Morphology Flashcards
Components of the cardiac septum
o Floor of the fossa ovalis (thin)
o Muscular rims around it
o Coronary sinus orifice
o Ventricular septum
o Tricuspid and mitral valve attachments
Proportion of CHD represented by ASD, AVSD and VSD
o ASD (8% CHD)
o AVSD (4% CHD)
o VSD (32% CHD)
Key features to note about a VSD
Size
Location
Tissue
Associated malformations
Proximity to important structures (valves and conduction system)
Nomenclature of VSDs
- Size 2. Tissue 3. Location
e.g., 3mm Perimembranous Outlet
Are VSDs the same size on RV and LV aspect?
No
Possible VSD locations
o Inlet
o Outlet
o Apical/trabercular
Possible VSD tissues
o Muscular
o Perimembranous
o Doubly committed / juxtaarterial
Key features of muscular VSD
- Often hard to see in pathological specimens, hidden in muscle layers
- Usually small, not associated with other congenital abnormalities
Key features of perimembranous VSD
- Associated with other congenital malformations
- Close to AV conduction bundle
- Involve any remnant of the membranous septum, therefore usually have a part muscular and part fibrous border
- Called multiple names: Infracrister/Kirklin II & III, Kawashima type 2, Tatsuno type 2
- Perimembranous inlet defects tend to extend further back into the inlet portion of the RV
Key features of doubly committed VSD
- Called multiple names: infundibular, supracristal, subpulmonary, Kawashima Type 1, Tatsuno Type 1
- Sits right underneath the semilunar valves, no muscle in between
- Can have perimembranous extension
Describe ASD
Communication between atrial chambers
Key features to note about an ASD
- Where in the septum
- Size of the defect
- The margins
- Proximity to important structures
Key thing about septum orientation to remember when assessing ASD
When visualizing in short axis images, the septum is ‘oblique’ rather than perfectly transverse. It is also relatively close to the aorta, this is something important to bear in mind when considering device closure, don’t want to ‘clip’ the aorta
Normal interatrial septum features
- From the RA, we can see the IVC entrance coming in
- We can see the fossa ovalis, and the muscular contour of the fossa
- Atrial defects are defects in the fossa or surrounding areas
List the types of ASD, starting SUPERIORLY
- Superior sinus venosus
- Oval fossa (secundum)
- Vestibular
- Atrioventricular (primum)
- Inferior sinus venosus
- Coronary sinus
ASD: Key features of secundum ASD (oval fossa)
o Persistence of the ‘ostium secundum’
o Deficient flap valve closing the ostium (flap valve = septum primum)
o Often has fenestrations
o Amenable to device closure, size variable
o Can have windsock configuration
ASD: Key features of superior sinus venosus defects
o Superior to the oval fossa
o Near where SVC enters the RA
o Associated nearly always with partial anomalous pulmonary venous connection
o PV entering the SVC
o Sinus node is close slightly anterior
o Therefore at risk during surgical procedures to repair
ASD: Key features of inferior sinus venosus defects
o Arises near where the IVC empties into the RA
o Relatively close to AV node
ASD: Features of coronary sinus defects
o Lesion at the position of the coronary sinus orifice
o Close to AV node
o Commonly associated with persistence of left SVC
ASD: Key features of vestibular defects
o In the region leading to the right AV valve orifice
o Between AV node and oval fossa
o In the sinus septum region of the RA
o Tend to be quite small
Describe atrioventricular septal defects
Also known as AV canal defect, ostium primum defect, endocardial cushion defect
There is a loss of offset between the atrioventricular valves, instead there is a hole in the septum
Key features characterising AVSD
- Common AV junctions
- Biventricular AV connections (2 atria, each connected to one ventricle)
Due to lack of AV junction, there is displacement of LVOTO to more anterior than normal (usually it sits in the anterior groove)
Valve configuration in AVSD
o 5-leaflet AV valve guards AV junction
o Superior and inferior bridging leaflets are distinctive
o Then three other leaflets with different configurations depending on the configuration of AVSD
Two main configurations of AVSD
- Common valve orifice (aka AV canal defect)
- Separate valve orifice (aka ostium primum)
Key characteristics of common valve orifice AVSD
One single opening between the five leaflets
Three-leaflet configuration for the morphologic atrioventricular connection
Key characteristics of separate valve orifices AVSD
Two separate openings, with fused superior and inferior bridging leaflets
Cleft between superior bridging and inferior bridging leaflets
