Master Class Tétralogie de Fallot

Hands-on session

Lucile HOUYEL

• Uniquemechanism=anteriormalalignmentandanteriordeviationoftheoutletseptum

Outlet VSD Aortic dextroposition Subpulmonary stenosis

Right ventricular hypertrophy

Tetralogy of Fallot : « monology » of Fallot

*

*

RV

RV

VSD

Earlylooping ConvergenceWEDGING

Ao AP

Wedging=rotationoftheaorticvalveandtransfertoLV

Normalheart

VD

VG

O

CT

Cardiacneuralcrest

Secondheartfield

Outletseptum=betweentheaorticandpulmonaryvalves

EndocardialcushionsoftheoutflowtractWedging(44-49days)

*

PA

TVSB

MB

Fomation of the outlet septum

RVLV

The outlet septum

VGVGRV RV

RVLV LV

Abnormal development of the outlet septum :Outlet VSD

❑ «Y»oftheseptalband=Zoneoffusionbetweentheoutletseptumandthemuscularprimitiveseptum

❑ Absenceoffusion(outletseptalmalalignment) outletVSD

❑ Anomaliesofthecardiacneuralcrestandsecondheartfield

AP

PA

OS

SBT

VSD

Conotruncal malformations (cardiac neural crest / second heart field defects)

• OutletVSD(malalignedorfibrousoutletseptum)

• TetralogyofFallot– Withpulmonarystenosis– Withpulmonaryatresia– Withabsentpulmonaryvalve

• DORVwithsubaorticordoublycommittedVSD

• Commonarterialtrunk• InterruptedaorticarchtypeB

PA

OS

SBT

VSD

• Anomaliesofwedging(rotation)andpositionoftheoutletseptum

• AllsharethesameVSD:outletVSD

Null Incomplete NormalExcessiveWEDGING

CAT TOFwPAtFallotOutletVSDNormalheartIAAtypeB

Conotruncal malformations (cardiac neural crest / second heart field defects)

Tetralogy of Fallot

Tetralogy of Fallot The ventricular septal defect

Tetralogy of Fallot : the VSD

• OutletVSD• Locatedbetweenthetwo

limbsoftheseptalband• Beneaththeoverriding

aorticvalvarorifice• Variations:

– Postero-inferiorrim– Absent(fibrous)outletseptum

• AdditionalmuscularVSD

Ao

PA

VSD

T

Ao-tricuspidfibrouscontinuity

47/71:66% Mostefa-KaraJTCS2015

139/164:85% KhanEJCTS2019

PA

T

AoAo

PA

The VSD in TOF: the postero-inferior rim

T

Fibrous(«perimembranous») Muscular

Tetralogy of Fallot : the VSD

The VSD: the conduction tissue• Importanceofthepostero-

inferiorrimforthesurgeon• Conductiontissue

vulnerableiffibrous(«perimembranous»)

OutletVSDwithfibrousposteroinferiorrim(perimembranousextension)

AoAo

Fibrouspostero-inferiorrim Muscularpostero-inferiorrim

PV

Outletseptum

The VSD in TOF: the postero-inferior rim

Tétralogie de Fallot Septum conal long

TetralogyofFallot:theVSD Juxta-arterialdoublycommittedVSD

Tetralogy of Fallot or DORV?

Tetralogy of Fallot or DORV « Fallot-type » ?

Tetralogy of Fallot : overriding aorta

Ao

PA

LVRV

DORV, subaortic VSD, subpulmonary stenosis « Fallot-type »

PA

Ao

*

*

Tetralogy of Fallot The pulmonary valve

TOF : the pulmonary valve

Tetralogy of Fallot with absent pulmonary valve

Tetralogy of Fallot The coronary arteries

TOF: the coronary arteries

HouyelL,BajolleF.etal.JAnat2013;222:349-357.

Anterior interventricular coronary artery connected to the RCA and crossing the RVOT

Tetralogy of Fallot: associations

Tetralogy of Fallot and atrioventricular septal defect

Tetralogy of Fallot Aorto-pulmonary window

Conclusion The anatomic variants of tetralogy of Fallot

❑ Commonanatomicbasis=Anteriormalalignmentanddeviationoftheoutletseptum➢ OutletVSD

➢ Overridingaorta➢ RVOTobstruction

❑ Anatomicvariants➢ Postero-inferiorrimoftheVSD

❑ Fibrous«perimembranous»❑ Muscular

➢ Outletseptum ❑ Muscular❑ Fibrous

➢ Pulmonaryvalve❑ Absent❑ Atretic

Fetalheart15WG

SubpulmonarystenosisOutlet

septum

Ao

RV