a cardiac surgery presentation about Atrioventricular septal defect,Definition, Prevalence,Anatomy,Classification,presentation ,diagnosis and management

1. FIRAS ALJANADI,MD
Cardiac surgeon
Damascus University
firasaljanadi@gmail.com
www.ctsnet.org/home/faljanadi

2. Definition
Atrioventricular (AV) canal defects encompass a spectrum of lesions in which
the common etiology appears to be abnormal development of the endocardial
cushions, resulting in a defect in the AV septum.
A deficiency or absence of septal tissue immediately above & below the normal
level of the AV valves including the region normally
occupied by the AV septum in heart with two ventricle and the AV
valves are abnormal to a varying degree.
Aortic valve is elevated, deviated anteriorly due to absence of usual
wedged position of aortic valve above the AV valve.

3. The prevalence
This group of lesions forms approximately 3% of all
major congenital cardiac defects
 In children with Down syndrome, AV canal defects
are seen in 20–25% or a 1000-fold increased risk when
compared with the incidincein the general
population.

4. History
Rogers, Edwards : Recognized in 1948
 Wakai, Edwards : Term of partial and complete
AV
 canal defect in 1956
 Rastelli : Described the morphology in 1966
 Lillehei : 1st repair of complete AV canal defect in
1954

5. Embryology
Formation of Atrioventricular Septum
dorsal AV cushion and ventral AV cushion approach
each other and fuse to form the AV septum. AV
septum partitions the AV canal into right AV canal
and left AV canal

6. ANATOMY
 The wide variability in the degree of development of the endocardial cushions
explains the variability in size and extent of the septal defects and the degree
of involvement of the AV valves
 Shortened dimension of the inlet septum-to-ventricular apex, giving the
interventricular septum a “scooped-out” appearance , deeper in complete AV
canal defects than in partial AV canal defects
 Lengthened dimension of the outlet septum-to-ventricular apex, resulting in a
“goose-neck” appearance and anterior displacement of the left ventricular
(LV) outflow tract
 Although the LV outflow tract is narrowed, true LV outflow tract obstruction
(LVOTO) is rare
 Absence of the usual wedged position of the aortic valve between the AV
valves, caused by maldevelopment of the endocardial cushions. This results in
elevation and anterior deviation of the aortic valve. n Apical displacement of
the attachments of the AV valves to the crest of the interventricular septum,
caused by the deficiency in the inlet septum

7. Anatomy
Decreased contribution of the left lateral leaflet to AV
valve circumference. In the normal situation the posterior
mitral leaflet forms two thirds of the mitral valve
circumference. In AV canal defects the left lateral leaflet,
which corresponds to the posterior mitral leaflet in the
normal heart, forms only one third of the circumference of
the AV valve
Variable degree of underdevelopment of the inlet portion
of the interventricular septum, resulting in absence of a
VSD (partial AV canal defects), a restrictive VSD
(transitional AV canal defects), or a large VSD (complete
AV canal defects).

8. Anatomy conduction tract
 Inferior displacement of the AV node and coronary sinus. The bundle of His is also
displaced inferiorly, coursing at the inferior rim of the scooped-out basal portion of the
interventricular septum

9. Anatomy conduction tract

10. Classification
Although AV canal defects constitute a continuum of related anatomical lesions, they can be
arbitrarily divided into the following three main groups
(partial, transitional, and complete AV canal defects), based on the extent of the interventricular
communication:
 Partial AV canal defects consist of a large ostium primum atrial septal defect (ASD) and a cleft
between the left superior and inferior leaflets, without an interventricular communication.
There are generally two distinct AV valve orifices, corresponding to the mitral and tricuspid
valves. Leaflet tissue joins the left superior and inferior leaflets together at the crest of the
interventricular septum, eliminating the interventricular communication. In general, partial
AV canal defects constitute approximately 5–10% of all ASDs.
 Transitional AV canal defects consist of an ostium primum ASD, a left-sided cleft, and a
restrictive ventricular septal defect (VSD) that is usually small, partially closed by the
attachments of chordae from the superior and inferior bridging leaflets to the crest of the
interventricular septum. Two AV valves are present, forming two separate orifices. At one
extreme the VSD may consist of a very small communication located at the point of
apposition of the left superior and inferior leaflets. In these cases the pathophysiology
resembles partial AV canal defects. In other cases of transitional AV canal defect, the
interventricular communication is larger, but is still restrictive to flow, with a measurable
gradient by echocardiography or cardiac catheterization

11. Classification
 Complete AV canal defects constitute the other end of the spectrum and are the most
common form of AV canal defects. There is generally an ostium primum ASD and a
nonrestrictive VSD in the inlet portion of the interventricular septum One common AV
valve orifice is present, with left and right components. An inlet-septal VSD alone does
not fall under AV canal defects because the AV septum is intact in these malformations.
On the other hand, some patients have an inlet-septal VSD and a cleft mitral valve with
a restrictive or absent interatrial communication; these should be considered to be
within the spectrum of AV canal defects.