Superior and inferior arrangement of the papillary muscles (usually obliquely arranged in morphological LV
What influence does AVSD have on inlet and outlet proportions
Leads to inlet-outlet disproportion
What are the consequences of the inlet outlet disproportion seen in AVSD
o Anterior displacement and elongation of LVOTO mean that outlet distance is longer than inlet distance (gooseneck deformity)
o Leads to unwedged aortic valve – AV displaced away from usual position
How do AVSDs influence the AV node placement
Displaced
o Triangle of Koch not identifiable
o Usually displacement of AV node inferior and toward IVC – important to know where to avoid heart block at time of surgical repair
Name the leaflets in AVSDs
1 – superior bridging
2 – inferior bridging
3- left mural
4- right anterosuperior leaflet
5- right inferior
Shunting in partial or incomplete AVSD (p-AVSD, ostium primum)
Inter-atrial shunting (defect above the atrioventricular valve attachment)
Shunting in Complete AVSD (canal)
AVSD with common valvular orifice
Interatrial and interventricular shunting – best appreciated in diastole
Tethering of superior and inferior bridging leaflets are not anchored at the level of the septum
Shunting in Transitional/intermediate AVSD
Separate valvular orifices because superior/inferior bridging leaflets are fused, but not anchored to septum (variation of complete AVSD)
Atrial and ventricular shunts
Shunting in Intraventricular AVSD
Bridging leaflets attached to the atrial septum
Interventricular shunting onlyd
Additional congenital defects associated with AVSD
RVOTO
LVOTO
Isomeric arrangement of atrial appendages
Other valvular abnormalities, coarctation
Deviation of ventricular or atrial septum
Chamber disproportion (‘unbalanced’ AVSD)
What does an unbalanced AVSD mean prognostically / for surgical planning
Makes surgical repair complex – if AVSD closed, LV might be too small to maintain adequate CO (and vice versa for pulmonary flow in RA, though the potential issues are more limited in this setting)
Rastelli classification for complete AVSD
Based on the relationship of the superior bridging leaflet and chordal attachments
Type A - Divided leaflets and attached to the crest of ventricular septum (multiple chordae). Associated with left-sided obstruction.
Type B - Partly divided into two components, not attached to crest of septum. Chordae from superior leaflet attached to papillary muscle in RV on septal surface. Least common form of the complete atrioventricular septal defect
Type C - Undivided and attached to ventricular septal crest (‘free floating’); attachments to papillary muscle and Associated with Tetralogy of Fallot and other complex congenital heart diseases
Rastelli Type A Complete AVSD
Type A - Divided leaflets and attached to the crest of ventricular septum (multiple chordae). Associated with left-sided obstruction.
Rastelli Type B Complete AVSD
Type B - Partly divided into two components, not attached to crest of septum. Chordae from superior leaflet attached to papillary muscle in RV on septal surface. Least common form of the complete atrioventricular septal defect
Rastelli Type 3 Complete AVSD
Type C - Undivided and attached to ventricular septal crest (‘free floating’); attachments to papillary muscle and Associated with Tetralogy of Fallot and other complex congenital heart diseases
Classification used for complete AVSD
Rastelli classification (Type A B C)
List the four left-to-right dominant lesions OUTSIDE the cardiac septum
PDA
CAT
APW
P-TAPVC
Relative proportion of
PDA
CAT
APW
P-TAPVC
among CHD
- PDA 7%
- CAT 1%
- APW <0.5%
- P-TAPVC 1%
Summary of PDA
Fetal structure coming off the pulmonary trunk and entering the aorta past the brachiocephalic > left common carotid > left subclavian
Usually enters the aorta just past the left subclavian
Exits the PT superiorly at the level of the bifurcation, enters the aorta inferiorly
Duct closure timings
Ductal closure begins in the immediate period of birth
Functional closure occurs in days/weeks, then full closure via growth of intimal cushions within months
Should be closed by 1 month in term infants
Might close as late as 3 months in premature infants
Importance of PDA in cyanotic disease
Can be useful as source of shunting in complex congenital cyanotic disease e.g., PAIVS, aortic atresia / hypoplastic left heart
How does PDA support circulation in PAIVS and Aortic Atresia
In HLH/Ao atresia, the aortic outflow will be small
So PDA will be the primary source of blood to the systemic circulation, including to the neck and arms and to the coronary arteries by retrograde flow
When can the duct be absent?
in common arterial trunk (CAT)
What is Common Arterial Trunk (CAT)?
