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Chapter 32
Disorders of Cardiac
Function
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Definition and Functions of the
Pericardium
• Definition
– A double-layered serous membrane
• Functions
– Isolates the heart from other thoracic structures
– Maintains its position in the thorax
– Prevents it from overfilling
– Contributes to coupling the distensibility between the
two ventricles during diastole; they both fill equally
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Types of Pericardial Disorders
• Pericardial Effusion
– The accumulation of fluid in the pericardial cavity
• Cardiac Tamponade
– Slow or rapid compression of the heart due to
accumulation of fluid, pus, or blood in the pericardial
sac
• Pericarditis
– An acute inflammatory process of the pericardium
– Can be acute, chronic, or constrictive
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Types of Pericardial Disorders (cont.)
• Constrictive Pericarditis
– Calcified scar tissue develops between the visceral
and parietal layers of the serous pericardium.
– Cardiac output and cardiac reserve become fixed.
– Ascites, pedal edema, dyspnea on exertion, and
fatigue, Kussmaul sign
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Clinical Manifestations
• Acute pericarditis is based on clinical manifestations.
– ECG, chest radiography, and echocardiography
– Friction rub
• Chronic pericarditis
– No pathogen identified
– Autoimmune disorders
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Cardiac Tamponade
• Pericardial effusion can lead to a condition called cardiac
tamponade, in which there is compression of the heart
due to the accumulation of fluid, pus, or blood in the
pericardial sac.
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Coronary Circulation
• Left main coronary artery
• Left anterior descending artery
• Circumflex branch
• Right coronary artery
• Posterior descending artery
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Coronary Heart Disease
• Impaired coronary blood flow that may cause:
– Angina
– Myocardial infarction or heart attack
– Cardiac arrhythmias
– Conduction defects
– Heart failure
– Sudden death
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Question
• Which of the following conditions will result in
pathological changes arising from pulseless electrical
activity?
– A. Pericardial effusion
– B. Cardiac tamponade
– C. Pericarditis
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Answer
• B. Cardiac tamponade
• Rationale: Cardiac tamponade is the result of restricted
movement of the muscle and will inhibit ventricular
contraction. The conduction is intact, but there will be
little or no SV.
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Basis for Diagnosis of Unstable Angina
• Pain severity and presenting symptoms
• Hemodynamic stability
• ECG findings
• Serum cardiac markers
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The Evaluation of Coronary Blood Flow
and Myocardial Perfusion
• ECG
– Changes in the pattern or orientation of wave forms
• Echocardiogram
– M-mode, two-dimensional, Doppler, and esophageal
• Exercise Stress Testing
– Motorized treadmill and bicycle ergometer
• Nuclear Cardiovascular Imaging Methods
– Myocardial perfusion imaging, infarct imaging, radionuclide
angiocardiography, and positron emission tomography
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Classification of Coronary Heart Disease
• Chronic Ischemic Heart Disease
– Chronic stable angina, silent myocardial ischemia,
and variant or vasospastic angina
• Acute Coronary Syndromes
– Represent the spectrum of ischemic coronary disease
ranging from unstable angina through myocardial
infarction
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Types of Angina
• Chronic Stable Angina
– Associated with a fixed coronary obstruction that
produces a disparity between coronary blood flow
and metabolic demands of the myocardium
• Stable Angina
– The initial manifestation of ischemic heart disease in
approximately half of persons with CAD
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Determinants of the ACS Status
• Persons with an ACS are routinely classified as low risk or
high risk for infarction based on the following:
– Presenting characteristics
– ECG variables
– Serum cardiac markers
– The timing of presentation
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Characteristics of Pain Associated with
Unstable Angina
• The pain has a more persistent and severe course and is
characterized by at least one of three features:
– It occurs at rest (or with minimal exertion), usually
lasting more than 20 minutes (if not interrupted by
nitroglycerin).
– It is severe and described as frank pain and of new
onset.
– It occurs with a pattern that is more severe,
prolonged, or frequent than previously experienced.
