- Chapter 34
- Alterations of Cardiovascular
- Function in Children
- Developmental Anatomy of the
Cardiovascular System - Embryology
- Cardiogenesis begins at approximately 3 weeks’ gestation.
- Heart arises from the mesenchyme.
- Develops as an enlarged blood vessel with a large lumen and muscular wall.
- Midsection grows faster than the ends by the fifth week.
- Heart tube elongates and rotates to the right, creating a bulboventricular loop by the 28th day.
- Fetal heart contractions begin by the 28th day.
- All of the fetal heart and vascular systems are present by 4 weeks’ gestation.
- Developmental Anatomy of the
Cardiovascular System (Cont.) - From muscular tube to full development
- Developmental Anatomy of the
Cardiovascular System (Cont.) - Cardiac septation
- Endocardial cushions
- Instrumental in closing the atrial septum, dividing the atrioventricular (AV) canals into the right and left AV orifices, and closing the septum
- Septum primum and septum secundum
- Atrial septation
- Ostium primum
- Gap that closes by the endocardial cushions
- Ostium secundum
- Fenestrations or openings that develop in the superior portion of the septum primum
- Developmental Anatomy of the
Cardiovascular System (Cont.) - Cardiac septation (cont.)
- Foramen ovale
- Nonfused septum secundum and ostium secundum result in the formation of a flapped orifice.
- Bulbus cordis
- Separates the aorta from the pulmonary artery.
- Truncus arteriosus
- Torsion occurs within the anterosuperior region of the loop.
- Ductus arteriosus
- Communication exists between the aorta and the pulmonary artery.
- Developmental Anatomy of the
Cardiovascular System (Cont.) - Development of cardiac septa
- In utero fetus blood circulation
- Foramen ovale
- Is the opening between the atria.
- Ductus arteriosus
- Joins the pulmonary artery to the aorta.
- Ductus venosus
- Connects the inferior vena cava to the umbilical vein.
- Developmental Anatomy of the
Cardiovascular System (Cont.)
- Foramen ovale
- In utero fetus blood circulation (cont.)
- Receives blood-carrying oxygen and nutrients from the placenta through the umbilical vein.
- Blood travels to the liver, where a portion enters the portal and hepatic circulation.
- Approximately one-half of the flow is diverted away from the liver through the ductus venosus and into the inferior vena cava.
- Blood enters the right atrium from the inferior vena cava and is shunted through the foramen ovale and then into the left atrium, left ventricle, and aorta.
- Developmental Anatomy of the
Cardiovascular System (Cont.) - In utero fetus blood circulation (cont.)
- Less-saturated blood returns from the upper body, head, neck, and arms and travels from the superior vena cava into the right atrium.
- A small portion of this blood flows into the right ventricle, out of the pulmonary artery, and enters the nonfunctioning lungs.
- Most of the blood bypasses the lungs by flowing through the ductus arteriosus and into the descending aorta.
- Blood from the descending aorta returns to the placenta through two umbilical arteries.
- Developmental Anatomy of the
Cardiovascular System (Cont.) - Fetal circulation
- Developmental Anatomy of the
Cardiovascular System - Transitional Circulation
- Circulatory changes take place after birth.
- Gas exchange shifts from the placenta to the lungs.
- Fetal shunts close.
- Ductus venosus
- After closure, the round ligament of the liver forms.
- Foramen ovale
- Closes from increased pulmonary venous return and decreased inferior vena cava return.
- Ductus arteriosus
- Closes from increased oxygen saturation in the systemic arterial blood.
- 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 (bpm).
- Newborns have a high oxygen demand.
- Postnatal Circulation
- Allows lungs to oxygenate the venous blood.
- Allows fully saturated blood to be delivered to the systemic circulation.
- Right ventricular myocardium thins as the pulmonary vascular resistance drops.
- Increased systemic vascular resistance causes the left ventricular myocardium to become thicker and more dominant as it is in the adult heart.
