Cardiac embryology diseases Flashcards
what is patent ductus arteriosus
persistence of distal left 6th aortic arch
where is patent ductus arteriosus incidence incr
1) babies born at elevation >9000
2) maternal rubella
3) infants <29 weeks gestation (1/3 spontaneous closure)
when does PDA functionally close
10-15 hrs after birth
delayed at high elev
when does PDA anatomically close
2nd-3rd wk of life
how does DA close
ductus = fewer elastic fibers and more muscular than aorta and pulm artery
increased PaO2 after birth causes contraction of spiral muscular fibers in PDA
why does DA not close in premature
contraction of spiral muscular fibers is weakened in premature
vascular remodeling after DA closes
1) form internal elastic membrane of ductus frag
2) intima and media proliferate
3) mucoid lakes form in intima and media
4) hyaline mass occludes lumen
why does DA stay open
PGE2 (vasoactive) = keeps DA open
how do you keep DA open?
administer PGE2 IV
where is PGE2 produced
from ductal wall
or placenta
what is clinical presentation of PDA
depends on size of “shunt”
what is shunt
connection btwn 2 chambers and vessels
what is left-to-right shunt imply?
blood flow from systemic into pulmonary chamber
when blood flows from systemic to pulm, what shunt is that
left-to-right
what are systemic chambers in heart
1) pulm veins
2) left atrium
3) left ventricle
4) aorta
what are pulm chambers in heart
1) systemic veins
2) right atrium
3) right ventricle
4) pulm arteries
are shunts equal
NO
what does magnitude of shunt depend on (2 things)
1) size of PDA
2) resistances of aorta and pulm artery
what is more common shunt
left to right
because aortic resistance > pulm resistance so blood go from aorta –> pulm artery
what if neonates have high pulm vascular resistance
PDA flow from right to left or bidirectional
when would a neonate have high pulm vascular resistance
1) premature
2) lung disease
3) born at altitude
what is clinical presentation of small PDA
asymptomatic
what is clinical presentation of moderate-large PDA
1) respiratory effect (pulm edema/hemorrhage)
2) CHF
3) feeding intolerance –> bowel ischemia (necrotizing enterocolitis)
4) hemorrhage/storke
5) death
what is clinical presentation of PDA in older infant/young child
1) hoarse cry
2) hx of pneumonia
3) incr work breathing
4) diaphoresis with activity and feeding
physical exam of large PDA with left to right flow
1) wide pulse pressure
2) bounding pulses (palpable palmar pulse)
3) incr work breathing
4) hyperactive precordium
what is classic murmur of PDA
continuous machine murmur along left upper sternal border (may have diastolic rumble if shunt large
where do you hear murmur of PDA
left upper sternal border
why could you not hear murmur of PDA
low velocty
tiny shunt
if there is pulm HTN with PDA what else would you hear
accentuated P2
systolic ejection
how do you dx PDA
H&P
chest radiograph
- can be normal if PDA small
- incr pulm vascular marking, large LA and LV
echo
how do you manage PDA
asymptomatic neonate
conservate
how do you manage PDA
symptomatic neonate
COX inhib (IV indomethacin or IV ibuprofen lysate)
surgical ligation via lateral thoracotomy
how do you manage PDA
symptomatic older child or
percutaneous occlusion
how do you manage PDA
asymptomatic oldr child
murmur –> percutaneous closure
silent –> no need to intervent
why do you use cox inhibitors
block prostaglandin (PGE2) (that keeps shunt open)
for cox inhibitors when would you use indocin
protective against intraventricular hemorrhage but decr blood to kidney and brain
for cox inhib when would you use ibuprofen lysine
renal disease/insufficiency
when is cox inhib most effect
first week but wait after 48 hrs to see if spontaneous closure
how does PDA progress
1) if large –> Eisenmenger’s - irrev pulm HTN
2) incr risk of subacute bacterial endocarditis
what does magnitude of PDA shunt depend on (2 things)
1) size of PDA
2) resistances of aorta and pulm artery
physical exam of large PDA with left to right flow
1) wide pulse pressure
2) bounding palmar pulses
3) incr work breathing
4) hyperactive precordium
what is classic murmur of PDA
continuous machine murmur along left upper sternal border (may have diastolic rumble if shunt large
how do you manage PDA
symptomatic older child
percutaneous occlusion
how do you manage small PDA
asymptomatic older child **skip
murmur –> percutaneous closure
b/c incr risk of bacterial endocarditis
silent –> no need to intervent
