congenital heart disease, by dr shaymaa fayad, el nasr hospital port said

Blood from the placenta is carried to the fetus by

the umbilical vein. Less than 50% of this enters the

fetal ductus venosus and is carried to the inferior vena

cava, while the rest enters the liver proper from the

inferior border of the liver.

The blood then moves to the right atrium of

the heart.

In the fetus, there is an opening between

the right and left atrium (the foramen ovale), and most

of the blood flows through this hole directly into the left

atrium from the right atrium, thus by

passing pulmonary circulation.

The continuation of this blood flow is into the left

ventricle, and from there it is pumped through

the aorta into the body.

blood from SVC entering the right atrium but does not

pass directly to the left atrium through the foramen

ovale, enters the right ventricle and is pumped into

the pulmonary artery.

Other special connection between the pulmonary

artery and the aorta found, called the ductus arteriosus,

which directs most of this blood away from the lungs

(which are not being used for respiration at this point as

the fetus is suspended in amniotic fluid).

Because the pulmonary arterial circulation is

vasoconstricted, only about 5% of ventricular outflow

enters the lungs.

The placenta is not as efficient an oxygen exchange

organ as the lungs, so that umbilical venous Po2 (the

highest level of oxygen provided to the fetus) is only

about 30-35 mm Hg.

Intracardiac pressure remains identical between the

right and left ventricles of the human fetus.

during fetal life the Rt ventricle is not only pumping

against systemic blood pressure but is also performing

a greater volume of work than the left ventricle.

Thickening of Rt ventricular wall.

Rt axis deviation in fetal and neonatal period.

Foramen ovale : � Closes at birth due to

1. decreased flow from placenta and IVC to hold open foramen

2.increased pulmonary blood flow and pulmonary VR to left

heart causing the pressure in the left atrium to be higher than

in the right atrium.

3.Some times foramen may remain probe patent for several

years.

�

Other changes in the heart:

The output from the right ventricle now flows entirely

into the pulmonary circulation.

By the end of the first month, the left ventricular wall is

thicker and the right ventricular wall becomes thinner

Ductus Arteriosus�

The DA constricts at birth, but there is often a small shunt

of blood from the aorta to the left pulmonary artery for a

few days in a healthy, full-term infant .

�

In premature infants and in those with persistent hypoxia

the DA may remain open for much longer.

�

Oxygen is the most important factor in controlling closure

of the DA in full-term infants.

When the PO2 of blood passing through the DA reaches about

50 mm Hg, the wall of the DA constricts.

Closure of the DA appears to be mediated by bradykinin( a

substance released by the lungs upon initial inflation), and by

Oxygen� effect on decreasing PG E2 and prostacylcin

secretion

As a result of reduced pulmonary vascular resistance, the

pulmonary arterial pressure falls below the systemic level and

the blood flow thrugh the ductus arteriosis is diminished.

The largest decline in pulmonary resistance level usually

occurs within the 1st 2-3 days but may be prolonged for 7

days or more.

Over the next several weeks of life, pulmonary vascular

resistance decreases even further.

This decrease in pulmonary vascular resistance significantly

influences the timing of the clinical appearance of many

congenital heart lesions that are dependent on the relative

levels of systemic and pulmonary vascular resistances.

Fetal Structure Foramen Ovale Umbilical Vein

(intra-abdominal part)

Ductus Venosus Umbilical Arteries

and ligaments abdominal

Ductus Arteriosum

Adult Structure Fossa Ovalis Ligamentum teres

Ligamentum venosum

Medial umbilical ligaments,superiorvesicular artery (supplies bladder)

Ligamentumarteriosum

Congenital Heart Disease

Congenital heart disease is a category of heart disease that

includes abnormalities in cardiovascular structures that occur

before birth.

May affect approximately 8 in 1000 live births,

2% in preterm.

Congenital heart defects may produce symptoms at birth,

during childhood, or not until adulthood. Other congenital

defects may cause no symptoms.