Condition where there is one single vessel providing both systemic and pulmonary blood flow
Four types of CAT depending on origin of the pulmonary arteries
Depending on origin of pulmonary arteries
o Type 1 – Single posterior origin that bifurcates
o Type 2 – Two distinct PA origins posteriorly
o Type 3 – Two distinct PA origins on the sides of the aorta
o Type 4 - no pulmonary trunk, lungs supplied via systemic to pulmonary collaterals
Details of Type I CAT
- Pulmonary artery arises from the posterior aspect of the ascending aorta
- Truncal valve overriding the septum
- Often associated with muscular VSD, dysplastic truncal valve, and left aortic arch
Details of Type II CAT
- Separate origins of pulmonary arteries posteriorly
- Often associated with muscular VSD, can be associated with dysplastic truncal valve
- Can be associated with interruption of aortic arch
- Interruption of the aortic arch is PDA dependent, PDA supplies blood flow between the pre and post interruption segment
Details of Type III CAT
- Can be associated with interruption of the aortic arch
Details of Type IV CAT
- No evidence of intrapericardial pulmonary arteries, pulmonary flow fed by collaterals
Typical lesions associated with CAT
Right arch with mirror imaged branching (30% of patients)
Arch interruption (15% of patients)
Double aortic arch (<1% of patients
Ventricular origin of the common trunk
o Balanced 75%
o Entirely RV 20%
o Entirely LV 5%
Ventricular septal defects
o Muscular outlet VSD is common
o The importance of the VSD depends on the origin of the CAT
o Atrioventricular septal defects might also be present
Truncal valve dysplasia / defects
o Number of leaflets, dysplasia
Aortic arch anomalies
o Right sided, interrupted, coarctation, vascular ring formation
Describe aortopulmonary window (APW)
Condition where a communication exists between the lumen of the aorta and the pulmonary arteries
Details about APWs
- Two sets of semilunar valves, then window superior to the semilunar valves in the wall between aorta and pulmonary trunk
- High risk of pulmonary vascular disease due to sizeable shunt
- Location and size of window varies from case to case
How are APWs described based on location of window?
Based on location of window
Proximal - window the origin of the vessels, just past valves
Intermediate - tissue above and below, window in middle
Distal - close to the point of division of the pulmonary trunk
Confluent - no tissue between Ao and PA until the pulmonary trunk separation
In confluent, there is often anomalous origin of right pulmonary artery orifice
Can have both originating after the separation, or overriding both semilunar valves, or can arise from the back of the aortic wall
Typical lesions associated with APWs
- Aortic arch stenosis or interruption
- Ventricular septal defect
- Complete transposition
- Tetralogy of Fallot
- Pulmonary atresia
What is anomalous pulmonary venous return
Condition where one, more than one (noncyanotic) or all (cyanotic) of the pulmonary veins do not drain into the left atrium
Key details to think about in APVR
- Proportion of anomalous connection
- Site of the connection
- Is anomalous pathway obstructed
- Any other associated defects
Where might the anomalous connection drain in APVR
o Right atrium
o SVC
o IVC
o Coronary sinus
o Brachiocephalic vein
Typical associated defects
o Superior or inferior sinus venosus defect
o ASD
o Persistent left SVC
o AVSD
o Atrial isomerism
What is Scimitar syndrome
o Anomalous PV draining part or all of the right lung to the IVC most commonly
o Associated with hypoplasia of right lung and right PA
o Sometimes anomalous systemic arterial supply from the descending aorta
Haemodynamic consequence of PAPVR
If IVC/SVC/RA drainage: Pulmonary hypertension due to high RV preload
If CS: dilation of coronary sinus
Key features of TAPVR
- None of the pulmonary veins enter the LA
- Systemic blood flow is dependent on an interatrial communication (ASD)
- The shunt is from right to left to maintain life
Classification of TAPVR based on location of entry of PVs into the right sided circulation
Supracardiac
Azygos, right SVC, or brachiocephalic
Cardiac
Direct to RA or to left SVC and coronary sinus
CS gets dilated when through sinus
Infracardiac
To IVC or hepatic portal vein
Can be associated with stenosis of the vein at the level of the diaphragm, and with isomerism
Cyanotic congenital heart diseases
TOF
TGA
TAPVR
Truncus arteriosis
Tricuspid atresia / PAIVS
Frequency among CHD of TOF, PAIVS and TGA
- TOF 5%
- Pulmonary atresia with intact ventricular septum 2%
- Complete transposition 4%
TOF characteristics
Tetralogy of: VSD, Subpulmonary stenosis, overriding aorta, RV hypertrophy
Might have pulmonary stenosis or atresia
What contributes to RVOTO in TOF?