12. Rastelli classification
The Rastelli classification for complete atrioventricular
(AV) canal defects.
A.In the Rastelli type A defect the superior bridging leaflet is
divided into two leaflets at the crest of the interventricular
septum, corresponding to the right superior leaflet (RSL)
and the left superior leaflet (LSL).
B.In the Rastelli type B defect the LSL bridges across the
septum and attaches to a papillary muscle within the right
ventricle
C.In the Rastelli type C defect there is marked bridging of
the superior bridging leaflet, making it free floating and
unattached to the underlying interventricular septum.

13. Rastelli classification

14. Rastelli classification

16. Associated cardiac anomalies
1. Major associated cardiac anomalies
1) PDA(10%) 2) TOF(10%) 3) DORV(3%) 4) TGA(rarely)
5) Unroofed coronary sinus with Lt. SVC (6%, frequent in
common atrium)
2. Minor associated cardiac anomalies
1) ASD
2) Unroofed coronary sinus without Lt. SVC
3) Partially unroofed coronary sinus
4) Azygos extension of IVC
3. Pulmonary vascular disease ; earlier onset than VSD
4. Down syndrome
1) Rare in partial form & common in complete form (75%)
2) Lt-sided obstruction & associated anomalies less common
3) Frequent advanced pulmonary disease

17. Diagnostic Considerations
depending on the size of the septal defects, the
direction and magnitude of the associated shunt, and
the associated lesions. Patients with partial AVSD
may have an asymptomatic cardiac murmur similar to
patients with secundum ASDs , when left AV valve
insufficiency is more pronounced, patients may have
symptoms of pulmonary congestion, cardiac failure,
and dyspnea
 Patients with complete AVSD are more likely to have
prominent left-to-right shunting and are similarly
more likely to have symptoms of congestive heart
failure, fatigue, and dyspnea.

18. Diagnostic Considerations
Physical examination often reveals a variety of cardiac
murmurs. A systolic ejection murmur may be found in the
pulmonary area because of increased flow across the
pulmonary valve. A holosystolic apical murmur is also
present when left AV valve regurgitation is significant. The
ASD and VSD may also have associated cardiac murmurs.
chest radiograph often reveals enlargement of the pulmonary
artery. The film may also show right ventricular hypertrophy
as symptoms of failure progress and left ventricular enlargement with
significant left AV valve regurgitation
electrocardiogram often reveals right ventricular
hypertrophy and sometimes left ventricular
hypertrophy as well

19. Diagnostic Considerations
 Echocardiography is the modality of choice for
establishing a definitive diagnosis in the current era.
Two-dimensional echocardiography
along with color Doppler studies usually provide complete preoperative information
for both partial AVSD and complete AVSD.
Three-dimensional
echocardiography is undergoing assessment in a number of centers and may ultimately help in the
surgeon's understanding
of AV valve morphology and in the planning of surgery
 Catheterization is required only when clinical evidence of pulmonary vascular disease exists, making
operability questionable, or when additional major cardiac anomalies coexist . can also be used to
measure pressures, flows, and resistances in the pulmonary and systemic circuits as well as the
direction and the magnitude of shunting

20. Natural history
Partial defect
a) Survival (w/o tx) unusual beyond 40 yo
 b) Dysrhythmias common
 Complete defect
96% 5-yr mortality w/o treatment
 Surgery recommended at 3-4 months
 Associated abnormalities may preclude biventricular
repair - need PA band early in infancy

21. Indications for operation
1. Partial AV canal defect
 Optimal age for operation is 1-2 years of age except
when CHF or growth failure is evident earlier in life.
2.Complete AV canal defect
 Operation is indicated early in the 1st year of life
 when the infants general condition is good,
 repair can be delayed until 3-6 months of age.

