ASD mainly kirklin based.

1. Atrial septal Defect
Tania Nusrat Shanta
Phase B,Cardiovascular & Thoracic surgery
BSMMU

2. OBJECTIVES
 Introduction
 Historical consideration
 Incidence
 Etiology
 Embryology
 Types of ASD
 Natural History
 Haemodynamics
 Clinical Manifestation
 Evaluation and Management

3. Introduction
 Atrial septal defect (ASD) is a form of congenital heart defect that enables blood
flow between the left and right atria via the interatrial septum.
 Severity depends on :
- size of defect
- size of shunt
- associated anomalies
 Resulting in spectrum from : asymptomatic to right sided overload, PAH , even
atrial arrhythmias.

4. Historical consideration
 Roesler in 1934, analyzed ASD among the 62 recorded autopsy cases only one had
been correctly diagnosed during life.
 By 1941, Bedford and colleagues were able to make the diagnosis clinically in a
number
of patients.
 In 1948 in Toronto, Murray reported closing an ASD in a child by external suturing.
 Lewis and Taufic reported the first successful open repair of an ASD in 1953.
 Gibbon started the era of open heart surgery in 1953 when he successfully repaired an
ASD in a young woman using a pump-oxygenator.
 By the late 1960s almost all surgeons used CPB exclusively for these repairs.
 Percutaneous catheter techniques for closing a fossa ovalis ASD using a polyester
double umbrella device were introduced by King and Mills in 1974.
 It is not certain who first repaired the sinus venosus syndrome, but the malformation
was clearly illustrated by Bedford and colleagues in 1957.
 Repair of PAPVC to the inferior vena cava was performed by Kirklin and colleagues at
Mayo Clinic in 1960 and was also subsequently reported by Zubiate and Kay in 1962.

5. INCIDENCE
 Atrial septal defect occurs as an isolated anomaly in 8% to 10% of all congenital
heart defects (CHDs).
 Incidence = 56 per 100,000 live births.
 Recent estimates are much higher (100 per 100,000 live births), likely due to
increased recognition in the era of common use of echocardiography.
 Male:Female = 1:2, For sinus venosus ASD= 1:1
 About 30% to 50% of children with CHDs have an ASD as part of the cardiac
defect.
 Excluding bicuspid aortic valve and mitral valve prolapse, ASD is the most
common form of congenital heart defect found among adults and is the most
common acyanotic shunt lesion in adults as well.

6. ETIOLOGY
 Actual etiology of this congenital defect is unknown.
 Some factors may play role as there are some evidences of being association with ASD.
 Factors include:
- Genetic factor
- Environmental factor including antenatal use of teratogenic drugs, congenital infection.
 Genetic factor:
- A familial predisposition to ASD is well documented.
-Numerous genetic conditions and syndromes known for their extracardiac manifestations are
also associated with ASD.
-ASD is the most common congenital cardiac defect associated with VACTERL.
-Genetic syndromes with associated ASD include Holt-Oram syndrome.
- Trisomy 21 is associated with ASD.
-Noonan syndrome is associated with ASD and pulmonary valve stenosis.
-DiGeorge syndrome (22q11.4 deletion) and Ellis–Van Creveld syndromes are associated with
primum ASD.

7. EMBRYOLOGY
 The primitive atrium is first
partitioned into right and left
atria by growth of the septum
primum—a thin,crescent-
shaped membrane that grows
from the roof of the primitive
atrium toward the endocardial
cushions.
 Foramen primum, composed
of the free edge of the septum
primum and the endocardial
cushions.

8.  Fenestrations develop in the
septum primum that coalesce
to form the ostium secundum.
 As the septum primum then
fuses with the endocardial
cushions, the ostium
secundum maintains a right-to-
left atrial flow that is
important in the fetal
circulation.
 Failure of this fusion results in
the development of a primum
ASD.

9.  A second septum, the septum
secundum, then forms to the
right of the septum primum,
growing toward the
endocardial cushions and
usually closing the ostium
secundum.
 Failure to close the ostium
secundum results in the
formation of a secundum ASD.

