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Chapter 18
Disorders of Cardiac Function
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Disorders That Affect the Whole Heart
• Pericardial disorders
• Coronary heart disease
• Myocardial diseases
• These disorders can cause symptoms of both
right- and left-sided heart failure
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The Pericardium Surrounds the Heart
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Pericarditis
• Inflammation of the pericardium causes:
– Pain
– Exudate
º Serous  pericardial effusion
 Cardiac tamponade: rapid accumulation
of exudate compresses the heart
º Fibrous  friction rub; adhesions
– ECG changes
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Pericarditis (cont.)
• Inflammation of the pericardium may restrict the
heart’s movement due to:
– Serous exudate filling the pericardial cavity
(pericardial effusion)
– Fibrous scar tissue making the pericardium
stick to the heart (constrictive pericarditis)
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Consequences of
Pericardial Effusion
fluid in pericardial
cavity
restricts heart
expansion
left ventricle
cannot accept
enough blood
right ventricle
cannot accept
enough blood
decreased
cardiac
output
increased venous
pressure; jugular
distension
decreased blood
pressure and
shock
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Question
What is the immediate treatment for severe cardiac
tamponade?
a. Oxygen
b. Cardiac drugs
c. Surgery
d. Pericardiocentesis (removal of fluid from the sac with a
needle)
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Answer
d. Pericardiocentesis (removal of fluid from the sac with a
needle)
Rationale: In severe cardiac tamponade, there is so much
fluid in the pericardial sac compressing the heart that its
function declines rapidly. The fluid must be removed
quickly by inserting a needle into the pericardial space
and aspirating the accumulated fluid.
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Pulsus Paradoxus
• On inhaling, the right
ventricle fills with extra
blood
• Because the heart cannot
expand fully when the right
ventricle is overfilled, the
left ventricle is compressed
and cannot accept much
blood
• On the next heartbeat, the
left ventricle does not send
out much blood: systolic BP
drops
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Coronary Heart Disease
• Atherosclerosis blocks coronary arteries
• Ischemia may cause:
– Angina
– Heart attack
– Cardiac arrhythmias
– Conduction deficits
– Heart failure
– Sudden death
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Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
•
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Chronic Ischemic Heart Disease
• Imbalance in blood supply and the heart’s demands
for oxygen
– Less blood
º Atherosclerosis
º Vasospasm
º Thrombosis
– Higher oxygen demand
º Stress
º Exercise
º Cold
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Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Kinds of Angina
• Stable angina
– Pain when heart’s oxygen demand increases
• Variant angina
– Pain when coronary arteries spasm
• Silent myocardial ischemia
– Myocardial ischemia without pain
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Acute Coronary Syndromes
• ECG changes
– T-wave inversion
– ST-segment depression or elevation
– Abnormal Q wave
• Serum cardiac markers
– Proteins released from necrotic heart cells
º Myoglobin, creatine kinase, troponin
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Question
Tell whether the following statement is true or false.
Chronic ischemic heart disease is more likely to result in
stable angina than acute coronary syndromes.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
True
Rationale: Ischemic heart disease is characterized by
stable angina, which is associated with plaques that are
fixed obstructions. Unstable angina is characterized by
plaques with platelets stuck to them (these are likely to
form a thrombus)—they cause a range of acute coronary
syndromes.
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Acute Myocardial Infarction
• Chest pain
– Severe, crushing, constrictive, OR like heartburn
• Sympathetic nervous system response
– GI distress, nausea, vomiting
– Tachycardia and vasoconstriction
– Anxiety, restlessness, feeling of impending doom
• Hypotension and shock
– Weakness in arms and legs
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An Acute MI (AMI) Leaves Behind an Area
of Yellow Necrosis
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Complications of AMI
• Heart failure
• Cardiogenic shock
• Pericarditis
• Thromboemboli
• Rupture of the heart
• Ventricular aneurysms
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Malfunctioning Heart Muscle
• Malfunctioning heart muscle can cause heart
failure if:
– Ventricles are unusually thick so there is not a
normal amount of room for blood inside them
(hypertrophic cardiomyopathy)
– Ventricles are too stiff to stretch (restrictive
cardiomyopathy)
– Ventricles are too weak to pump out the blood
that is in them (MI, myocarditis, dilated
cardiomyopathy)
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Myocardial Disorders
• Myocarditis
• Cardiomyopathies
– Dilated cardiomyopathies
– Hypertrophic cardiomyopathies
– Restrictive cardiomyopathies
– Peripartum cardiomyopathy
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Hypertrophic Cardiomyopathy
• Defects in their
contractile proteins
make cells too
weak
• They hypertrophy
to do the same
amount of work as
normal cells
• Need more oxygen
and perform less
efficiently, so the
person is prone to
heart failure and
may suffer sudden
death during
exertion
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Question
Which type of cardiomyopathy is characterized by
weakened ventricles?