- Septo-marginal trabeculation [structure that divides near the RVOT into an anterior limb (towards OT) and posterior limb (towards TV)] can become hypertrophic
- Outlet septum [a muscular structure that divides the PV from the AV] is deviated anterocephelad in TOF squeezing the RVOT
- Septoparietal trabeculations (SPT) that in the TOF setting hypertrophy and therefore add to sub-pulmonary obstruction
Potential ventriculoarterial configurations in TOF
o Aorta predominantly supported by LV (effectively concordant connections)
o Aorta predominantly supported by RV (essentially double outlet connection)
Potential levens of pulmonary obstruction/stenosis in TOF
o At mouth of infundibulum – stenosis or atresia
o Pulmonary valve - stenosis to atresia
o Within RV
o Distally within PA
Typical other malformations associated with TOF
o Pulmonary atresia
o Absent leaflets of PV
o Straddling TV
o AVSD
o Anomalous coronary arteries
o Right sided aortic arch in 3-5%
o Muscular inlet VSD
o Arterial wall anomalies
Key features of TOF with pulmonary atresia
- Also called pulmonary atresia with ventricular septal defect
- RV outlet to aorta via VSD
- Variable mature of atretic outlet
- Variable types of VSD
- Other intracardiac defect
- Variable lung vascular supply
Potential types of mature atretic outlet in TOF with PA
o Muscular atresia (no remnant of pulmonary valve at all)
o Imperforate membrane
o Solitary arterial trunk (no existing pulmonary trunk)
Potential types of VSD in TOF with PA
o Perimembranous
o Muscular
o Multiple
Possible pulmonary vascular supply in TOF with PA
o Unilateral or bilateral duct
o Systemic to pulmonary collateral arteries (SPCA)
o APW, fifth aortic arch, coronary/pulmonary fistula
Key features to summarize in the assessment of TOF
- Extent of aortic override
- RV margins of VSD
- Nature and anatomy of subpulmonary obstruction
- Pulmonary valve malformations
- Associated other malformations
Describe PAIVS
Cyanotic congenital defect where there is no flow from the RV to the PA due to (1) pulmonary atresia and (2) lack of VSD
Key features of PAIVS
o Systemic venous return MUST cross ASD, exit via aorta, duct, PA
o Pulmonary supply is therefore duct dependent
o Pulmonary arteries are usually good in size
o Pulmonary trunk hypoplastic if the atresia is muscular, normal in size if atresia is imperforate in origin
What does RV cavity typically look like in PAIVS
o Hypoplastic to varying degree (can rarely be normal in morphology)
o RV wall hypertrophy is the rule
o Tricuspid valve abnormalities are commeon
Key features to report in PAIVS
- Nature of pulmonary atresia (muscular or imperforate valve)
- Degree of hypoplasia of RV cavity
- Morphology of tricuspid valve
- Fistulous communications of coronary arteries
Typical lesions associated with PAIVS
ASD
Coronary arterial anomalies
o Anomalous origin
o Sinusoids
o Atretic segments in coronaries
Key features of d-TGA
- The aorta is to the right of the pulmonary artery
- D-TGA is the most common form of TGA and is also called ‘complete’ TGA
- This type of TGA almost always needs to be repaired in the first year of life.
Key features of L-TGA
- The aorta is to the left of the pulmonary artery
- Another term for L TGA is congenitally corrected TGA
- This type of TGA, in the absence of other heart defects, may not require repair early in life
Sequential segmental analysis description of d-TGA
o Usual or mirror-imaged atrial arrangements
o Atrioventricular concordance
o Ventriculoarterial discordance
What happens in the absence of a shunt in d-TGA after birth
After birth if the ducts close if there are no communications between the right and left heart this would be immediately lethal
Two types of d-TGA
Simple vs Complex
Simple d-TGA features
Intact IVS, no further malformations
However, might not be so simple: there can be
* Anomalies in the coronary arteries E.g., RCA coming from left hand sinus, LCx coming from left hand sinus, LAD from right hand sinus running between the Ao and PA and then descending
* Abnormal arterial courses
* Infundibular morphology might be abnormal
Complex d-TGA features
VSD
- 40-45% of cases, with misalignment of the outlet septum
Subpulmonary or subaortic obstruction - 25% of cases
Subaortic obstruction (RVOTO) may arise from
o Muscular infundibulum
o Abnormal muscle bundles
o Anomalous tension apparatus
o Deviated outlet septum with VSD
o Aortic coarctation will contribute to poor aortic flow
Subpulmonary (LVOTO) may arise from:
o Valvular stenosis
o Aneurysmal tissue tags
o VSD with deviated septum
o Fibrous diaphragm or tunnel
o Abnormal insertions of mitral valve
Valvular abnormalities
- Atrioventricular or arterial
Aortic coarctation
- 5% of cases
List four obstructive congenital heart defects and relative % among CHD
- Pulmonary stenosis 7%
- Aortic stenosis 4%
- Aortic arch malformations 5%
- Vascular ring <1
Key features to determine when examining PS
Level of stenosis
Association with chromosomal or genetic abnormalities
Potential levels of stenosis in PS
