Cardiac Embryology Flashcards
Which organ is the first to form in the developing embryo?
The cardiovascular system
From which germ layer does the cardiovascular system arise?
Splanchnic lateral plate mesoderm
What are the three germ layers called?
Ectoderm, mesoderm and endoderm
How does mesoderm subdivide?
Paraxial mesoderm, intermediate plate mesoderm, lateral plate mesoderm (somatic and splanchnic)
How do somites subdivide?
Dermatomes, myotomes and sclerotomes
What do dermatomes, myotomes and sclerotomes form respectively?
Dermis of skin (dermatome), muscle (myotome) and bone (sclerotome)
What are the four main stages in heart development?
- Heart primordia fusing to make primitive heart tube
- Heart looping
- Atrial and ventricular septa forming
- Outflow tract septation
During which week of development does the heart start functioning (and beating)?
Around week 4 (beating around day 24)
What are the regions of the primitive heart tube from bottom to top (inlet to outlet)?
Sinus venosus Atrium Ventricle Bulbus cordis Truncus arteriosum
What are the three veins on either horn of the sinus venosus which drain into it in an embryo?
Vitelline vein; Umbilical vein; Common cardinal vein
What do the vitelline, umbilical and common cardinal veins drain respectively?
Yolk sac; Placenta; Embryo body
Which region of the primitive heart tube gives rise to the right ventricle?
Bulbus cordis
Where is the foramen ovale found?
In interatrial septum secundum
How are the aorta and the pulmonary trunk formed and separated?
Top part of bulbus cordis and truncus arteriosus undergo spiral septation
What region of the primitive heart tube gives rise to the left atrium?
Primitive atrium
What region of the primitive heart tube gives rise to the right atrium?
Sinus venosus
What region of the primitive heart tube gives rise to the aorta and pulmonary trunk?
Truncus arteriosus
List the four defects in Tetralogy of Fallot
- Pulmonary stenosis
- RV Hypertrophy
- Ventricular Septal Defect
- Overriding aorta
What causes Tetralogy of Fallot?
Anterior displacement of aorticopulmonary septum in truncus arteriosus (larger space for aorta and smaller for pulmonary trunk)
What heart defect is often found in Turner’s Syndrome?
Aortic coarctation
What heart defect is often found in Down’s Syndrome?
VSD
Which sex is more likely to develop atrial septal defect?
Females
Which sex is more likely to develop ventricular septal defect?
Males
What is transposition of the great arteries?
Aorta coming off right ventricle and pulmonary trunk coming off left ventricle
What are the two causes of transposition of the great arteries?
- Failed spiral septation
2. Abnormal neural crest cells migration
Which two congenital abnormalities are more common in females?
ASD and patent ductus arteriosus (PDA)
What makes up the membranous interventricular septum?
The bottom of the spiralled aorticopulmonary septum
What happens to the first and second aortic arches?
Becomes the maxillary arteries coming off the external carotid arteries
What happens to the third aortic arches?
Become carotid arches (form internal carotid arteries)
What happens to the fourth aortic arches?
Right - becomes right subclavian artery
Left - becomes aortic arch
What happens to the fifth aortic arches?
Disappear or don’t appear at all
What happens to the sixth aortic arches?
Right - becomes proximal end of right pulmonary artery
Left - becomes left pulmonary artery and forms ductus arteriosus (later ligamentum arteriosum)
List four common heart defects associated with aortic arches
- Aberrant subclavian artery
- Coarctation of aorta
- Double aortic arch
- Patent Ductus Arteriosus (PDA)
What happens to the embryonic umbilical arteries?
Proximal end - become internal iliac and superior vesical arteries
Distal end - become umbilical ligaments
What happens to the embryonic vitelline veins?
They become part of the hepatic portal circulation
Name the three main embryonic circulation bypass structures and their function
- Ductus venosus (allows blood to bypass liver)
- Ductus arteriosus (allows blood to bypass lungs)
- Foramen ovale (allows blood to bypass lungs)
What happens to the ductus venosus, ductus arteriosus and foramen ovale after birth?
They become ligamentum venosus, ligamentum arteriosus and fossa ovale
What disease often causes patent ductus arteriosus (PDA)?
Maternal rubella during early pregnancy
What happens to the umbilical veins?
Right - disappears
Left - becomes ligamentum teres in liver
What happens to the cardinal veins?
They anastomose and become the IVC and SVC
List the abnormalities that can occur in IVC and SVC development
Double IVC, double SVC, absent IVC, left SVC
