2. Congenital Heart Diseases
Incidence:
Most common type heart disease among children.
Incidence is 1% of live births.
The incidence is higher in premature infants and
in stillborns.
Etiology and Pathogenesis:
Chromosomal abnormalities ( trisomies 13, 15, 18,
and 21, and Turner syndrome).
Trisomy 21 ( Down syndrome) is most common
genetic cause of CHD.
3. Environmental factors: congenital rubella or
teratogens.
Multifactorial : genetic, environmental, and
maternal factors account for remaining of cases.
Clinical Features:
CHD fall into three major categories:
Malformations causing left-to-right shunt.
Malformations causing right-to-left shunt .
Malformations causing obstruction.
4. LEFT-TO-RIGHT SHUNTS:
Cause cyanosis several months or years
after birth.
Include:
o Atrial Septal Defects( ASD)
o Ventricular Septal Defects( VSD )
o Patent (or persistent) Ductus Arteriosus( PDA)
o AV Septal Defects (AVSD ).
Atrial Septal Defect ( ASD ):
Abnormal opening in atrial septum.
Usually asymptomatic until adulthood.
5. Usually isolated ( not associated with other
anomalies).
Irreversible pulmonary hypertension develops
in fewer than 10% of cases.
Mortality is low, and postoperative survival is
comparable to that of normal population.
6. Morphology:
Three major types classified according to their
location in septum : secundum, primum, and
sinus venosus.
o Secundum ASD ( 90% of ASDs ) located at and
resulting from a deficient oval fossa.
o Primum ASD (5% of ASDs) occur adjacent to AV
valves .
o Sinus venosus defects (5%) located near entrance
of superior vena cava.
7.
8. Ventricular Septal Defect (VSD ):
Incomplete closure of ventricular septum.
Associated with other defects, such as tetralogy
of Fallot ( 70% ).
30% occur as isolated anomalies.
Morphology:
90% involve region of membranous septum
(membranous VSD).
The remainder ( 10% ) lie below pulmonary valve
(infundibular VSD) , or within muscular septum.
50% of small muscular VSDs close spontaneously.
9. Large defects:
o Membranous or infundibular.
o Remain patent and permit significant
left-to-right flow.
o Right ventricular hypertrophy and pulmonary
hypertension are present from birth.
o Over time, irreversible pulmonary vascular disease
develops leading to shunt reversal ( right to left ),
cyanosis, and death.
o Correction is indicated at age 1 year before
becomes irreversible.
10.
11. Patent Ductus Arteriosus ( PDA ):
Ductus arteriosus remains open after birth.
90% occur as an isolated anomaly.
The remainder ( 10% ) are associated with VSD,
coarctation of aorta, or pulmonary or aortic stenosis.
Continuous harsh murmur "machinery-like"
The shunt first is left-to-right, so no cyanosis.
Obstructive pulmonary vascular disease
eventually ensues.
12. Conversely, preservation of ductal patency
(by administering prostaglandin E) assumes great
importance in survival of infants with various CHD
such as aortic valve atresia.
Therefore PDA may be either life-threatening, or
life-saving.
13. Atrioventricular Septal Defect (AVSD):
Abnormal development of AV canal.
Superior and inferior endocardial cushions fail
to fuse adequately.
Resulting in incomplete closure of AV septum and
inadequate formation of tricuspid and mitral valves .
14.
15. RIGHT-TO-LEFT SHUNTS:
Cause cyanosis early in postnatal life:
Tetralogy of Fallot:
Four features of tetralogy of Fallot are:
(1) VSD.
(2) obstruction to right ventricular outflow
( subpulmonary stenosis).
(3) aorta that overrides VSD.
(4) right ventricular hypertrophy.
16. The clinical consequences depend on severity
of subpulmonary stenosis:
o If mild, the abnormality resembles an isolated VSD
and the shunt may be left-to-right without cyanosis
(pink tetralogy).
o If sever, there is greater resistance to right
ventricular outflow , right-to-left shunting with
cyanosis (classic tetralogy of Fallot).
17. Morphology:
The heart is often enlarged and may be
"boot-shaped“ owing to marked right ventricular
hypertrophy, particularly of apical region.
The VSD is usually large.
18.
19. Transposition of Great Arteries (TGA):
Aorta arises from right ventricle and
pulmonary artery emanates from left ventricle.
The AV connections are normal ( with right atrium
joining right ventricle and left atrium emptying
into left ventricle).
The result is separation of systemic and pulmonary
circulations, a condition incompatible with postnatal
life unless a shunt exists for adequate mixing of
blood.
20. Patients with TGA and VSD ( 35%) have a stable
shunt.
Those with only patent foramen ovale or PDA ( 65%)
have unstable shunts that tend to close , therefore
require immediate intervention to create a shunt
(such as balloon atrial septostomy) within first few
days of life.
21. Truncus Arteriosus :
Developmental failure of separation of embryologic
truncus arteriosus into aorta and pulmonary artery.
This results in a single great artery that receives
blood from both ventricles.
Because blood from right and left ventricles mixes,
there is early systemic cyanosis.
22.
23. Tricuspid Atresia :
Complete occlusion of tricuspid valve orifice .
Associated with underdevelopment (hypoplasia)
of right ventricle.
The circulation is maintained by a right-to-left shunt
through inter-atrial communication (ASD or patent
foramen ovale).
Cyanosis is present from birth, and there is high
mortality in first weeks or months of life.
24.
25. OBSTRUCTIVE CONGENITAL ANOMALIES:
Coarctation of Aorta:
Two classic forms :
(A) Infantile form : proximal to PDA.
(B) Adult form : just opposite the closed ductus
arteriosus (ligamentum arteriosum).
26. (A) Infantile form:
leads to manifestations early in life.
do not survive without surgical intervention.
Unoxygenated blood through PDA produces cyanosis
in lower half of body.
27. (B) Adult form:
most of children are asymptomatic.
may go unrecognized until adult life.
hypertension in upper extremities, but weak pulses
and lower blood pressure in lower extremities.
manifestations of arterial insufficiency
(claudication and coldness).
28. Pulmonary Stenosis and Atresia:
Obstruction at pulmonary valve, may be
mild to severe.
May occur as an isolated defect, or as part of
tetralogy of Fallot .
Right ventricular hypertrophy often develops.
Mild stenosis may be asymptomatic and compatible
with long life.
Sever stenosis is associated with cyanosis and
earlier appearance.
29. Aortic Stenosis and Atresia:
Three major types : valvular, subvalvular, and
supravalvular.
Prominent systolic murmur and sometimes a thrill.
Hypertrophy of left ventricle.
Well tolerated unless very severe.
Mild stenoses can be managed conservatively with
antibiotic prophylaxis and avoidance of strenuous
activity.
Sudden death with exertion always expected.