This document discusses several types of congenital heart defects including abnormalities of cardiac looping, atrial and ventricular septal defects, defects of the heart valves and major blood vessels, and venous system defects. Some of the most common defects mentioned are ventricular septal defects, tetralogy of Fallot, transposition of the great vessels, coarctation of the aorta, patent ductus arteriosus, and atrial septal defects. The causes of these defects involve abnormalities in the development of the embryonic heart structures.

1. Congintal anomalies of the
heart and blood vessels
Dr. Mohammed Mahmoud Mosaed

2. Abnormalities of Cardiac Looping
• Dextrocardia in which the heart lies on
the right side of the thorax instead of
the left.
• Dextrocardia may coincide with Situs
inversus, a complete reversal of
asymmetry in all organs.
• Situs inversus usually is associated
with normal physiology, although there
is a slight risk of heart defects

4. Atrial septal defects (ASD)
• Atrial septal defect (ASD) is a congenital heart abnormality
2:1 prevalence in female to male infants
• The ostium secundum defect, characterized by a large
opening between the left and right atria. It is caused either
by excessive cell death and resorption of the septum
primum or by inadequate development of the septum
secundum.
• Complete absence of the atrial septum is the most
serious abnormality in this group. This condition, known as
common atrium or cor triloculare biventriculare,
• Premature closure of the oval foramen, leads to massive
hypertrophy of the right atrium and ventricle and
underdevelopment of the left side of the heart. Death
usually occurs shortly after birth.

6. Ventricular septal defect (VSD)
• Ventricular septal defect (VSD) involving the membranous
portion of the septum is the most common congenital cardiac
malformation, VSD is often associated with abnormalities in
partitioning of the conotruncal region.

7. Tetralogy of Fallot
• Tetralogy of Fallot, the most frequently occurring
abnormality of the conotruncal region is due to an
unequal division of the conus resulting from anterior
displacement of the conotruncal septum.
• Displacement of the septum produces four
cardiovascular alterations:
(a) Pulmonary infundibular stenosis;
(b) a large defect of the interventricular septum;
(c) an overriding aorta that arises directly above the septal
defect
(d) hypertrophy of the right ventricular wall because of
higher pressure on the right side.
• Tetralogy of Fallot, which is not fatal

9. Defects of bulbus cordis
• Persistent truncus arteriosus results when the
conotruncal ridges fail to fuse and to descend toward
the ventricles, the pulmonary artery arises some
distance above the origin of the undivided truncus. the
persistent truncus is always accompanied by a
defective interventricular septum. The undivided
truncus thus overrides both ventricles and receives
blood from both sides.
• Transposition of the great vessels occurs when the
conotruncal septum fails to follow its normal spiral
course and runs straight down . As a consequence,
the aorta originates from the right ventricle, and the
pulmonary artery originates from the left ventricle,
sometimes is associated with a defect in the
membranous part of the interventricular septum. It is
usually accompanied by an open ductus arteriosus.

10. Persistent truncus arteriosus

11. Transposition of the great vessels

12. Defects of the valves of the heart
• persistent atrioventricular canal due to failure of
fusion of endocardial cushions. combined with a
defect in the cardiac septum. This septal defect has
an atrial and a ventricular component, separated by
abnormal valve leaflets in the single atrioventricular
orifice.
• Tricuspid atresia, which involves obliteration of the
right atrioventricular orifice, is characterized by the
absence or fusion of the tricuspid valves. Tricuspid
atresia is always associated with (a) patency of the
oval foramen, (b) ventricular septal defect, (c)
underdevelopment of the right ventricle, and (d)
hypertrophy of the left ventricle.

