Heart Disease
Myocardial Infarction
Myocardial Infarction
 Heart
attack
 Leading
 Usually
 Males
in life
cause of death in the US
caused by an occluded vessel
more often affected until later
Assuming the individual survives
the MI:
 18
to 24 hours:
 The damaged heart tissue will
appear pallor (white in color, not
pink)
2
to 4 days:
 The dead tissue will appear yellowbrown and soft
 10
days:
 Scar tissue forms at the margin of
the infarction
 Called
metaplasia
Metaplasia
 Replacement
of one type of mature
differential (specialized) cell into
another type (due to injury)
 Scar
tissue (fibroblast cells)
forms—you can often see the nuclei
of these cells
Symptoms:
Intense, crushing pain located below the
sternum
 Pain often radiates down left shoulder,
arm, or jaw
 Breathlessness
 Anxiety
 Nausea
 Vomiting
 Perspiration

 Many
people do not realize they are
having heart attacks
 Mistake
symptoms for indigestion
 After
the onset of a MI, there may be
no obvious problems
 Or
 Arrhythmias
occur
or pump failure may
 Before
we begin arrhythmias, how
does a normal heart function and
how does the pattern appear on an
EKG?
 Each
heartbeat originates as an
electrical impulse from a small area
of tissue in the right atrium: sinus
node
– Impulse is a wave of negative ions
 The
impulse travels cell by cell to the
atrioventricular node —a cluster of
cells in the center of the heart (the
only electrical connection between
the heart chambers)
 It
travels along the Bundle of HIS
 The
impulse is delayed at the
atrioventricular node until the atria
fully contract.
 The
atria fully contract before the
ventricles are stimulated.
Heart
 An
EKG consists of 12 leads that can
pick up these negative ion waves
 We
mainly focus on only one lead
(called lead 2)
Normal Heart Pattern on an EKG
©http://students.med.nyu.edu/erclub/ekgexpl0.html


P wave: atria depolarize (release of ions
and contraction of atria)
QRS complex: ventricles depolarize
– Spike appears because there are many more
heart cells depolarizing
 Release

of ions and contraction of ventricles
T wave: repolarization of the ventricles
– Getting ready for the next heartbeat
 PQRS:
 T:
indicate systole
indicates diastole
 http://www.youtube.com/watch?v=lI
QXzgesdDg
 How
would an atrial problem look on
an EKG?
 How
would a ventricular problem
look on an EKG?
 Deep
Q
 Shows
an old infarction
 Person
had a MI in the past
 The
deeper the Q, the greater the
infarction
Arrhythmia
 Irregular
 This
heartbeat
is what usually kills the
individual
 The
MI acts as an extra pacemaker—
releases negative ions
 There
are different types of
arrhythmias
 Can
be seen on an EKG
 People
die because the cells cannot
control these ions, not because of
the damage to the heart
Types of Arrhythmias
 Flutter
 Mild
quivering of atria or ventricles
 Fibrillation
 Entire
chamber of the heart
undergoes quivering with chaotic
impulses
– Can affect the atria or the ventricles
Types of Arrhythmias
 Atrial
fibrillation
 Atria only pumps approximately 30%
of blood into ventricles—the rest
“falls out” (churning)
 Most
people survive this
 Problem?
thrombus may form
 Thrombus
may form
Types of Arrhythmias
 Most
individuals are on an
anticoagulant (blood thinner)
 Usually
 Not
seen in older people
typically associated with MIs
Types of Arrhythmias
 Ventricular
 Very
 No
fibrillation
dangerous—why?
blood is really pumping
Types of Arrhythmias

On board

How would you describe this to a doctor?

ST problem —elevated ST segment

Very significant problem

The heart is in ischemia usually due to a
clot
 Nicknamed
Tombstone Effect
– Looks like a headstone
 If
you can get the person antithrombolic drugs soon enough, he
should be okay
 If
not, heart will go into ventricular
fibrillation

How do we stop fibrillation?

Defibrillate

“Knocks” out all of the ions and starts over

Person flat lines—heart stops and then
restarts itself with a normal pattern
 Only
use a defibrillator if the person
is in fibrillation
 Can
implant a defibrillator into a
person’s chest
Types of Arrhythmias
 PVC:
pre-ventricular contraction
 Has
been seen in teenagers, but
most outgrow it
 Not
good in older people
Types of Arrhythmias
 Tachycardia
 Any
heart rate faster than 100
beats/min
 Brachycardia
A
slow rhythm, less than 60
beats/min
Treatment for Arrhythmias
 Treatment:
Pacemaker
 Can
speed up the heart, slow down
the heart, assist with irregular
beating
 Most
pacemakers also have a
defibrillator
Implanted Defibrillator
Long QT Syndrome
Ruptured Septum
after MI
©http://www-tc.pbs.org/wgbh/nova/heart/images/aneurysm.jpeg?Log=0
For MI Lab
Normal Heart Tissue
3 Days After MI
Normal vs. Infarction
Vocabulary
 Intercellular
 Edema:
 Leukocytes:
spaces:
Vocabulary
 Metaplasia:
 Ischemia:
 Infarction: