Cardiac Structural
Disorders
Outcomes
• Describe congenital heart defects
• Describe non-congenital structural heart defects
• Understand how these defects affect blood flow
Structural Heart Defects
• Group of structural abnormalities that occur during gestation and result in
abnormal blood flow through the heart in the postnatal period
• Congenital defect-develop during the embryonic period of cardiac
development, mainly during weeks 6–9
• Genetics: deletions, duplications, mutations
• Environment: drugs, alcohol, cigarette smoking, secondhand smoke
• Maternal: viral infections, metabolic disorders, increased maternal age
Murmur
• Not unusual to auscultate a murmur in the first few hours of a newborn’s life
• Murmur indicates turbulent blood flow through valve
• Congenital heart defect
• Ventricular septal defect
• Patent ductus arteriosus
• Intensity directly correlates with size of murmur
Murmurs are Graded on a Six-point Scale
•
•
•
•
•
•
•
Grade 1: Barely audible
Grade 2: Louder than grade 1
Grade 3: Loud but without thrill
Grade 4: Loud and associated with palpable thrill
Grade 5: Associated with thrill and murmur; audible with stethoscope partially off chest
Grade 6: Audible without stethoscope
Murmurs louder than grade 3 considered pathologic and require further evaluation by
pediatric cardiologist
CHD Classifications
•
•
•
•
Increased pulmonary blood flow
Decreased pulmonary blood flow
Obstructed blood flow
Mixed blood flow
Critical CHD Diagnosis (CCHD)
• Begins with identification of clinical signs and symptoms
• Proceeds with:
• Electrocardiography (ECG)
• Echocardiography
• Most reliable diagnostic tool
• Chest x-ray
• Identifies increased pulmonary blood flow and possible chamber hypertrophy
Increased Blood Flow Defects
• Most common type of CCHD, includes four different types of defects, all of which increase blood flow to
the pulmonary system
• Types of openings between right and left sides of heart:
•
•
•
Atrial septal defect (ASD)
Ventricular septal defect (VSD)
Patent ductus arteriosus
• Blood naturally flows:
•
•
From area of high pressure (left side)
To area of low pressure (right side)
• Murmur heard on auscultation
Atrial Septal Defect
Treatment of ASD
• Closed heart procedure
• Utilizes cardiac catheterization
• Inserts synthetic patch on atrial septum to close defect
• Open heart procedure
• Involves surgery
• Puts patient on cardiac bypass during procedure
• Affixes synthetic patch to septum
• Closes septal defect
• Symptoms improve and pulmonary congestion decreases
VSD
•
•
•
•
•
25–30% of all CCHDs
In small- to medium-sized (restrictive) VSD:
Left-to-right shunt occurs
Murmur is heard
In large VSD:
• Pressures nearly equal
• Shunting left to right and right to left
VSD
VSD
• With large left-to-right shunt:
• Pulmonary hypertension gradually develops
• Flow across shunt decreases
• If pulmonary vascular resistance exceeds systemic vascular resistance:
• Direction of shunt reverses
• Eisenmenger syndrome: Cyanosis develops after several years
Treatment of VSD
•
•
•
•
Treatment depends on clinical course.
Large VSD that causes pulmonary congestion requires:
Surgical repair
Medical management to reduce afterload
Medical Management
• Afterload: Resistance heart must overcome to eject volume of blood from
ventricle, expressed as total peripheral resistance
• Includes:
• Diuretic to help decrease pulmonary volume
• Afterload-reducing agent
• Possibly digoxin to improve ventricle contractility
Surgical Repair of VSD
• Open heart surgery-Patient placed on cardiac bypass
• Defect repaired using synthetic patch
• Recommended in first year of life to prevent complications
Patent Ductus Arteriosus
• CHD in which connection present in utero that allows blood to bypass the lungs after right ventricular ejection.
