Download Atrioventricular Canal Defect

Atrioventricular Septal Defect
Seoul National University Hospital
Department of Thoracic & Cardiovascular Surgery
Atrioventricular Septal 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
Atrioventricular Septal Defect
• Historical note
Rogers, Edwards : Recognized morphology of ostium
primum ASD in 1948
Wakai, Edwards : Term of partial and complete AV
canal defect in 1956
Bharati & Lev : Term of intermediate & transitional
in 1980
Ugarte : Term of leaflet bridging ventricular septum
in 1976
Rastelli : Described the morphology of common anterior
leaflet in 1966
Lillehei : 1st repair of complete AV canal defect
using cross circulation in 1954
Kirklin, Watkins, Gross ; Open repair using oxygenator
Atrioventricular Septum
• That portion of cardiac septum which lies between the
right atrium and the left ventricle
• It consists of a superior membranous portion and an
inferior muscular portion
• The atrioventricular septum is apparent because the
septal attachment of tricuspid valve is more apical than
the mitral valve
• The AV node lies in the atrial septum adjacent to the
junction between the membranous and muscular
portions of atrioventricular septum, and His bundle
passes toward the right trigone between these two
components
Atrioventricular Septal Defect
Pathophysiology
• Partial AV canal defects result from the failure of the
endocardial cushions to meet the septum primum
producing a low-lying (ostium primum) defect in the
atrial septum ; a cleft mitral valve is also usually present.
• Complete AV canal defects result from maldevelopment of
the endocardial cushions, producing a single, common AV
valve & VSD in addition to an ostium primum ASD.
• Pathophysiology results from left-to-right shunting at the
atrial and/or ventricular level as well as AV valve
insufficiency, producing pulmonary overcirculation and
congestive heart failure, particularly during early infancy.
Morphology of A-V Septal 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 AV valve tissue 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 obst.
7. Conduction system; LAD
Morphology of AV Septal 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
Atrioventricular Septal Defect
LV Outflow & Inflow Obstruction
• Incidence
1% in unoperated cases
Higher incidence after operation
• Etiology
1. Elongation & narrowing due to more extensive area
of direct fibrous continuity aortic valve & LSL
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
Schematic Drawings of AVSD
Partial AVSD
Complete AVSD
LVOT and AV Septal Defect
Normal
AVSD
After Repair
Clinical Features and Diagnosis
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
. Common atrium , Lt SVC, Isomerism, LVOTO
Natural History of AVSD
1. Incidence
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
. PV 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
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
AV Valve Repair in AVSD
Principles
• The most anterior point of LSL-LIL opposing edge
should be found and sutured through it, and the
anterior edges be sutured to the polyester patch
• The patch must be appropriate dimension &
configuration and tailoring the waist of the patch is
critical
• Remodeling leaflet closure by suturing portions of left
superior leaflet and left inferior leaflet together in areas
of regurgitation.
• Annuloplasty at commissure and making the edge of
the pericardial patch along it shorter than the
combined length of the base of leaflet
AV Septal Defect
Complete AVSD. Operative View
Partial
AVSD
Complete AVSD
Septal Patch for AVSD Repair
Too wide patch, theoretically left ventricular outflow obstruction &
long patch with high AV valve level, possible AV valve regurgitation
Complete
AVSD (1)
Complete
AVSD (2)
AVSD. Repair of Mitral Cleft
Partial Annular Plication
• Two furling stitches with 3 pledgets or three furling stitches with 4
pledgets are placed along the annulus of either or both sides for
mitral valve regurgitation
AV Valve Replacement
After AVSD Repair
• Lengthening the mitral-aortic septum, thus the valve is
well away from the LVOT
Features of Postoperative Care
1. Vigilance must be exercised to detect any
important imperfections in the repair
2. LAP is higher 6 mmHg than CVP
: suggest mitral valve stenosis or insufficiency
3. Prophylaxis against PA hypertensive crisis
4. Evaluation on left AV valve regurgitation
: predispose patient to death within 1 year
5. Evaluation of left to right shunt
6. Reoperation is indicated in severe regurgitation
and significant residual shunt
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) need for reoperation
10) single papillary m.
11) hypoplasia of ventricle
4. Heart block & arrhythmia
5. Functional class
6. AV valve function
7. LVOT obstruction
8. Residual pulmonary
hypertension
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.
3. Coexisting cardiac anomalies
Although certain major cardiac anomalies increase
risk of AVSD, their presence rarely alters the
indication for operation
Special Situation & Controversies
1. Pulmonary artery banding
2. Septal patches
1) Atrial
2) Ventricle
3. Avoiding heart block
4. Hypoplastic ventricle
5. Late reoperation
6. Extended atrial patch repair for c-AVSD
Isolated Cleft Mitral Valve
• Morphogenetically, there are two types: ICMV with
normally related great arteries, and ICMV with
abnormal conus associated with transposition in D- or
L-ventricular loops or DORV.
• The group with normally related great arteries shares
several characteristics with complete forms of AV canal
and considered as a milder variation of the AV canal.
In this group, the mitral valve cleft results in progressive
mitral regurgitation.
• The group with abnormal conus is characterized by the
presence of a conoventricular VSD & lack of similarities
with AV canal malformations.
Mitral valve cleft is seldom associated with significant
mitral regurgitation but often produces obstruction of
left ventricular outflow tract.