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Alterations of Cardiovascular Function in ChildrenChapter 31

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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

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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

Closure of fetal shunts Ductus venosus Foramen ovale Ductus arteriosus

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Postnatal Development Changes in the position of the heart Changes in the size of the right ventricle Hemodynamics

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 Underlying cause is known in only 10% of

defects Prenatal, environmental, and genetic risk

factors Maternal rubella, insulin-dependent diabetes,

alcoholism, PKU, and hypercalcemia Drugs Chromosome aberrations

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Complications of Congenital Heart Defects Congestive heart failure Hypoxemia

Cyanosis Eisenmenger syndrome

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Defects Increasing Pulmonary Blood Flow Patent ductus arteriosus (PDA)

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 Atrial septal defect

Abnormal communication between the atria 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 the ventricles Most common type of congenital heart lesion Types

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 Atrioventricular canal defect (AVC)

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 Tetralogy of Fallot

Syndrome represented by four defects 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 Tricuspid atresia

Imperforate tricuspid valve Lack of communication between the right atrium

and right ventricle 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

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 Aortic stenosis

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 Pulmonary stenosis

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 Hypoplastic left heart syndrome

Abnormal development of the left-sided cardiac structures 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 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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Transposition of the Great Arteries

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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

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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

A cause of the 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 engagement of sedentary activities (TV, computer use, etc.)

Association with parental obesity