Lecture 5 Flashcards
Congenital heart defects
What is a congenital heart defect?
structural abnormalities of the heart present from birth. They affect blood flow through the heart and to the rest of the body.
How many babies are born with some kind of congenital heart defect?
1 in 100
How many CHD are chromosomal?
16%
How many CHD are from maternal diabetes?
2%
How many CHD are from syndromes?
2%
How many CHD are from unknown environmental factors?
80%
What is the first organ in the body to develop?
The heart
What is the thick layer of cardiac muscle in the heart called?
Myocardium
What are the individual cells that make up the myocardium called?
Cardiomyocytes
What is the endothelial layer that lines the inside of the heart called?
The endocardium
What does the endocardium give rise to?
The endocardial cushions which are precursors of the valves and membranous septa.
What cells are essential components of the outflow tract cushions?
Neural crest cells
What are the great arteries coated in?
Smooth muscle cells
What is the single layer of epithelial cells lining the heart called?
Epicardium
What is the whole heart enclosed in?
The pericardium.
How long is the embryonic stage of development and what occurs?
8 weeks. Many differentiation and formation of the different organs. Differentiation of cells.
How long is the foetal stage of development and what occurs?
Last 32 weeks of pregnancy. Mainly growth of the foetus.
What are the three distinct layers that form during gastrulation?
Ectoderm, mesoderm and endoderm
What does the ectoderm fold into?
The neural tube (brain and spinal cord)
What two distinct regions does the mesoderm become?
Splenic mesoderm and the pre-myocardium
What do the two types of mesoderm form?
The cardiac crescent
What are the two fields of cell types that form the hear?
Primary and secondary heart fields
What do cells from the primary heart field become?
The left ventricle and some atria
What do cells from the secondary heart field become?
The right ventricle, outflow tract and most atria.
What are the two types of foetal shunts?
Arterial duct and foreman ovale
What type of shunt is the arterial duct?
Right to left
Where is the foreman ovale?
Between the atria. It is also a right-to-left shunt.
In what CHD is keeping the arterial duct open beneficial?
Transposition of the great arteries.
What is produced during pregnancy to keep the arterial duct open?
Prostaglandins PGE1 and PGE2
What receptors do the prostaglandins act on?
EP2 and EP4
Which prostaglandin and receptor pair is major in induced AD dilation?
PGE2 and EP4. Levels of their expression go down after birth to close the duct.
What are the three types of intracardiac malformations?
ASD, VSD and tetralogy of Fallot
What type of shunt is VSD and ASD?
left-to-right
What three things is occurring in tetralogy of Fallot?
VSD, overriding aorta and pulmonary stenosis. Causes a right to left shunt.
What is a symptom of ToF?
Blue colour/cyanosis from right-to-left shunt
What are the valves derived from?
endocardial cushions
Where do cardiac neural crest cells stem from?
The cranial portion of the neural tube
Where do cardiac neural crest cells migrate through?
Pharyngeal arches 3, 4 and 6 to form the outflow tract, valves and arteries.
What are three types of outflow tract malformations?
Transposition of great arteries, double-outlet right ventricle and common arterial trunk
Which is most severe?
CAT
What other defect does DORV have to come with or it would be fatal?
VSD
Which process does not occur properly in DORV?
twisting
What is CAT?
Common arterial trunk. septation does not occur so there is just one outflow tract.
How many cusps does each valve have?
mitral valve is bicuspid, all rest are tricuspid (aortic, pulmonary and right AV valve)
What is hypoplastic left ventricle syndrome?
Narrowed aorta and very small left ventricle
What mutation is present in 65% of people with charge syndrome?
CHD7 on chromosome 8
In down syndrome, what are the more common heart defects?
AV septal defects or VSD. 5% have tetralogy of Fallot.
What gene defect is associated with Holt Oram syndrome?
TBX5