ETIOLOGY

Usually the cause of congenital heart disease is

unknown.

Risk factors include:

1.Genetic or chromosomal abnormalities in the child, such

as Down syndrome.

2.Taking certain medications or alcohol or drug abuse

during pregnancy.

3.Maternal viral infection, such as rubella (German measles) in

the first trimester of pregnancy.

4.The risk of having a child with congenital heart disease may

double if a parent or a sibling has a congenital heart defect.

Classification

a cyanotic CHD that subdivided into:

a-with increased pulmonary blood flow.

b-with normal pulmonary blood flow(stenotic lesion).

cyanotic CHD that subdivided into:

a-with increased pulmonary blood flow.

b-with decreased pulmonary blood flow.

1-VSD

2-ASD

3-COMPLETE A-V CANAL DEFECT

4-PDA

5-Partial anomaly pulmonary venous return

6-Aorticopulmonary window defect

1.Aortic stenosis

2.Pulmonary stenosis

3.Coarctation of the aorta

4.Congenital mitral stenosis

Abnormal communication in

ventricular septum dividing RV

and LV.

The most common cardiac

anomaly about 15-25% of cases

of CHD.

According to size of the defect divided into

Restrictive VSD:

small defect <0.5cm2. Lt to Rt shunt occur due to higher Lt

ventricular pressure, Rt ventricular pressure usually normal →

increased pulmonary blood flow, pulmonary congestion and

CHF.

Non restrictive VSD:

large defect >1cm2. The pressure in both ventricles is equalized

and the direction and magnitude of the shunt dependent on

the ratio between pulmonary and systemic circulation.

According to size of the defect and pulmonary blood flow and

pressure.

1. asymptomatic and discovered accidently during routine

examination: small defect or early in first few days of life

where pulmonary pressure and resistance still high.

2. congestive lung symptoms: dyspnea, cough, and repeated

chest infection.

3. low cardiac output symptoms (interrupted feeding, syncope).

4. if not corrected can lead to Eisenmenger syndrome.

5.Low cardiac output signs(small pulse volume, pallor, cold

extremities and excessive sweating when heart failure occur,

duskiness may seen during infection or crying but cyanosis is

usually absent.

6. precordial bulging.

7. biventricular hypertrophy.

8. pulmonary artery diltation (pulsations seen and felt with palpable

S2).

9. increase ps2(pulmonary area)

10. Lt parasternal area:

Harsh pansystolic murmur.

Mid diastolic murmur (functional MS) due to increase blood

flow across mitral valve.

1)X-ray chest:

Lung congested.

Heart : biventricular hypertrophy , pulmonary artery

dilatation.

2) ECG:

Early and small VSD :mainly LT ventricular hypertrophy.

Large VSD :biventricular hypertrophy.

3) Echo (2 dimensional and doppler)

Shows position and size of the defect.

Examining the degree of volume overload in Lt atrium

and ventricle to estimate size of the defect.

AR.

Pressure gradient across the defect(restrictive or non

restrictive type).

4) Catheterization:

hemodynamics of VSD.

1. Repeated chest infection.

2.HF.

3. Infective endocarditis.

4. Acquired infundibular PS

5. Eisenmenger’s syndrome: increase pulmonary blood flow

with pulmonary congestion →p arteriolar V.C → increase

pulmonary artery pressure → increase Rt sided pressure up

to reversal of the shunt → cyanosis

First reversible V.C then permanent sclerotic changes occur

and permanent V.C and reversal of the shunt.

A significant number (30-50%) of small defects close

spontaneously, most frequently during the 1st 2 yr of

life.

Small muscular VSDs are more likely to close (up to

80%) than membranous VSDs (up to 35%).

Surgical correction for infants with large defects have

repeated episodes of respiratory infection and heart

failure despite optimal medical management.

Abnormal communication in atrial septum.

can occur in any portion of the atrial septum

(secundum, primum, or sinus venosus).

