dr ranjith mp av canal defect

Dr Ranjith MPSenior Resident

Department of CardiologyGovernment Medical college

Kozhikode

Atrioventricular Septal Defects are characterized by complete absence of AV septum

Additional features

A common atrioventricular ring

A five leaflet valve that guards the common AV orifice

An unwedged left ventricular outflow tract

LV mass characterized by longer distance from apex to aortic valve than from apex to left AV valve

Also known as Endocardial cushion defect, AV canal defect, canalisatrioventricularis communis, persistent atrioventricular ostium

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AVSDs account for 4% to 5% of congenital heart disease

New England Regional Infant Cardiac Program - 0.118/1000 livebirths

Baltimore–Washington Infant study defined a prevalence of 0.362

The Alberta Heritage study the prevalence was 0.203 and 0.242 per 1000 live births using invasive or noninvasive methodology for the diagnosis respectively

Gender distribution is approximately equal or may show a slight female preponderance

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Rogers, Edwards : Recognised morphology of 10ASD 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

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Result from Faulty development of the endocardial cushions and of the atrioventricular septum

In partial AVSDs, incompletefusion of the superior andinferior endocardial cushions results in a cleft in the midportion of the AML , often associated with MR

Complete AVSD associated with lack of fusion between the superior and inferior cushions

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Mitral & tricuspid valves achieve the same septal insertion level because the mitral annulus is displaced toward the apex

The distance from mitral annulus

to the left ventricular apex is less

than the distance from the aortic

annulus to the apex

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In the normal heart, the aortic valve is wedged between the mitral and tricuspid annuli. In AVSD the aortic valve is displaced anteriorly and creates an elongated, so-called gooseneck deformity of the LVOT

Based on the relationships of the anterior bridging leaflets to the crest of the ventricular septum or RV papillary muscles

Rastelli type A : the anterior bridging leaflet is tightly tethered to the crest of the IVS, occurring in 50% to 70%

Rastelli type B : (3%), the anterior bridging leaflet is not attached to the IVS; rather, it is attached to an anomalous RV papillary muscle and is almost always associated with unbalanced AV canal with right dominance

Rastelli type C : (30%) a free-floating anterior leaflet is attached to the anterior papillary muscle.

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Kiyoshi suzuki et al J Am Coll Cardiol 1998;31:217–23

Partial AVSD Most common 20 ASD & LSVC to CS

Less frequently- PS, TS or atresia, cor triatriatum, CoA, PDA, membranous VSD, PV anomalies, and HLV

Complete AVSD Type A usually is an isolated defect and is frequent in patients

with Down syndrome.

Type C – TOF, DORV, TGA and heterotaxy syndromes

The combination of type C complete AVSD with TOF is observed Down's syndrome, whereas DORV is a feature of patients with asplenia

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M. Cristina Digilio et alCardiogenetics 2011; 1:e7

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Anatomy of AVSD expected to demonstrate one or more of the following hemodynamic changes Shunting across the atrial septal defect

Shunting through the ventricular septal defect

Mitral regurgitation

Tricuspid regurgitation

Patterns of shunting: obligatory shunting

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Greater proportion of SVC blood with a low oxygen saturation may cross the IAS to the LA

If AV insufficiency were present blood being ejected from LV to RA

Increase the PO2 of blood in RA, RV, PA

Slightly higher PO2 of blood perfusing the lungs would decrease pulmonary vasoconstriction and increase pulmonary blood flow

It is possible that the lesser degree of constriction of the pulmonary arterioles may retard the development of a thick medial muscle layer, so that a more rapid decrease in PVR may occur after birth

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Fetal physiology

Infants with ostium 10 defect usually present the same hemodynamic features as those with 20 ASD

As PVR falls after birth, RV after load falls & RV stroke volume increases and exceeds that of the LV. The RV fills preferentially and thus left-to right shunting occurs through the ASD

MR and LV to RA shunting are not usually prominent features in infants with 10 defect

If MR present, in early infancy cardiac failure develops within weeks after birth

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Early infancy

Pulmonary blood flow is increased even though PVR may still be high, because shunting occurs from a high-pressure to a low-pressure chamber

The increased pulmonary blood flow and PA pressure interfere with the normal postnatal maturation of the pulmonary arterioles

The thick medial muscle layer is maintained and the fall in PR is delayed

An interesting association may develop in some infants of an obligatory left-to-right shunt through the atrioventricular septal defect and simultaneous right-to-left shunting through the ductus arteriosus

Pulmonary vascular resistance may be increased above systemic arterial resistance

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later infancy

Partial AVSD

Patients with 10 ASD are usually asymptomatic during childhood.

Dyspnea, easy fatigability, recurrent RTI and growth retardation may be present early in life if associated with major MR or common atrium

Patients with 10 ASD usually have earlier and more severe symptoms than patients with 20 ASD

Complete AVSD

Tachypnea and failure to thrive invariably occur early in infancy & virtually all patients have symptoms by 1 year of age.

