Congenital heart diseases 1

Congenital Heart Diseases
By
Dr.jawhar
Lecture 1

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.

 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.

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.

 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.

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.

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.

 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.

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.

 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.

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 .

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.

 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).

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.

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.

 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.

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.

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.

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).

(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.

(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).

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.

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.

Congenital heart diseases 1

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