Morphology Flashcards
Features to describe
3 Segments: Atria, Ventricles, Arteries
2 Junctions: AV and VA
Atrial Morphology
LA:
Long, tubular hooked appendage with narrow junction to the main atrial compartment
RA:
Triangular appendage with broad junction
Atrial Arrangements
Usual (Situs solitus)
Mirror-Image (Situs inversus)
Isomeric left or right
Left Ventricle Morphology
MV ALWAYS goes with LV
- not attached to the septum, instead shares fibrous continuity with the aortic valve
Fine apical trabeculation
Right Ventricle Morphology
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
Biventricular Atrioventricular Connections
Concordant (Usual or mirror-image atria)
Discordant (Usual or mirror-image atria)
Ambiguous (Isomeric atria)
Univentricular AV Connection
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
Absent Ventricle
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
Areas of CHDs
Inflow Tract Atrial Suptum AV Junction Ventricular Septum VA Junction Outflow Tract
Atrial Septum
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)
Conduction
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
The AV node
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.
VSD and possible locations
- Failure off descending septum primum and ascending ventricular septum to fully fuse
- Adjacent to AV or VA junction
- Underneath/Overridden by a valvular orifice
Morphologic Features of VSD
- 90% involve the membraneous septum
Infundibular VSD: Below the PV
Muscular VSD: Often multiple holes in the muscular septum
Considerations in VSDs
- 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
Size in VSDs
- Small holes may close over spontaneously
- Large holes may leak underneath both OFTs and won’t close spontaneously
Peri-membraneous VSD
- Most common form of VSD (~80%)
- Partly muscular rim, part of rim is continuous with the membraneous septum
Muscular VSD
- 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
Doubly-committed and Juxta-arterial VSD
- Rare (~3%)
- Hole is underneath the aortic and pulmonary valves
- AV and PV and normally offset (angle and level) but are adjacent here
Normal AV Junction
- Aorta should be in the centre
- TV and MV should surround it like a figure-of-8
AVSD
- Cause
- Structure
- AVN
- 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
Variation in AVSD shunting
Varied by the bridging leaflet attachments:
- VS: interatrial shunting
- AS: interventricular shunting
- Floating bridging leaflets: IA and IV shunting
Length of Outlet
- Longer outlet is less efficient
- Risk of OFT obstruction
Tetralogy of Fallot
- Narrowed pulmonary outlet
- Large VSD (underneath the RVOFT)
- Overriding aorta (supplied by both ventricles)
- Hypertrophy of RV
Ebstein Malformation
- Failure of TV to delaminate away from the RV wall
- TV is deep within the ventricle
- RV volume decreased (essentially absent RV)
Bicuspid AV
- 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
Common Arterial Trunk
- Failure of the OFT to divide
- All blood leaves the heart via a common truncus
Arterial duct
- Patent duct
- Coarctation of the aorta
- 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
Double-committed or juxta-arterial VSD
- 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)
Absent Ventricle
- Imaging
- Treatment
- 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
Absent Left Ventricle (LA inlet and LV outlet missing)
- Blood route
- Enters RA
- Goes to LA (ASD)
- LV
- Goes to RV (VSD)
- Pulmonary trunk
AV Valve Defects
- Imperforate, stenotic, common valve
In VSD
- Valve, chordae or both may overlie the septum
