Download atrial septal defect

ATRIAL SEPTAL DEFECT
Dr. M. A. Sofi
MD; FRCP (London); FRCPEdin; FRCSEdin
Atrial septal defect
• Atrial septal defect is characterized by a defect in the
interatrial septum allowing pulmonary venous return from
the left atrium to pass directly to the right atrium.
• Depending on the size of the defect, size of the shunt, and
associated anomalies, this can result:
– No significant cardiac sequelae
– Right-sided volume overload
– Pulmonary arterial hypertension
– Atrial arrhythmias.
 The subtle physical examination minimal symptoms
during the first 2-3 decades contribute to a delay in diagnosis

until adulthood
Majority (more than 70%) of which is detected by the fifth
decade.
Atrial septal defect
Frequency
• The 3 major types of atrial
septal defect (ASD) account
for 10% of all CHD and as
much as 20-40% of
congenital heart disease
presenting in adulthood
• Ostium secundum: Most
common accounting for 75%
of ASD cases
• Ostium primum: Second
most common accounting for
15-20% ASDs
• Sinus venosus: Least
common of the three,
accounting for 5-10% ASDs
Sex: F- M ratio of approximately
2:1.
Age: ASD can be asymptomatic
through infancy and childhood
• Clinical presentation depends
on the degree of left-to-right
shunt.
• By the age of 40 years, 90% of
untreated patients have
symptoms of
• Exertional dyspnea
• Fatigue, palpitation
• Sustained arrhythmia
• Heart failure
CLASSIFICATION — ASDs are classified according to their location and the
nature of the embryologic defect: Isolated ASDs include patent foramen ovale
(PFO), ASD at the fossa ovalis (secundum ASD), superior sinus venosus defect,
inferior sinus venosus defect, and coronary sinus defects
• Secundum ASD — Defects in the
foramen ovalis are classified as
secundum type ASD. This type of
ASD can result from poor growth of
the secundum septum or excessive
absorption of the primum septum
• This defect accounts for 70 to 75
percent of all ASDs and is more
common in females.
• The rare combination of an ASD
with mitral stenosis, the result is
known as Lutembacher syndrome
• Primum ASD — The primum type
ASD develops if the primum septum
does not fuse with the endocardial
cushions, leaving a defect at the
base of the interatrial septum that is
usually large .
• This type of defect accounts for 15
to 20 percent of ASDs.
• It has been suggested that both
partial and complete AV canal
defects are related to maldevelopment of the ventricular
septum rather than a decrease in
atrial septal tissue
Atrial septal defects
A. The normal atrial septum
B. Secundum ASD is formed by
the poor growth of the septum
secundum or excessive
absorption of the septum
primum.
C. Primum ASD is formed by
the failure of the septum
primum to fuse with the
endocardial cushions. The
fossa ovalis is normal.
D. Sinus venosus ASD is caused
by the malposition of the
insertion of the superior or
inferior vena cava and is
outside the area of the fossa
ovalis.
Pathophysiology: Left-to-right shunting occurs primarily in late ventricular systole
and early diastole, with some augmentation during atrial systole. Even when the right
and left atrial pressures are equal, as occurs with a large defect, left-to-right shunting
still occurs because of the greater compliance of the right compared to left ventricle.
Clinical presentation
• Significant mitral
regurgitation is
associated with septum
primum ASD
• Its incidence, extent, and
degree of dysfunction
increases with age.
• Mitral valve
insufficiency leads to
further increase in left
atrial pressure and a
higher degree of left-toright shunt.
• Most common presenting
symptoms include:
• Dyspnea
• Fatigability
• Palpitations
• Arrhythmia
• Syncope
• Stroke
• Heart failure
PHYSICAL FINDINGS: Classic physical findings of ASD are related
to the size and location of the defect, the size of the shunt at atrial level,
and the pulmonary arterial pressure.
• Precordial palpation —
large left-to-right shunts
can lead to:
• An enlarged right ventricle
with right ventricular heave.
• It can also cause left
precordial bulge.
• Enlarged of the pulmonary
artery with a palpable
pulmonary artery impulse.
• This may be more
pronounced in patients with
pulmonary hypertension.
