1. Alterations of Cardiovascular Function in Children
Chapter 31

2. 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

3. Developmental Anatomy of the Cardiovascular System

4. Developmental Anatomy of the Cardiovascular System
Cardiac septation
Endocardial cushions
Septum primum and the septum secundum
Ostium primum
Ostium secundum
Foramen ovale
Ductus arteriosus

5. Developmental Anatomy of the Cardiovascular System

6. 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

7. 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

8. 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

9. Complications of Congenital Heart Defects
Congestive heart failure
Hypoxemia
Cyanosis
Eisenmenger syndrome

10. 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

11. Patent Ductus Arteriosus (PDA)

12. 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

13. Atrial Septal Defect

14. 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

15. Ventricular Septal Defect (VSD)

16. 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

17. Atrioventricular Canal Defect

18. 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

19. Tetralogy of Fallot

20. 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

21. Tricuspid Atresia

22. 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

23. Coarctation of the Aorta

24. 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

25. Aortic Stenosis

26. Obstructive Defects Pulmonary stenosis
Narrowing of the pulmonary outflow tract
Abnormal thickening of the valve leaflets
Narrowing of the valve
Pulmonary semilunar valve atresia

27. Pulmonary Stenosis

28. 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

29. Hypoplastic Left Heart Syndrome

30. 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

31. Transposition of the Great Arteries

32. 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

33. Total Anomalous Pulmonary Venous Connection (TAPVC)

34. 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

35. Truncus Arteriosus

36. Acquired Cardiovascular Disorders
Kawasaki disease
Also known as mucocutaneous lymph node syndrome
Acute, self-limiting systemic vasculitis that may result in cardiac sequelae

37. 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

38. 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

39. 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

40. 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