Alterations of Cardiovascular Function in Children

Chapter 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 Mosby items and derived items © 2006 by Mosby, Inc.

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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 Mosby items and derived items © 2006 by Mosby, Inc.

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Developmental Anatomy of the Cardiovascular System Mosby items and derived items © 2006 by Mosby, Inc.

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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 Mosby items and derived items © 2006 by Mosby, Inc.

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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 Mosby items and derived items © 2006 by Mosby, Inc.

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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 Mosby items and derived items © 2006 by Mosby, Inc.

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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) Mosby items and derived items © 2006 by Mosby, Inc.

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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 Mosby items and derived items © 2006 by Mosby, Inc.

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Atrial Septal Defect Mosby items and derived items © 2006 by Mosby, Inc.

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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) Mosby items and derived items © 2006 by Mosby, Inc.

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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 Mosby items and derived items © 2006 by Mosby, Inc.

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Atrioventricular Canal Defect Mosby items and derived items © 2006 by Mosby, Inc.

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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 Mosby items and derived items © 2006 by Mosby, Inc.

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Tetralogy of Fallot Mosby items and derived items © 2006 by Mosby, Inc.

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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 Mosby items and derived items © 2006 by Mosby, Inc.

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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 Mosby items and derived items © 2006 by Mosby, Inc.

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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 Mosby items and derived items © 2006 by Mosby, Inc.

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Aortic Stenosis Mosby items and derived items © 2006 by Mosby, Inc.

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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 Mosby items and derived items © 2006 by Mosby, Inc.

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Pulmonary Stenosis Mosby items and derived items © 2006 by Mosby, Inc.

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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 Mosby items and derived items © 2006 by Mosby, Inc.

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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) Mosby items and derived items © 2006 by Mosby, Inc.

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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 Mosby items and derived items © 2006 by Mosby, Inc.

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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

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