Heart sounds: Characteristic
finding is fixed splitting of the
second heart sound (S2).
Heart murmurs:
• Mid systolic pulmonary flow/
ejection murmur loudest over
the 2nd left intercostal space
• Mitral regurgitation: due to a
cleft mitral valve in ostium
primum defects and mitral valve
prolapse in secundum defects.
• A diastolic rumble due to the
increased flow across the TV
Clinical presentation
Atrial arrhythmias: Common
manifestation of an ASD.
• The risk of atrial arrhythmias
increases with increasing age.
• Patients with AF are at risk
for embolic events.
Stroke due to paradoxical
embolization:
• Patients with a PFO or, much
less often, an ASD with a
right-to-left shunt are at risk
for stroke due to paradoxical
embolization (stroke, TIA, or
peripheral emboli).
• Migraine headache: Evidence
is conflicting whether migraine
is associated with right to left
shunt via PFO or ASD
• Pulmonary hypertension and
Eisenmenger syndrome: The
development of pulmonary
vascular injury is related to the
degree and duration of right
heart volume overload.
• Cyanosis — Cyanosis in ASD
is either concomitant pulmonary
valve stenosis resulting in
elevated right heart pressures,
and thus right-to-left shunt, or
Eisenmenger syndrome
Physical examination
• Depend on the degree of
left-to-right shunt
• Hyperdynamic right
ventricular impulse due to
large stroke volume
• Pulsation of the
pulmonary artery and an
ejection click can be
detected
• S1 is typically split, and
increased in intensity
second component
• S2 is often widely split
and fixed
• Systolic ejection murmur
in the second intercostal
space
• Ostium primum defect an
apical systolic regurgitant
murmur of mitral
regurgitation may be
present.
Laboratory Studies
Routine laboratory studies
should for ASD include:
• CBC/LFT/TFT/BUN/
• Metabolic profile or chemistry
• Coagulation studies
(prothrombin time [PT] and
activated partial
thromboplastin time [aPTT])
Electrocardiogram:
• The ECG may be normal with
an uncomplicated ASD and
small shunt.
• Atrial arrhythmias often occur
beyond the third decade
(especially atrial fibrillation
but also atrial flutter and
supraventricular tachycardia).
Echocardiogram — is the
imaging modality of choice
for ASD diagnosis
Imaging Studies
CXR may reveal:
• Cardiomegaly because of
dilatation of the right
atrium and right
ventricular chamber.
• Prominent Pulmonary
artery and pulmonary
vascular markings
• Left atrial enlargement is
rare only if clinically
significant mitral
regurgitation.
• Dilatation of the superior
vena cava can be seen in
sinus venosus defect.
• Transthoracic and Transesophageal
echocardiography can
provide excellent definition
of the atrial septum.
• TEE is also useful in
guiding device placement
during catheter ASD
occlusion procedures and
in providing immediate
intra-operative assurance
that defect closure is
accomplished.
ASD with pulmonary arterial
hypertension
Normal chest radiograph
The plain frontal chest radiograph in a patient with a known atrial septal
defect demonstrates typical features including an enlarged right atrium
and right ventricle with marked prominence of the hilar or proximal
pulmonary arterial vasculature (arrows).
Treatment
• The decision to repair any
kind of atrial septal defect
(ASD) is based on clinical
and echocardiographic
information
• The size and location of
the ASD
• Hemodynamic impact of
the left-to-right shunt
• The presence and degree
of pulmonary arterial
hypertension
• Elective closure is
advised for all ASDs
with right ventricular
overload or with a
clinically significant
shunt
• The widespread use of
catheter closure of
secundum ASD with
lower mortality has
raised the question
regarding the need to
close even small defects
Contraindications to surgical repair
• Closure of ASD is not
recommended in patients
with a clinically
insignificant shunt
• Those who have severe
pulmonary arterial
hypertension or
irreversible pulmonary
vascular occlusive disease
• Those who have a
reversed shunt with atrest arterial oxygen
saturations of less than
90%.
• In addition to the high
surgical mortality and
morbidity risk, closure of
a defect in the latter
situation may worsen the
prognosis.
• Those patients whose
condition is diagnosed
well in the sixth decade of
life would benefit from
surgical closure remains
controversial.