10. ANATOMY
 When viewed from its right aspect,
the atrial septum is composed of
interatrial and atrioventricular
regions.
 The interatrial portion is
characterized by the fossa ovalis,
which is the anatomic hallmark of a
morphologic right atrium.
 When viewed from the left atrium,
the atrial septum is entirely
interatrial because the
atrioventricular component lies
below the mitral annuls between the
left ventricle and right atrium.

11. Anatomic Types
 Ostium Secundum defect
 Posterior defect
 Ostium Primum defect
 Sinus Venosus defect
 Coronary Sinus septal defect
 Confluent defect

12. Ostium secundum defects or
secundumASDs
 The most common type, 70% to 75% of
ASDs.
 Location: in the midportion of the atrial
septum, within or including the fossa
ovalis.
 Defects result from a deficient septum
primum or an abnormally large foramen
secundum.
 Two times more common in female
patients.
 Association:
-Mitral valve prolapse and other forms of
congenital heart disease.
-It may also be associated with rheumatic
mitral stenosis (i.e.Lutembacher syndrome).

13. Ostium primum defects or primumASDs
 15% to 20% of ASDs and are part of the spectrum of atrioventricular (AV) septal
defects (also known as AV canal defects or endocardial cushion defects).
 Location: These defects occur in the inferior–anterior portion of the atrial
septum.
 Association: Cleft in the anterior leaflet of the mitral valve, leading to varying
degrees of mitral regurgitation.
 In their complete form, they include a large ventricular septal defect and a
common AV valve.
 Most common ASD type associated with Down’s syndrome.

14. Sinus venosus defects
Constitute the remaining 5% to 10% of
septal defects.
 These lesions involve the portion of the
atrial wall derived from the sinus venosus
 Location: Sinus venosus defects are
typically at the orifice of the superior
vena cava (SVC) at the junction of the
right atrium or, less frequently, in the
region of the inferior vena cava (IVC).
 Association: with partial anomalous
pulmonary venous drainage of the right
pulmonary veins

17. ACCORDING TO SIZE:
 In younger children – In older children
Small defect: <3 mm Small defect: <6 mm
Moderate defect: 3-8mm Moderate defect:6 – 12mm
Large defect: >8 mm Large defect: >12 mm

18. Natural History
 In patients with an ASD smaller than 3 mm in size diagnosed before 3 months of
age, spontaneous closure occurs in 100% of patients at 1½ years of age.
 Spontaneous closure occurs more than 80% of the time in patients with defects
between 3 and 8 mm before 1½ years of age.
 An ASD with a diameter larger than 8 mm rarely closes spontaneously.
 Spontaneous closure is not likely to occur after 4 years of age
 Most children with an ASD remain active and asymptomatic. Rarely, congestive
heart failure (CHF) can develop in infancy.

19.  If a large defect is untreated, CHF and pulmonary hypertension begin to develop
in adults who are in their 20s and 30s, and it becomes common after 40 years of
age.
 With or without surgery, atrial arrhythmias (flutter or fibrillation) may occur in
adults. The incidence of atrial arrhythmias increases to as high as 13% in patients
older than 40 years of age.
 Infective endocarditis does not occur in patients with isolated ASDs.
 Cerebrovascular accident, resulting from paradoxical embolization through an
ASD, is a rare complication.

20. HEMODYNAMICS
 LEFT-TO-RIGHT SHUNT
 In early infancy, when pulmonary resistance is high, left and right ventricular compliances
are similar, and net shunting through an ASD is typically slight.
 As the left ventricle matures, it becomes less compliant in diastole than the right, and left
atrial pressure rises. This drives a left-to-right shunt at the atrial level in the presence of an
ASD.
 With age, the disparity between systemic and pulmonary resistance, and in turn between
left and right ventricular compliance, results in increased left-to-right shunting and
advancing right ventricular volume loading.
 Over time, right ventricular volume load results in dilation and hypertrophy, eventually
affecting the function of both ventricles.
 Atrial enlargement may contribute to the late incidence of atrial fibrillation. Right
ventricular volume overload is noted to occur as a rule when ASDs are larger than 6 mm in
diameter.

