Chapter 12: CHD: OBSTRUCTIVE CONGENITAL ANOMALIES

Question 1

OBSTRUCTIVE CONGENITAL ANOMALIES

Answer 1

• Coarctation of the Aorta
• Pulmonary Stenosis and Atresia
• Aortic Stenosis and Atresia

Question 2

What are Obstructive Congenital Anomalies?

Answer 2

Congenital obstruction to blood flow may occur at the level of the heart valves or within a great
vessel. [42]

Relatively common examples include stenosis or atresia of the aortic or pulmonary valves, and coarctation of the aorta. Obstruction can also occur within a chamber, as with subpulmonary stenosis in TOF.

Question 3

What is coarctation of aorta?

Answer 3

Coarctation (narrowing, constriction) of the aorta ranks high in frequency among the common
structural anomalies.

Question 4

Which gender is more affected in coarctation of aorta?

Answer 4

Males are affected twice as often as females, although females with
Turner syndrome frequently have a coarctation ( Chapter 5 ).

Question 5

Coarctation of the Aorta is associated with what syndrome?

Answer 5

Turner syndrome frequently have a coarctation ( Chapter 5 ).

Question 6

What are the two classic forms of Coarctation of the Aorta?

Answer 6

Two classic forms have been
described:

• (1) an “infantile” form
• (2) an “adult” form

Question 7

What is the infantile form of Coarctation of the Aorta?

Answer 7

Two classic forms have been
described:

an “infantile” form with tubular hypoplasia of the aortic arch proximal to a patent
ductus arteriosus that is often symptomatic in early childhood.

Question 8

Describe the adult form of Coarctation of the Aorta.

Answer 8

an “adult” form in which there is a discrete ridgelike infolding of the aorta, just opposite the closed ductus arteriosus (ligamentum arteriosum) distal to the arch vessels ( Fig. 12-8 ).

Encroachment on the aortic
lumen is of variable severity, sometimes leaving only a small channel and at other times
producing only minimal narrowing.

Although coarctation of the aorta may occur as a solitary defect, it is accompanied by a bicuspid aortic valve in 50% of cases and may also be
associated with congenital aortic stenosis, ASD, VSD, mitral regurgitation, or berry aneurysms
of the circle of Willis in the brain.

Question 9

Although coarctation of the aorta may occur as a solitary defect, it is accompanied by a bicuspid aortic valve in 50% of cases and may also be
associated with ________________

Answer 9

• congenital aortic stenosis,
• ASD,
• VSD,
• mitral regurgitation, or
• berry aneurysms of the circle of Willis in the brain.

Question 10

Answer 10

FIGURE 12-8 Diagram showing coarctation of the aorta with and without patent ductus
arteriosus (PDA). Ao, aorta; LA, left atrium; LV, left ventricle; PT, pulmonary trunk; RA, right
atrium; RV, right ventricle; PDA, patent ductus arteriosus

Question 11

What are the clinical manifestations of Coarctation of the Aorta?

Answer 11

Clinical manifestations depend on the severity of the narrowing and the patency of the ductus
arteriosus.

Question 12

When can Coartation of the Aorta usually leads to manifestation early in life?

Answer 12

Coarctation of the aorta with a patent ductus arteriosus usually leads to
manifestations early in life; indeed, it may cause signs and symptoms immediately after birth.
Many infants with this anomaly do not survive the neonatal period without surgical or catheterbased
intervention.

In such cases, the delivery of unsaturated blood through the patent ductus arteriosus produces cyanosis localized to the lower half of the body.

Question 13

How is the Coarctaion of the Aorta with a Patent Ductus arteriosus?

Answer 13

The outlook is different with coarctation of the aorta without a patent ductus arteriosus, unless it
is very severe.

Most children are asymptomatic, and the disease may go unrecognized until well
into adult life.

Typically there is hypertension in the upper extremities; in contrast, there are
weak pulses and hypotension in the lower extremities, associated with manifestations of arterial
insufficiency (i.e., claudication and coldness).

Question 14

What is the particular characteristic of Coarctation of the Aorta in adults?

Answer 14

Particularly characteristic in adults is the
development of collateral circulation between the precoarctation arterial branches and the
postcoarctation arteries through enlarged intercostal and internal mammary arteries, which
produce radiographically visible erosions (“notching”) of the undersurfaces of the ribs.

Question 15

What happens when there is significant coarctations?

Answer 15

With significant coarctations, murmurs are present throughout systole; sometimes a thrill may
be present.

There is cardiomegaly due to left ventricular pressure-overload hypertrophy.