Isolated secundum ASDs account for ≈7% of congenital

heart defects

The majority of cases of ASD are sporadic; autosomal

dominant inheritance does occur as part of the Holt-

Oram syndrome (hypoplastic or absent radii, 1st-degree

heart block, ASD)

Dependent on the size of the shunt and PVR

In large defects, a considerable shunt of oxygenated blood

flows from the left to the right atrium

Shunting of blood from Lt atrium to Rt atrium during

systole→ Rt ventricular hypertrophy and dilatation

Despite the large pulmonary blood flow, pulmonary

arterial pressure is usually normal because of the

absence of a high-pressure communication between the

pulmonary and systemic circulations.

Pulmonary vascular resistance remains low throughout

childhood, although it may begin to increase in

adulthood and may eventually result in reversal of the

shunt and clinical cyanosis.

May be a symptomatic

Congestive lung symptoms

Complications as HF (rare in early childhood), infective

endocarditis and Eisenmenger’s

Mild Lt pericordial pulg (Rt ventricular enlargement)

Wide fixed split of S2

No murmur because of the shunt

Functional PS → ejection systolic murmur over

pulmonary area

Functional tricuspid stenosis →mid diastolic over

tricuspid area

X-ray chest

Congested lung

Rt ventricular hypertrophy

Pulmonary artery dilatation

ECG

Rt axis deviation may be present

Rt ventricular hypertrophy

Echo

1.Features of Rt ventricular volume over load e.g.,

flattening and abnormal motion of ventricular septum

2.The location and size of ASD

Catheterization

1.Confirm the presence of the defect

2. Directly measures pulmonary artery pressure and

compare pulmonary artery to systemic artery pressure

Most ASDs <8 mm spontaneously close

Surgical repair of large defect usually after first year of

age and before entering school

Mortality rate in childhood <1 %, more in adulthood

Lt to Rt shunt at both atrial and ventricular level →↑↑

pulmonary blood flow and early onset pulmonary

hypertension (↑↑ risk of eisenmenger’s syndrome)

MI and TI→ volume overload on both Lt and Rt venrticle

The liver is enlarged and the infant shows signs of failure

to thrive

Early onset of HF (pulmonary congestion, low CO, systemic

congestion)

Transient episodes of cyanosis

Complete endocardial cushion is common in children with

Down syndrome.

Auscultatory signs produced by the left-to-right shunt

include:

a normal or accentuated 1st heart sound.

wide, fixed splitting of the 2nd sound.

a pulmonary systolic ejection murmur sometimes

preceded by a click.

If there’s large VSD component, S2 will be single.

additional apical holosystolic murmur caused by mitral

insufficiency.

x-ray chest

Cardiomegaly with enlargement of all chambers

Lung congestion

ECG

1.Lt axis deviation

2.Combined ventricular hypertrophy

3.May show combined atrial enlargement

Echo

1.is characteristic

2. “gooseneck” deformity of the left ventricular outflow tract.

3.The presence of associated lesions such as patent ductus

arteriosus (PDA) or coarctation of the aorta.

4.Doppler echocardiography will demonstrate left-to-right

shunting at the atrial and ventricular level.

Catheterization:

is rarely required unless pulmonary vascular disease is

suspected, such as in a patient in whom diagnosis has

been delayed beyond early infancy, especially with

Down syndrome

Because of the risk of pulmonary vascular disease

developing as early as 6-12 mo of age, surgical

intervention must be performed during infancy.

Treatment of heart failure if present

Persistence of fetal connection between pulmonary artery and

aorta

F:M is 2:1

Increased incidence in prematurity, trisomy 21 and maternal

rubella.

Lt to Rt shunting → pulmonary congestion and increased

pulmonary artery pressure.

Increase blood passing to Lt ventricle → Lt ventricular

hypertrophy

Increase pulse pressure due to run off of blood into

pulmonary artery during diastole

A small PDA is usually asymptomatic

A large PDA will result in heart failure similar to that in

infants with a large VSD.

Retardation of physical growth

Bounding peripheral arterial pulses

a wide pulse pressure

apical impulse is prominent and heaving.

