ATRIOVENTRICULAR
SEPTAL DEFECTS.

INTRODUCTION
• Group of anomalies that share a
defect in atrioventricular septum
and abnormal AV valves.
• Also known as Endocardial cushion
defect, AV canal defect, canalis
atrioventricularis communis,
persistent atrioventricular ostium
• Broadly divided into partial and
complete forms.

DEMOGRAPICS
• 4 TO 5 % Of congenital heart defects.
• Estimated occurrence of 0.19 in 1,000 live births
• Male = female or slight female preponderance.
• Downs syndrome: 40 to 45% have heart disease.
• Of which 45% have avsd.
• > 75 % of these are the complete form.
• Conversely approximately 50% of avsd patients have
downs syndrome.

HISTORY
 Rogers, Edwards : Recognised morphological similarity
of ostium primum ASD and complete defect in 1948
 Wakai, Edwards : Term of partial and complete AV
canal defect in 1956
 Bharati & Lev : Term of Intermediate & Transitional in
1980
 Rastelli: Described the of common anterior leaflet in
1966
 Lillehei : 1st repair of AVSD in 1954
 Kirklin, Watkin, Gross: Open repair using oxygenator

EMBRYOGENESIS.

• Defect in endocardial cushion development and fusion.
• Additional pathways have now been illustrated, which
shows that “dorsal mesenchymal protrusion”(vestibular
spine) is responsible for formation of avsd.
• In partial AVSDs, incomplete fusion of the superior and
inferior endocardial cushions results in a cleft in the mid-
portion of the left AV valve anterior leaflet often associated
with regurgitation.
• In contrast, complete AVSD is associated with lack of
fusion between the superior and inferior cushions and,
consequently, with the formation of separate anterior and
posterior bridging leaflets along the subjacent ventricular
septum

• Since the dextrodorsal conus cushion contributes to the
development of the right AV valve and the outflow tracts lie
adjacent to their respective inflow tracts, AVSDs may be
associated with conotruncal anomalies, such as tetralogy of
Fallot and double-outlet right ventricle (RV).
In addition, shift of the AV valve orifice may result in
connection of the valve primarily to only one ventricle,
creating disproportionate or unbalanced ventricles.

MORPHOLOGY

Pathology
 In the normal
heart, the aortic
valve is wedged.
 In AVSD the
aortic valve is
displaced
anteriorly and
creates an
elongated, k/a
gooseneck
deformity of the
LVOT
14

VALVE MORPHOLOGY

• Normal MV –
Posterior leaflet : 2/3
circumference
• AVSD MV – Left
lateral leaflet : 1/5
circumference

CONDUCTION SYSTEM

ANATOMICAL CLASSIFICATION
(RASTELLI)
• Prior to 1964, hospital mortality
for patients with AVSD was 60 %.
• Rastelli et al. from the Mayo
Clinic published their work in
1968 and operative mortality
between 1964 and 1967
decreased to 20 % .

Anatomical Classification of AVSD
(Rastelli’s, 1966)
Based bridging of LSL across
IVS
Rastelli type A : (55%) Anterior
bridging leaflet divided and
attached to crest of ventricular
septum.
• Interventricular communication
beneath the anterior bridging
leaflet may be minimal or
absent in some cases owing to
extensive interchordal fusion.
20

Anatomical Classification of AVSD
(Rastelli’s, 1966)
Rastelli type B : (3%)
anterior bridging leaflet
larger , straddles the
septum and papillary
muscle attachment to
the septum/moderator
band of RV.
Chordal anchors are absent
,hence interventricular
communication is
present.
21

Anatomical Classification of AVSD
(Rastelli’s, 1966)
 Rastelli type C : (30%)
anterior bridging leaflet
is larger than in type B.
• its medial papillary
muscle attachments fuse
to the right-sided anterior
papillary muscle.
• Free interventricular
communication is
present.
• Also called free floating
chordae.
22

• The subtype of complete
AVSD has some bearing
on the likelihood of
associated lesions.
• Type A usually is an
isolated defect and is
frequent in patients with
Down syndrome
• Type C is encountered
with other complex
anomalies, such as
tetralogy of Fallot, double-
outlet RV, complete
transposition of the great
arteries, and heterotaxy
syndromes

CLASSIFICATION

PARTIALAVSD.

• Two separate annuli
• Ostium primum asd and cleft left anterior av valve.
• The cleft in the left AV valve anterior leaflet is directed
toward the midportion of the ventricular septum, along the
anteroinferior rim of the septal defect.
• The left AV valve orifice is triangular rather than elliptical (
as in a normal heart) and resembles a mirror-image
tricuspid valve orifice.
• The cleft left AV valve usually is regurgitant and, with time,
becomes thickened and exhibits histologic alterations that
resemble myxomatous mitral valve prolapse.

• Although patients with partial AVSD may be asymptomatic
until adulthood, symptoms of excess pulmonary blood flow
typically occur in childhood
• Tachypnea and poor weight gain occur most commonly
when the defect is associated with moderate or severe left
AV valve regurgitation or with other hemodynamically
significant cardiac anomalies.
• Patients with primum ASDs usually have earlier and more
severe symptoms, including growth failure, than patients
with secundum ASDs.

COMPLETE AVSD
• Tachypnea and failure to thrive invariably occur early in
infancy as a result of excessive pulmonary blood flow
• All patients with complete AVSD have symptoms by 1year
of age
• AV valve regurgitation compounds these problems.

