AVSD Flashcards
What are endocardial cushions
- Normally partition the fetal AV canal
o Dorsal endocardial cushion + septum primum → fuse to close ostium primum in IAS
o Dorsal + ventral endocardial cushion → fuse to divide L and R AV canal
What is the atrioventricular septum
btw LVOT and RA
Normally, MV is higher vs TV
Etiology of AVSD
failure of primitive AV canal to separate → incomplete/lack of fusion of superior and inferior endocardial cushions
* Communication btw all 4 chambers
* From abnormal development of endocardial cushions
o Failure to fuse leads to abnormally longer LVOT
Low AV valves
High AoV
o Absence of atrioventricular septum → common AV orifice w common fibrous ring
5 leaflet valve: L and R mural leaflets, R cranial-ventral leaflet, 2 bridging leaflets
Abnormal pap muscle position: cranial and caudal
Rastelli classification
Classification will depend on how bridging leaflets connect to each other
Pathophys
- ASD: allow blood to flow from LA → RA
- Systole: equal pressures in L and R heart
o VSD: allow blood to flow from LV → RV
o AV valve regurgitation: blood flow from LV → LA + RA - Diastole: atrial blood flow → RV or LV
- L to R shunting + regurgitation → severe bilateral atrial + ventricular volume overload
- Pulmonary hypertension initially from ↑ pulmonary blood flow
o Pulmonary arterial pathology develops over time → ↑PVR
o Eisenmenger physiology: can result in reversal of shunting in R to L if PVR > SVR
Clinical features/progression
- CHF/death at young age
- Stunted growth
- Loud systolic murmur over cranial ventral thorax
- CTX: cardiomegaly, ECG: BBB
Echo
R parasternal 4 chamber view
o Large ASD and VSD
o Dysplastic MV and TV OR 1 common AV valve
o RA, RV, LA +/- LV dilation
o Disorganized color flow on Doppler: defects are so large that hard to determine direction of flow
Type A rastelli
most common
o Anterior bridging leaflet inserts along anterosuperior rim of IVS
Commissure w R sided anterior leaflet
o Distinct medial papillary muscle OR multiple direct chordal insertions along septum
Below commissure
o Ventricular communication minimal/absent → chordal fusion
Type B Rastelli
least common
o Larger anterior bridging leaflet
Straddles septum, dividing at RV pap muscle
Associated with pap muscle attachment on septal/moderator band
o Smaller R sided anterior leaflet (vs type A)
o Free ventricular communication → chordal anchors not present
Type C rastelli
often with other congenital anomalies
o Free floating/undivided superior leaflet = extreme bridging
o Largest anterior bridging leaflet compared to other types
o Medial pap muscle attachment fused to R sided anterior pap muscle
o Free ventricular communication → bridging leaflet not attached to septum
Type of AVSD
Complete
Intermediate
Transitional
Partial
Complete AVSD
- Primum ASD → often large
- Inlet VSD → unrestrictive
- Common AV valve with single annulus
o Often include common septal leaflet serving both ventricles
Contain cleft/notches → regurgitation
Intermediate AVSD
- Primum ASD: often large
- Inlet VSD
- Distinct R and L AV valve orifices
Transitional AVSD
- Primum ASD
- Small inlet VSD → restrictive
o Partially occluded by dense chordal attachments - Distinct MV and TV annuli
Partial/incomplete AVSD
- Primum ASD
o NO VSD → ASD physiology - Distinct MV and TV annuli
o MV cleft
Double outlet RA: etiology
- Extreme leftward deviation of lower IAS
o Fuse w/ medial aspect of endocardial cushion → malignment of IAS and IVS
o Abnormal atrial balance - Large primum ASD
DORA pathophys
- RA empty in both RV and LV
- True LA: supravalvular obstruction of inflow
o Receive all PVs
o Normal LAA
Classification DORA
A. Leftward atrial septal malalignment, 1 AV valve
B. Leftward atrial septal malalignment, 2 AV valve
C. Rightward ventricular septal malalignment, 3 AV valves, adequate RV
D. Rightward ventricular septal malalignment, 3 AV valves, hypoplastic RV
Common features on gross path
- Primum ASD, variable size
- Absent AV septum
- AV valve insert at same level at heart crux
o ↓ distance to LV apex - Elongated LVOT: goose neck
- Anterior/unwedge Ao
- Left AV valve cleft → MR
Balanced
AV inlet equally shared
Unbalanced
1 ventricle hypoplastic and other dominant
What is most important for pathophys
Defect size
C/s
- CHF/death at young age
- Stunted growth
PE
- Auscultation
o Loud apical holosystolic murmur (MR) over cranial ventral thorax
o Systolic basilar ejection murmur: relative PS
CTX
- Cardiomegaly
- Pulmonary overcirculation
ECG
- BBB
- ↑PR from displacement of AV conduction tissue
- L axis deviation
Echo
- R parasternal 4 chamber view
o Large ASD and VSD
o Dysplastic MV and TV OR 1 common AV valve
o RA, RV, LA +/- LV dilation
o Disorganized color flow on Doppler: defects are so large that hard to determine direction of flow
Echo: all types will have
o Inlet VSD
o Inferior displacement of AV valves (cardiac crux)
o MV attachment to septum