1. Atrioventricular Canal Defect
Seoul National University Hospital
Department of Thoracic & Cardiovascular Surgery

2. Atrioventricular Canal Defect
Definition
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.
AV septal defect
AV defect
ECD (Endocardial cushion defects)
Ostium primum atrial septal defects
Common AV orifice

3. Atrioventricular Canal Defect
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

4. Morphology of A-V Canal Defect (I)
1. Interatrial communication
1) Ostium primum ASD
2) Common atrium
entire limbus & fossa ovalis are absent
3) Absence of interatrial shunt
rarely, due to complete attachment
of Lt. AV valve to atrial septum
2. Interventricular communication
1) Partial form
2) Complete form
3. AV valves
1) Two AV valve orifice
2) Common AV valve orifice
3) Unusual AV valve
combination
4) Accessory orifice ; 5 %
5) Single papillary m.; 5 %
4. Ventricle
hypoplasia in 7%
5. Septal malalignment
6. LVOT or inflow obstruction
7. Conduction system
Lt axis deviation

5. Left Ventricular Outflow & Inflow Obstruction
Incidence
1% in unoperated
Higher incidence after operation
Etiology
1. Elongation & narrowing due to more extensive area
of direct fibrous continuity
2. Short, thick chordae that anchor to the crest of
ventricular septum
3. Bulging of anterolateral muscle bundle(m of Moulart)
4. Morphologically discrete subaortic membrane
or excrescences of aortic valve orifice
5. Abnormally positioned papillary muscle

6. Morphology of AV Canal Defect (II)
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

7. Types of AVSD

8. AV Septal Defect

9. Partial AVSD

10. Complete AVSD

11. Clinical Features and Diagnostic Criteria
1. Pathophysiology
1) Shunt at atrial, ventricle level
2) AV valve incompetence
. Prevalent in older patients with complete form
. Partial : 10-15%
. Complete : 20% (moderate), 15% (severe)
2. Symptoms and Signs
. Related to amount of shunt and AV valve regurgitation
3. Chest radiography
4. Electrocardiogram
5. Two-dimensional echocardiogram
6. Cardiac catheterization and cineangiogram
7. Special situation and associated defects

12. Natural History of ECD 1. Incidence 3) Complete form 1) 4% of CHD
(30-40% in Down syndrome)
2) High incidence (14%) born to
mother of ECD (other : 2-4%)
2. Type of ECD
1) Partial form, mild AV valve
incompetence
. favorable, similar to large ASD
2) Partial form, significant AV
valve incompetence
. 20% symptomatic in infancy
. Pulm. venous hypertension &
shunt
3) Complete form
. 80% unoperated on die by age
2 years
. Pulmonary vascular disease
under 1yr of age : 30%
under 2yr of age : 80%
under 3-5yr of age : 90%
3. Mode of death
1) Refractory CHF, recurrent
pulmonary infection
2) Valve incompetence and
pulmonary vascular disease

13. 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

14. c-AVSD ; Operative View

15. Partial AVSD

16. Complete AVSD (1)

17. Complete AVSD (2)

18. AVSD - Repair of Mitral Cleft

19. Results of Operation 1.Survival 1) early death
2) time related survival
2. Mode of death
1) early : acute cardiac failure and
pulmonary dysfunction
2) late : chronic or subacute
cardiac failure
3. Incremental risk factors for premature death
1) earlier date of operation
2) functional class
3) prerepair AV valve incompetence
4) interventricular communication
5) accessory valve orifice
6) major associated cardiac
anomalies
7) young age ; not now
8) Down syndrome
9) Single papillary m.
10) hypoplasia of ventricle
4. Heart block & arrhythmia
5. Functional class
6. AV valve function
7. LVOT obstruction
8. Residual pulmonary hypertension

20. 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.

21. Special Situation & Controversies
1. Pulmonary artery banding
2. Septal patches
1) Atrial
2) Ventricle
3. McGoon method of avoiding heart block
4. Fontan-type repair

22. Special Features of Postoperative Care
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