The conotruncus comprises collectively two myocardial subsegments, the conus and the truncus. Conus is the myocardial segment between ventricle and semi lunar valves which gives rise to sub arterial coni. Truncus is the fibrous segment between semi lunar valves and aortic sac which gives rise to great arteries.

1. Conotruncus Embryology & Anomalies
Msn Pavan Kumar
Nizam’s Institute of Medical Sciences
,Panjagutta,Hyderabad,India.
msnpavan@gmail.com

2. Conotruncus Embryology & Anomalies
 The conotruncus comprises collectively two myocardial subsegments,
the conus and the truncus.
 Conus is the myocardial segment between ventricle and semi lunar
valves which gives rise to sub arterial coni.
 Truncus is the fibrous segment between semi lunar valves and aortic sac
which gives rise to great arteries.

3. Conotruncus Embryology & Anomalies
 Embryology
1. Septation of conus and truncus.
2. Rotation and absorption.
3. Development of semi lunar valves.
4. Important structures involved
a) Neural crest cells.
b) Secondary heart field.
 Congenital heart diseases d/t conotruncus
 Genetic defects in Conotruncal

4. Conotruncus Embryology & Anomalies
Embryology - Septation of conus and truncus.
 4 truncus and 2 conal cushions develop.
 Dextro- sinistro cushions of both conus and truncus fuse to form
Conotruncal septum.
 Intercalated cushions play an role in formation of semi lunar valves

5. Conotruncus Embryology & Anomalies
Embryology - Septation of conus and truncus.
 Because the cushions are
dextro-superior and sinistro
inferior in truncus and
dextro-dorsal and sinistro-
ventral in conus union
forms a spiral septum than
true lineal relation.
For convenience it is represented as linear structure

6. Conotruncus Embryology & Anomalies
Embryology - Rotation and absorption.
 Aorta will be in connection with RV and PA with LV.
 There are two rotations one at conoventricular junction and other
at Conotruncal junction.
 Both rotations are counterclockwise around 110º

7. Conotruncus Embryology & Anomalies
Embryology - Rotation and absorption.
 Conoventricular rotation brings aorta in continuation with LV and
PA with RV.
 Conotruncal rotation brings the normal position of aorta in relation
to PA ( left and posterior to PA)

8. Conotruncus Embryology & Anomalies
Embryology - Rotation and absorption.
 Second most important thing is absorption of conus.
 Out of the two coni which ever remains persistent and grows
pushes the artery more anterior and superior direction bringing it
in direct connection with RV.
 In normal heart sub aortic conus is absorbed completely.

9. Conotruncus Embryology & Anomalies
Embryology – Semilunar valves.
Septation at valvular level occurs in intercalated cushions
leading to formation partial aortic and pulmonary valve.
The remaining part is formed by Conotruncal cushions.

10. Conotruncus Embryology & Anomalies
Embryology – Important Structures For Development Of Conotruncus.
 Second heart field cells and neural crest cell play important role in
development of conotruncus

11. Conotruncus Embryology & Anomalies
 Conotruncal defects
1. Truncus
2. TOF (with absent PV& PA)
3. DORV
4. DOLV
5. D-TGA
6. Conoventricular septal defects
7. Interrupted aortic arch type B

12. Conotruncus Embryology & Anomalies
Truncus arteriosus.
Failure of aortopulmonary septum to Septation give rise to
persistent truncus arteriosus.
Truncus
Conus

13. Conotruncus Embryology & Anomalies
TOF:
Infundibular septum which arises from conal septum moves
anteriorly and superiorly causing components of TOF

14. Conotruncus Embryology & Anomalies
DORV
Conoventricular
rotation is based on
which coni persists.
Artery with coni will
be anterior and
superior and
connected to RV
If both coni are
present both arise
from RV - DORV

15. Conotruncus Embryology & Anomalies
DORV
In DORV, rotation of great arteries driven by conal development that changes not
the position of VSD.
Type More prominent Less prominent VSD commited
coni coni to
TOF(40%) Subpulmonic Sub aortic Aorta
VSD (15%) Subpulmonic Sub aortic Aorta
TGA(20%) Subaortic Sub pulmonic PA
Variants ---- Both Both
(DC<10%)
Variants Both ---- Non committed
(NC<10%)

16. Conotruncus Embryology & Anomalies
DOLV
In DOLV both coni
are absent hence
both arteries are
posterior and arising
from LV

17. Conotruncus Embryology & Anomalies
D - TGA

18. Conotruncus Embryology & Anomalies
Cono ventricular septal defects.
 Absence of conal(Infundibular) septum leads to formation of
malaligned , subinfundibular , subpulmonic VSD .

19. Conotruncus Embryology & Anomalies

20. Conotruncus Embryology & Anomalies

21. Conotruncus Embryology & Anomalies

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