13. persistent atrioventricular canal

15. • Valvular stenosis of the pulmonary artery, the trunk of the
pulmonary artery is narrow or even atretic. The patent oval
foramen then forms the only outlet for blood from the right side
of the heart. The ductus arteriosus, always patent, is the only
access route to the pulmonary circulation.
• Aortic valvular stenosis, fusion of the thickened valves may
be so complete that only a pinhole opening remains. The size
of the aorta itself is usually normal.
• Aortic valve atresia When fusion of the semilunar aortic valves
is complete. The aorta, left ventricle, and left atrium are
markedly underdeveloped. The abnormality is usually
accompanied by an open ductus arteriosus, which delivers
blood into the aorta.
• Ectopia cordis is a rare anomaly in which the heart lies on the
surface of the chest. It is caused by failure of the embryo to
close the ventral body wall

18. Arterial System Defects
• Under normal conditions, the ductus
arteriosus is functionally closed through
contraction of its muscular wall shortly after
birth to form the ligamentum arteriosum.
Anatomical closure by means of intima
proliferation takes 1 to 3 months
• A patent ductus arteriosus, one of the most
frequently occurring abnormalities of the
great vessels especially in premature infants,
either may be an isolated abnormality or may
accompany other heart defects.

21. • Coarctation of the aorta; the aortic lumen below the
origin of the left subclavian artery is significantly narrowed.
Since the constriction may be above or below the entrance of
the ductus arteriosus, two types (preductal and postductal)
may be distinguished. The cause of aortic narrowing is
primarily an abnormality in the media of the aorta, followed by
intima proliferations.
• In the preductal type, the ductus arteriosus persists;
• In the postductal type, which is more common, this channel is
usually obliterated. In the latter case, collateral circulation
between the proximal and distal parts of the aorta is
established by way of large intercostal and internal thoracic
arteries. In this manner, the lower part of the body is supplied
with blood.
• Classic clinical signs associated with this condition include
hypertension in the right arm concomitant with lowered blood
pressure in the legs

24. Abnormal origin of the right
subclavian artery
• It occurs when the artery is formed by the distal
portion of the right dorsal aorta and the seventh
intersegmental artery.
• The right fourth aortic arch and the proximal part of
the right dorsal aorta are obliterated. With
shortening of the aorta between the left common
carotid and left subclavian arteries, the origin of the
abnormal right subclavian artery finally settles just
below that of the left subclavian artery. Since its
stem is derived from the right dorsal aorta, it must
cross the midline behind the esophagus to reach the
right arm. This location does not usually cause
problems with swallowing or breathing, since neither
the esophagus nor the trachea is severely
compressed.

26. Double aortic arch
• the right dorsal aorta persists between the
origin of the seventh intersegmental artery
and its junction with the left dorsal aorta. A
vascular ring surrounds the trachea and
esophagus and commonly compresses
these structures, causing difficulties in
breathing and swallowing

28. Right aortic arch
• The left fourth arch and left dorsal aorta are obliterated and
replaced by the corresponding vessels on the right side.
Occasionally, when the ligamentum arteriosum lies on the left
side and passes behind the esophagus, it causes complaints
with swallowing.
• An interrupted aortic arch is caused by obliteration of the
fourth aortic arch on the left side. It is frequently combined
with an abnormal origin of the right subclavian artery. The
ductus arteriosus remains open, and the descending aorta
and subclavian arteries are supplied with blood of low oxygen
content. The aortic trunk supplies the two common carotid
arteries.

30. Venous System Defects
• A double inferior vena cava occurs when the left
sacrocardinal vein fails to lose its connection with the left
subcardinal vein.
• The left common iliac vein may or may not be present, but the
left gonadal vein remains as in normal conditions.
• Absence of the inferior vena cava arises when the right
subcardinal vein fails to make its connection with the liver and
shunts its blood directly into the right supracardinal vein.
• Hence, the bloodstream from the caudal part of the body
reaches the heart by way of the azygos vein and superior
vena cava. The hepatic vein enters into the right atrium at the
site of the inferior vena cava. Usually, this abnormality is
associated with other heart malformations.

32. • Left superior vena cava is caused by persistence of
the left anterior cardinal vein and obliteration of the
common cardinal and proximal part of the anterior
cardinal veins on the right. In such a case, blood
from the right is channeled toward the left by way of
the brachiocephalic vein. The left superior vena cava
drains into the right atrium by way of the left sinus
horn, that is, the coronary sinus.
• A double superior vena cava is characterized by
the persistence of the left anterior cardinal vein and
failure of the left brachiocephalic vein to form. The
persistent left anterior cardinal vein, the left superior
vena cava, drains into the right atrium by way of the
coronary sinus.