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Overview of congenital heart diseaseIntroductionConditionsReferencesImagesCredits

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IntroductionCongenital heart disease (CHD) is the most common birth defect, although still relatively rare. The surgical and

medical treatment of CHD has markedly improved over the last 50 years. Corrective surgery for intra-cardiac

defects first began at the Mayo Clinic and the University of Minnesota in the 1950s.[1] It was the introduction of

machines that perfused the vital organs while a surgeon carefully repaired a non-beating heart that

revolutionised the field of corrective surgery. Survival well into adulthood is now expected for most babies born

with CHD.

Epidemiology

Occurs in 0.8% of live births. In North America, it is estimated that there are more than 1 million adults with CHD;

for the first time, the number of adults now exceeds the number of children with CHD.

Classification

Left-to-right shunts

Lesions that allow blood to shunt from the left side to the right side of the heart. They are associated with

varying degrees of increased pulmonary blood flow and are typically acyanotic. In some defects, the site of the

shunt may not be within the heart itself.

Cyanosis occurs only if the lesions are large and not repaired in childhood, and if the patient develops

pulmonary vascular obstructive disease (Eisenmenger's physiology). Echocardiography is the primary imaging

modality, and, in the current era, the role of cardiac catheterisation is primarily for intervention.[2]

Examples include:

o Ventricular septal defect (VSD)

o Atrial septal defect (ASD)

o Atrioventricular septal defect (AVSD)

o Patent ductus arteriosus (PDA)

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o Partial anomalous pulmonary venous connection (PAPVC).

Right-to-left shunts

Lesions that result in de-oxygenated blood reaching the aorta and are associated with an increased or

decreased pulmonary blood flow.

Examples include:

o Tetralogy of Fallot (TOF)

o Pulmonary valve atresia with or without a VSD

o d-Transposition of the great arteries (d-TGA)

o Truncus arteriosus

o Ebstein's anomaly

o Total anomalous pulmonary venous connection (TAPVC)

o Hypoplastic left heart syndrome (HLHS).

Obstructive valvular and non-valvular lesions

Left ventricular outflow tract (LVOT) obstruction

Coarctation of the aorta

Pulmonary valve stenosis (PS)

Aortic valve stenosis (AS)

Conditionshide allVentricular septal defect (VSD)

see our comprehensive coverage of Ventricular septal defects

This is the most common form of CHD, accounting for 20% of all cases, excluding bicuspid aortic valve

and mitral valve prolapse.[3] Sub-types based on location include: peri-membranous (in the area of the

membranous septum); outlet (below 1 or both semilunar valves); inlet (inferior to the atrioventricular [AV]

valves); and muscular (in the muscular or trabeculated portion of the ventricular septum). View image

Peri-membranous defects can sometimes close spontaneously by apposition of the septal leaflet of the

tricuspid valve to the defect. Outlet defects may be large and associated with more complex forms of

congenital heart disease. Both peri-membranous and outlet VSDs are in close proximity to the right cusp

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of the aortic valve. Because of the Venturi effect, these defects can cause prolapse of an aortic valve

cusp, which results in both a restriction to flow through the VSD and regurgitation of the aortic

valve.[4] Inlet defects do not close spontaneously and may be associated with AVSD and AV valve

regurgitation. Muscular defects are the most common type of VSDs in newborns and the vast majority

close spontaneously before 2 years of age. View image

Children with a small VSD develop normally and are asymptomatic. With larger defects, the baby may

develop signs of excess pulmonary blood flow such as tachypnoea, tachycardia, pallor, poor feeding,

and poor weight gain once pulmonary vascular resistance declines at 6 to 8 weeks of age. Pulmonary

vascular obstructive disease usually does not develop in infants, but can develop by 2 years of age.

Eisenmenger's physiology, a right-to-left shunt due to irreversible pulmonary vascular obstructive

disease, does not typically occur until later in life. Once a patient develops Eisenmenger's physiology,

the VSD cannot be closed safely.

Patients have a low-to-mid frequency holosystolic murmur, a prominent pre-cordial impulse, and, in

patients with pulmonary HTN, a loud and single second heart sound. If the left-to-right shunt is large,patients develop a mid-diastolic flow murmur ("rumble") across the mitral valve.

