Block III: Congenital malformations (conf 4) Flashcards
WHat is the main purpose of the heart?
oxygenate blood by delivering deoxygenated blood into the lungs for oxygenation
from where does SVC and IVC drain blood from?
upper body, head and neck; lower trunk and lower limbs
what vessels carry oxygenated blood from arch of aorta into head and upper limbs?
Brachiocephalic a.
Left common carotid a.
Left subclavian a.
explain the circulation of blood (in adult)
- deoxygenated blood enters the right atrium through IVC and SVC
- From the right atrium, passes through the tricuspid valve into the right ventricle
- From right ventricle passes through the pulmonary valve into th epulmonary trunk and into the lungs to be oxygenated.
- blood enters the heart again, oxygenated through the pulmonary veins into the left atrium.
- From left atrium enters through the mitral valve into the left ventricle.
- From left ventricle goes through the aortic valve into the aortic arch and goes through whole body by braciochephalic artery, left common carotid artery, left subclavian artery and the descending aorta.
What structure in the cadaver remains that we had infoldings that closed?
linea alba
explain the segmentation of the heart tube
unsegmented tube covered by a segmented tube
What are the 3 main concepts of the development of heart?
- It all starts with an unsegmented tube
- Followed by invagination of the laminar structure of the embryo
- And by rotation of the (“primordial heart”) tube.
where is the heart before the cranio-caudal folding? (hint: se me sale el corazon por la boca, garganta colorá)
anterior to the oropharyngeal membrane
where does heart tube incorporate with the cranio-caudal folding?
coelomic cavoty into the pericardial cavity
when does the formation of the cardiac loop occur?
22-24 days
explain the cardiac loop?
ventricules are originally above atriums, they rotate to the front and down into the right and the atriums are originally below the ventricles but they move posterior and left. Thus, atriums are on top and ventricles on the bottom
Where does primary heart field develop ?
develops cranial to the neural pliegues
where does the primary heart field comes from?
from neural crest
explain how does the primary heart field develops
Progenitor heart cells lie in the epiblast, immediately adjacent to the cranial end of the primitive streak. From there, they migrate through the streak and into the visceral layer of lateral plate mesoderm where some form a horseshoe-shaped cluster of cells.
what do progenitor heart cells form?
These cells form portions of the atria and the entire left ventricle
How does the secondary heart field form and what structures they form?
Cells reside in the visceral (splanchnic) mesoderm ventral to the pharynx. They form The right ventricle and outflow tract (conus cordis and truncus arteriosus) and the atria at the caudal end of the heart.
what is the venous pole?
big vessels that enter and exit heart
What is the outflow tract?
allows heart to be connected to the rest of the body
What is the master gene of heart development?
NKX2.5 gene
What activates the cascade of heart differentiation?
Secretion of BMP 2.4, crescent and cerberus by the endoderm produces inhibition of WNT genes and activation of NKX2.5 gene
What secretes BMP2.4?
secreted by the endoderm and lateral plate mesoderm; transforming growth factors B
What does WNT inhibitor genes secrete?
crescent and cerberus; inhibiting neural crest by inhibiting WNT 3a and WNT 8 which are secreted by neural tube
Who secretes WNT?
secreted by the endoderm in the anterior half of the embryo
What is syndromic?
congenital malformations
Which valves appear first?
tricuspid and mitral
What is the foramen ovale?
space between septum secundum and endocardial cushion
which is the potential anatomical space?
foramen ovale
why does the flap valve close?
due to first breath and low pressure in the right side
What is the purpose of the coronary sinus?
Brings low O2 blood from myocardium to right atrium for caval circulation (blood circulation of whole body/systemic)
What happens if foramen ovale closes too early?
results in problem where all blood will go into the left atrium
how does heart loops?
ventrally; heart goes from tubular structure into a four chamber structure with valves
when are congenital heart defects produced?
when developmental processes that mediate heart transformation are disrupted
what is the incidence of congenital heart defects in stillborns?
10%
what is the prevalence of congenital heart defects?
1% of live born infants. It makes up for the largest category of human birth defects.
what are the co-morbidities of congenital heart defects?
30% of heart defects occur in infants with other major malformations
33% of newborns with a chromosomal defect also have a heart defect
What are some examples of syndromes that can be accompanied by heart malformations?
Edwards Syndrome (Trisomy 18), Down Syndrome (Trisomy 21), golderhay syndrome (oculoauroculovertebral spectrum), DiGEORGE SYNDROME
What is the etiology of congenital heart defects?
Approximately 2% of heart defects are due to environmental agents, but most are
caused by a complex interplay between genetic and environmental influences;
(multifactorial causes); ie. idiopathic
What are some cardiovascular teratogens?
Rubella virus, Thalidomide, Retinoic acid (Accutane), Alcohol
- Insulin-dependent diabetes and hypertension of the mother has also been linked to cardiac defects.
What is the percentage of distribution of congenital defects by sex?
varon - 52%
hembra- 46%
intersex - 3%
cuales son los municipios con mayor numero de casos de defectos congénitos por densidad poblacional?
San juan (242), bayamon (125), ponce (106), carolina (53) y caguas (53)