1. Cardiac embryology
Karina & Allison

2. What we are going to cover…
Cardiac embryology
Septal formation: atrial, ventricular and arterial outflow
Heart defects
Timeline of cardiac development

3. What type of folding moves the brain, mouth and heart into the adult position? And when does this happen?
Longitudinal folding. Day 19.
Heart is initially situated above the head then through longitudinal folding it moves into the adult position
Green line = position of the heart

4. What is this called? And what is its clinical significance?
Transverse pericardial sinus
Sits between arterial outflow & venous input
Significance: clamp off arterial flow during surgery.

5. Dilations appear in the heart tube. Name them…

6. Dilations appear in the heart tube. Name them…
Left Horn
Of Sinus
Right Horn
Of sinus
Sinus Venosus
Bulbus Cordis
Truncus Arteriosus
Aortic sac
Atria
Ventricle
Smooth wall of right atria
Rough wall of both atria
Ventricles
Mainly outflow of ventricles
Initial part of aorta & pulmonary trunk

7. And then what happens?
Pulmonary veins grow out of the left atrial wall and branch. The proximal parts get absorbed into the atrial wall = smooth part
Coronary sinus
Vena Cavae LA LV
Outflow
Aorta RA RA
Outflow
Pulm Trunk RV
Septum between left and right sides of the heart.
Septa form and divide chambers and outflow tract to create the left right sides of the heart

8. Shunting takes place to avoid the developing lungs
Shunting takes place to avoid the developing lungs. Which direction does this happen in?
Coronary sinus
Vena Cavae LA LV
Outflow
Aorta RA RA RV
Outflow
Pulm Trunk
R  L shunting

9. What is this called? TA BC V
Normal A SV
Dextrocardia
Dextrocardia

10. Atrial Septum: Days 24-35

11. Atrial Septum Septum primum RA LA Foramen primum Endocardial cushion
Foramen secundum RA LA
Septum secundum RA LA
Endocardinal cushion grow across the AV canal from anterior to posterior.
The cushion is a swelling in mesenchyme.
Septum secundum RA LA
Valve of Foramen ovale
Foramen ovale

12. What is the function of the foramen ovale in the fetus?
Lungs are fluid filled with high pulmonary resistance.
Want to avoid them
Therefore blood is shunted through the foramen ovale from R  L
As soon as they take their first breathe the foramen ovale closes as the pressure changes. RA LA
The septum secundum is muscular and stiff
The septum primum is relatively floppy – it acts as a valve cusp

13. Sometimes fusion of foramen ovale does not occur
Sometimes fusion of foramen ovale does not occur. What problems could this cause in later life?
Valsava maneuver can briefly increase right sided pressure over left
This opens the foramen ovale
Can result in emboli passing from right atria to left atria
Increases possibility of TIA and stroke.
Test using micro bubble test (ultrasound).

14. Ventricular Septum. Day 35-42.
What three things come together to form the ventricular septum?
Muscle, membrane and endocardial cushion
Which of these three parts is most likely to go wrong?
Two membranous ridges grow down
Membranous part
Endocardial cushion
Muscular septum

15. Common ventricular outflow septum. Day 35.
A P A P
What are the ridges derived from?
Septum forms in truncus arteriosus and bulbus cordis
Neural crest mesenchyme
Septum spirals through ____o creating the aorta and the pulmonary trunk
180

16. Name all the defects.. Defects Which ones are cyanotic?
Truncus arteriosus
Ventricular septal
Tetraology of fallot
Atrial septal
Transposition the great vessels
Critical pulmonary stenosis
Patent ductus arteriosus
Which ones are cyanotic?
To be coloured blue or red

17. What is this defect?
Patent ductus arteriosus

18. Truncus arteriosus. What are the two types?
Failure of bulbar ridge formation
Failure of equal division

19. What is this defect? Transposition of great vessels
2 isolated circulations
What other defect can be good to have in this condition to help compensate?
Patent ductus arteriosus

20. Multiple cardiac defects can occur together in the tetraology of fallot. What are the 4 components?
VSD
Overriding aorta
RV hypertropy
Pulmonary stenosis
The heart has been vorped…

21. Cardiac Embryology Timeline

22. Name the main cardiac embryology events…