Supravalvar
Discrete or diffuse stenosis of PA
Valvar
Most common isolated lesion
Subvalvar
Associated with VSD, Fallot, subdivision of RV
Three genetic/chromosomal associations of PS
Noonan, Williams, Alagille
Valvular PS key fatures
Most common type
Different potential morphologies
o Dome shaped subtotal fusion of zones of apposition, pinhole orifice, leaflets not thickened - Most common
o Three thick leaflets, no fusion of zones of apposition
o Three thick leaflets with partial fusion of zones of apposition
o Bicuspid (bifoliate)
o Unicuspid (unifoliate)
Subvalvar PS key features
- Double chamber RV
o Shelf coming across the cavity of the RV
o Can either be high or low on the septum
Possible levels of stenosis in AS
Supravalvar
Valvar
Subvalvar
Anomalous valvular insertion
Septal hypertrophy, shelf, tunnel
Valvar AS: key features to distinguish
o Number of leaflets – usually three, two if bicuspid, rarely four leaflets
o Character of leaflets – thickened, proportion, calcifications
Valvar AS: key specific veatures for bicuspid aortic valve
o Variable levels of obstruction depending on how well formed, proportionate and pliable the leaflets are
o Might not lead to any issues throughout life
o Can sometimes see a remnant of the raphe in the bicuspid leaflets
o Rarely can be unicuspid
o Can be dome shaped
Supravalvar AS: three potential configurations of obstruction
- Hourglass
- Diaphragm
- Diffuse hyperplasia
Characteristics of hourglass supravalvar AS
o Dilated distal portion of ascending aorta
o Sinotubular junction constricted
o Aortic valve leaflets thickened and deep
o Associated with isolation of coronary orifice: Left coronary artery tries to enter in aortic sinus but free margin of the valvular leaflet might be plastered across the coronary orifice
Characteristics of diaphragm supravalvar AS
o We see a flap sitting above the valvular leaflets at the sinotubular junction
Characteristics of diffuse hypoplastic supravalvar AS
o Characterised by narrow but thickened vessels, including the aorta and neck and arm arteries
Key features to assess in aortic coarctation or interruption
- Site and morphology of obstruction
- Associated lesions
- Arterial duct
Types of coarctation
Coarctation (waist lesion)
Coarctation (discrete shelf lesion) with tubular hypoplasia
Tubular hypoplasia of isthmus
Describe Coarctation waist lesion
Discrete obstruction due to narrowing in vessel
Can be preductal, paraductal, or post ductal
Present in 4-10% of CHD patients
80% of coarctations are sole lesions
Describe coarctation discrete shelf lesion
Discrete obstruction due to a shelf/encircling of lumen in the inner vessel
Describe coarctation tubular hypoplasia of isthmus
Segment of obstruction at the isthmus of ductus
Location relating to the isthmus (area of the aorta between origin of the L subclavian and the entrance of the duct)
Can occur at the isthmus, affecting region from the left common carotid until insertion of the duct, or can involve the whole transverse aortic arch
Complications of coarctation
Rupture of the aorta
Aortic aneurysms post coarctation lesion
Arch interruption types depending on site
At isthmus
Between left common carotid and left subclavian
Between right and left common carotid
Key features of arch interruption
Can be complete (no flow past) or atretic (some remnant of flow but insufficient to sustain life, still duct dependent)
Account for 1.3% of critical congenital anomalies
Lethal within first few weeks after birth
Classified by location relating to carotid/subclavians
Ventriculoarterial connections are variable in patients with arch interruptions
* Might be concordant
* Might have common arterial trunk
* Might be discordant
* Might have double outlet right ventricle
Typical associations for CoA + interruption
o Mitral stenosis
o Aortic stenosis (VSD with malalignment of outlet septum)
o Bicuspid aortic valve (20-40% of CoA)
Describe vascular rings
Part of the aorta or its branches form a ring around the trachea, the oesophagus or both, potentially leading to tracheo/esophageal obstruction
Three different configurations of vascular rings
Ring
Sling
Loop (partial ring)
Normal embryonic development of the aortic arch
Ascending aorta develops as a component of the primitive heart tube.
The primitive heart develops from five dilations:
the truncus arteriosus,
conus cordis,
primitive ventricle,
primitive atrium, and
the sinus venosus.
The truncus arteriosus forms the basis for developing the ascending aorta and pulmonary trunk, beginning during the fifth week of development.
The truncus starts as a single outflow tract from the right and left ventricles but is eventually divided by the aorticopulmonary septum into separate vascular outflow channels.
The truncal and conal ridges are invaded by neural crest cells, leading to spiraling that forms the aorticopulmonary septum.
The arch of the aorta develops from multiple structures.
The portion of the arch proximal to the brachiocephalic trunk arises directly from the aortic sac.