A thrill, maximal in the 2nd left interspace

Increase PS2 over pulmonary area

murmur is described as being like machinery in quality,

starts just after S1 and ends in the late diastole

X-ray chest

prominent pulmonary artery with increased pulmonary

vascular markings.

the left atrium and left ventricle enlarged

Echo

left atrial and left ventricular dimensions are increased.

The ductus can easily be visualized directly and its size

estimated

Color Doppler examinations demonstrate systolic or

diastolic (or both) retrograde turbulent flow in the

pulmonary artery, and aortic retrograde flow in diastole

Catheterization

In patients with atypical findings

Demonstrate increased pressure in the right ventricle

and pulmonary artery

presence of oxygenated blood shunting into the

pulmonary artery confirm diagnosis

Indomethacin: for uncomplicated PDA in preterm

neonates

Surgical ligation : secondary option for uncomplicated

PDA in preterm, term, infants, and children; first option

for complicated PDA

Catheter device closure: uncomplicated PDA in child

Narrowing in the aorta causing obstruction to

flow usually below origin of Lt subclavian artery at the origin of

ductus (juxtaductal)

Infantil type→ coarctation with arch hypoplasia (sever form)

Adult type → isolated juxtaductal (mild form)

M to F ratio is 2:1

It may be a feature of Turner syndrome

aortic obstruction leading to:

1.High pressure in proximal part of the

aorta → Lf ventricular hypertrophy and

↑↑ blood pressure in the upper part of

the body

2.Low pressure in distal part of the aorta →

low blood pressure in the lower part of

the body

3. Collateral circulation development

4. Sever coarctation+ PDA → differential cyanosis

Usually asymptomatic during infancy and childhood

Heart failure in sever condition

Manifestations of hypertension e.g., headache,

epistaxis, cerebral hemorrhage.

Differential cyanosis

Weak or absent femoral pulsation

Prominent radial pulsation

Radial femoral delay →femoral pulse felt after radial pulse

Blood pressure in LL lower than in UL

Lt ventricular hypertrophy

Ejection systolic murmur best heard in the left infrascapular

area

a systolic ejection click or thrill in the suprasternal notch

suggests a bicuspid aortic valve (present in 70% of cases).

Mid diastolic murmur at the apex of MS if present

murmur of mild aortic stenosis can be heard in the 3rd

right intercostal space

In older patients with well-developed collateral blood

flow, systolic or continuous murmurs may be heard over

the left and right sides of the chest laterally and

posteriorly

Neonates or infants with more severe coarctation:

1.Initially have signs of lower body hypoperfusion

2.Acidosis

3.Severe heart failure.

4. On physical examination, the heart is large, and a systolic

murmur is heard along the left sternal border with a loud 2nd

heart sound.

These signs may be delayed days or weeks until after

closure of the ductus arteriosus.

If detected before ductal closure, patients may exhibit

differential cyanosis, best demonstrated by

simultaneous oximetry of the upper and lower

extremities

X-ray

Lt ventricular hypertrophy

Rib notching

Enlarged left subclavian artery→ a prominent shadow in the

left superior mediastinum.

ECG

Evidence of left ventricular hypertrophy in older

patients.

Neonates and young infants display right or

biventricular hypertrophy.

Echo

The segment of coarctation can be visualized

Associated anomalies of the mitral and aortic valve can

also be demonstrated

CT, MRI

valuable noninvasive tools for evaluation of coarctation

when the echocardiogram is equivocal.

Cardiac catheterization with selective left ventriculography and aortography

is not usually required before surgery

In neonates with severe coarctation of the aorta

1.prostaglandin E1 infusion

2. surgical repair→ Once a diagnosis has been confirmed

and the patient stabilized

Older infants with heart failure but good perfusion

1.anticongestive measures

2.surgical intervention

Surgical repair should be as soon as possible because

delay lead to less successful operation because of

decreased left ventricular function and degenerative

changes in the aortic wall.