Embryology & congenital defects Flashcards
Where is co2 eliminated in the fetus? Since they dont have a lung
Via placenta
What causes the foramen ovale to close up during birth
respiration begins, LA pressure increase and blood shunt backwards to the RA and closes up the formaen ovale (septum primum closes on secundum
6th arch of aortic arch forms _________
Pulmonary trunk
Which emryonic tissue gives rise to the cvs
Mesoderm
In which week of development does the embryo fold
4th
How many shunts r there in fetal circularion
DA
DV
foramen ovale
What is coarctation of the aorta? Would this increase or decrease afterload? What could this lead to
Narrowing of the aorta in the area of the ligamentum arteriosum.
Increase in afterload causing ventricular hypertrophy
What is most common congenital heart disease
VSD
What is most common cyanotic congenital heart disease
Tetralogy of fallot
When will patient develop a cyanosis
If Hb amount is more that 5gm/dl
what might u expect the femoral pulses to be like in a patient with coarctation of the aorta?
very weak pulses & there will be a radio-femoral delay
describe tetralogy of fallot, will a patient with these defects be cyanosed?
[4 DEFECTS]—-POVR
- pulmonary stenosis
- overriding aorta
- VSD
- RV hypertrophy
describe the transposition of great arteries and explain why it is compatible with life in utero but not after birth.
the pulmonary artery and aorta switch places> bc in utero they have the DA and foramen ovale to compensate
several cvs defect r associated with well known genetic defects and syndromes, describe one
marfan
turners
trisonomy 21
(look them up alaa)
what would u hear through a stethoscope in an infant with ‘patent ductus arteriosis’
you would hear a continuous murmur throughout systole and diastole “machinery murmur
Name the asynotic defects in congentital heart defects
LEFT >RIGHT SHUNTS
- ASD
- VSD
- PDA
OBSTRUCTIVE LESIONS
- coarctation of aorta
- pulmonary stenosis
- obstructive lesions
what is VSD? what part is this most common in?
abnormal opening in the inter ventricular septum
-membraneous portion
what is function of DA in a fetus? where is it located?
shunts blood from pulmonary >aorta before lungs r functioning
-attaches to the final part of the arch of aorta (the isthmus of aorta) and the first part of the pulmonary artery(where it bifurcates)
what is PDA? describe what happens
DA does not close, BF will be from aorta >pulmonary, pulmonary circulation overloaded w/ blood > pulmonary hypertension.
Due to low CO, (bc blood from aorta is moving to pulmonary) LV wants to maintain CO, so it will hypertrophy > Heart failure
does L > R shunting cause cyanosis?
not really (in some cases depending extent ex; if eisenmenger occurs) but no,
what causes pulmonary hypertension?
too much blood entering pulmonary circulation, arterioles hypertrophy and constrict as a compensatory mechanism causing PH.
explain the hemodynamic effects in Atrial septal defects
- O2 saturation in RA is high
- chronic volume overload (blood coming from LA and inferior and sup vena cava)
- increased pulmonary BF
- RV & RA undergo hypertrophy
- eventual heart failure
what is eisenmenger syndrome?
condition of severe pulmonary vascular obstruction that results from L>R shunting. the high pulmonary vascular resistance cause a reverse in shunting R>L and systemic CYANOSIS
what happens in AV septal defect? what type of patient r mostly associated with this?
problem in development in endocardial cushions, leading to deficiency of the atrioventricular septum of the heart.
1/3 of the patients r associated with DOWN SYNDROME
ventricular septum has 2 components, name them, which one forms MOST of the septum
muscular, membranous
the muscular grows upwards towards the EC & forms the most
a patient with PDA comes in with cyanosis in the lower limbs, how and why did this occur in the lower part
he developed eisenmenger sydrome, (R>L shunt)
bc the DA is located after the vessels that supply the head ( so the blood going to the head is safe)
Name the cyanotic defects in CHD (star)
atresia of tricuspid valves Tetralogy of Fallot Total anomalous pulmonary venous return Transposition of the great arteries Truncus arteriosus
when can u develop cyanosis?
if amount of deoxyhemoglobin is less than 5gm/dl
what r the symptoms what accompanies R>L shunt
(triangle) clubbing, polycyhtemia, cyanosis
in tetralogy of fallot, why is there R>L shunt?
due to pulmonary stenosis, right ventricle has to work hard to push blood out> RV hypertrophy> increased pressure causes R>L shunt
a patient with tetralogy of fallot performs a squatting position, why does this help?
it compresses on femoral artery>increases pressure on aorta> blood is forced to go to pulmonary artery!
patients in cyanosed CHD, can present with secondary polycythemia, why is this so?
deoxygenated blood goes to kidney>casues them to release EPO> stimulates eryhtropoeiss>polycythemia
what is meant by an over riding aorta
aorta makth in path mal both ventricles
what shape is the heart with tetrology of fallot?
boot shaped
describe the process of septation
look at picture in lecture
musular portion grows from down to up, membraneous grows from up to down
describe formation and looping of primitive heart tubes
a pair of blood island appear in the cariogenic field in 2 sides, they meet each other in the midline and form the primitive heart tube
name the regions of the developing heart
aortic roots truncus arteriosus bulbus cordis ventricle atrium sinus venosus
describe in brief the development of great vessels
ss
describe the functional importance of transposition of great arteries
s
what is cortication of the aorta
narrowing of aortic lumen in the region of the ligament arteriosum, narrowing of aorta increases after load on LV>hypertrophy.
describe effects of cortication of the aorta
Arterial hypertension in the arms w/ low blood pressure in the lower extremities
weak pulses in femoral arteries and arteries of the feet are found
what is a hypoplastic left heart?
LV and Ascending aorta fail to develop properly
what is the cardogenic field
zone w/in the mesoderm that has the capacity to differentiate into the CVS
describe septation of outflow
creating a separate PT & A
endocardial cushions grows into the truncus arteriosis forming a spiral septum that twists upwards seperating PT & A
(look at pic)
where the places that endocardial tissues form?
in truncus arteriosis and
how is foramen oval built
look at lecture slides