- Blood flow follows the same pathway as adults.
- Congenital Heart Defects
- Is the leading cause of death (except for prematurity) in the first year of life.
- Cause is known in only 10% of defects.
- Prenatal, environmental, and genetic risk factors
- Maternal: rubella, lupus, insulin-dependent diabetes, alcoholism, illicit drug use, age (> 40 years) phenylketonuria (PKU), and hypercalcemia
- Chromosomal aberrations
- Classifications
- Based on blood flow
- Lesions increasing pulmonary blood flow
- Defects that shunt from high-pressure left side to low-pressure right side with pulmonary congestion; a cyanosis
- Lesions decreasing pulmonary blood flow
- Generally complex with right-to-left shunt and cyanosis
- Obstructive lesions
- Right- or left-sided outflow tract obstructions that curtail or prohibit blood flow out of the heart; no shunting
- Mixing lesions
- Desaturated blood and saturated blood mix in the chambers or great arteries of the heart.
- Heart Failure
- Is a common condition associated with congenital birth defects.
- Is also called congestive heart failure (CHF).
- Occurs when the heart is unable to maintain sufficient cardiac output to meet the metabolic demands of the body.
- Neurohumoral and hemodynamic changes create abnormal ventricular wall stress and cause the myocardium to hypertrophy.
- Heart Failure (Cont.)
- Clinical manifestations
- Poor feeding and sucking; leads to failure to thrive
- Dyspnea, tachypnea, diaphoresis, retractions, grunting, nasal flaring, wheezing, coughing, rales
- Skin changes, such as pallor or mottling
- Hepatomegaly
- Heart Failure (Cont.)
- Treatment
- Decrease cardiac workload and increase the efficiency of heart function.
- Administer diuretics, such as furosemide.
- Reduce afterload: Administer angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers, and beta-blockers.
- Supplement calorie intake.
- Anticoagulation and mechanical circulatory support
- Hypoxemia
- Is a condition associated with congenital birth defects.
- Heart defects that allow desaturated blood to enter the systemic system without passing through the lungs result in hypoxemia and cyanosis.
- Hypoxemia: Arterial oxygen tension is below normal and results in low oxygen arterial saturations and cellular function alteration.
- Cyanosis: Blue discoloration of mucous membranes and nail beds; is the result of deoxygenated hemoglobin.
- Hypoxemia (Cont.)
- Eisenmenger syndrome
- Pulmonary vascular resistance increases that exceed or equal vascular resistance, resulting in a reversal of shunting
- Defects that cause hypoxemia and cyanosis
- Lesions that cause obstruction and shunting from the right side of the heart to the left side, as in the tetralogy of Fallot
- Defects involving the mixing of saturated and unsaturated blood, as in the univentricular heart
- Transposition of the great arteries
- Hypoxemia (Cont.)
- Clinical manifestations
- Mild hypoxemia
- Cyanosis only occasionally when stressed
- Severe hypoxemia
- Feeding intolerance, poor weight gain, tachypnea, and dyspnea
- Chronic hypoxemia
- Small for their age, may display cognitive and motor skill delays.
- Polycythemia, shortness of breath with exertion, easily fatigued, and exercise intolerance
- Clubbing of the nail beds
- Hypoxemia
- Mild hypoxemia
- Heart defects that allow desaturated blood to enter the systemic system without passing through the lungs result in hypoxemia and cyanosis.
- Lesions increasing pulmonary blood flow
- Ductus venosus
- Foramen ovale
- Endocardial cushions
Defects Increasing Pulmonary
Blood Flow
- Patent ductus arteriosus (PDA)
- Failure of the ductus arteriosus to close
- Normally closes within first few hours of birth.
- PDA allows blood to shunt from the pulmonary artery to the aorta.
- Clinical manifestation
- Continuous, machinery-type murmur
- Bounding pulses, active precordium, thrill upon palpation, and signs and symptoms of pulmonary overcirculation.