With uncomplicated coarctation of the aorta, surgical resection and end-to-end anastomosis or
replacement of the affected aortic segment by a prosthetic graft yields excellent results

Question 16

What is Pulmonary Stenosis and Atresia?

Answer 16

This relatively frequent malformation constitutes an obstruction at the pulmonary valve, which

• *may be mild to severe;** the lesion can be isolated or part of a more complex anomaly—either
• *tetralogy of Fallot or transposition of the great arteries.**

Question 17

What is the accompanying congenital anomaly in pulmonary stenosis or atresia ?

Answer 17

TOF or TGA

Question 18

Right ventricular hypertrophy often
develops in Pulmonary stenosis or atresia, and there is sometimes poststenotic dilation of the pulmonary artery due to injury of
the wall by “jetting” blood.

T or F

Answer 18

True

Question 19

What happens when the pulmonary stenosis coexist with subpulmonary stenosis ( as in TOF) ?

Answer 19

With coexistent subpulmonary stenosis (as in tetralogy of Fallot), the
high ventricular pressure is not transmitted to the valve, and the pulmonary trunk is not dilated
and may in fact be hypoplastic.

When the valve is entirely atretic, there is no communication between the right ventricle and lungs.

In such cases the anomaly is associated with a
hypoplastic right ventricle and an ASD; blood reaches the lungs through a patent ductus
arteriosus.

Mild stenosis may be asymptomatic and compatible with long life, whereas
symptomatic cases require surgical correction.

Question 20

Aortic Stenosis and Atresia

Congenital narrowing and obstruction of the aortic valve can occur at three locations:

Answer 20

• valvular,
• subvalvular, and
• supravalvular.

Question 21

What happens in the valvular aortic type stenosis?

Answer 21

With valvular aortic stenosis the cusps may be **hypoplastic

(small) , dysplastic (thickened, nodular),orabnormal in number (usually acommissural or**
* *unicommissural)**.

In severe congenital aortic stenosis or atresia, obstruction of the left
ventricular outflow tract leads to underdevelopment (hypoplasia) of the left ventricle and
ascending aorta, sometimes accompanied by dense, porcelain-like left ventricular endocardial
fibroelastosis.

The ductus must be open to allow blood flow to the aorta and coronary arteries.
This constellation of findings, called the hypoplastic left heart syndrome, is nearly always fatal in
the first week of life, when the ductus closes, unless a palliative procedure is done.

Less severe
degrees of congenital aortic stenosis may be compatible with long survival.

Congenital aortic
stenosis is an isolated lesion in 80% of cases

Question 22

What is hypoplastic left heart syndrome?

Answer 22

• In severe congenital aortic stenosis or atresia, obstruction of the left ventricular outflow tract leads to underdevelopment (hypoplasia) of the left ventricle and ascending aorta, sometimes accompanied by dense, porcelain-like left ventricular endocardial fibroelastosis. The ductus must be open to allow blood flow to the aorta and coronary arteries.

This constellation of findings, called the hypoplastic left heart syndrome, is nearly always fatal in
the first week of life, when the ductus closes, unless a palliative procedure is done.

Less severe
degrees of congenital aortic stenosis may be compatible with long survival. Congenital aortic
stenosis is an isolated lesion in 80% of cases.

Question 23

What is subaortic stenosis?

Answer 23

Subaortic stenosis can be caused by a thickened ring (discrete type) or collar (tunnel type) of
dense endocardial fibrous tissue below the level of the cusps.

Question 24

What is Supravalvular aortic stenosis?

Answer 24

Supravalvular aortic stenosis is
an inherited form of aortic dysplasia in which the ascending aortic wall is greatly thickened,
causing luminal constriction.

In some cases it is a component of a multiorgan developmental disorder resulting from deletions on chromosome 7 that include the gene for elastin.

Other features of the syndrome include hypercalcemia, cognitive abnormalities, and hallmark facial anomalies (Williams-Beuren syndrome). [43]

Mutations in the elastin gene probably cause
supravalvular aortic stenosis by disrupting elastin–smooth muscle cell interactions during
arterial morphogenesis.

Question 25

What is subaortic stenosis?

Answer 25

Subaortic stenosis is usually associated with a prominent systolic murmur and sometimes a
thrill.

Pressure hypertrophy of the left ventricle develops as a consequence of the obstruction to
blood flow, but congenital stenoses are well tolerated unless very severe.

Mild stenoses can be
managed conservatively with antibiotic prophylaxis (to prevent endocarditis) and avoidance of
strenuous activity, but owing to left ventricular hypertrophy the threat of sudden death with
exertion always looms.