CXR and ECG can be normal in small VSDs. In larger defects, there is cardiac enlargement and

increased pulmonary vascular markings on CXR, View image and ECG reveals left ventricle

hypertrophy; right ventricle hypertrophy can occur with larger defects. Inlet-type VSDs are associated

with left axis deviation on ECG. Echocardiography provides important information regarding the anatomy

of the defect, the volume of the shunt and right ventricular pressure.[5]

The goal of treatment is to ensure adequate somatic growth and prevent pulmonary vascular obstructive

disease. Small VSDs and those unassociated with excessive pulmonary blood flow do not require

closure. Large VSDs and defects associated with aortic regurgitation due to aortic valve cusp prolapse

or excess pulmonary blood flow may require diuretics and an increased caloric formula, followed by

closure of the defect (either surgical closure or transcatheter device closure). Those with increased

pulmonary blood flow and failure to thrive are closed surgically between 1 and 4 months of age; most

large defects are typically closed by 6 to 9 months of age.

Atrial septal defect (ASD)

see our comprehensive coverage of Atrial septal defects

Represents 6% to 10% of all CHD and has a female-to-male predominance of 2:1.[6] There are 4 sub-

types: View image ostium secundum defect (60% to 70% of ASDs) in the area of the fossa ovalis;ostium primum defect, a form of AVSD, in the inferior aspect of the atrial septum; View imagesinus

venosus defect, not a true ASD, which occurs at the entry of the superior vena cava into the right atrium

due a failure of the normal incorporation of the right pulmonary veins into the left atrium; and unroofed

coronary sinus, the least common type. Unroofed coronary sinus, also known as a coronary sinus ASD,

is not a true atrial septal defect. It occurs when a hole in the roof of the coronary sinus allows the

coronary sinus and left atrium to communicate.

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Children with isolated ASDs are frequently asymptomatic. It is the most commonly missed CHD

diagnosis in childhood, frequently not discovered until adulthood. An untreated defect leads to exercise

intolerance, atrial arrhythmias, increased pulmonary blood flow, and pulmonary vascular obstructive

disease in the third or fourth decade of life. The patient may be at risk of stroke secondary to paradoxical

embolisation through the defect.

In moderate to large ASDs, examination reveals an increased right ventricular impulse, a widely split

fixed second heart sound, and a soft systolic ejection murmur best heard at the upper left sternal border.

The murmur is caused by increased blood flow through the pulmonary valve, not through the ASD. In

large defects, a diastolic murmur may also be present at the lower sternal border secondary to

excessive blood flow through the tricuspid valve.

CXR is not helpful in determining the sub-type and may be normal with a small ASD. ECG may also be

normal in small secundum, sinus venous, and unroofed coronary sinus ASDs. With a larger shunt, there

may be right atrial enlargement, right ventricular hypertrophy, or right axis deviation.View imageView

image Ostium primum-type defects are characterised by an initial counterclockwise frontal plane loop

and left axis deviation.[7]

Treatment involves either an operation or percutaneous device closure.[8] View image Device closure is

the preferred method for ostium secundum defects if there are adequate septal rims to secure a device,

but cannot be used in other sub-types due to the close proximity of the defects to other cardiac

structures. Partial AVSD (ostium primum ASD and a cleft mitral valve) can be repaired after the age of

18 to 24 months in most patients and involves closure of the mitral cleft in addition to the ASD.

Atrioventricular septal defect (AVSD)

Represents 4% to 5% of all CHD and is found in 40% of children with Down's syndrome.[9]The defects

are also called endocardial cushion defects or AV canal defects. Endocardial cushions close the ostium

primum and form portions of the AV valves and the ventricular septum. AVSDs may be partial or

complete; 1 type of a partial AVSD is a primum ASD. A complete AVSD consists of a primum ASD and a

contiguous inlet VSD. View image

Presentation and findings on examination of patients with complete and partial AVSDs are similar to

patients with a VSD or ASD, respectively. Severity is also determined by the volume of the shunt, extent

of the AV valve abnormalities, associated cardiac and extra-cardiac anomalies, and the relative size of

the 2 ventricles.