• Pulmonary pressure is higher than aortic pressure in fetus so blood flows from pulmonary artery to the aorta which in the
fetus has a lower pressure
• 5–10% of all CCHDs
• Higher incidence in:
•
•
•
Premature infants
Infants with trisomy 21
2:1 female:male incidence
• Ductus normally closes in first 48 hours of life-ligamentum arteriosum is the remnant
• If ductus fails to close in first 48 hours of life:
•
Left-to-right shunt across ductus returns blood to pulmonary circulation
Patent Ductus Arteriosis
Surgical Treatment
•
•
•
•
•
•
Necessary if:
Medications fail to close PDA
Infant is term and hemodynamically symptomatic
In most cases, closed heart procedure (catheter closure) is performed.
In some cases, an open heart procedure is necessary.
Medical Management
• Premature infants, medical management is the first course of action.
• Administration of nonsteroidal anti-inflammatory agent (NSAID) to inhibit
prostaglandin production
• For preterm infant with hemodynamically clinically significant PDA:
• Fluid restriction
• Oxygen administration
Decreased Pulmonary Blood Flow Defects
•
Obstruction of pulmonary blood flow to lungs increases pressure on right side of heart
•
Includes:
•
•
•
•
Tetralogy of Fallot
•
Pulmonary stenosis
•
Pulmonary atresia
•
Tricuspid atresia
Tetralogy of Fallot
•
10% of all CCHDs
•
Most common cause of cyanotic heart disease
Pulmonary stenosis
•
8–12% of all CCHDs
•
Second most common cause of cyanotic heart disease
Tetralogy of Fallot (TOF)
• Four defects: The four defects include a ventricular septal defect (VSD), pulmonary
valve stenosis, a misplaced aorta and a thickened right ventricular wall (right ventricular
hypertrophy)
• Taken together cause cyanosis
• TOF is a ductal-dependent cardiac lesion.
• PS causes right ventricular hypertrophy.
• Deoxygenated blood returned from body cannot move to lungs
• Pressure (right ventricle) is higher than (left ventricle)
• Right-to-left shunting through the VSD
• Deoxygenated blood mixes with oxygenated blood and leaves left ventricle as cardiac output
Tetralogy of Fallot
Surgical Treatment
• Current treatment recommendation is corrective repair early in infancy.
• Surgical repair
• Occurs under cardiopulmonary bypass
• Involves:
• Closure of VSD
• Resection of stenotic areas
• Relief of right ventricular outflow tract obstruction
Surgical Treatment
• Staged procedures may be performed to increase stability and survivability
• First stage procedure establishes pulmonary blood flow independent of
ductal patency
• Primary corrective and staged repair postoperative survival rates are 90–95%
at 20 years old
Pulmonary Stenosis
• AKA right ventricular outflow tract obstruction
•
•
•
•
Valve is narrowed, blood flow to the lungs decreases
Dome-shaped pulmonary valve is most common; caused by fused pulmonary valve cusps
Right ventricle may show some degree of hypertrophy
Pulmonary artery may be dilated
• Slight to mild stenosis, followed and treated medically
• Moderate to severe stenosis-surgical intervention-related to severity of pressure
gradient
Pulmonary Stenosis
Obstructed Systemic Blood Flow Defects
• Pulmonary blood flow is obstructed, resulting in little or no blood reaching lungs to be oxygenated
• Cardiac defects that obstruct blood flow to periphery often cause infants with these defects to be cyanotic:
•
•
•
•
Coarctation of the aorta
Aortic stenosis: Narrowing of aortic valve opening
Hypoplastic left heart syndrome (HLHS)
Mitral stenosis: Narrowing of mitral valve
• Interrupted aortic arch: Uncommon genetic disorder that occurs in association with nonrestrictive ventricular septal
defect and ductus arteriosus
• Infants born with left outflow tract obstruction most commonly have:
•
•
Coarctation of the aorta
Hypoplastic left heart syndrome
Coarctation of the Aorta
•
Narrowing of aorta, usually around area of arch; most common in thoracic area
•
•
•
•
Symptoms vary depending on the degree of constriction
Infant with COA will have:
•
High left ventricular pressures
•
Low systemic pressures, especially in legs
When ductus arteriosus closes, foramen ovale may open leading to:
•
Left-to-right shunt
•
Right atrial and ventricular congestion
•
Possible hypertrophy
When foramen ovale does not open:
•
Pulmonary congestion results.
