole body, well it’s got a valve. It’s called the aortic
valve, and in some people, over time, this valve
gets tighter and narrower with age, until it becomes so small that very little blood
can be pumped through. Severe aortic stenosis is said to exist when the area of the valve is less than one centimeter squared. In other words, all of
the oxygen-rich blood that the body needs to
survive is being forced through an opening no bigger than one centimeter by one centimeter, which is not really a lot
and which easily leads to congestive heart failure symptoms. Now when heart failure develops
because of aortic stenosis, the valve must be fixed
because they average life expectancy of
patients with symptomatic aortic stenosis is about
two or three years. So it’s a very serious problem. Now patients who have aortic
stenosis, they tend to be older because it takes time for
the valve to narrow like this so they’re usually at
least in their late 60s. But this problem is so
serious that patients who have symptomatic aortic stenosis will get a valve
replacement surgery, even if they’re in their 80s,
or maybe in their 90s, if they’re otherwise healthy. Now another situation that
I see heart failure caused by bad valves is in IV drug users. Every time IV drugs are
injected, there is a risk of injecting bacteria
along with the drugs. The bacteria will move
around in the circulation and one of the places
that the bacteria likes to setup camp is a heart valve. The bacteria grow and
multiple around the valve and they basically eat the valve alive. And in this case, the
problem isn’t so much a tight valve, like with the aorta, but an incompetent valve. And what this means is
that because the valve is being eaten up, it’ll
let blood leak backwards, making the heart far less efficient. And again, leading to
symptoms of heart failure. (upbeat music) Viral infections are a common
cause of heart failure. Now in this situation,
what happens is that the virus infects the body. And it infects many parts of the body, including the heart muscle. This infection, when it occurs,
causes so much inflammation that it causes the heart
muscle to lose strength and heart failure symptoms develop. This condition is called
viral cardiomyopathy. Now let’s make a distinction here because while heart failure
caused by IV drug abuse is because of an infected valve that is rendered incompetent, viral infections of the heart is a different kind of
infection all together. Besides the fact that one
is a bacterial infection and the other is a virus,
the other thing to remember is that while IV drug abuse
requires the individual to inject themselves with
the drugs, heart failure from a viral infection can
just happen to anybody. Anybody can get it at any
time, even if the patient is actually healthy, and
it usually does affect younger people, generally
in the range of about 30 to 50 years of age. We’ve identified many
viruses that have been known to cause heart failure and some of these, you may not have heard of before like parvovirus B19, and coxsackie virus. Maybe you’ve heard of another one called the Epstein-Barr Virus. But it can also be caused
by just the influenza virus, and even by HIV. So a patient may come
in and the only symptoms they’ll have are cold-like symptoms or a bad flu-like symptoms
where everything is hurting. They may have respiratory issues as well, and then a couple of weeks later, they may develop symptoms
of heart failure, and we only realize after the fact, that the flu-like symptoms
were actually part of a larger disease that was
also affecting the heart. Now the prognosis is
also somewhat variable with about half of the
patients making a full recovery a few months later. But in the other half, the
weakness of the heart muscle is devastating and is permanent. And a lot of patients in this
category of heart failure end up eventually getting
a heart transplant, because they’re already on
the younger side anyway. And a heart transplant allows
the to live a normal life without having to deal with heart failure for the rest of their natural lives. (upbeat music)

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