a. Dilated cardiomyopathy
b. Hypertrophic cardiomyopathy
c. Restrictive cardiomyopathy
d. Peripartum cardiomyopathy
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Answer
a. Dilated cardiomyopathy
Rationale: In dilated cardiomyopathy, the ventricles are
too weak to pump blood, resulting in a diminished
cardiac output (CO). The other types listed are caused
by thick ventricles, stiff ventricles, or LV dysfunction in
late pregnancy or postpartum, respectively.
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Valvular Disorders and Heart Defects
• By interfering
with normal
blood flow,
these often
cause the
signs and
symptoms of
left- or rightsided heart
failure
body
left
heart
right
heart
lungs
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The Endocardial Structures
• The endocardial structures lining the heart can
cause heart failure
– If the AV valves leading into the ventricles do
not work (mitral or tricuspid problems)
– If the semilunar valves leading out of the
ventricles do not work (aortic or pulmonary
problems)
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Cardiac Cycle
Discussion:
Arrange these steps in the proper order:
– Ventricles relax
– First heart sound
– Systole
– Semilunar valves open
– Diastole
– AV valves close
– AV valves open
– Semilunar valves close
– Ventricles contract
– Second heart sound
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Valve Defects
• Each of the four valves can be defective
• Stenosis: valve will not open all the way; it is
harder to force blood through it
• Regurgitation: valve will not close all the way; it
leaks when it should be closed
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Question
Tell whether the following statement is true or false.
Mitral valve regurgitation results in a diminished stroke
volume.
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Answer
True
Rationale: If the mitral valve does not close as it should, a
portion of the stroke volume (amount of blood ejected by
the ventricle/beat) leaks back into the left atrium,
decreasing the amount of blood that is ejected during
that beat (SV).
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Discussion
Defects in which valves might cause:
• Severe dependent edema?
• Paroxysmal nocturnal dyspnea?
• Congested liver?
• Distended jugular veins?
• Productive cough with frothy sputum?
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Identifying Defective Valves
• The blood going through the valve makes a noise
• These are called heart murmurs
• You can identify them by:
– Where they are—which valve are they near?
– How they sound—high- or low-pitched?
– When they happen—systole or diastole?
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When Will You Hear Murmurs?
• If a valve is stenotic, you
will hear a murmur of blood
shooting through the narrow
opening when the valve is
open
• If a valve is regurgitant,
you will hear a murmur of
blood leaking back through
when the valve should be
closed
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Left-sided Valvular Disorders
• Mitral valve disorders
– Mitral valve stenosis
– Mitral valve regurgitation
– Mitral valve prolapse
• Aortic valve disorders
– Aortic valve stenosis
– Aortic valve regurgitation
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Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Congenital Heart Defects
• Atrial septal defects
• Ventricular septal defects
• Endocardial cushion defects
• Patent ductus arteriosus
• Pulmonary stenosis
• Tetralogy of Fallot
• Transposition of the great vessels
• Coarctation of the aorta
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Shunts
• A shunt is an opening or connection that lets
blood move from one side of the circulation to
the other
• Most shunts occur in the heart and move
blood either from the left to the right or from
the right to the left
• Because the left side is stronger, blood is
usually pushed from the left to the right side
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Shunts (cont.)
• Shunts are normal before birth
• Foramen ovale
– Lets blood go from the right atrium to the left
atrium to bypass the lungs
• Ductus arteriosus
– Lets blood go from the pulmonary trunk to the
aorta to bypass the lungs
• Ductus venosus
– Lets blood go from the visceral veins to the vena
cava, bypassing the liver
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Left-to-right Shunt
body
right
heart
Less blood
goes to body
Blood moves from
left to right
More blood
goes to lungs
left
heart
lungs
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Right-to-left Shunt
body
right
heart
Deoxygenated
blood goes to
body
Blood moves from
right to left
Less blood goes
to lungs
left
heart
lungs
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Discussion
Show how the diagram would look
for:
• Patent ductus arteriosus
• Transposition of the great vessels
• Tetralogy of Fallot
body
left
heart
right
heart
lungs
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