•
Infant presents with symptoms of pulmonary overload.
Initial Treatment of COA
• Diuretics to ease pulmonary congestion
• Continuous infusion of prostaglandins to:
• Maintain patency of ductus arteriosus
• Allow for systemic circulation
• Inotropic infusions to maintain renal perfusion
• When infant is medically stable, surgical intervention is considered
• Mild COA, balloon angioplasty with placement of aortic stents
• Severe COA, surgical procedures depend on infant’s anatomy
Hypoplastic Left Heart Syndrome
• Left side of heart does not fully develop during gestation, including many or
all left-side structures
• Infants born with HLHS require:
• Ductus arteriosus to remain patent
• Prostaglandin infusion to allow for oxygenated systemic blood flow
Hypoplastic Left Heart Syndrome
Treatment
•
Begins with prostaglandin infusion to maintain ductus arteriosus
•
Several staged repairs:
•
•
•
•
Bypass underdeveloped left side of heart
•
Establish systemic blood flow
First staged repair
•
Norwood procedure
•
Establishes right ventricle as main pumping chamber of heart
Second staged repair
•
Bidirectional Glenn shunt
•
Performed about 6 months after Norwood procedure
•
Directs half of returning blood directly to lungs, bypassing ventricle
Third staged repair
•
Fontan procedure-a type of open-heart surgery. The goal is to: Make blood from the lower part of the body go directly to the lungs. This lets the blood pick up oxygen without
having to pass through the heart
Treatment
• Staged procedures improve systemic perfusion but are not curative, so
children:
• Have lifelong complications
• May require heart transplant
• Overall 5-year survivability after all three staged repairs
• Approximately 70%
• Significant risks for postoperative complications
Mixed Blood Flow Defects
• Transposition of the great arteries (TGA) Oxygenated and deoxygenated blood
become mixed because of a structural defect, causing either increased or decreased
pulmonary blood flow or obstructed systemic flow
• Pulmonary artery arises from left ventricle and aorta arises from right ventricle
• Pulmonary and cardiac circulations are parallel rather than serial.
• Deoxygenated blood is:
• Returned to right side
• Pumped out aorta to periphery
• Oxygenated blood continually loops from left ventricle to lungs
Surgical Management
•
•
•
•
Only treatment for TGA
Performed early in infant’s life
Arterial switch reestablishes correct pulmonary and cardiac circulation.
Postoperative survivability is greater than 90%
TGA
Total Anomalous Pulmonary Venous
Return (TAPVR)
•
•
•
•
Pulmonary veins drain into right side of heart
3 different presentations of vessels
Infant cyanotic
May have VSD that assists in delivering small fraction of oxygenated blood
to periphery
Total Anomalous Pulmonary Venous
Return (TAPVR)
Treatment
• Infants with TAPVR require stabilization with prostaglandin to:
• Maintain ductus arteriosus
• Allow oxygenated blood to be pumped to periphery
• After stabilization, surgical repair:
• Redirects pulmonary veins to left ventricle
• Reestablishes oxygenated blood flow to periphery
• Postoperative prognosis
• Greater than 90% in infants with two ventricles
• Less than 60% in infants with only one ventricle and more complex TAPVR presentation
Signs and Symptoms of Critical Congenital
Heart Defects
• Blood flow alteration causes several common signs and symptoms.
