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Alterations of
Cardiovascular Function in
Children
Chapter 31
1
Developmental Anatomy of the
Cardiovascular System
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Embryology
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Cardiogenesis begins at approximately 3 weeks’ gestation
The heart arises from the mesenchyme
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Develops as an enlarged blood vessel with a large lumen and
muscular wall
Midsection grows faster than the ends
The heart tube elongates and rotates to the right, creating
a bulboventricular loop
Fetal heart contractions begin by approximately the 28th
day
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Developmental Anatomy of the
Cardiovascular System
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Developmental Anatomy of the
Cardiovascular System
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Cardiac septation
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Endocardial cushions
Septum primum and the septum secundum
Ostium primum
Ostium secundum
Foramen ovale
Ductus arteriosus
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Developmental Anatomy of the
Cardiovascular System
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Transitional Circulation
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Circulatory changes take place that affect
blood flow, vascular resistance, and oxygen
tension
Closure of fetal shunts
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Ductus venosus
Foramen ovale
Ductus arteriosus
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Postnatal Development
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Changes in the position of the heart
Changes in the size of the right ventricle
Hemodynamics
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Decreased pulmonary vascular resistance
Increased systemic vascular resistance
Heart rate ranges from 100 to 180 beats per
minute
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Newborns have a high oxygen demand
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Congenital Heart Defects
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Underlying cause is known in only 10% of
defects
Prenatal, environmental, and genetic risk
factors
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Maternal rubella, insulin-dependent diabetes,
alcoholism, PKU, and hypercalcemia
Drugs
Chromosome aberrations
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Complications of Congenital Heart
Defects
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Congestive heart failure
Hypoxemia
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Cyanosis
Eisenmenger syndrome
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Defects Increasing Pulmonary
Blood Flow
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Patent ductus arteriosus (PDA)
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Failure of the ductus arteriosus to close
PDA allows blood to shunt from the pulmonary
artery to the aorta
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Patent Ductus Arteriosus (PDA)
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Defects Increasing Pulmonary
Blood Flow
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Atrial septal defect
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Abnormal communication between the atria
Three major types
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Ostium primum defect
Ostium secundum defect
Sinus venosus defect
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Atrial Septal Defect
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Defects Increasing Pulmonary
Blood Flow
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Ventricular septal defect (VSD)
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Abnormal communication between the ventricles
Most common type of congenital heart lesion
Types
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Perimembranous VSD
Muscular VSD
Supracristal VSD
AV canal VSD
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Ventricular Septal Defect (VSD)
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Defects Increasing Pulmonary
Blood Flow
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Atrioventricular canal defect (AVC)
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Results from nonfusion of the endocardial
cushions
Demonstrates abnormalities in the atrial and
ventricular septa and atrioventricular valves
Complete, partial, and transitional AVCs
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Atrioventricular Canal Defect
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Defects Decreasing Pulmonary
Blood Flow
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Tetralogy of Fallot
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Syndrome represented by four defects
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Ventricular septal defect (VSD)
Overriding aorta straddles the VSD
Pulmonary valve stenosis
Right ventricle hypertrophy
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Tetralogy of Fallot
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Defects Decreasing Pulmonary
Blood Flow
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Tricuspid atresia
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Imperforate tricuspid valve
Lack of communication between the right atrium
and right ventricle
Additional defects
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Septal defect
Hypoplastic or absent right ventricle
Enlarged mitral valve and left ventricle
Pulmonic stenosis
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Tricuspid Atresia
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Obstructive Defects
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Coarctation of the aorta
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Narrowing of the lumen of the aorta that impedes
blood flow
Coarctation of the aorta is almost always in a
juxtaductal position, but it can occur anywhere
between the origin of the aortic arch and the
bifurcation of the aorta in the lower abdomen
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Coarctation of the Aorta
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Obstructive Defects
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Aortic stenosis
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Narrowing of the aortic outflow tract
Caused by malformation or fusion of the cusps
Causes an increased workload on the left
ventricle
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Aortic Stenosis
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Obstructive Defects
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Pulmonary stenosis
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Narrowing of the pulmonary outflow tract
Abnormal thickening of the valve leaflets
Narrowing of the valve
Pulmonary semilunar valve atresia
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Pulmonary Stenosis
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Obstructive Defects
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Hypoplastic left heart syndrome
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Abnormal development of the left-sided cardiac
structures
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Obstruction to blood flow from the left ventricular
outflow tract
Under development of the left ventricle, aorta and
aortic arch, and mitral atresia or stenosis
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Hypoplastic Left Heart Syndrome
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Mixed Defects
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Transposition of the great arteries
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Aorta arises from the right ventricle and the
pulmonary artery arises from the left ventricle
Results in two separate, parallel circuits
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Unoxygenated blood circulates continuously through
the systemic circulation
Oxygenated blood circulates continuously through the
pulmonary circulation
Extrauterine survival requires communication
between the two circuits
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Transposition of the Great Arteries
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Mixed Defects
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Total anomalous pulmonary venous
connection (TAPVC)
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Pulmonary veins connect to the right side of the
heart, directly or indirectly through one or more
systemic veins that drain into the right atrium
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Total Anomalous Pulmonary
Venous Connection (TAPVC)
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Mixed Defects
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Truncus arteriosus
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Failure of the embryonic artery and the truncus
arteriosus to divide into the pulmonary artery and
the aorta
The trunk straddles an always present VSD
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Truncus Arteriosus
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Acquired Cardiovascular Disorders
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Kawasaki disease
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Also known as mucocutaneous lymph node
syndrome
Acute, self-limiting systemic vasculitis that may
result in cardiac sequelae
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Kawasaki Disease
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Stages
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One (0-12 days): capillaries, venules, arterioles, and the
heart become inflamed
Two (12-35 days): inflammation of larger vessels;
coronary aneurysms appear
Three (26-40 days): medium-sized arteries begin
granulation process; small vessel inflammation decreases
Four (day 40 and beyond): scarring of vessels, thickening
of tunica intima, calcification, coronary artery stenosis
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Kawasaki Disease
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Diagnosis (5 of 6 major findings)
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Fever for 5 or more days (unresponsive to antibiotics)
Bilateral conjunctivitis without exudation
Erythema of oral mucosa (strawberry tongue)
Changes in the extremities, such as peripheral edema and
erythema with desquamation of palms and soles
Polymorphous rash
Cervical lymphadenopathy
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Acquired Cardiovascular Disorders
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Systemic hypertension
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Hypertension in children differs from adult
hypertension
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Often have an underlying disease
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Renal disease or coarctation of the aorta
A cause of the hypertension in children is almost
always found
Children with hypertension are commonly
asymptomatic
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Acquired Cardiovascular Disorders
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Childhood obesity
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Multivariable and multidimensional
Risk factors
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Race, socioeconomic status, and lack of health
insurance
Childhood nutrition, level of physical activity, and
engagement of sedentary activities (TV, computer use,
etc.)
Association with parental obesity
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