21. HEMODYNAMICS

22.  Volume-induced hypertrophy of the right ventricle produces a loss of coronary reserve
and eventual impairment of right ventricular systolic and diastolic function.
 Left ventricular functional reserve is diminished by adulthood in most patients with ASD.
 Although left ventricular systolic function may be normal at rest, the left ventricle exhibits
a subnormal diastolic dimension, and a loss of functional reserve at exercise.
 Mechanisms that account for left ventricular dysfunction include
(1) septal displacement secondary to right ventricular dilation and hypertrophy and
(2) systolic anterior movement of the mitral valve.
 In general, the functional loss in the left and right ventricles is normalized 6 months
following ASD closure in children and young adults.

23. CARDIAC CHAMBERS IN ATRIAL SEPTAL DEFECT
 Typically in ASD and related conditions, the RIGHT ATRIUM is greatly enlarged
(at least grade 3 or 4 on a scale of 1 to 6) and thick walled.
 The LEFT ATRIUM is not enlarged.
 RIGHT VENTRICULAR (RV) diastolic size is increased, often greatly, because
of volume overload imposed by the left-to- right shunt.
 Whereas normal RV diastolic dimensions are between 0.6 and 1.4 cm · m2, in
patients with large left-to- right shunts at atrial level they average 2.66 cm · m2
and may be as large as 4 cm · m2.
 Morphologically, the LEFT VENTRICLE (LV) is normal or slightly decreased in
size.However, important LV dynamic abnormalities are present in most patients.

24.  Mitral Prolapse
 Mitral valve prolapse occurs in association with fossa ovalis ASD, sinus venosus
and probably other types of ASDs and related conditions that result in left-to-
right shunts at the atrial level. Prevalence of true prolapse is about 20% .
 Mitral Regurgitation
 Mitral prolapse in ASD can lead to mitral regurgitation, as does ordinary mitral
prolapse. True prevalence of regurgitation in unselected patients varies because
older patients and those with larger pulmonary blood flows have a higher
prevalence of this abnormality and prolapse.

25. CLINICAL
MANIFESTATIONS

26. SYMPTOMS AND SIGNS
Vary with the size of defect.
 Small defect: Asymptomatic and is
usually,diagnosed during a routine
health check up.
 Large defect: Symptomatic and
patients usually present with
 Breathlessness
 Paltitation
 Recurrent Pulmonary infections
 Failure to thrive.
 Easy fatigability.
 Tachycardia
 Tachypnea
 Paroxysmal atrial tachycardia
 Atrial fibrillation
 Older patient with CHF : elevated JVP
,edema, hepatomegaly,cardiac
cachexia.
 Patient with severe PHTN: may
present with cyanosis ,hemoptysis.
 Platypnea
 Orthodeoxia

27.  General examination
 Appearance: Usually normal
 Heart rate: Normal
 Respiratory rate: Normal
 Weight and height: may be less than 10th centile.
 Precordium
 Inspection:
 Normal or Slight prominence of precordium
 Palpation:
 Apex beat may be shifted to left
 P2 may be palpable
 Left parasternal heave may be present

28.  Auscultation:
 S1 is normal
 S2 is widely splitted and fixed
 Ejection systolic murmur,medium pitched, soft, grade 1-3/6 & best heard at left 2nd &
3rd ICS.
 A mid-diastolic tricuspid flow murmur (in fourth and fifth left intercostal spaces) present in
borderline situations only on inspiration.

29. INVESTIGATIONS
Diagnostic Investigations includes
 -X-ray
 -ECG
 -Echocardiography
 - cardiac catheterization
 -Cardiac MRI

30. Xray Findings
 Cardiomegaly
 RA enlargement
 RV enlargement
 Full pulmonary conus
 Increased pulmonary vascular
markings
 Plethoric lung fields

31. ECG
Secundum ASD:
 RSR’ pattern in lead V1
 QRS duration < 0.11 seconds
(incomplete right bundle branch
block)
 Right-axis deviation
 RV hypertrophy
 First-degree AV block (20%)
 RA enlargement (about 50%) with a
prominent P wave in lead II
Primum ASD:
 RSR’ pattern in lead V1
 Left-axis deviation
 First-degree AV block, classically seen
with right bundle branch block and
left anterior fascicular block

