MYOCARDIAL INFARCTION
HARIKRISHNA.S
512

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At the end of session each student
should be able to:-
Define Myocardial infarction
Explain causes of Myocardial
infarction
List the Pre-disposing factors of
Myocardial infarction
Describe the pathophysiology of
Myocardial infarction
Mention sign and symptoms of

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Normal Heart

Myocardial infarction is commonly known as a
heart attack, “Myo” means muscle “cardial”
pertains to the heart and “infarction” means
death of tissue due to lack of blood supply.
The heart like any organ requires blood for
oxygen and other nutrients, so it can do its work.
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Coronary Arteries for the heartCoronary Arteries for the heart

 Myocardial infarction (MI) or heart attack is a
medical emergency condition in which the blood
supply to the heart suddenly reduces or stop,
causing the myocardium to die from lack of
oxygen.
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 Heart is the main organ in cardiovascular
system, which includes different types of
blood vessels.
 Some of the most important vessels in
your body are the Coronary arteries. They
take blood, rich in oxygen, to every location
in the body.
 When arteries become blocked or
restricted by buildup, they can cause blood

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Several factors may cause a heart attack:
Bad Cholesterol: -
 Also called low-density lipoprotein (LDL), is
one of the leading problems that cause
blockage.
 Cholesterol can stick to the walls of the arteries
and produce plaque. Plaque is a hard matter
that blocks blood flow in the arteries.

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Saturated Fats (found mostly in meat):-
 May contribute to the buildup of plaque in the
coronary arteries.
 Saturated fat may lead to acute myocardial
infarction by increasing the amount of bad
cholesterol in the blood system and reducing the
good HDL (high-density lipoprotein)
cholesterol.

Certain risk factors may make to susceptible for
heart attack which includes:-
High Blood Pressure
Obesity
Diabetes or High Blood Sugar
Smoking
Overweight
Excessive alcohol intake
Stress
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The most common cause of an MI is a
blood clot (thrombosis) that forms inside
a coronary artery, or one of its
branches.
This blocks the blood flow to a part of
the heart.
Blood clots do not usually form in
normal arteries. However, a clot may04/29/16 CRITICAL CARE 11

Atheroma is like fatty patches or
plaques that develop within the inside
lining of arteries. (This is similar to
water pipes that get furred up.)
Plaques of atheroma may gradually
form over a number of years in one or
more places in the coronary arteries.
Each plaque has an outer firm shell with04/29/16 CRITICAL CARE 12

 What happens is that a crack develops in the outer shell of
the atheroma plaque. This is called plaque rupture.
 This exposes the softer inner core of the plaque to blood.
 This can trigger the clotting mechanism in the blood to
form a blood clot. Therefore, a build-up of atheroma is the
root problem that leads to most cases of Myocardial
Infarction.
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The diagram below shows four patches of atheroma as an
example. However, atheroma may develop in any section
of the coronary arteries.

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