UNIT 3 AVSD Anomalies

What is an atrioventricular septal defect, and list the 4 other names used for it.

An atrioventricular septal defect is characterized by what? with abnormalities where?

An atrioventricular septal defect is characterized by a deficiency in the AV septum with abnormalities of the inflow valves.

1. AVSD

2. Atrioventricular defect

3. AV canal defect

4. Endocardial cushion defect

(AV septal defects are between the IAS and Ventricular septum, its still more of the muscular portion of the ventricular septum will be in the inlet area and also the primum area of the Atrial spetum b/c of the location it causes inflow anomalies)

The pic shows the nob of tissue / button of the AVSD

List the 6 factors that determine the severity of an AVSD.

The severity of the defects are characterized by the involvement of:

• Involvement of the atrial septum

• Involvement of the ventricular septum

• Extent of the inflow-valve abnormalities

• Presence of a common annulus or 2 separate valve openings

• Associated cardiac anomalies

• Differences in ventricular size

List the 4 incidence and association facts about AVSDs.

1. Has a high association with what disease?

2. what % of children with what chromosomal abnormalities have AV canal defect***

3. They are associated with what abdominal situs?

4. what gender are they more common?

• High associated with congenital heart disease

• About 45% of children with trisomy 21 have an AV canal defect**

• They are associated with heterotaxy, including asplenia (bilateral Right siedness)

• They are more common in females

What embryologic abnormality causes an AVSD, and list the 4 structures normally formed with help from them^?

AVSDs result from abnormal development of the endocardial cushions.

The endocardial cushions help form:

1. Atrial septum

2. Ventricular septum

3. Septal leaflet of the tricuspid valve

4. Anterior leaflet of the mitral valve

List the 4 AVSD forms or subtypes.

• Partial AVSD

• Transitional AVSD

• Complete AVSD

• Incomplete AVSD

What structures are present in a partial AVSD? List 3

A partial AVSD consists of:

1. Primum ASD

2. Cleft mitral valve

It may also include a common atrium.

List the 3 main features of a transitional AVSD.

• Two separate AV valve annuli

• Primum ASD

• Inlet VSD

List the 4 main features of an intermediate AVSD.

• A single /one AV valve annulus

• The annulus is divided by tissue into right and left orifices / openings

• Primum ASD

• Large inlet VSD

Chat: It has one common AV valve annulus, but tissue divides it into two openings/right and left orifices.

Basically: one shared valve structure, two holes for blood to pass through.

List the 3 main components of a complete AVSD.

1. Primum ASD

2. Inlet VSD

3. One common AV valve with 5 leaflets

List the 5 leaflets of the common AV valve.

• Superior bridging leaflet

• Inferior bridging leaflet

• Anterior leaflet on the right side

• Right lateral leaflet

• Left lateral leaflet

List the 5 anatomical features shared by AVSDs.

1. what Level are the AV valves for all types? - what is the best view to see this?

2. How is the aortic valve placed?

3. what is the appearance of the LVOT?

4. How are the LV papillary muscles are rotated?

5. The (right ot left?) AV valve has a what component directed toward where?

• The right and left AV valves insert at the same level at the cardiac crux - A4C is the best view

• The aortic valve is unwedged and displaced anteriorly

• The LVOT is elongated

• The LV papillary muscles are rotated counterclockwise

• The left AV valve component has a cleft directed toward the ventricular septum

Why do the right and left inflow-valve components insert at the same level in AVSD?

The AV septal deficiency removes the normal offset between the valves, causing both inflow-valve components to insert at the same level.

How does an AVSD produce an elongated LVOT, and what appearance does it create? Name 3 views you can see this in?

The aortic valve is unwedged and displaced anteriorly. This lengthens the LV outflow tract and produces the gooseneck appearance.

(views PLAX, LVOT, A5C) (pic A is normal, B gooseneck appearance.

How does the relationship between the ventricular inlet and outlet differ in a normal heart versus AVSD?

In a normal heart, the inlet and outlet distances are equal. In an AVSD, the distance from the apex to the outflow tract is longer because the LVOT is elongated.

What papillary-muscle position occurs in all forms of AVSD, and what complication can it cause? what view can you see this in?

The LV papillary muscles rotate counterclockwise to approximately the 3-o’clock and 7-o’clock positions. This rotation may contribute to LVOT obstruction.

(in PSAX can see this)

What valve abnormality is found in a partial AV canal defect, and where is the opening directed?