32. ECG
Enlarged ‘p’
wave
indicating
Right atrial
hypertroph
y
rsR’ seen and tall R
wave
Indicating RBBB and
RVH

33. Echocardiography
 Primary diagnostic imaging modality for ASD.
 Provides:
- exact localization of ASD
- size of ASD
- measurement of septal rims
- Confirmation of the shunt
- Abnormal motion of ventricular septum.
- Associated lesions can be identified

34. Echocardiography
A two-dimensional echocardiographic study is diagnostic. The study
shows the position as well as the size of the defect, which can best be
seen in the subcostal four chamber view.
A. The SVC type of sinus venosus defect shows a defect in the
posterosuperior atrial septum.
B. In secundum ASD, a dropout can be seen in the midatrial septum.
C. The primum type shows a defect in the lower atrial septum.

35.  Indirect signs of a significant
left-to-right atrial shunt
include RV enlargement and
RA enlargement, as well as
dilated PA, which often
accompanies an increased flow
velocity across the pulmonary
valve.
 Pulsed Doppler examination
reveals a characteristic flow
pattern with the maximum
left-to-right shunt occurring in
diastole.
 Color-flow mapping enhances
the evaluation of the
hemodynamic status of the
ASD.

36.  In older children and adolescents,
especially in those with overweight,
adequate imaging of the atrial
septum may not be possible with the
ordinary transthoracic
echocardiographic study.
Transesophageal echocardiography
(TEE) may be used as an alternative.

37. Cardiac catheterization
 Typically not required for diagnostic purposes except to assess pulmonary
pressures and resistance or as part of a planned transcatheter device closure.
 Hemodynamic assessment: An important assessment is comparison
of pulmonary artery pressure with systemic pressure and measurement of
pulmonary vascular resistance. If pulmonary pressures are elevated, the response
to oxygen or other vasodilators should be assessed. Alternatively, the ASD can be
balloon occluded with assessment of hemodynamics to ensure that closure is
safe.
Cardiac MRI : Can be helpful, as it can provide additional information
beyond echocardiography.

38. MANAGEMENT
 Patients with small shunts and normal RV size are generally
asymptomatic and require no therapy but need longtime follow
up for spontaneous closure.
 Moderate to large shunt and/or symptomatic ASD should be
managed with following strategies:
- Medical therapy
- Interventional therapy
- Surgical therapy

39. Medical management
 Aim to reduce volume overload and to strengthen functions of heart muscles.
 Symptomatic children :
 Diuretics:
-These agents relieve ventricular overload, peripheral and pulmonary congestion
 Digoxin:
-Helps to strengthen the heart muscle, enabling it to pump more efficiently.
 Afterload reducers: - Enalapril
- Captopril
 Exercise restriction is no necessary.
 Prophylaxis for infective endocarditis is not indicated
Atrial arrythmias : Appropriate Antiarrhythmic drugs.
Atrial fibrillation : Antiarrhythmic drugs +anticoagulants.
 Irreversible PAH :dobutamine, calcium channel blockers (high dose), diuretics,
prostacycline, sildenafil or oxygen therapy.
 Treatment of Other complications, like pulmonary infections, thrombo- embolic events or
heart failure should also be treated accordingly.

40. Interventional therapy
 Closure of ASD :
In patients with small secundum ASDs and minimal left-to-right shunts without right
ventricular enlargement, closure is not required
 Indications of ASD closure-
-All symptomatic patients
-Asymptomatic patients with-
• Qp : Qs ratio of at least 2 : 1
• Right ventricular enlargement
Presence of sufficient rim of tissue( at least 5 mm)
 Time of closure- usually after the 1st yr and before entry into school

41.  Contraindication:
Sinus venosus, coronary sinus or primum ASD
Extensive congenital cardiac anomaly.
Known sepsis within one month prior to implantation or any untreated systemic infection
prior to device placement.
Bleeding disorder, untreated ulcer or any other contraindications to aspirin therapy.
Demonstrated intracardiac thrombi on echo.
Any patient whose size or condition would cause to be a poor candidate for cardiac
catheterization.