22. Contraindications to surgery
are based on fixed severe elevation of pulmonary
vascular resistance. Pulmonary vascular resistance >10
units/m2
of body surface area (or a pulmonary-to-
systemic resistance ratio >0.7) represents a
contraindication to repair
Elevated pulmonary vascular resistance of <10
units/m2
(or a pulmonary-to-systemic resistance ratio
of <0.7) represents an indication for more urgent
surgical intervention
 The assessment of elevated pulmonary vascular resistance should
include cardiac catheterization under conditions of oxygen, nitric oxide,
and prostacyclin to assess reversibility

23. Techniques of Operation
1. Direction
1) Closure of atrial communication
2) Closure of ventricular communication
3) Avoidance of damage to conduction
4) Creation of two competent valves
2. Technique
1) Repair of partial AV canal defect
2) Repair of complete AV canal defect
one - patch technique
two - patch technique
3) Repair of associated cardiac anomalies

24. Partial A-V septal defect
1) Valve repair
a)Approximate tips (kissing edge) of left superior and
inferior leaflets with a suture - do not tie
b) This defines septal commisure (cleft)
c) Close cleft with interrupted 5-0 or 6-0 sutures
d) Some (Carpentier) recommend leaving three-leaflet valve
- can become severe regurgitation
e) Size valve according to BSA
2) Closure of ASD
a)Pericardial patch
b) Close CS into LA or RA

27. Repair of transitional atrioventricular (AV) canal defect. A, Transitional AV canal defect with a small
restrictive interventricular communication at the crest of the interventricular septum, between the
left superior leaflet (LSL) and the left inferior leaflet (LIL). B, A pledgeted suture is taken through the
crest of the interventricular septum, then through the LSL and LIL, to close the ventricular septal
defect (VSD). The mitral valve cleft is closed. Repair is completed by closure of the ostium primum
atrial septal defect (ASD) with a pericardial patch. (Modified from Castaneda AR, Jonas RA, Meyer JE
Jr, Hanley FL: Atrioventricular canal defect. In Castaneda AR, Jonas RA, Mayer JE Jr, Hanley FL,
editors: Cardiac Surgery of the Neonate and Infant. Philadelphia: W B. Saunders, 1994.(

28. Complete a-v septal defect
1) L A-V valve repair as above
2) Two-patch technique (Carpentier)
a)Superior bridging leaflet is not divided
b) VSD patch (dacron)
(1)Interrupted or running suture along right side of
ventricular septum
(2) Suture top edge of patch to middle of bridging leaflets
(3) Now close septal cleft
(4) Measure valve orifice
c) ASD patch (pericardium)
(1) Close CS into LA or RA

31. 2(One-patch technique
a) Superior common (bridging) leaflet is divided to
annulus (veering a bit to the right to increase Left
A-V valve orifice
b) Divide inferior bridging leaflet
c) Suture patch (Dacron or PTFE)to right side of
septum, staying 3-5mm from crest
d) Valve leaflets attached to patch w/ interrupted
sutures +/- pledgets
e) Closure of ASD as above (CS to LA or RA)

35. Special Features of Postoperative
Care
A. Pulmonary HTN
B. B. Reactive pulmonary vasculature
1) Fentanyl prophylaxis
2) Phenoxybenzamine
3) Prostacyclin
4) Nitric oxide
5) pO2 > 150mmHg
6) pCO2 < 35mmHg
 1. LAP is higher 6mmHg than CVP
suggest mitral valve stenosis or insufficiency
 2. PA hypertensive crisis
 3. Evaluation on Lt. AV valve regurgitation
: predispose the patient to death within 1 year

36. Results
A. Risks for premature sudden death:
1) Severe pre-op Left A-V valve incompetence
2) Poor status
3) Accessory A-V valve orifice
4) Down’s syndrome
B. 98% 1-yr, 96% 20-yr survival (Mayo)
1) Reoperation in 18 (9%)
C. Down’s syndrome
1) Survival not influenced
2) Fewer associated cardiac anomalies
D. Age - controversial
E. Date of operation - earlier = worse
F. Hanley - 7% re-operation for Left A-V valve problems
G. Higher mortality for complete w/o VSD

37. Summary
--AV canal defect under two main titles:
--Partial: without VSD.Repair is preferred electively in
the 1st
so when diagnosed year unless there are risk
factors
--Complete : Repair should be asearly as possible ,less
than 6 months old ,results are better after 1987.
--Questions ??? -- The best way to repair splitted mitral
and tricuspid components
--Two ventricle or one ventricle correction?