Atrioventricular Septal Defect

Slide 1

Atrioventricular Septal DefectDr Ranjith MPSenior ResidentDepartment of CardiologyGovernment Medical collegeKozhikodeAtrioventricular Septal Defects are characterized by complete absence of AV septum

Additional featuresA common atrioventricular ringA five leaflet valve that guards the common AV orificeAn unwedged left ventricular outflow tractLV 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, canalis atrioventricularis communis, persistent atrioventricular ostiumDefinition2AVSDs account for 4% to 5% of congenital heart disease

New England Regional Infant Cardiac Program - 0.118/1000 livebirths

BaltimoreWashington 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

Incidence3Rogers, 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 oxygenatorHistorical note4Result from Faulty development of the endocardial cushions and of the atrioventricular septum

In partial AVSDs, incomplete fusion of the superior and inferior 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 cushionsEmbryogenesis5

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

Embryogenesis6

7In 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

Embryogenesis

Morphoogy8

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. 9Anatomical Classification of AVSD(Rastellis, 1996)

Relation Between the Associated Anomalies andRastelli Classification10

Kiyoshi suzuki et al J Am Coll Cardiol 1998;31:21723Partial AVSD Most common 20 ASD & LSVC to CSLess 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

Associated anomalies11Clinical characteristics of genetic disorders associated with AVSD12

M. Cristina Digilio et alCardiogenetics 2011; 1:e713

M. Cristina Digilio et alCardiogenetics 2011; 1:e7

Clinical characteristics of genetic disorders associated with AVSD14M. Cristina Digilio et alCardiogenetics 2011; 1:e7Clinical characteristics of genetic disorders associated with AVSD

Anatomy of AVSD expected to demonstrate one or more of the following hemodynamic changesShunting across the atrial septal defectShunting through the ventricular septal defectMitral regurgitationTricuspid regurgitation

Patterns of shunting: obligatory shuntingHemodynamic changes15Greater 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 birthHemodynamic changes16

Fetal physiologyInfants 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 birthHemodynamic changes17

Early infancyPulmonary 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 resistanceHemodynamic changes18

later infancyPartial AVSDPatients 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 atriumPatients with 10 ASD usually have earlier and more severe symptoms than patients with 20 ASD

Complete AVSDTachypnea 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

Clinical manifestations19Physical examination20

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 ECGSuperior QRS axis with the QRS axis between -40 and -1500Most of the patients have a prolonged PR intervalMore than 50% have atrial enlargementRVH 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 LVHChest X-rayIn 10 ASD findings are same as 20 ASD except for enlargement of the LA & LV when MR is significantIn complete AVSD cardiomegaly is always present and involves all four cardiac chambers. Pulmonary vascular markings are increased, and the main PA segment is prominentECG & X-ray21

Primary imaging technique for diagnosing AVSDThe internal cardiac crux is the most consistent imaging landmarkApical four-chamber imaging plane clearly visualizes the internal crux The 10 ASD is seen as an absence of the lower IAS

Echocardiography22

Several echocardiac features are shared by all forms of AVSD: Deficiency of a portion of the inlet ventricular septum Inferior displacement of the AV valvesAttachment of a portion of the left AV valve to the septumThe two separate AV valve orifices are equidistant from the cardiac apex

23Echocardiography

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

Echocardiography24

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

Echocardiography25

Echocardiography-126



Echocardiography-129Echocardiography-230






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

Documents

Atrioventricular Septal Defect