AVSD

Question 1

What are endocardial cushions

Answer 1

• 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

Question 2

What is the atrioventricular septum

Answer 2

btw LVOT and RA

Normally, MV is higher vs TV

Question 3

Etiology of AVSD

Answer 3

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

Question 4

Rastelli classification

Answer 4

Classification will depend on how bridging leaflets connect to each other

Question 5

Pathophys

Answer 5

• 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

Question 6

Clinical features/progression

Answer 6

• CHF/death at young age
• Stunted growth
• Loud systolic murmur over cranial ventral thorax
• CTX: cardiomegaly, ECG: BBB

Question 7

Echo

Answer 7

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

Question 8

Type A rastelli

Answer 8

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

Question 9

Type B Rastelli

Answer 9

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

Question 10

Type C rastelli

Answer 10

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

Question 11

Type of AVSD

Answer 11

Complete
Intermediate
Transitional
Partial

Question 12

Complete AVSD

Answer 12

• 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

Question 13

Intermediate AVSD

Answer 13

• Primum ASD: often large
• Inlet VSD
• Distinct R and L AV valve orifices

Question 14

Transitional AVSD

Answer 14

• Primum ASD
• Small inlet VSD → restrictive
  o Partially occluded by dense chordal attachments
• Distinct MV and TV annuli

Question 15

Partial/incomplete AVSD

Answer 15

• Primum ASD
  o NO VSD → ASD physiology
• Distinct MV and TV annuli
  o MV cleft

Question 16

Double outlet RA: etiology

Answer 16

• 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

Question 17

DORA pathophys

Answer 17

• RA empty in both RV and LV
• True LA: supravalvular obstruction of inflow
  o Receive all PVs
  o Normal LAA

Question 18

Classification DORA

Answer 18

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