The medial area of the arch, between the brachiocephalic trunk and the left common carotid artery, arises from the left 4th aortic arch.
The portion of the arch distal to the left common carotid artery arises from the dorsal aorta.
The descending aorta arises from the dorsal aortae.
Early in development, paired right and left dorsal aortae are confluent with the aortic sac.
The right and left dorsal aortae later fuse along vertebral levels T4 to L4, forming a single, continuous dorsal aorta.
The dorsal aorta ultimately gives off many vital branches, including intersegmental, splanchnic or visceral, and umbilical arteries. T
he dorsal aorta in this region is later referred to as the descending thoracic and abdominal aorta
NB the ductus arteriosus develops from the left 6th aortic arch
Aorta develops as component of the
primitive heart tube
The primitive heart develops from five dilations:
the truncus arteriosus,
conus cordis,
primitive ventricle,
primitive atrium, and
the sinus venosus.
When does the aorta development begin
week 5
Truncus arteriosus forms the basis for
Ao and PA
The truncus starts as
a single outflow tract from the right and left ventricles but is eventually divided by the aortopulmonary septum into separate vascular outflow channels
The truncal and conal ridges are invaded by
neural crest cells, leading to spiraling that forms the aorticopulmonary septum
The arch of the aorta develops from the following structures
The portion of the arch proximal to the brachiocephalic trunk arises directly from the aortic sac.
The medial area of the arch, between the brachiocephalic trunk and the left common carotid artery, arises from the left 4th aortic arch.
The portion of the arch distal to the left common carotid artery arises from the dorsal aorta.
The descending aorta arises from the dorsal aortae.
Early in development, paired right and left dorsal aortae are
confluent with the aortic sac.
The right and left dorsal aortae later fuse along vertebral levels …
T4 to L4, forming a single, continuous dorsal aorta.
The dorsal aorta ultimately gives off many vital branches, including …
intersegmental, splanchnic or visceral, and umbilical arteries. The dorsal aorta in this region is later referred to as the descending thoracic and abdominal aorta
The ductus arteriosus develops from the following aortic arch
6th
Aberrant embryological development of aorta in vascular rings - right sided aortic arch
Right sided aortic arch (mirror image)
Right sided 4th aortic arch has persisted (instead of left sided 4th aortic arch), leading to downstream right sided dorsal aorta persistence
Associated with TOF (25%) and common arterial trunk (50%)
Sequentially from LVOTO, the first branch to come off is the left brachiocephalic, then right common carotid, then right subclavian
Aberrant embryological development of aorta in vascular rings - left sided aortic arch
In this configuration, we have LVOTO > R common carotid > common carotid > L subclavian > R subclavian
The aberrant right subclavian loops backwards and around the back of trachea and oesophagus and might therefore lead to compression
Aberrant embryological development of aorta in vascular rings - double aortic arch
Persistence of both right and left 4th aortic arch
Usually independent right and left artery origins (4 in total)
Usually associated with bilateral duct
Join into the descending or dorsal aorta
Key features of R aortic arch with vascular ring
- 12-15% of vascular rings
- From RVOTO, first branch is L common carotid, then R common carotid, then R subclavian, finally the aberrant L subclavian posteriorly, travelling behind the oesophagus and trachea, and might connect to the left duct to complete the ring
- Might also be associated with a remnant of the dorsal aorta (Diverticulum or Kommerell)
- Persistent ductus arteriosus or dutal ligament can anchor down the L subclavian, leading to a kinking that might worsen trachea-esophageal compression
Key features of double aortic arch
Usually
* L arch 2/3 size of the R arch
* L arch tubular hypoplasia or atresia
* 20% associated with other CHD – commonly CAT
* L arch anterior to trachea / esophagus, R arch posterior
* Sometimes L arch referred to as the ‘anterior’ and R arch referred to as ‘posterior’
Can be a partial double arch
* Persistence of part of the right dorsal aorta (diverticulum of Kammerell) in the setting of the right sided arch (see below)
Describe a PA sling
- Embryologic vascular anomaly where the origin of the left pulmonary artery arises from the right pulmonary artery, instead of the main pulmonary artery
- This compresses the distal trachea and right mainstem bronchus between the trachea and oesophagus towards supplying the left lung, known as vascular sling
- Not true vascular ring, but symptoms similar to full vascular ring
Key characteristics of PA sling
o Narrow affected pulmonary artery