HEMODYNAMICS

 The outcome of live-born patients with AVSD depends on
the
 specific morphology of the defect
 The size of the ventricular septal defect
 Degree of ventricular hypoplasia
 Degree of AV valve regurgitation
 Presence or absence of LVOT obstruction
 Presence or absence of coarctation of aorta
 Associated syndromes (cardiac and noncardiac)
Natural History
35

 Patients with the complete form of AVSD and large VSD not
undergoing repair die in infancy with CHF & PAH
 Those who survive without surgery into childhood usually
develop pulmonary vascular obstruction and eventually die with
Eisenmenger’s syndrome
 Berger and his colleagues found that only 54% of patients born
with a complete form of AVSD were alive at 6 months of age, 35%
at 12 months, 15% at 24 months, and 4% at 5 years of age
 This data would support surgical intervention in the first 3–6
months of age
36
Natural History
Berger TJ,et al Ann Thorac Surg 1979; 27: 104–11.

 Infants with 10 ASD presenting in infancy have a poor outcome,
mainly because of the associated risk factors that bring these
infants to early attention
 Those with the partial form of AVSD and minimal left AV valve
regurgitation seem to fare the best without surgery, although
there is still likely considerable morbidity and mortality
 According to Somerville, 50% die before 20 years of age and only
25% survive beyond 40 years of age
 Atrial fibrillation in these patients was an important cause of late
morbidity and mortality
37
Natural History

 ECG
 Superior” QRS axis with the QRS axis between -40 and -1500
 Most of the patients have a prolonged PR interval
 More than 50% have atrial enlargement
 RVH or RBBB is present in all cases (2/3rd have rsR, RSR or Rr in lead
V1, and the rest have a qR or R pattern) & many have LVH
 In 10 ASD findings are same as 20 ASD except for enlargement of the
LA & LV when MR is significant
 In complete AVSD cardiomegaly is always present and involves all
four cardiac chambers. Pulmonary vascular markings are increased,
and the main PA segment is prominent
ECG
38

 Primary imaging technique for diagnosing AVSD
 The internal cardiac crux is the most consistent imaging
landmark
 Apical four-chamber imaging plane clearly visualizes the
internal crux
Echocardiography
39

 Several echocardiac features are shared by all forms of
AVSD:
 Deficiency of a portion of the inlet ventricular septum
 Inferior displacement of the AV valves
40
Echocardiography

 The most common left AV valve abnormality, a cleft, is best
visualized from the parasternal and subcostal short-axis
imaging planes.
Echocardiography
42

 In the transitional form of partial AVSD, there is aneurysmal
replacement of a portion of the inlet ventricular septum
Echocardiography
43

 Rarely required for diagnosis
 In older patient it may have a role in assessing the degree of
pulmonary vascular obstructive disease or CAD
 A large Lt to Rt shunt at the atrial level demonstrated by a
significantly higher oxygen saturation sampled from the RA
compared with the blood in the IVC & SVC
 In complete AVSD the PASP is invariably at or near systemic level,
while in partial AVSDs, the PASP is usually <60% of systemic pressure
 LV angiography - gooseneck deformation of the LVOT
Cardiac Catheterization & Angiography
44

 Left to-right shunting increases the oxygen saturation in RA
 Sample from high in the SVC usually represents the best
mixed venous oxygen saturation (normal or 40 to 50%)
 Usually a further increase in oxygen saturation in the RV
 Pulmonary venous oxygen saturation is frequently reduced
to 93–95% in older individuals with very large L to R shunts
 LA & LV O2 saturation is often decreased to as low as 86–88%
45

INDICATIONS
• Complete AVSD
a. Uncontrolled heart failure:
Complete surgical repair as soon as possible (Class I)
b. Controlled heart failure: Complete surgical repair by 3 months
of age (Class I)
c. Pulmonary artery banding: May be considered in select
patients under 3 months of age (Class IIb).
ii. Partial or intermediate AVSD, stable, and with normal
pulmonary artery pressures: Surgical repair at 2–3 years of age
(Class I)
iii. Associated moderate or severe AV valve regurgitation may
necessitate early surgery in partial or intermediate forms.
iv. Pulmonary artery banding is reserved for complex cases and
in patients with contraindications for cardiopulmonary bypass
(Class IIb).

Surgery for moderate-to-severe left AV valve regurgitation
is recommended as per the guidelines for mitral
regurgitation.(Class I).
vi. Surgery for left ventricular outflow tract obstruction is
reasonable with a peak systolic gradient of ≥50 mmHg, or
at a lesser gradient if heart failure symptoms are present,
or if concomitant moderate-to-severe atrioventricular or
aortic regurgitation is present (Class IIa).
vii. Those presenting beyond 6 months of life with
significant pulmonary hypertension and suspected elevated
PVR should be referred to a higher center for further
evaluation to assess operability.

SURGICAL STEPS

SIZING THE PATCH
• Too wide: LVOTO
• Too long : AV Valve
regurgitation.

SINGLE PATCH

Australian technique (Modified single
patch technique)
• For complete AV
canal defect with
minimal AV valve
distortion

PARTIALAVSD REPAIR

AV VALVE REGURGITATION.

Results (single v/s double patch)

Results (single v/s double patch)

Results (single v/s double patch)

What to perform ??

FOLLOW UP
Recommendations for follow-up
i. Lifelong follow-up is required.
ii. In patients with no significant residual abnormality,annual
follow-up is required till 10 years of age followed by 2–
3-yearly follow-up.
The patient should undergo physical examination, ECG,
and echocardiography at each visit, and a Holter monitor
test may be required in select cases.
iii. IE prophylaxis is recommended for 6 months after
surgical closure. However, all patients are advised to
maintain good oro-dental hygiene after this period also.