Lecture 6 - Development of cardiovascular system 2 Flashcards
(24 cards)
Dextrocardia
result of abnormal cardiac looping
may be induced during gastrulation when laterality is determined
What is isolated dextrocardia associated withʔ
other structural defects including abnormal connections with veins, arteries or abnormal septation of heart/
Patent ductus arteriosus
allows shunting of blood from aorta to pulmonary artery. oxygenated blood returns to lungs from aorta and pumped out again - increases cardiac workload - pulmonary hypertension,ventricular hypertrophy and heart failure.
may be an isolated defect or occur with other cardiac defects
Why does the ductus arteriosus close at birthʔ
due to an increasing oxygen tension and decrease in circulating prostaglandins.
how is ductus arteriosus treatedʔ
prostaglandin inhibitors
Atrial septal defects
failure of septum primum and secundum to fuse at birth - probe patent foramen ovale. its a possibility that they do not overlap and leave a gap. most commonly defects in septum secundum
probe patent foramen ovale
occurs 1 in 4 people
usually asymptomatic, higher pressure in lA pushes septum primum against secundum and mechanically shuts valve.
Why would pulmonary hypertension cause problems in Patent foramen ovaleʔ
There is higher pressure in right atrium. pushes flimsy septum primum open and allow blood flow from right to left
Ostium secundum defects
excessive apoptosis, in septum primum or inadequate development of septum secundum such as foramen ovale.
Blood shunted from left to right
can enlarge ra and ventricle
small defects asymptomatic, larger defects - surgical repair
common atrium
complete absence of atrial septum.
no development of septum primum or secundum
Premature closure of foramen ovale
hypertrophy of the right side of the heart and underdevelopment of the left side. baby usually dies after birth shortly.
Ventricular septal defect
most common congenital defect down's syndrome can effect membranous or muscular part muscular part - often resolve themselves left - right shunting can result in pulmonary hypertension and hypertrophy of right ventricle
Sepatational defects of the truncus arteriosus
septum formation depends on migration of neural crest cells
abnormal neural crest cell migration can lead to defects in septation of truncus arteriosis into pulmonary trunk and aorta.
What are the different types of septational defects of truncus arteriosusʔ
Persistent truncus arteriosus
transposition of great vessels
tetralogy of fallot
persistent truncus arteriosus
conotruncal septum absent
undivided truncus communicates with both ventricles - receives ox and deox bloody.
Symptoms - cyanosis, lethargy, breathlessness, delayed growth
corrected surgically
Transposition of great vessels
septum does not spiral, runs straight down
aorta arises from right ventricle and pulmonary artery from lv.
incompatible with life unless accompanying shunt such as VSD or patent foramen ovale or ductus arteriosus exists.
cyanosis - can be corrected surgically
how can a ventricular septal defect be beneficialʔ
when great vessels are transposed, an accompanying shunt will reverse the process
Tetralogy of Fallot
unequal division of truncus arteriosus caused by anterior displacement of the aorticopulmonary septum.
What are the 4 classical cardiac defects in tetralogy of fallot
- pulmonary stenosis due to enlarged right ventricle
- ventricular septal defect
- overriding aorta
- right ventricular hypertrophy
leads to cyanosis
Coarctation of aorta
narrowing of aorta that occurs near ductus arteriosus.
cause unknown - may be due to abnormal migration of cells from ductus arteriosus.
preductal or post -ductal
Preductal coarctation of the aorta
during development ductus arteriosus compensates for narrowing
after birth, usually remains patent
then obliteration occurs, causes rapid decline of infant - hypoperfusion of lower body
how is preductal coarctation of aorta treated
using prostaglandins - keeps ductus arteriosus open
What is differential cyanosisʔ
upper body and head well perfused, lower body cyanotic
Post - ductal coarctation of the aortaʔ
more common than preductal
collateral circulation established
blood passes from subclavian - internal thoracic - intercostal arteries - descending aorta
internal thoracic and intercostal arteries enlarge to carry greater flow
