Chapter 31
Alterations of Cardiovascular
Function in Children
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Developmental Anatomy of the
Cardiovascular System

Embryology


Cardiogenesis begins at approximately 3 weeks’
gestation
The heart arises from the mesenchyme
• 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

Cardiac septation

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



Circulatory changes take place that affect blood
flow, vascular resistance, and oxygen tension
Shift of gas exchange from placenta to lungs
Closure of fetal shunts



Ductus venosus
• Round ligament of the liver
Foramen ovale
• Pressure gradient change
Ductus arteriosus
• Ligamentum arteriosum
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Postnatal Development



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
• Newborns have a high oxygen demand
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Congenital Heart Defects



Leading cause of death (except for prematurity)
in first year of life
Cause known in only 10% of defects
Prenatal, environmental, and genetic risk factors



Maternal rubella, insulin-dependent diabetes,
alcoholism, PKU, and hypercalcemia
Drugs
Chromosomal aberrations
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Complications of
Congenital Heart Defects




Congestive heart failure (acquired)
Insufficient cardiac output relative to demand
Cardiomyopathy most common cause
Hypoxemia


Cyanosis
Eisenmenger syndrome
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Complications of
Congenital Heart Defects

Clinical signs of congestive heart failure
(acquired)

Poor feeding and sucking; leads to failure to thrive
 Dyspnea, tachypnea, diaphoresis, retractions,
grunting, nasal flaring
 Wheezing, coughing, rales are rare (even with
significant heart failure)
 Skin changes, such as pallor or mottling
 Hepatomegaly
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Defects Increasing
Pulmonary Blood Flow

Patent ductus arteriosus (PDA)



Failure of the ductus arteriosus to close
• Normally closes within 15 hours to 2 weeks of age
PDA allows blood to shunt from the pulmonary artery
to the aorta
Prevalence
• 5%-10% full-term infants
• Up to 45% premature infants
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Patent Ductus Arteriosus (PDA)
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Defects Increasing
Pulmonary Blood Flow

Atrial septal defect

Abnormal communication between the atria
• Allows blood to be shunted from left to right due to higher
pressure of the left atrial chamber and lower pulmonary
vascular resistance as compared to systemic vascular
resistance
• Right atrial enlargement


Often asymptomatic, diagnosed by murmur
Three major types
• 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

Ventricular septal defect (VSD)




Abnormal communication between ventricles
Common congenital heart lesion (25%-33%)
Pulmonary overcirculation accounts for symptoms
associated with a large VSD
Types
• Perimembranous VSD
• Muscular VSD
• Supracristal VSD
• Atrioventricular (AV) canal VSD
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Ventricular Septal Defect (VSD)
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Defects Increasing
Pulmonary Blood Flow

Atrioventricular canal defect (AVC)



Results from nonfusion of the endocardial
cushions
Demonstrates abnormalities in the atrial and
ventricular septa and AV valves
Complete, partial, and transitional AVCs
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Atrioventricular Canal Defect
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Defects Decreasing
Pulmonary Blood Flow

Tetralogy of Fallot


Syndrome represented by four defects
• Ventricular septal defect (VSD)
• Overriding aorta straddles the VSD
• Pulmonary valve stenosis
• Right ventricle hypertrophy
Most cases corrected surgically in early infancy
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Tetralogy of Fallot
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Defects Decreasing
Pulmonary Blood Flow

Tricuspid atresia

Imperforate tricuspid valve
 No communication between right atrium and right
ventricle
 Central cyanosis
• Exertional dyspnea, tachypnea, hypoxemia
• Polycythemia, clubbing
 Additional defects
• 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

Coarctation of the aorta


Narrowing of the lumen of the aorta that impedes
blood flow (8%-10% of defects)
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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Obstructive Defects

Coarctation of the aorta

Newborns usually present with congestive heart
failure
• Once the ductus closes, rapid deterioration hypotension,
acidosis, and shock

Older children
• Hypertension in upper extremities
• Decreased or absent pulses in lower extremities
• Cool mottled skin
• Leg cramps during exercise
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Coarctation of the Aorta
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Obstructive Defects

Aortic stenosis




Narrowing of the aortic outflow tract (5% of defects)
Caused by malformation or fusion of the cusps
Causes an increased workload on the left ventricle
Symptoms
• Often asymptomatic
• Signs of exercise intolerance in preadolescence
• Syncopal episodes, epigastric pain, and exertional chest pain
in more severe forms
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Aortic Stenosis
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Obstructive Defects

Pulmonary stenosis





Narrowing of the pulmonary outflow tract
Abnormal thickening of the valve leaflets
Narrowing of the valve
Pulmonary semilunar valve atresia
Symptoms
• Often asymptomatic

Exertional dyspnea, fatigue
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Pulmonary Stenosis
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Obstructive Defects

Hypoplastic left heart syndrome

Abnormal development of the left-sided cardiac
structures
• Obstruction to blood flow from the left ventricular outflow
tract

Underdevelopment 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

Transposition of the great arteries

Aorta arises from the right ventricle and the
pulmonary artery arises from the left ventricle
 Results in two separate, parallel circuits
• 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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Mixed Defects

Total anomalous pulmonary venous
connection (TAPVC)

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

Truncus arteriosus


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

Kawasaki disease

Also known as mucocutaneous lymph node syndrome
 Acute, self-limiting systemic vasculitis that may result
in cardiac sequelae
 80% of cases occur in children under age 5
 Cause
• Unknown
• Theories: an immunologic response to an infectious, toxic, or
antigenic substance (including superantigen)
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Kawasaki Disease

Stages




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

Diagnosis (5 of 6 major findings)






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

Systemic hypertension

Hypertension in children differs from adult
hypertension
• Often have an underlying disease

Renal disease or coarctation of the aorta
• Cause of hypertension in children is almost always found
• Children with hypertension are commonly asymptomatic
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Acquired Cardiovascular Disorders

Childhood obesity


Multivariable and multidimensional
Risk factors
• Race, socioeconomic status, and lack of health insurance
• Childhood nutrition, level of physical activity, and engagemnt in
sedentary activities (TV, computer use, etc.)



Association with parental obesity
Places child at risk for asthma, sleep apnea,
hypertension, type 2 diabetes, dyslipidemia,
cardiovascular disease
Social and economic consequences
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