A cleft of the anterior mitral valve leaflet is present, and the opening is directed toward the ventricular septum.

Common Valve - Rastelli Classifications:

What do the superior bridging leaflet corresponds to?

What does the inferior bridging leaflets represent? List 2

How many leaflets does the common valve have?

• The superior bridging leaflet corresponds to the anterior mitral leaflet.

• The inferior bridging leaflet represents fusion of the septal tricuspid leaflet with the inferior part of the anterior mitral leaflet.

• TV has 3 leaflets and MV 2 leafelts = 5 leafelts

What does the Rastelli classification evaluate?

It evaluates the superior bridging leaflet and how it attaches to the ventricular septum.

What is the best view for identifying the Rastelli classification? And which Type is the most common?

The subcostal short-axis view.

Type A is the most common

Describe Rastelli Type A.

The superior bridging leaflet is: Divided & Attached to the ventricular septum crest

Describe Rastelli Type B.

The superior bridging leaflet is:

1. Partially divided

2. Not attached directly to the septum

3. Connected by chordae from superior bridging leaflet to an RV papillary muscle near the septum

Describe Rastelli Type C.

The superior bridging leaflet is:

1. Undivided

2. Not attached to the ventricular septum

3. Free floating over the bridging leafelt

4. Attached to an RV free-wall papillary muscle

What papillary-muscle abnormality should be checked for, and with which AVSD type is it more common?

Look for a single papillary muscle, which is more common with a partial AVSD.

Why must atrial and ventricular balance be determined in AVSD?

Balance determines how what is distributed and helps decide whether the patient needs a _____-ventricle or __ - ventricular surgical repair.

Balance determines how blood flow is distributed and helps decide whether the patient needs a single-ventricle or biventricular surgical repair.

In unbalanced AVSDs which dominance is most common?

two-thirds are right dominant.

What does ventricular dominance mean in an AVSD?

The larger ventricle is called the dominant ventricle, while the opposite ventricle may be hypoplastic.

Describe an unbalanced AVSD with right-ventricular dominance.

The LV is hypoplastic, and more than half of the AV junction is committed to the RV.

List the 4 conditions commonly associated with partial and transitional AVSDs.

• Persistent left superior vena cava

• Pulmonary stenosis

• Ellis–van Creveld syndrome

• DiGeorge syndrome

List the 5 conditions commonly associated with complete and intermediate AVSDs.

• LVOT obstruction

• ******Patent ductus arteriosus*********

• Tetralogy of Fallot

• Down syndrome (complete AVSD, Trisomy 21)

• Double-orifice mitral valve

Explain the pathophysiology of a partial AVSD.

The cleft in the mitral valve prevents what and produces varing degrees of what?

The primum ASD causes what direction of atrial shunting?

The cleft in the mitral valve prevents complete closure and produces varying degrees of MR.

The primum ASD causes left-to-right atrial shunting.

Pathophysiology of a partial AVSD:

Together, the MR and ASD shunt create what? List 4

The combination of MR and ASD flow lead to a volume overload of

the right sided chambers

This increases the amount pulmonary blood flow and overtime

increases pulmonary vascular resistance and causes PHTN

(Dirctotic Notch flying W of pulmonary valve)

Pathophysiology for Transitional AV canal defects:

Why does a transitional AVSD behave similarly to a partial AVSD?

The inlet VSD is restrictive (small hole), so most of the shunting occurs between the atria through the primum ASD.

Explain the pathophysiology of an intermediate AVSD.

where does blood shunt across? what increases the amount of blood flow? what does the Inlet VSD add to what side of the heart causing what?

Blood shunts across the primum ASD, and MR increases the amount of blood flow. The inlet VSD also adds to the right-sided volume overload, causing dilation of the right heart.

Explain the pathophysiology of a complete AVSD.

The what valve is malformed and creating a what valve which results in varying degrees of what?

The MV is malformed and creating a common valve which results in varying degrees of MR

Explain the pathophysiology of a complete AVSD:

The primum ASD shunts blood in what direction?

The inlet VSD shunts blood from what direction?

The primum ASD shunts blood flow from left to right atrium

The inlet VSD shunts blood from the left to right ventricle

Explain the pathophysiology of a complete AVSD.

The combination of what (list 3) lead to a ____overload of the which chamber?

The combination of MR, VSD and ASD flow lead to a volume overload of the right and left chambers

Explain the pathophysiology of a complete AVSD.