• Most infants, regardless of CCHD, experience some degree of:
• Dyspnea
• Feeding difficulties
• Fatigue
Signs and Symptoms
•
•
•
•
•
Symptoms related to alteration in blood flow
Dyspnea related to decreased oxygen saturation of infant’s blood
Low arterial saturation
•
Increase in infant’s respiratory rate
•
Leads to tachypnea that worsens with exertion
Poor feeding is a common symptom related to the infant’s:
•
Increased work of breathing
•
Tachypnea
Cyanosis present in infants with CCHD that involves:
•
Decreased pulmonary blood flow
•
Obstructive blood flow
•
Mixed blood flow
Surgical Management
• Surgical intervention may be indicated if medications are ineffective to improve:
• Perfusion
• Oxygenation
• Prognosis for long-term survivability for infants diagnosed with CCHD depends on
many factors, including:
• Age at time of diagnosis
• Presenting symptoms
• CHD critical or noncritical
Medical Management
• All infants with CCHD are managed medically until surgical interventions can be
performed.
• In addition to respiratory support, common medications include:
•
•
•
•
•
Diuretics
Prostaglandins
Antihypertensives
Cardiac glycosides
Inotropes
Non-congenital Structural Heart Defects
• Main SHDs
• Valvular changes caused by rheumatic heart disease
• Endocarditis
• Calcification of the valves
Rheumatic Heart Disease
• Changes to cardiac valves that occur after repeated exposure to group A betahemolytic streptococcus
• Single exposure to bacterium typically does not cause RHD.
• With repeated attacks, valve leaflets become deformed, rigid, shortened
• Manifestations of RHD depend on:
• Affected valve
• Type of damage
Rheumatic Heart Disease
Endocarditis
• Inflammation of heart caused by pathogens that enter bloodstream and colonize
valve structures
• Individuals are more prone to developing this disorder if they have:
• Previous heart valve damage
• Prosthetic valve devices
• Valves may be damaged from:
• Infection
• Inflammation
Endocarditis
Pathophysiology of Endocarditis
• Bacteria colonize valve leaflets and are covered by:
•
•
•
•
•
•
•
•
•
Phagocytes
Fibrin
Platelets
Over time, these break off and create microemboli
Microemboli enter general circulation
Microemboli cause microhemorrhages and petechiae
Osler nodes: Small red painful growths on finger and toe pads
Janeway lesions: Small nonpainful purple lesions on palms of hands and soles of feet
Roth spots: Small white spots seen on retinas
Calcification of the Aortic Valve
• Calcification can occur with any cardiac valve, but the aortic valve is most
prone to this disorder.
• In the absence of any other cardiac disorder that can affect valve structure,
aortic valve calcification has been linked to atherosclerosis
• Thickening of aortic valve from calcium deposits leads to aortic stenosis
Calcification of the Aortic Valve
Diagnostic Tests
• Test to diagnose valve damage caused by SHDs
•
•
•
•
•
Electrocardiography
Echocardiography
Chest x-ray
Exercise tolerance testing
Cardiac catheterization
• For endocarditis, additional testing through blood cultures identifies offending
microorganism
Medical Treatment
•
•
•
•
•
•
Symptom management
Prevention or treatment of heart failure
Diuretics
ACE
Vasodilators to reduce preload and afterload
Potentially digoxin to maintain cardiac output
Medical Treatment
• For endocarditis
• Antibiotic therapy begins as soon as offending organism is identified.
• Additional medications may be necessary to maintain cardiac output.
• Medications for calcification of the aortic valve
• Prevent or treat heart failure
• Address elevated blood lipid levels
Surgical Management
• Valvuloplasty
• Open commissurotomy: Procedure to open fused valve
• Annuloplasty: Procedure to repair narrowed valve
• Valve replacement
• Indicated when valve dysfunction cannot be repaired by any other route
• For endocarditis, valve replacement may be indicated if antibiotic therapy is
unsuccessful.
• Individuals with aortic calcification may need valvuloplasty or valve replacement
depending on severity of symptoms
Summary
• It is remarkable how often the heart develops normally
• The congenital defects listed above can be managed and in most cases
repaired
• The adult non-congenital heart defects discussed are secondary to infective
and atherosclerosis