ECG is likely to reveal an initial counter-clockwise frontal plane loop and a superior QRS axis. Viewimage Patients with complete AVSDs usually have cardiomegaly and increased pulmonary vascular

markings on CXR.[10]

Children with a complete AVSD require surgical repair, usually performed at 3 to 6 months of age. They

require life-long follow-up, as approximately 15% of patients develop progressive AV valve regurgitation

or left ventricle outflow tract (LVOT) obstruction.[11]

Patent ductus arteriosus (PDA)

see our comprehensive coverage of Patent ductus arteriosus

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A ductus arterious normally closes within several days of birth and is an essential component of normal

in utero cardiovascular physiology. Persistent patency occurs in 1 in 5000 live births in full-term infants

but is much more common in pre-term neonates.[12] In pre-term infants, a PDA has been noted during

admission to hospital in 42% of neonates weighing 500 to 999 g, 21% weighing 1000 to 1499 g, and 7%

weighing 1500 to 1750 g.[13] There is also a 30-fold higher incidence in patients born at higher

altitudes. PDA represents 9% to 12% of all CHD.

Patients are asymptomatic when the ductus is small. With increasing size, newborns present with signs

of increased pulmonary blood flow, a wide pulse pressure, and "bounding" pulses. Eisenmenger's

physiology, secondary to pulmonary vascular obstructive disease and shunt reversal, may occur if the

PDA is large and long standing, and results in cyanosis only in the lower half of the body.

Typically, a PDA produces a continuous murmur, best heard at the left infraclavicular area. The murmur

is continuous because the aortic pressure is higher than the pulmonary artery pressure during both

systole and diastole. If the shunt is large, a diastolic mitral flow murmur also may be heard. In some pre-

term and newborn infants, the murmur may be heard only in systole and can be confused with themurmur of a VSD.

ECG and CXR often are normal. In a large PDA, bi-ventricular hypertrophy on the surface ECG, and

increased pulmonary blood flow and cardiomegaly on CXR may be present. Echocardiography allows

delineation of the PDA anatomy, and direction and volume of the shunt.[12]

In pre-term infants, the ductus can often be closed with indometacin (indomethacin) or ibuprofen, or

failing that, ligated surgically.[14] In older children and adults, PDAs are closed percutaneously using

coils or devices.[11] Diuretics can be used to treat patients with excess pulmonary blood flow until

definitive closure.

Partial anomalous pulmonary venous connection (PAPVC)

An anomaly where 1 (but not all) pulmonary veins connect to the systemic veins or right atrium, instead

of to the left atrium. This defect represents

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Pulmonary atresia with an intact ventricular septum

This defect is rare and severity depends upon commonly associated right ventricular and tricuspid valve

hypoplasia. Coronary artery-to-right ventricle fistulae are also associated with this defect.[19]A large,

unrestrictive ASD is required for survival as there is no outlet from the right ventricle to the pulmonary

arteries.

There are no examination findings characteristic of this defect. CXR reveals cardiomegaly with aprominent right atrium and ECG shows atrial enlargement. Echocardiography is utilised to determine

right ventricular size and tricuspid valve hypoplasia.

A restrictive ASD is a medical emergency in these patients and requires an urgent balloon atrial

septostomy. Patients should be treated with prostaglandin E1 to maintain ductal patency since the PDA

is the only source of pulmonary blood flow.[20] Most patients require staged operations that potentially

allow the tricuspid valve and right ventricle to increase in size. A modified Fontan's operation or a 1.5

ventricle repair may be necessary if the right ventricle and tricuspid valve to do not reach an adequate

size to allow a 2 ventricle repair. A 1.5 ventricle repair involves a bi-directional cavopulmonary shunt to

divert superior vena caval blood flow to the pulmonary arteries to reduce right ventricular pre-load,

closure of the ASD and establishment of right ventricle-to-pulmonary artery continuity. Patients with

coronary artery-to-right ventricle fistulae require a modified Fontan's operation.

d-Transposition of the great arteries (d-TGA)

A common CHD representing 4% of all defects. In this defect, the aorta arises from the right ventricle

and the pulmonary artery arises from the left ventricle. As a result, de-oxygenated systemic venous

blood travels from the right ventricle to the aorta without passing through the lungs, and pulmonary

venous blood travels from the left ventricle to the lungs via the pulmonary artery. The systemic and

pulmonary circulations are in parallel rather than series. This is not compatible with life without a

communication between the 2 circuits, such as a VSD, ASD, or PDA. Most patients with d-TGA do not

have a VSD and a third of those with a VSD have associated pulmonary stenosis.