What quickly leads to symptoms of congestive heart failure in early infancy?

The heavy workload on the heart and lungs to manage the excess pulmonary blood flow quickly leads to symptoms of congestive heart failure in early infancy

When do partial and transitional AVSDs usually present, and what are their symptoms similar to?

They may not present until early childhood, and their symptoms are similar to those of an ASD.

What finding can cause early congestive heart failure in partial or transitional AVSD?

Severe mitral valve regurgitation.

List the 6 clinical findings associated with intermediate and complete AVSDs.

• Holosystolic murmur, Split wide Fixed S2

• Congestive heart failure

• Frequent respiratory infections

• Poor growth and poor feeding

• Tachycardia or AV block

• Volume overload with pressure overload

What chest X-ray finding may occur with AVSD?

Cardiomegaly.

What ECG conduction abnormality may occur?

AV block.

How should the atrial septum, ventricular septum, and inflow valves be examined? List 4

Use careful, slow sweeps from posterior to anterior to evaluate:

1. Atrial septum

2. Ventricular septum

3. Inflow-valve morphology

4. Whether the AVSD is partial or complete

List the 5 things evaluated from the subcostal views.

and From subcostal sax determine 7

• Size of the ASD and VSD

• Location of the defects

• Shape of the defects

• Number of defects using 2D and color Doppler

• IVC for estimation of RAP

• From subcostal sax determine:

• Number of valve leaflets and whether there is a cleft or common valve

• Rastelli classification and ventricular balance

• Papillary-muscle rotation, number, and attachments

List the 4 findings assessed from PLAX.

• RV size and volume-overload pattern

• Gooseneck deformity of the LVOT

• Assess for MR

• LVOTO

List the 8 findings assessed from PSAX of the ventricle level

• Sweep from the base to apex to determine VSD size

• Determine whether the VSD is restrictive or nonrestrictive

• Evaluate inflow-valve morphology

• Identify the valve cleft and its attachment to the septum

• Assess mitral or left AV valve regurgitation

• Determine ventricular balance

• Identify papillary-muscle rotation

• Evaluate the Rastelli type

List the 3 additional findings assessed at the PSAX great-vessel level.

• PDA

• RVOT obstruction

• Tricuspid regurgitation

List the 11 assessment points from the apical four-chamber view.

• Size of the ASDs

• Location of the ASDs

• Shape of the ASDs

• Number of ASDs with 2D and color Doppler

• Peak velocities and gradients

• AV valve annuli inserting at the same level

• Left and right inflow-valve regurgitation or stenosis

• Regurgitant-volume and stenosis quantification

• Pulmonary-vein PW Doppler

• Balance of the atria and ventricles

• RVSP & QP/QS

List the 4 findings assessed from the apical five-chamber view.

• Gooseneck deformity of the LVOT

• RVOT obstruction

• LVOT obstruction

• Peak velocities and gradients across the LVOT - to get the TVI for the QP/QS

List the 2 main differential considerations for an AV canal defect.

• Single-ventricle anatomy

• Other types of AV canal defects (like Partial, transitional, intermediate or complete AVSD)

List the 3 Medical Management approaches for AVSD.

• Medications for heart failure

• Endocarditis prophylaxis

• Palliative pulmonary artery banding to reduce symptoms

What are the 2 main goals of AVSD surgery?

• Close all atrial and ventricular septal defects

• Create functional right and left AV valves

List the 5 surgical procedures that may be used to repair an AVSD.

• Patch repair of the ASD and VSD with either 1 or 2 patches

• Suture repair of the valve

• Division of the common leaflet

• Inflow-valve replacement when severe stenosis or regurgitation is present

• Resection of a subaortic obstruction

Post OP Echo Investigation:

List the 6 things that should be evaluated after AVSD repair.

• Residual ASD shunting

• Residual VSD shunting, including direction and gradients

• AV valve function and regurgitation

• AV valve stenosis

• Systolic and diastolic ventricular function

• RVSP and possible subaortic stenosis

Compare the 4 AVSD types by their main anatomical components.

• Partial: Primum ASD and cleft mitral valve

• Transitional: Primum ASD, restrictive inlet VSD, and 2 separate AV valve annuli

• Intermediate: Primum ASD, large inlet VSD, and one annulus divided into right and left openings

• Complete: Primum ASD, inlet VSD, and one common 5-leaflet AV valve