- Treatment
- Surgical closure involving ligation by incision, catheter, or video-assisted thoracoscopy
- Defects Increasing Pulmonary
Blood Flow (Cont.) - PDA (cont.)
- Defects Increasing Pulmonary
Blood Flow (Cont.) - Atrial septal defect
- Abnormal communication between the atria
- Allows blood to be shunted from left to right.
- Clinical manifestations: Often asymptomatic; diagnosed by murmur
- Three major types of defect
- Ostium primum
- Ostium secundum
- Sinus venosus
- Treatment
- Surgical closure before school age results in better health.
- Defects Increasing Pulmonary
Blood Flow (Cont.) - Atrial septal defect (cont.)
- Defects Increasing Pulmonary
Blood Flow (Cont.) - Ventricular septal defect (VSD)
- Abnormal communication between ventricles
- Shunting from the high-pressure left side to the low-pressure right side
- Common congenital heart lesion (15% to 20%)
- Pulmonary overcirculation accounts for symptoms associated with a large VSD.
- Symptoms depend on age of child, size of defect, and level of PVR.
- Treatment
- Catheter closure
- Transcatheter muscular devices
- Defects Increasing Pulmonary
Blood Flow (Cont.) - Defects Increasing Pulmonary
Blood Flow (Cont.) - VSD (cont.)
- Defects Increasing Pulmonary
Blood Flow (Cont.) - Atrioventricular canal (AVC) defect
- Results from nonfusion of the endocardial cushions.
- Abnormalities demonstrated in the atrial and ventricular septa and AV valves
- Complete, partial, and transitional AVC defects
- Clinical manifestations: Presents with a murmur; heart failure; respiratory tract infections.
- Treatment: Complete repair between 3 and
6 months of life
- Defects Increasing Pulmonary
Blood Flow (Cont.) - AVC defect (cont.)
- Defects Increasing Pulmonary Blood Flow
- Defects Decreasing Pulmonary
Blood Flow - Tetralogy of Fallot
- Syndrome represented by four defects
- Large VSD
- Overriding aorta straddles the VSD
- Pulmonary stenosis
- Right ventricle hypertrophy
- Cyanosis, hypoxia, and clubbing, feeding difficulty, dyspnea, restlessness, squatting
- Hypercyanotic spell or a “tet spell” that generally occurs with crying and exertion
- Most cases corrected surgically in early infancy before 1 year of age; Blalock-Taussig shunt, transcatheter pulmonary valve replacement, patch
- Syndrome represented by four defects
- Defects Decreasing Pulmonary
Blood Flow (Cont.) - Tetralogy of Fallot (cont.)
- Defects Decreasing Pulmonary
Blood Flow (Cont.) - Tricuspid atresia
- Imperforate tricuspid valve
- No communication between the right atrium and the right ventricle
- Additional defects
- Septal defect
- Hypoplastic or absent right ventricle
- Enlarged mitral valve and left ventricle
- Pulmonic stenosis
- Defects Decreasing Pulmonary
Blood Flow (Cont.) - Tricuspid atresia (cont.)
- Clinical manifestations
- Central cyanosis and growth failure
- Exertional dyspnea, tachypnea, and hypoxemia
- Polycythemia, clubbing, hepatomegaly
- Treatment
- Prostaglandin administration
- Blalock-Taussig shunt
- Rashkind procedure: balloon atrial septostomy
- PA band
- Closure of septal defects
- Defects Decreasing Pulmonary
Blood Flow (Cont.) - Tricuspid atresia (cont.)
- Obstructive Defects
- Coarctation of the aorta
- Narrowing of the lumen of the aorta that impedes blood flow (8% to 10% of defects)
- Is almost always found in the juxtaductal position, but it can occur anywhere between the origin of the aortic arch and the bifurcation of the aorta in the lower abdomen.
- Clinical manifestations: Newborns usually exhibit HF.
- Once the ductus closes, rapid deterioration occurs from hypotension, acidosis, and shock.