42.  Transcatheter device closure of secundum type ASD was first performed in 1976 by Mills
and King.
 Different ASD closure devices:
Clamshell(TM) device
Buttoned device
Angel wings(TM) device
Atrial septal defect occluder system device
 In the United States, currently only the Amplatzer septal occluder and Helex septal
occluder are approved by FDA for secundum ASD closure.

43.  Complications of Device Closure:
Device misalignment/embolization
Device erosion of atrial wall or aorta
Device impingement on adjacent structures AV valve, Coronary sinus,
SVC, Pulmonary veins, Aorta
Infection including endocarditis
Thromboembolic Complication
Allergic reaction
Residual shunt

44.  Postdevice Closure Follow-up
• After closure, antiplatelet therapy, frequently aspirin and clopidogrel, is
prescribed for a minimum of 6 months, after which time the device is generally
believed to have endothelialized.
• Postprocedure echocardiographic studies check for a residual atrial shunt and
unobstructed flow of pulmonary veins, coronary sinus, and venae cavae, and proper
function of the mitral and tricuspid valves.
• If 1-month and 1-year follow-up echocardiography findings are normal then
yearly or biennial follow-up will suffice.

45. Surgical management
 Surgical closure has been the “gold standard” form of treatment of ASD
 Surgeons need proper training and expertise in performing operations.
 The surgical approach can be by right thoracotomy or sternotomy ,partial or
full submammary skin incision,hemisternotomy, and more limited incisions
are feasible with either approach.
 Procedure- Simple suture or patch closure
 Timing-
Surgery is usually delayed until the patient is 2 to 4 years of age because
the possibility of spontaneous closure exists.
In infancy- If CCF not respond to medical management.

47.  Indication:
 ASD with RA and RV enlargement with / without symptoms.
 ASD minimum diameter > 10 mm on echocardiography
 A sinus venosus, coronary sinus or primum ASD
 Chronic atrial arrythmia with ASD
 Contraindication:
 Patients with severe irreversible PAH & reverse shunt
 SPO2 < 90%

48.  Preoperative risk factors:
• Older age at operation,
• Presence of atrial fibrillation, and
• Elevated pulmonary pressure and resistance.
 Mortality: < 0.5%
 Complications:
• Cerebrovascular accident
• Postoperative arrhythmias may develop in the immediate postoperative period.
• Postpericardiotomy syndrome

49.  Advantages of Surgery-
Can be performed in any type of
ASD
Associated anatomical abnormality
can be corrected concurrently.
Excellent late outcome.
 Disadvantages of Surgery-
Costly
Needs expertise hands
Long Hospital stay
pain and residual thoracotomy
scars

50.  Postoperative Follow-up
• Cardiomegaly on chest radiographs and enlarged RV dimension on echo as
well as the wide splitting of the S2 may persist for 1 or 2 years after surgery.
• The ECG typically demonstrates RBBB (or RV conduction disturbance).
• Atrial or nodal arrhythmias occur in 7% to 20% of postoperative patients.
• Occasionally, sick sinus syndrome, which occurs especially after the repair of a
sinus venosus defect, may require antiarrhythmic drugs, pacemaker therapy, or both.

51.  PROGNOSIS:
Patients generally survive up to adulthood without surgical or
percutaneous intervention mainly with small to moderate size ASD and many
patients live to advanced age.
The results after surgical or device closure in children with moderate to
large shunts are excellent.
Mortality is less than 2% after surgical closure of uncomplicated ASD.
Mortality and morbidity increase with pulmonary vascular disease.

52. TAKE –HOME MESSAGES
 Atrial septal defects are relatively common CHD
 Early symptoms are usually rare except very large deffect.
 Any kind of closure is safe and effective and associated with improved life
expectancy
 A comprehensive treatment plan should include input from the primary care
provider, the Paediatric Cardiologist and the Paediatric Cardiovascular
surgeon.