o Narrow trachea
o Small lung on affected side
Types of complex CHD and % among CHD
- DORV counts for 2% CHD
- Hearts with single ventricle physiology overall (e.g., HLHS) count for 4%
Key features of DORV
Congenital lesion where the great arteries are for the major part supported by the morphological RV
Potential morphology in DORV
o Any pattern of atrial arrangement and situs
o Any pattern or atrioventricular connection
o Variable infundibular morphology
o Rarely without a VSD
Most commonly usual atrial arrangement and concordant atrioventricular connections
Other names for DORV
o Taussig-Bing malformation
o Tetralogy of Fallot with extreme dextroposition of the aorta
o Eisenmenger’s anomaly (Eisenmenger’s VSD)
Physiology of DORV
Varied
- Simple VSD-like
- Fallot
- Transposition
- Single ventricle
VSD types in DORV
Subaortic
Subpulmonary
Doubly commmitted
Noncommitted
Subaortic VSD in DORV
o Located inferior to the aorta above the septomarginal trabeculation but below the ventriculoinfundibular fold
o Can be associated with sub pulmonary stenosis
o There might be fibrous continuity between the aortic, tricuspid and mitral valve (lack of conus/infundibulum)
Subpulmonary VSD in DORV
Transposition type
Can be muscular VSD
Outlet septum fuses with VIF posteriorly or SMT posterior limn
Can be peri membranous
Outlet septum fuses with VIF, VIF not fused to SMT
Pulmonary-mitral-tricuspid continuity
Associated malformations
Aortic stenosis
Arch hypoplasia
Restrictive VSD
Abnormal TV attachments
DOuble committed and noncommitted VSD in DORV
- Doubly committed VSD
o Lack of outlet septum
o Muscular postero-inferior rim - Non-committed VSD
o Remote VSD or cannot be connected to a specific outlet
o Below SMT, e.g., inlet VSD
o Can be an AVSD
Key features to note in DORV patients
- Analyse DORV independent of position of great arteries and bilateral infundibulums
- Note location and size of VSD
- Presence or absence of pulmonary or aortic OTO
- Fallot with DORV when aorta is mainly from RV
- Other associated malformations e.g., in subpulmonary VSD
Types of functionally univentricular hearts
- Hearts with solitary or indeterminate ventricle
- Hearts with unbalanced ventricular mass
Subcategories of functionally univentricular hearts with unbalanced ventricular mass
o Hearts with univentricular AV connection
o Hearts with straddling AV valves
o Hearts with unbalanced AVSD
o Hearts with intact ventricular septum and critical stenosis or atresia of outflow tracts
Assessment of morphology in functionally univentricular hearts
o Atrial arrangement: usual, mirror, right isomerism, left isomerism
o AV connection univentricular: absent right, double inlet, absent left
o Ventricular morphology: dominant left with rudimentary right, solitary and indeterminate, dominant right with rudimentary left
Solitary indeterminate ventricle: morphology
o Any atrial arrangement
o Double inlet AV connection
o Solitary and indeterminate ventricle
Solitary indeterminate ventricle: features
- Ventricle might have a small posterior ridge
- Trabeculations in single indeterminate ventricle are very coarse
Unbalanced ventricular mass with univentricular AV Connection: morphology
o Any atrial arrangement
o Any AV connection
o Ventricles either dominant left or right
Hearts with univentricular AV connection: Any atria, double inlet, dominant left with rudimentary right
o Most common
o Pulmonary trunk from the rudimentary RV, Aorta from dominant LV
o Rudimentary RV directly anterior to the LV
o Might have two separate AV valves, or might have a common AV valve especially in the setting of right isomerism
o Double inlet AV connections to LV, concordant VA connections (DILV)
Hearts with univentricular AV connection: - Any atria, double inlet, dominant right with rudimentary left ventricle
o Double inlet AV connections to RV (DIRV)
o Straddling of the left AV valve is common
Hearts with univentricular AV connection: Any atria, absent right sided AV connection, dominant LV with rudimentary RV
Type 1: Imperforate tricuspid valve = tricuspid atresia
Biventricular AV connection but TV imperforate
Type 2: Total absence of AV valve (not technically atresia)
Univentricular AV connection
Associated with ASD +/- VSD
Pulmonary trunk arises form the rudimentary RV
Hearts with univentricular AV connection:- Any atria, absent left sided AV connection, dominant RV with rudimentary LV
Type 1: Imperforate mitral valve = mitral atresia
Biventricular AV connection but MV imperforate
Type 2: Absent AV valve
Univentricular AV connection
Associated with ASD +/- VSD
Hearts with intact ventricular septum and critical stenosis or atresia of outflow tracts: list the underlying types
Pulmonary atresia
Aortic atresia or stenosis
Mitral atresia or stenosis
Hearts with intact ventricular septum and critical stenosis or atresia of outflow tracts: pulmonary atresia