- Obstructive Defects (Cont.)
- Coarctation of the aorta (cont.)
- Clinical manifestations: Older children
- Hypertension in the upper extremities
- Decreased or absent pulses in the lower extremities
- Cool mottled skin
- Leg cramps during exercise
- Treatment
- Prostaglandin administration
- Mechanical ventilation
- Inotropic support
- Maintain cardiac output
- Surgery
- Obstructive Defects (Cont.)
- Clinical manifestations: Older children
- Coarctation of the aorta (cont.)
- Obstructive Defects (Cont.)
- Aortic stenosis
- Narrowing of the aortic outflow tract (10% of defects)
- Caused by malformation or fusion of the cusps.
- Causes an increased workload on the left ventricle.
- Clinical manifestations
- Often asymptomatic
- Signs of exercise intolerance in preadolescence
- Syncopal episodes, epigastric pain, and exertional chest pain in more severe forms
- Murmur
- Treatment
- Commissurotomy; aortic valvotomy; Ross procedure
- Obstructive Defects (Cont.)
- Aortic stenosis (cont.)
- Obstructive Defects
Question 4 - Obstructive Defects
- Pulmonary stenosis
- Narrowing of the pulmonary outflow tract
- Abnormal thickening of the valve leaflets
- Narrowing of the valve
- Pulmonary atresia: Severe form
- Clinical manifestations
- Often asymptomatic
- Exertional dyspnea, murmur, fatigue, thrill, cyanosis, HF
- Treatment
- Mild: Not treated, closely observed
- Severe: Balloon angioplasty; pulmonary valvotomy
- Obstructive Defects (Cont.)
- Pulmonary stenosis (cont.)
- Obstructive Defects (Cont.)
- Hypoplastic left heart syndrome
- Left-sided cardiac structures develop abnormally.
- Obstruction to blood flow from the left ventricular outflow tract
- Left ventricle, aorta, and aortic arch are underdeveloped; mitral atresia or stenosis is observed.
- As the ductus closes, systemic perfusion is decreased, resulting in hypoxemia, acidosis, and shock.
- Left-sided cardiac structures develop abnormally.
- Obstructive Defects (Cont.)
- Hypoplastic left heart syndrome (cont.)
- Treatment
- Prostaglandin administration
- Correction of acidosis
- Inotropic support for adequate cardiac output
- Ventilatory manipulation
- Obstructive Defects (Cont.)
- Hypoplastic left heart syndrome (cont.)
- Treatment
- Surgical intervention includes a three-stage approach.
- Norwood procedure: Atrial septectomy, pulmonary-to-systemic artery shunt, permanent communication between the right ventricle and aorta, and patching the hypoplastic aorta.
- Glenn procedure: Performed between 2 and 9 months of age; the superior vena cava is joined to the pulmonary artery, and the takedown of the shunt to the lungs.
- Fontan procedure: Performed between 2 and 4 years of age, separates the systemic from the pulmonary circulation.
- Cardiac transplantation
- Surgical intervention includes a three-stage approach.
- Obstructive Defects (Cont.)
- Hypoplastic left heart syndrome (cont.)
- 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 continuously circulates through the systemic circulation.
- Oxygenated blood continuously circulates through the pulmonary circulation.
- Extrauterine survival requires communication between the two circuits.
- Clinical manifestations: Cyanosis may be mild shortly after birth and worsen during the first day.
- Treatment: Surgery to switch the arteries.
- Mixed Defects (Cont.)
- Transposition of the great arteries (cont.)
- Mixed Defects (Cont.)
- 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.
- Nonobstructive vs. obstructive
- Clinical manifestation: Cyanosis
- Treatment
- Obstructed lesions are repaired at the time of diagnosis.
- Unobstructed lesions are generally repaired during infancy.
- Surgery: Anastomosis of the common pulmonary vein to the left atrium; closure of the atrial septal defect.
- Mixed Defects (Cont.)
- TAPVC (cont.)
