Pathology
Lecture 24 Congenital Heart Disease
1) Relate the incidence and etiology of congenital heart disease in general and
common specific types of congenital heart disease.
Incidence: congenital heart disease is the most common type of heart disease among
children (approximately 1% of live births) with higher incidence among premature
infants and stillborns, 12 disorders account for 85% of cases (see table)
Malformation
Ventricular septal defect
Pulmonary stenosis
Tetrology of Fallot
Atrioventricular septal defect
Transposition of great arteries
Total anomalous pulmonary venous
connection
% of Incidence
42%
8%
5%
4%
4%
1%
Malformation
Atrial septal defect
Patent ductus arteriosus
Coarctation of aorta
Aortic stenosis
Truncus arteriosus
Tricuspid atresia
% of Incidence
10%
7%
5%
4%
1%
1%
Etiology: unknown in 90% of cases. Some causes include: Chromosomal
abnormalities, e.g., trisomys 13, 15, 18, 21; Turner's syndrome. Viral infection
during pregnancy (e.g. rubella), drugs, and radiation.
2) List the common causes of left to right shunts, describing their gross morphology
and the physiologic consequences.
Cause
Atrial Septal
Defect (ASD)
Ventricular Septal
Defect (VSD)
Patent Ductus
Arteriosus (PDA)
Atrioventricular
Septal Defect
(AVSD)
Gross morphology
Abnormal opening between right and left atria: Sucumdum-type
involves limits or valve of fossa ovalis most common (90%),
premium is low on septum adjacent to AV valves, and sinus
venosis is near the entrance of the superior vena cava.
Abnormal opening in ventricular septum. Most common
anomaly, occurring either alone or with other defects. Two
types membranous and muscular (depending on part of septum)
Persistence of normal fetal structure. Isolated defect in most
cases.
Partial AVSD: premium ASD with cleft mitral intruder leaflet.
Complete AVSD: premium ASD, membranous VSD producing
a hole in the center of heart in the common AV valve ring.
Physiologic consequences
Pulmonary hypertension is infrequent
in a late complication
Can eventually result in cyanotic heart
disease (Eisenbenger’s syndrome)
May sustain life certain complex
cyanotic congenital heart diseases
3) List the obstructive congenital anomalies, describing their gross appearance and
physiologic consequences.
Cause
Coarctation of
Aorta
Pulmonary
Stenosis and
Atresia (PS/PA)
Aortic Stenosis or
Atresia (AS/AA)
Gross morphology
1) An "infantile" form with tubular hypoplasia of the aortic arch
proximal to a PDA.
2) An "adult" form with a discrete ridge like in folding of the
aorta, just opposite the ligamentum arteriosum distal to the arch
vessels
Obstruction at the pulmonary valve, which may be mild to
severe. Isolated defect or with tetralogy of Fallot or TGA.
Narrowing and obstruction of the aortic valve. Three types:
valvular, subvalvular, and supravalvular.
Physiologic consequences
Variable encroachment on the aortic
lumen from severe occlusion to only
minimal narrowing. Hypotension in
the legs and shunting around
narrowing
Right ventricular hypertrophy often
develops. Mild stenosis may be
asymptomatic compatible w/ long life.
Severe stenosis leads to hypoplasia of
the left ventricle and ascending aorta.
4) List the common causes of right to left shunts, describing their gross morphology
and the physiologic consequences.
Cause
Tetrology of Fallot
Gross morphology
4 features: VSD, obstruction to the right ventricular outflow
tract, an aorta that overrides the VSD, and right ventricular
hypertrophy. Anterosuperior displacement of the infundibular
septum.
Transposition of
Great Arteries
(TGA)
Truncus Arteriosus
The aorta arises from the right ventricle and the pulmonary
artery emanates from the left ventricle. This results in
separation of systemic and pulmonary circulations.
Failure of separation of embryonic truncus arteriosus into aorta
and pulmonary artery. Single great artery with a VSD.
Tricuspid Atresia
Complete occlusion of the tricuspid valve due to unequal
division of the AV canal, and thus the mitral valve is larger than
normal. Hypoplasia of the right ventricle. VSD also present.
No pulmonary veins directly join the left atrium due to failure
of the common pulmonary vein to develop, causing primitive
systemic venous channels from the lungs to remain patent. A
patent foramen ovale or an ASD is always present.
Total Anomalous
Pulmonary Venous
Connection
(TAPVC)
Physiologic consequences
Depends primarily on the severity.
When the resistance reaches the level
of systemic vascular resistance right to
left shunting predominates resulting in
cyanosis. Surgery required.
Incompatible with postnatal life unless
a shunt exists (e.g. PDA" for adequate
mixing of blood. Surgery required.
Early systemic cyanosis with
increased pulmonary flow, irreversible
pulmonary hypertension.
Cyanosis is president from birth and
there is a high mortality rate in the
first weeks or months.
Volume and pressure hypertrophy of
the right atrium and right ventricle
which are dilated along with the
pulmonary trunk. Cyanosis may be
present.
5) Describe the causes and significance of pulmonary hypertension in congenital
heart disease. Left right shunts (such as ASD, VSD, and PDA) increased pulmonary
blood flow resulting in pulmonary hypertension. The pulmonary arteries respond to
the increased pressure by medial hypertrophy in vasoconstriction, which maintains
relatively normal distal pulmonary capillary and venous pressures, helping prevent
pulmonary edema. This stimulates development of irreversible obstructive intimal
lesions. Eventually the resistance reverses the shunt to right to left causing on
oxygenated blood in the systemic circulation. This situation is irreversible.
6) Define the following terms: Eisenmenger’s syndrome, atrioventricular canal,
hypoplastic left heart syndrome.
Eisenmenger’s syndrome - This consist of a large left to right shunt (VSD), which
causes severe pulmonary hypertension with resulting reversal of the direction of
shunting. This shunting with increase pressure causes the lung arteries to narrow due
to thickening of their walls and cause obstruction.
Atrioventricular canal - refers to a congenital heart defect (AVSD) involving an
opening low in the atrial septum, an opening high in the ventricular septum, and
abnormal development of the mitral and/or tricuspid valves.
Hypoplastic left heart syndrome - a congenital heart defect (aortic stenosis and
atresia) in which the left side of the heart is poorly developed, resulting in small
mitral valve, left ventricle, and aorta.