Patients present in the first few hours of birth with cyanosis as a medical emergency.

Examination reveals a prominent right ventricular impulse, a single loud second heart sound (due to the

anterior position of the aorta), and no murmur, or a systolic ejection murmur in those with a VSD and

pulmonary stenosis.

Prostaglandin E1 is used to maintain patency of the ductus arteriosus and most patients also require an

atrial septostomy to enhance mixing at the atrial level. The arterial switch operation is the best option for

patients with d-TGA and a normal pulmonary valve, and is performed in the first weeks of life. Once the

pulmonary vascular resistance decreases, the left ventricle is no longer conditioned to pump against the

higher resistance associated with the systemic circulation. TGA-VSD should be repaired in the newborn

period if identified at that time. However, successful late repair (1 to 2 months of age) has been reported,

albeit with increased morbidity. Around 80% of patients who underwent an atrial switch operation, known

as a Senning or a Mustard procedure, during the 1960s to mid-1980s have had good outcome several

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decades after surgery. However, long-term complications, including arrhythmias, systemic or pulmonary

venous obstruction, and systemic right ventricular dysfunction, are known in adulthood.[11]

Truncus arteriosus

Comprises

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Comprising

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can appear normal for several days after birth but are dependent on a PDA. Once the ductus closes,

they develop shock.

Examination reveals diminished lower extremity pulses and an increased right ventricular impulse.

Untreated, HLHS is lethal, although mortality has been markedly reduced in the last decade. Patients

require a staged surgical approach.[24] Stage 1 is a Norwood procedure, consisting of reconstruction of

the aortic arch using the main pulmonary artery and a modified Blalock-Taussig shunt supplying blood

flow to the pulmonary artery branches. Recently, placement of a right ventricle to pulmonary artery

(Sano) shunt has been used as an alternative to a Blalock-Taussig shunt during stage 1

palliation.[25] Stage 2 consists of replacing the modified Blalock-Taussig shunt (or Sano shunt) with a

bidirectional cavopulmonary (Glenn) anastomosis. Stage 3 consists of a modified Fontan's operation,

which directs lower extremity venous return to the pulmonary arteries. In recent years, hybrid

surgical/interventional catheterisation procedures have been utilised with branch pulmonary artery bands

to restrict pulmonary blood flow, and stent deployment to maintain ductal patency, although the utility of

this approach remains unclear. Cardiac transplantation is sometimes pursued as an alternative strategy

to staged surgery.[26]

Left ventricular outflow tract (LVOT) obstruction

Includes of 4 sub-types: aortic valve stenosis, supravalvular stenosis, discrete subvalvular stenosis, and

tunnel subaortic stenosis.

Aortic valve stenosis is the most common and represents 5% of all CHD.[27] The leaflets or cusps are

usually malformed or thickened. Approximately 2% of the general population has a bicuspid aortic valve,

but many of these individuals never develop clinically significant aortic valve stenosis or regurgitation.

Supravalvular stenosis occurs as an area of discrete or diffuse narrowing just distal to the sinotubularjunction in the ascending aorta. It is frequently associated with Williams syndrome or a defect in the

elastin gene on chromosome 7. Discrete subvalvular stenosis occurs when there is a fibromuscular ridge

that causes obstruction just below the aortic valve. Turbulence of blood flow can cause damage to the

valve leaflets of the aortic valve, resulting in progressive aortic regurgitation. Tunnel subaortic stenosis

refers to a longer stenotic segment of the outflow tract when compared to discrete subvalvular stenosis.

Presentation depends on the severity of the obstruction. Most patients are asymptomatic. Older patients

may present with chest pain or syncope. A sub-set of patients present with poor left ventricular function,

low cardiac output, and signs of shock and congestive heart failure ("critical" aortic stenosis).

Examination reveals a crescendo-decrescendo systolic murmur, heard best at the left sternal border with

radiation to the upper right sternal border. Moderate or severe stenosis results in a palpable thrill and

delayed pulses. An ejection click may also be heard just after the first heart sound in patients with aortic

valve stenosis. The click does not vary with respiration, in contrast to a pulmonary valve ejection click.