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Manifestations of ST-segment Elevation
AMI
• Abrupt onset
• Severe and crushing pain, usually substernal, radiating to
the left arm, neck, or jaw
• Gastrointestinal complaints (nausea and vomiting)
• Complaints of fatigue and weakness
• Tachycardia, anxiety, restlessness, feelings of impending
doom
• Pale, cool, and moist skin
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Causes of Unstable Angina
• Atherosclerotic plaque disruption
• Platelet aggregation
• Secondary hemostasis
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Factors Determining the Extent of an
Infarct
• Location and extent of occlusion
• Amount of heart tissue supplied by the vessel
• Duration of the occlusion
• Metabolic needs of the affected tissue
• Extent of collateral circulation
• Heart rate, blood pressure, and cardiac rhythm
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Involvement of Heart Muscle in an Infarct
• Transmural Infarcts
– Involve the full thickness of the ventricular wall
– Occur when there is obstruction of a single artery
• Subendocardial Infarcts
– Involve the inner one third to one half of the
ventricular wall
– Occur more frequently in the presence of severely
narrowed but still patent arterial ductus
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Populations Affected by Silent Myocardial
Ischemia
• Persons who are asymptomatic without other evidence of
CAD
• Persons who have had a myocardial infarct and continue
to have episodes of silent ischemia
• Persons with angina who also have episodes of silent
ischemia
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Medical Management Following Infarct
• Thrombolytic therapy
• Revascularization interventions
– Coronary artery bypass grafting (CABG)
– Percutaneous coronary intervention (PCI)
– Atherectomy
• Cardiac rehabilitation programs
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Nonpharmacologic Treatment of Angina
• Smoking cessation in persons who smoke
• Stress reduction
• Regular exercise program
• Limiting dietary intake of cholesterol and saturated fats
• Weight reduction if obesity is present
• Avoidance of cold or other stresses that produce
vasoconstriction
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Antiplatelet and Anticoagulant Therapy
• Aspirin
– The preferred antiplatelet agent for preventing
platelet aggregation in persons with CAD
– Inhibits synthesis of prostaglandin, thromboxane A2
• Ticlopidine and clopidogrel
– May be used when aspirin is contraindicated
– Irreversibly inhibits the binding of ADP to its receptor
on the platelets; no effect on prostaglandin synthesis
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Antiplatelet and Anticoagulant Therapy
(cont.)
• Platelet Receptor Antagonists
– Target a single step in the aggregation process
– Block the receptor involved in the final common
pathway for platelet adhesion, activation, and
aggregation
– Treat acute coronary syndrome
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Question
• Which type of angina is brought about by exercise or
stress?
– A. Stable
– B. Unstable
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Answer
• A. Stable
• Rationale: Stable angina does not present as a problem
until there is an increase in workload.
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Myocardial Diseases
• Myocarditis
– Inflammation of the heart muscle and conduction
system without evidence of myocardial infarction
• Primary Cardiomyopathies
– Heart muscle diseases of unknown origin
• Secondary Cardiomyopathies
– Conditions in which the cardiac abnormality results
from another cardiovascular disease, such as
myocardial infarction
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Types of Cardiomyopathies
• Dilated
• Hypertrophic
• Restrictive
• Arrhythmogenic right ventricular
• Peripartum
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Cardiomyopathies
• A heterogeneous group of diseases of the myocardium
associated with mechanical and/or electrical dysfunction
that usually (but not invariably) exhibit inappropriate
ventricular hypertrophy or dilatation and that are due to
a variety of causes that frequently are genetic.
• Cardiomyopathies either are confined to the heart or are
part of generalized systemic disorders, often leading to
cardiovascular death or progressive heart failure–related
disability.
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Primary and Secondary Cardiomyopathy
• Primary
• Secondary
– Genetic
• Hypertrophic
– Acquired
cardiomyopathies
• Myocarditis
• Arrhythmogenic right ventricular
• Left ventricular noncompaction
cardiomyopathy
– Peripartum
cardiomyopathy
• Inherited conduction system
disorders
– Stress
cardiomyopathy
• Ion channelopathies
– Mixed cardiomyopathy
– Alcoholic
cardiomyopathy
• Dilated cardiomyopathy
• Restrictive cardiomyopathy
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Treatment of Cardiomyopathy
• Treatment depends on the type of
– Medication
– Implanted pacemakers
– Defibrillators
– Ventricular assist devices
– Ablation
– The goal of treatment is often symptom relief, and
some patients may eventually require a heart
transplant.