Stenosis of the RVOTO at the level of the valve
Type 1: Valvar or membranous atresia (imperforate PV
Type 2: Muscular atresia: blind-ending outflow tract with absence of the tissue valve
Associated with persistent PDA which fully feeds pulmonary flow
Hearts with intact ventricular septum and critical stenosis or atresia of outflow tracts: aortic atresia or stenosis, mitral atresia or stenosis are commonly known as…
Hypoplastic left heart
Hypoplastic left heart refers to any of the underlying pathologies of:
aortic atresia or stenosis, mitral atresia or stenosis
leading to heart with intact ventricular septum and critical stenosis or atresia of outflow tracts
how common is HLHS
o 0.2 per 1000 live births
Key features of HLHS
RV expands to form the apex
LV endocardial fibroelastosis
Stenotic MV and AoV
Fibrous communications with coronary arteries
o Coronary arteries are fed via backward flow from PT > DA > Ao > CA
o There might be minimal flow via the hypoplastic left heart
o HLHs is duct dependent – only minimal Ao flow except via duct
Coronary artery flow in HLHS
Coronary arteries are fed via backward flow from PT > PDA > Ao > CA
Associations of HLHS
LV fibroelastosis
Fibrous connections between LV and CA
Atrial septal defects
Abnormalities in AV junction
Abnormal mitral valve
Abnormal tricuspid valve
Ventriculoarterial junction abnormalities
Aortic arch abnormalities
How to distinguish RV and LV in univentricular hearts
Trabeculations
Moderator band
Septal attachments of AV valve
In univentricular hearts
o In dominant LV, the dominant ventricle should be seen posteriorly and the rudimentary RV anterior and superiorly
o Similarly in dominant RV, the rudimentary LV will be sitting posteroinferiorly
Key features of isomerism of atrial appendages
Associated with complex cardiac malformations approximately 30% of times
- Associated with malrotation of gut 70%
- Midline defects (MSK, genitourinary, cleft palate in 50%
- Varied vessel arrangement
Possible vascular arrangement in isomerism of atrial appendages
o Usually vessels posterior situated, one to either side of spine, vein anterior, aorta posterior
o Left isomerism vein and artery both to the left of the spine, aorta anterior and vein posterior
o Right isomerism vein and artery to the same side, vein anterior, aorta posterior
Right isomerism of atrial appendages: Lung and spleen morphology
Bilateral short bronchi (epiarterial) 89%
Asplenia 57%
i. Solitary 14%
ii. Multiple 3%
Left isomerism of atrial appendages: Lung and spleen morphology
Bilateral long bronchi (hyparterial) 98%
Multiple spleens 64%
i. Solitary 7%
ii. Absent 3%
Biliary atresia 10%
Examples of isomerism with univentricular circulation
Right atrial isomerism, double inlet solitary indeterminate ventricle
Left atrial isomerism, AVSD, double outlet RV with rudimentary LV
o Associated with azygos continuation of IVC
Describe Ebstein’s anomaly
Congenital abnormality characterised by apical and downward displacement of the tricuspid valve (rarely mitral valve or common AV valve)
Ebstein’s key features
- Apical and downward displacement of the tricuspid valve (rarely mitral valve or common AV valve)
- Reduced separation of the leaflet from the myocardium, leading to lack of delamination, such that the leaflet is not upwardly mobile to the level of the annulus (hinge line)
- Likely to result from a halting in the delamination process during development
- Pathognomic feature is origin of part of the hinge line of the TV leaflets within the RV cavity rather than at the AV junction
Different types of Ebstein’s
o Can be isolated displacement
o Can be associated with dysplasia of valve
o Can be associated with thinning of the ventricular wall above the displaced hinge line, ‘atrialisation’ of ventricular tissue
Quantifying degree of displacement and damage in Ebstein’s
Degree of displacement
o Can be linked to the MV insertion
o Normal offset between MV and TV <0.8cm/m^2 BSA
Degree of damage to valve
o How many leaflets are affected (one to three, septal and posterior are the most commonly affected)
o How badly are the leaflet affected
o Associated anomalies of leaflet
Typical associations in Ebstein’s
Atrial septal defects
Pulmonary atresia with intact septum
Discordant atrioventricular connections (ccTGA)
- Usual or mirror arrangement, discordant AV connections AND discordant VA connections (figure below)
- So essentially only the ventricle is switched (unless mirror image)
- Note AV conduction bundle is abnormal, and more prone to fibrosis / heart block
- Characterised on echo by reversed offset of AV valves
* Tricuspid valve on the left side, mitral valve on the right side
* Therefore right sided valve higher than left sided valve
* Can be further aggravated by Ebstein’s of the TV (which is now on the left side)
Ventricular pre-excitation
In 25% of Ebstein’s due to lack of separation of conduction at TV level