If these symptoms do not develop early on, the clinician should suspect premature development of pulmonary vascular obstructive disease

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Usually undernourished and have signs of CHF

Hyperactive precordium with a systolic thrill at the lower left sternal border is common

S1 is accentuated. S2 narrowly splits, P2 increases in intensity.

A grade 3 to 4/6 holosystolic murmur

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

Chest X-ray

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

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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

The 10 ASD is seen as an absence of the lower IAS

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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

Attachment of a portion of the left AV valve to the septum

The two separate AV valve orifices are equidistant from the cardiac apex

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

Rarely parachute mitral valve and double-orifice mitral valve also occur

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In the transitional form of partial AVSD, there is aneurysmalreplacement of a portion of the inlet ventricular septum

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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

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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%

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The LV angiogram shows features characteristic of AVCD& are best revealed in the hepatoclavicular orientation

The LV outflow tract is elongated and appears narrow

A concavity of the medial border LV that extends along the outflow region to the aorta due to the abnormal attachment of the AML. If it attaches to the ventricular septum or right papillary muscle, LVOT obstruction may be evident

Detect AV valve regurgitation

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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)

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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

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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

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The complete form of AVSD is the most frequent type of CHD associated with trisomy 21

70% of children with complete AVCD display this aneuploidy

Children with Down syndrome show a simple form of AVCD which is usually complete & rarely associated with additional cardiac anomalies (with the only notable exception of TOF)

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Left-sided obstructive lesions are significantly rare in children with AVCD and Down syndrome compared to patients with AVCD without Down syndrome

Accordingly, some types of situs abnormalities such as l-loop of the ventricles, atresia of the AV valves and TGA are virtually absent in subjects with Down syndrome

Surgical correction of AVCD in individuals with Down syndrome results in lower mortality and morbidity rates, compared to the children without trisomy (12.6% Vs 17.8%)

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Patients are at increased risk for the development of pulmonary vascular obstructive disease

These patients have a greater degree of elevation of pulmonary vascular resistance in the first year of life and more rapid progression to fixed pulmonary vascular obstruction than patients without Down syndrome

Chronic upper airway obstruction with macroglossia and an inherently small hypopharynx, hypotonia, the predisposition to chronic infection, an abnormal capillary bed morphology, and the suggestion of pulmonary hypoplasia can all adversely affect the pulmonary vascular bed

surgical correction should be carried out by 6 months

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Incidence 1% in unoperated cases

Higher incidence in operated cases

10% may require reoperation to relieve LVOT obstruction

more common in partial than in complete AVSD

Etiology Attachments of SBL to ventricular septum

Extension of the anterolateral papillary muscle into LVOT

Discrete fibrous subaortic stenosis

Tissue from an aneurysm of the membranous septum bowing into the LVOT

Septal hypertrophy

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Systolic (left) and diastolic (right) echocardiographics demonstrating LVOT obstruction in a 17-year-old who had repair of a partial AVSD at age 15 months

PA banding is now performed infrequently in infants with AVSD because the surgical risks of intracardiac repair are not significantly greater than the palliative procedure

Perioperative mortality is about 5%

It is reserved for those few patients in whom intracardiac repair is likely to be associated with a high risk like Single papillary muscle

Severe left ventricular outflow obstruction

Unbalanced commitment of the AV valve to the ventricles

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Objectives - closure of the interatrial communication and restoration and preservation of left AV valve competence

These objectives can be accomplished by careful approximation of the edges of the valve cleft with interrupted nonabsorbable sutures

The repair is completed by closure of the interatrial communication (usually with an autologous pericardial patch), avoiding injury to the conduction tissue

This repair results in a two-leaflet valve

Alternatively, if the left AV valve is to be considered a trileaflet valve, with the cleft viewed as a commissure, surgical repair demands that this commissure be left unsutured and that various annuloplastic sutures be placed to promote coaptation of the three leaflets

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A: Surgical exposure

B: Closure of the mitral valve cleft

C: Prosthetic patch closure of an 10 defect

D: Repair completed

Surgical repair of complete forms of AVSD is indicated earlier in life than for the partial forms of AVSD

Repair should be done electively before 6 months of age & earlier repair should be considered for infants with failure to thrive

For the symptomatic infant, surgical options include palliative pulmonary artery banding and complete repair of the anomaly

In the modern era complete repair appears to be the procedure of choice

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Closure of interatrial and interventricular communications, construction of two separate and competent AV valves from available leaflet tissue, and repair of associated defects

Techniques are based on the use of a single patch or double patch (separate atrial and ventricular patches) to close the ASD and VSD and then reconstruction of the left AV valve as a bileaflet valve

Some surgeons consider the cleft of the left AV valve, a true commissures and envision this valve as a trileaflet valve. This is the basis for Carpentier technique for repair of complete AVSD

The two-patch technique has become the method of choice

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52Carpentier technique for repair of complete AVSD with the double-patch technique.