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Question
• Which of the following may result in the development of
a cardiomyopathy?
– A. Valvular stenosis
– B. Valvular regurgitation
– C. MI
– D. Ischemia
– E. All the above
– F. None of the above
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Answer
• E. All the above
• Rationale: All the above can contribute to the
development of a cardiomyopathy.
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Predisposing Factors for Endocarditis
• A damaged endocardial surface
• A portal of entry by which the organism gains access to
the circulatory system
– The presence of valvular disease, prosthetic heart
valves, or congenital heart defects provides an
environment conducive to bacterial growth.
– In persons with preexisting valvular or endocardial
defects, simple gum massage or an innocuous oral
lesion may afford the pathogenic bacteria access to
the bloodstream.
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Infective Endocarditis
• Invasion of the heart valves
and endocardium by a
microbial agent
– Formation of bulky,
friable vegetations and
destruction of
underlying cardiac
tissues
– Systemic manifestations
• Streptococci
• Enterococci
• Haemophilus sp.
• Actinobacillus
actinomycetemcomitans
• Cardiobacterium hominis
• Eikenella corrodens
• Kingella kingae
• Gram-negative bacilli
• Fungi
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Manifestations of Rheumatic Fever
• Acute Stage
– History of an initiating streptococcal infection
– Involves mesenchymal connective tissue of the heart,
blood vessels, joints, and subcutaneous tissues
• Recurrent Phase
– Extension of the cardiac effects of the disease
• Chronic Phase
– Permanent deformity of the heart valves
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Function and Disorders of the Heart
Valves
• Function: Promote directional flow of blood through the
chambers of the heart
• Dysfunction results in disorders:
– Congenital defects
– Trauma
– Ischemic damage
– Degenerative changes
– Inflammation
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Disruptions Occurring with Valvular Heart
Disease
• Narrowing of the valve opening, so it does not open
properly
– Stenosis
• Distortion of the valve, so it does not close properly
– Incompetent or regurgitant valve: permits
backward flow to occur when the valve should be
closed
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Valve 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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Cardiac Auscultation and
Echocardiography
• Valvular heart disorders produce blood flow turbulence
and often are detected through cardiac auscultation.
• Echocardiography is still the most widely used diagnostic
test to check for structure and function of the heart. It
uses ultrasound signals that are inaudible to the human
ear.
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Factors Affecting Postnatal Pulmonary
Vascular Development
• Prematurity
• Alveolar hypoxia
• Lung disease
• Congenital heart defects
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Signs and Symptoms of Childhood
Congenital Heart Disease
• Symptoms associated with altered heart action
• Heart failure
• Pulmonary vascular disorders
• Difficulty in supplying the peripheral tissues with oxygen
and other nutrients
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Fetal Blood Flow
• Parallel rather than in series
• The right ventricle delivering most of its output to the
placenta for oxygen uptake
• The left ventricle pumping blood to the heart, brain, and
primarily upper body
• Umbilical vein and two umbilical arteries
• Foramen ovale
• Ductus arteriosus
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Cyanosis and Shunting
• Defects that increase resistance to aortic outflow
increase left-to-right shunting.
• Defects that obstruct pulmonary outflow increase rightto-left shunting.
• Crying, defecating, or stress of feeding may increase
pulmonary vascular resistance and cause an increase in
right-to-left shunting.
• Resulting cyanosis
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Types of Congenital Heart Defects
• Patent ductus arteriosus
• Atrial septal defects
• Ventricular septal defects
• Endocardial cushion defects
• Pulmonary stenosis
• Tetralogy of Fallot
• Transposition of the great vessels
• Coarctation of the aorta
• Kawasaki disease
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Kawasaki Disease
• The skin, brain, eyes, joints, liver, lymph nodes, and heart
• Vasculitis in the small vessels and progresses to involve some
of the larger arteries
• Immunologic in origin
– Acute phase: fever, conjunctivitis, rash, involvement of
the oral mucosa, redness and swelling of the hands and
feet, and enlarged cervical lymph nodes
– Subacute phase: defervescence and desquamation
– Convalescent phase: complete resolution of symptoms
until all signs of inflammation have disappeared after
about 8 weeks
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