Morphology

Question 1

Features to describe

Answer 1

3 Segments: Atria, Ventricles, Arteries

2 Junctions: AV and VA

Question 2

Atrial Morphology

Answer 2

LA:
Long, tubular hooked appendage with narrow junction to the main atrial compartment

RA:
Triangular appendage with broad junction

Question 3

Atrial Arrangements

Answer 3

Usual (Situs solitus)
Mirror-Image (Situs inversus)
Isomeric left or right

Question 4

Left Ventricle Morphology

Answer 4

MV ALWAYS goes with LV
- not attached to the septum, instead shares fibrous continuity with the aortic valve

Fine apical trabeculation

Question 5

Right Ventricle Morphology

Answer 5

TV ALWAYS goes with RV
- septal leaflet is attached to septum

Moderator band from septum to free wall, joining the anterior papillary muscle

Course apical trabeculation

Question 6

Biventricular Atrioventricular Connections

Answer 6

Concordant (Usual or mirror-image atria)
Discordant (Usual or mirror-image atria)
Ambiguous (Isomeric atria)

Question 7

Univentricular AV Connection

Answer 7

Usually two ventricles, but one dominates and the other lacks direct AV connection

Dominant ventricle may have single or double atrial inlet

Describe the absent AV connection

Question 8

Absent Ventricle

Answer 8

Failed connection of an atrium to the ventricle causes its absence within the first 58 days of development

Seen at 12-14w echo, either absent flow or no crossover

Question 9

Areas of CHDs

Answer 9

Inflow Tract
Atrial Suptum
AV Junction
Ventricular Septum
VA Junction
Outflow Tract

Question 10

Atrial Septum

Answer 10

Patent Foramen Ovale

• Tissue flap covers the hole, only shunting if uncovered under certain conditions.
• Muscle thickens the fibrous layer

ASD (Oval fossa defect)

• Not enough tissue covering the oval fossa, continuous shunting of blood
• Fibrous/Muscular fenestrations (like a web)

Question 11

Conduction

Answer 11

AP from SAN propagates through specifically orientated atrial myocardium (not dedicated conduction tissue)

AVN surrounded by fibrous-fatty tissue to isolate it from the ventricles

Penetrating bundle of His carries AP down ventricular septum (splits to R+L bundle)

Purkinje fibres carry AP from apex, rapidly up the ventricles

Question 12

The AV node

Answer 12

Found in the triangle of Koch, its borders are:

• The Tricuspid valve
• The Coronary sinus
• The Eustachian valve *
• acts in the foetal heart at the IVC, to shunt oxygenated, placental blood from the RA to the LA.

Question 13

VSD and possible locations

Answer 13

• Failure off descending septum primum and ascending ventricular septum to fully fuse
• Adjacent to AV or VA junction
• Underneath/Overridden by a valvular orifice

Question 14

Morphologic Features of VSD

Answer 14

• 90% involve the membraneous septum

Infundibular VSD: Below the PV

Muscular VSD: Often multiple holes in the muscular septum

Question 15

Considerations in VSDs

Answer 15

• Margins of the defect
• Direction of communication (initially from LV to RV, then possibly reversed in pulm.HTN)
• Relationship of defects to conduction tissue
• Malalignment of the fused septa

Question 16

Size in VSDs

Answer 16

• Small holes may close over spontaneously

- Large holes may leak underneath both OFTs and won’t close spontaneously

Question 17

Peri-membraneous VSD

Answer 17

• Most common form of VSD (~80%)

- Partly muscular rim, part of rim is continuous with the membraneous septum

Question 18

Muscular VSD

Answer 18

• Second-most common form of VSD (~17%)
• Muscle forms the entire border of the defect, conduction system is not nearby
• Located in inlet, outlet or apical regions

Question 19

Doubly-committed and Juxta-arterial VSD

Answer 19

• Rare (~3%)
• Hole is underneath the aortic and pulmonary valves
• AV and PV and normally offset (angle and level) but are adjacent here

Question 20

Normal AV Junction

Answer 20

• Aorta should be in the centre

- TV and MV should surround it like a figure-of-8

Question 21

AVSD

• Cause
• Structure
• AVN

Answer 21

• When AV cushions do not fully separate in development, a large 5-leaflet valve may form
• May have one common orifice, if superior and inferior bridging leaflets fuse then may have two
• AVN deviated, sits at AV myocardial border

Question 22

Variation in AVSD shunting

Answer 22

Varied by the bridging leaflet attachments:

• VS: interatrial shunting
• AS: interventricular shunting
• Floating bridging leaflets: IA and IV shunting

Question 23

Length of Outlet

Answer 23

• Longer outlet is less efficient

- Risk of OFT obstruction

Question 24

Tetralogy of Fallot

Answer 24

1. Narrowed pulmonary outlet
2. Large VSD (underneath the RVOFT)
3. Overriding aorta (supplied by both ventricles)
4. Hypertrophy of RV

Question 25

Ebstein Malformation

Answer 25

- Failure of TV to delaminate away from the RV wall - TV is deep within the ventricle - RV volume decreased (essentially absent RV)

Question 26

Bicuspid AV

Answer 26

- One of the most common genetic variations in man - sometimes due to congenital lack of 3rd leaflet - sometimes due to fusion of 2 of the 3 leaflets

Question 27

Common Arterial Trunk

Answer 27

- Failure of the OFT to divide | - All blood leaves the heart via a common truncus

Question 28

Arterial duct - Patent duct - Coarctation of the aorta

Answer 28

- In foetus, a duct feeds the pulmonary vessels - After birth, pulmonary blood pressure increases, ductal cushions emerge and thicken, duct closes and may remain as a ligament or disappear completely Patent duct: May stay open, mixing blood Coarctation: ductal tissue may constrict the aortic arch

Question 29

Double-committed or juxta-arterial VSD

Answer 29

- More rare form of VSD (~3%) | - VSD beneath the AV and PV (they are normally offset in angle and level but are next to each other in this condition)

Question 30

Absent Ventricle - Imaging - Treatment

Answer 30

- Failure of A and V to connect Imaging - 12-14w echo - flow disturbance (no aorta-pulm cross-over) Treatment - Surgery, usually leaving single ventricle heart

Question 31

Absent Left Ventricle (LA inlet and LV outlet missing) | - Blood route

Answer 31

- Enters RA - Goes to LA (ASD) - LV - Goes to RV (VSD) - Pulmonary trunk

Question 32

AV Valve Defects

Answer 32

- Imperforate, stenotic, common valve In VSD - Valve, chordae or both may overlie the septum