Concept of a trileaflet left atrioventricular valve

The risk of hospital death for repair is 3%

Determinants of hospital mortality include CHF , cyanosis, failure to thrive, age at operation of <4 years, and moderate to severe MR

20- and 40-yr survivals after repair is 87% and 76% respectively

Closure of the mitral cleft and age <20 years at time of operation is associated with better survival

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Partial AVSD: Regurgitation or stenosis of the left AV valve Subaortic stenosis Residual recurrent ASD

Reoperation for MR occurs in 10% to 15% of survivors of primary repair of partial AVSD

Risk factors for reoperation include significant residual MR as assessed intraoperatively at the time of initial repair, the presence of a severely dysplastic mitral valve, and failure to close the cleft in the AML

Repeat repair is possible if valve dysplasia is not severe or when the mechanism of regurgitation is through an unsutured cleft

Replacement of the mitral valve may be required in the presence of a severely dysplastic valve

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Complete AVSD

Needed in 17% of patients during the first 20 years after surgical repair

Lesions requiring reoperation include - left and right AV valve regurgitation, left AV valve stenosis (native and prosthetic), and residual/recurrent ASDs or VSDs

Residual left AV valve regurgitation may result from inadequate surgical reconstruction

Right AV valve regurgitation requiring reoperation is rare . It is more apparent with the presence of PAH or in association with TOF with RV dysfunction owing to persistent RVOT obstruction or PR

Residual shunts are rare causes for late reoperation55

Parachute Deformity of the Mitral Valve Closure of the mitral cleft at the time of repair may result in an

obstructed mitral orifice

If the patient has significant AV valve regurgitation, valve replacement may be the only suitable option

Double-Orifice Mitral Valve The surgeon must resist the temptation of joining the two

orifices by incising the intervening leaflet tissue. The combined opening of both orifices is satisfactory for adequate mitral valve function

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Right or Left Ventricular Hypoplasia The only option for definitive surgical treatment is the modified

Fontan's procedure preceded by adequate pulmonary artery banding in infancy

Subaortic Stenosis If discovered at the time of initial preoperative evaluation,

subaortic stenosis tends to be of the fibromuscular membrane type and should be treated by appropriate resection during surgical repair

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Common atrium is characterized by near absence of the atrial septum

In the presence of two ventricles, it always is associated with an AVSD

Most patients with common atrium present in infancy with symptoms of excess pulmonary blood flow

These patients are symptomatic earlier in life than patients with only a 10 ASD

The precordium is hyperactive with a prominent RV impulse. S2 is widely split and fixed

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P2 intensity proportionate to the severity of pulmonary hypertension

An ESM present over the upper left sternal border. A distinct holosystolic murmur of MR may be heard at the apex. A middiastolic murmur commonly is detected over the lower left sternal border resulting from an increase in right atrial to right ventricular blood flow

The radiographic and electrocardiographic characteristics of patients with common atrium are indistinguishable from those with other forms of AVSD

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Echocardiography Subcostal four-chamber view is most suitable for accurate diagnosis

A muscle bundle or band coursing through the atrium should not be interpreted as an atrial septum

Cardiac Catheterization and Angiography The hemodynamic diagnosis of common atrium depends on the

demonstration of complete mixing of systemic and pulmonary venous blood

The oxygen saturations of pulmonary and systemic arterial blood are nearly identical

Pulmonary blood flow exceeds systemic flow, except in patients with PAH

Right ventricular pressure is increased more often than in 20 ASD or partial AVSD 60

If definitive repair is delayed, significant pulmonary vascular obstructive disease may develop more easily than in patients with secundum ASD or partial AVSD

Treatment Medical therapy -Digoxin and diuretic therapy are traditional

forms of therapy

Surgical repair, which should be performed early in life because the patient usually has symptoms and is at risk for developing pulmonary vascular obstructive disease

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One ventricle and its corresponding AV valve are hypoplasticwhile the other ventricle receives the larger portion of the common AV valve

The most common arrangement is a dominant right ventricle with a hypoplastic left ventricle

The left-sided component of the common AV valve may be stenotic after two-ventricle repair has been performed

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1. Down syndrome most commonly associated with Type A

2. Most common form complete AVCD is Type B.

3. Free interventricular communication exists in type A

4. In type A anterior bridging leaflet has been described as free floating

1. Sinus rhythm is present in most patients with a 1⁰ ASD

2. P-wave changes indicating right atrial, left atrial, or biatrialenlargement are seen in 54% of patients.

3. The mean QRS axis ranges from +30⁰ to +120⁰

4. ventricular volume overload results in the rsR or RSR pattern in the right precordial leads in 84%.

