Cardiac embryology
Karina & Allison
What we are going to cover…
1. Cardiac embryology2. Septal formation: atrial, ventricular and
arterial outflow3. Heart defects4. Timeline of cardiac development
What type of folding moves the brain, mouth and heart into the adult position? And when does this happen?
Longitudinal folding. Day 19.
Green line = position of the heart
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.
Dilations appear in the heart tube.Name them…
Dilations appear in the heart tube.Name them…
AtriaSinus
Venosus VentricleBulbus Cordis
Truncus Arteriosus
Smooth wall of right atria
Rough wall of both
atria
Ventricles Mainly outflow of ventricles
Initial part of aorta & pulmonary trunk
Aortic sac
Left HornOf Sinus
Right HornOf sinus
And then what happens?
LARA
LV Outflow
Coronary sinus
Vena Cavae
Aorta
RA RV Outflow Pulm Trunk
Pulmonary veins grow out of the left atrial wall and branch. The proximal parts get absorbed into the atrial wall = smooth part
Septa form and divide chambers and outflow tract to create the left right sides of the heart
Shunting takes place to avoid the developing lungs. Which direction does this happen in?
• R L shunting
LARA
LV Outflow
Coronary sinus
Vena Cavae
Aorta
RA RV Outflow Pulm Trunk
What is this called?
Dextrocardia
BCVA
SV
TA
Normal
Dextrocardia
Atrial Septum: Days 24-35
Atrial Septum Septum primum
Foramen primum
Septum secundum
Septum secundum
Foramen ovale
Foramen secundum
RA
RA
RA
RA
LA
LA
LA
LAValve of Foramen ovale
Endocardial cushion
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
RA LA
The septum primum is relatively floppy – it acts as a valve cusp
The septum secundum is muscular and stiff
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.
Ventricular Septum. Day 35-42.• What three things come together to form the
ventricular septum?
Two membranous ridges grow down
Muscular septumEndocardial cushion
Which of these three parts is most likely to go wrong?
Muscle, membrane and endocardial cushion
Membranous part
Common ventricular outflow septum. Day 35.
AP
A P
PA
Septum forms in truncus arteriosus and
bulbus cordis
Septum spirals through ____o creating the aorta and the pulmonary trunk
What are the ridges derived from?
Neural crest mesenchyme
180
Name all the defects..
Defects
Truncus arteriosus
Ventricular septal
Tetraology of fallot
Atrial septalTransposition
the great vessels
Critical pulmonary
stenosis
Patent ductus
arteriosus
Which ones are cyanotic?
What is this defect?
Patent ductus arteriosus
Truncus arteriosus. What are the two types?
Failure of equal division Failure of bulbar ridge formation
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
Multiple cardiac defects can occur together in the tetraology of fallot. What are the 4 components?
1. VSD 2. Overriding aorta 3. RV hypertropy 4. Pulmonary stenosis
The heart has been vorped…
Cardiac Embryology Timeline
Name the main cardiac embryology events…
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