- Mixed Defects (Cont.)
- Truncus arteriosus
- Is the failure of the embryonic artery to divide into the pulmonary artery and aorta.
- Trunk straddles an always present VSD.
- Types I through IV
- I: Most common; the main pulmonary artery arises from the truncus.
- II: Pulmonary arteries arise from the posterior aspect of the truncus.
- III: Pulmonary arteries arise from the lateral aspect of the truncus.
- IV: Pseudotruncus; is a severe form of tetralogy of Fallot with the bronchial arteries arising from the descending aorta to supply the lungs.
- Mixed Defects (Cont.)
- Truncus arteriosus (cont.)
- Clinical manifestations
- Cyanosis; mild-to-moderate cyanosis that worsens with activity
- Murmur
- Treatment
- Modified Rastelli procedure involving VSD patch closure to divert the blood flow from the left ventricle outflow tract into the truncus
- Correct pulmonary arteries
- Mixed Defects (Cont.)
- Hypoplastic left heart syndrome (HLHS)
- Abnormal development of left-sided cardiac structures
- Obstructs blood flow from the LV outflow tract.
- Clinical manifestations
- Hypoxemia, acidosis, shock
- Loud and single second heart sound
- Treatment
- Prostaglandin infusion
- Correction of acidosis
- Inotropic support
- Ventilatory manipulation
- Surgery
- Mixed Defects (Cont.)
- Truncus arteriosus
- Acquired Cardiovascular Disorders
- Kawasaki disease
- Formerly known as mucocutaneous lymph node syndrome.
- Is an acute, self-limiting systemic vasculitis that may result in cardiac sequelae.
- Approximately 80% of cases occur in children under the age of 5.
- Cause
- Unknown
- Theories: An immunologic response to an infectious, toxic, or antigenic substance (including superantigen)
- Acquired Cardiovascular Disorders (Cont.)
- Acquired Cardiovascular Disorders (Cont.)
- Acquired Cardiovascular Disorders (Cont.)
- Kawasaki disease (cont.)
- Diagnosis
- Fever
- Conjunctivitis
- Oral changes (strawberry tongue)
- Irritability
- Rash
- Lymphadenopathy
- Treatment
- Aspirin and intravenous (IV) administration of immunoglobulin during the acute phase
- Acquired Cardiovascular Disorders Question 5
- Acquired Cardiovascular Disorders
- Systemic hypertension
- Hypertension in children differs from adults.
- Children often have underlying renal disease or coarctation
of the aorta. - Children with hypertension are commonly asymptomatic.
- Children often have underlying renal disease or coarctation
- Treatment: Appropriate diet, regular physical activity, avoidance of smoking, drugs
- ACE inhibitors
- ARBs
- Calcium channel blockers
- Acquired Cardiovascular Disorders (Cont.)
- Childhood obesity
- Is considered an epidemic.
- Centers for Disease Control and Prevention (CDC) suggests two levels of overweight.
- 85th percentile: “At-risk” level
- 95th percentile: More severe level
- Is multivariable and multidimensional.
- Risk factors
- Race, socioeconomic status, lack of health insurance
- Early childhood nutrition
- Low level of physical activity, engagement in sedentary activities (television viewing, computer use)
- Sleep disturbances
- Acquired Cardiovascular Disorders (Cont.)
- Childhood obesity (cont.)
- Is associated with parental obesity.
- Places the child at risk for asthma, sleep apnea, hypertension, type 2 diabetes, dyslipidemia, cardiovascular disease.
- Has social and economic consequences.
- Treatment: Prevention
- Combines physical activity with nutritional improvements.
- Needs intervention, immediate referral, and support from health care professionals.
- Requires change in lifestyle at home and involvement of family members.
- Hypertension in children differs from adults.
- Diagnosis
- Clinical manifestations
- Treatment
- Treatment
- Clinical manifestations
- Abnormal communication between ventricles
- Abnormal communication between the atria
- Failure of the ductus arteriosus to close