1. Single papillary muscle

2. Severe left ventricular outflow obstruction

3. Unbalanced commitment of the AV valve to the ventricles

4. Associated TOF

1. The only option for definitive surgical treatment in Right or Left Ventricular Hypoplasia is the modified Fontan's procedure preceded by adequate pulmonary artery banding in infancy

2. In double-orifice Mitral Valve, better results by joining two orifices by incising the intervening leaflet tissue

3. Closure of the mitral cleft at the time of repair may result in an obstructed mitral orifice in Parachute Deformity of the Mitral Valve

4. If discovered at the time of initial preoperative evaluation, subaorticstenosis tends to be of the fibromuscular membrane type & should be treated by appropriate resection during surgical repair

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1. Oxygen saturation step up from RA to RV

2. Mixed venous sample best represented by low SVC sample

3. Oxygen saturation 93 to 95 in pulmonary vein

4. Left atrial and left ventricular oxygen saturation is often decreased to as low as 86–88%

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1. Noonan syndrome

2. Down syndrome

3. CHARGE syndrome

4. Ellis-van creveld syndrome

1. 20- and 40-yr survivals after repair is 87% and 76% respectively

2. Closure of the mitral cleft and age <20 years at time of operation is associated with better survival

3. Right AV valve regurgitation requiring reoperation is rare

4. The risk of hospital death for repair is 12- 16%

1. Gender distribution is approximately equal or may show a slight female preponderance

2. A five leaflet valve that guards the common AV orifice

3. An wedged left ventricular outflow tract

4. LV mass characterized by longer distance from apex to aortic valve than from apex to left AV valve

1. Inferior displacement of the AV valves

2. The two separate AV valve orifices are not equidistant from the cardiac apex

3. The internal cardiac crux is the most consistent imaging landmark

4. Deficiency of a portion of the inlet ventricular septum

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1. Reoperation for MR occurs in 10% to 15% of survivors of primary repair of partial AVSD

2. Replacement of the mitral valve may be required in the presence of a severely dysplastic valve

3. Residual shunts are common causes for late reoperation

4. The risk of hospital death for repair is 3%

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1. Down syndrome most commonly associated with Type A

2. Most common form complete AVCD is Type B.

3. Free interventricular communication exists in type A

4. In type A anterior bridging leaflet has been described as free floating

1. Sinus rhythm is present in most patients with a 1⁰ ASD

2. P-wave changes indicating right atrial, left atrial, or biatrialenlargement are seen in 54% of patients.

3. The mean QRS axis ranges from +30⁰ to +120⁰

4. ventricular volume overload results in the rsR or RSR pattern in the right precordial leads in 84%.

1. Single papillary muscle

2. Severe left ventricular outflow obstruction

3. Unbalanced commitment of the AV valve to the ventricles

4. Associated TOF

1. The only option for definitive surgical treatment in Right or Left Ventricular Hypoplasia is the modified Fontan's procedure preceded by adequate pulmonary artery banding in infancy

2. In double-orifice Mitral Valve better results by joining two orifices by incising the intervening leaflet tissue

3. Closure of the mitral cleft at the time of repair may result in an obstructed mitral orifice in Parachute Deformity of the Mitral Valve

4. If discovered at the time of initial preoperative evaluation, subaorticstenosis tends to be of the fibromuscular membrane type & should be treated by appropriate resection during surgical repair

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1. Oxygen saturation step up from RA to RV

2. Mixed venous sample best represented by low SVC sample

3. Oxygen saturation 93 to 95 in pulmonary vein

4. Left atrial and left ventricular oxygen saturation is often decreased to as low as 86–88%

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1. Noonan syndrome

2. Down syndrome

3. CHARGE syndrome

4. Ellis-van creveld syndrome

1. 20- and 40-yr survivals after repair is 87% and 76% respectively

2. Closure of the mitral cleft and age <20 years at time of operation is associated with better survival

3. Right AV valve regurgitation requiring reoperation is rare

4. The risk of hospital death for repair is 12- 16%

1. Gender distribution is approximately equal or may show a slight female preponderance

2. A five leaflet valve that guards the common AV orifice

3. An wedged left ventricular outflow tract

4. LV mass characterized by longer distance from apex to aortic valve than from apex to left AV valve

1. Inferior displacement of the AV valves

2. The two separate AV valve orifices are not equidistant from the cardiac apex

3. The internal cardiac crux is the most consistent imaging landmark

4. Deficiency of a portion of the inlet ventricular septum

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1. Reoperation for MR occurs in 10% to 15% of survivors of primary repair of partial AVSD

2. Replacement of the mitral valve may be required in the presence of a severely dysplastic valve

3. Residual shunts are common causes for late reoperation

4. The risk of hospital death for repair is 3%

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dr ranjith mp av canal defect

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