Patients with concurrent aortic regurgitation also have a decrescendo diastolic murmur and a wide pulse

pressure.

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ECG inconsistently shows evidence of left ventricular hypertrophy. Severe LVOT stenosis is associated

with flattening or inversion of the T waves in leads V5 and V6.[28] CXR may reveal a prominent aorta as

a result of post-stenotic dilation. Echocardiography helps accurately evaluate aortic valve morphology

and estimate the pressure gradient across the LVOT. In valvular aortic stenosis, the Doppler-estimated

mean gradient is utilised to assess severity. The gradient will vary with the cardiac output.

Patients with "critical" aortic stenosis require emergency relief of the stenosis. Symptomatic patients also

require relief of the obstruction, regardless of the degree of the stenosis. Infants with severe valvular

stenosis require balloon valvuloplasty, although surgery may be required for co-existent aortic

regurgitation. Surgical valvotomy or valve replacement is considered for older children and adults.

Patients with severe stenosis followed in the Second Natural History Study of Congenital Heart Defects

had a 25-year survival rate of 81%.[29]

Aortic coarctation

see our comprehensive coverage of Aortic coarctation

Constitutes 5% of CHD and is more common in males; aortic coarction is associated with Turner's

syndrome in females. It consists of a posterior ledge of tissue that protrudes into the aorta and is

typically described as juxtaductal because it occurs across the ductus arteriosus. It is commonly

associated with a bicuspid aortic valve (in 70% of patients) and less commonly with a VSD or

subvalvular aortic stenosis.

Patients with mild obstruction may not present until adolescence with a heart murmur or systemic HTN.

In those with severe obstruction, the PDA is the major source of systemic blood flow distal to the

obstruction, which means that neonates develop metabolic acidosis and shock as the ductus closes.

The lower extremities have lower oxygen saturation and decreased pulses, in addition to CHF in patients

with severe obstruction. It is important to take the BP in both upper extremities and 1 leg before making

the diagnosis as it is easy to miss the diagnosis in patients with a coarctation proximal to the left

subclavian artery or those with an anomalous origin of the right subclavian artery. Turbulent blood flow

through the area of coarctation produces a systolic murmur. Patients with an associated bicuspid aortic

valve have an ejection click.

Infants, paradoxically, have right ventricular hypertrophy on ECG and echocardiography because of the

PDA supplying the aorta distal to the obstruction. Older patients have signs of left ventricular

hypertrophy. CT and MRI may be useful in defining the anatomy of the coarctation in older and larger

patients.

Native coarctation is amenable to surgical repair or balloon dilation. Repair in the newborn period is

associated with an increased incidence of recurrence. Recurrence is best treated by balloon dilation with

or without stent placement. Despite repair, all patients with coarctation are at an increased risk of stroke,

early onset CAD, MI, and systemic HTN, compared to the general population.[30] Life-long follow-up,

even in patients who do not have a residual obstruction, is extremely important.

Pulmonary valve stenosis

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see our comprehensive coverage of Pulmonary stenosis

Represents up to 8% of all CHD and is commonly found in patients with Noonan's syndrome. Most

children present with an asymptomatic murmur. However, neonates with critical pulmonary valve

stenosis present with cyanosis secondary to a right-to-left shunting of blood at the atrial level.

Examination reveals an increased right ventricular impulse, a click following the first heart sound thatvaries with respiration, a normally split to a widely split second heart sound depending on the severity,

and a crescendo-decrescendo ejection murmur. With increasing severity of stenosis, the pulmonary

ejection click occurs earlier in systole; in the most severe cases, the click may merge with the first heart

sound and become inaudible.[31] Conversely, the second heart sound splits more widely with

increasing severity of stenosis and may become fixed in severe stenosis. In very severe stenosis, the

pulmonary component of the second sound may become difficult to hear due to the loud murmur that

spills into diastole. A fourth heart sound may be heard in patients with right ventricular failure.

ECG may reveal right axis deviation and a CXR may show signs of right ventricular enlargement.

Typically, there is post-stenotic dilation of the pulmonary arteries.

Balloon valvuloplasty is the preferred treatment, and 85% of patients do not require further intervention.

The long-term outcome is excellent.

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