Flashcards in Paediatric Cardiology Deck (65)
Describe the fetal circulation
oxygenated blood enters body via umbilcal vein
bypasses liver via ductus venosus
passes into LA via foramen ovale
any blood not in LA continues to RV and pulmonary arteries
ductus arteriosus to aorta to bypass lungs
umbilical arteries from internal iliacs back to placenta
Why do the duuctus venosus, foramen ovale and ductus arteriosus exist?
to conserve oxygen and nutrients for the whole of the body
bypassing liver and lungs
What happens to the ductus venosus at birth?
umbilical cord cut
leads to umbilical vein shutting off
leads to no ductus venosus!
becomes ligamentum venosum
What happens to the foramen ovale at birth?
at birth, air enters the lungs
pulmonary arterioles were vasoconstricted due to hypoxic vasocontriction
at birth, the alveoli become full of oxygen, leading to vasodilation of the arterioles
the previously high pressure pulmonary circulation becomes low pressure
pressure in RV falls to below pressure of LV
this causes the foramen ovale to close in the first few minutes after birth!
becomes fossa ovalis
What happens to the ductus arteriosus at birth?
placenta was releasiign prostaglandin into the fetal circulation, keeping it open
at birth, the increase in o2 and the drop in prostaglandins causes the ductus arteriosus to close within a day
becomes the ligamentum arteriosum within 2 weeks
Describe the effects of patent ductus arteriosus (PDA)
failure to close leads to overloading of the lungs as blood flows from aorta to pulmonary arteries
can lead to pulmonary HTN
What are the effects of pulmonary HTN in PDA
can lead to reversal of blood flow back to aorta as pulmonary P >aorta P. R to L
differential cyanosis - cyanosis in lower extremities
branches to upper extremities and head have left aorta before the PDA
What are the features of PDA
continuous machinery murmur
thrill at upper left sternal border
bounding peripheral pulse
Why is there a bounding peripheral pulse in PDA
run off into pulmonary circulation from aorta
leads to wide pulse pressure
causes bounding peripheral pulse
What is the treatment for PDA
surgery to close
How does the atrial septum form?
septum primum grows down. ostium primum forms inferiorly, septum fuses with endocardial cushions. ostium secundum forms superiorly. ostium primum regresses.
septum secundum grows on the right hand side of septum primum. foramen ovale forms in it.
blood passes through the foramen ovale and ostium secundum from RA to LA
What causes an ASD
secundum ASD = septum secundum growth insufficient
primum ASD = ostium primum remains open
sinus venosus defect
coronary sinus defect
What are the features of ASD in a child
What are the features of ASD in an adult
Why does Eisenmenger's occur in ASD
L to R shunt
overloading of pulmonary circulation
leads to switch to R to L shunt as RA P > LA P
What are the signs on examination in ASD
widely split second heart sound
soft systolic ejection murmur at left sternal border
What is a paradoxical embolism?`
occurs if shunt switches to R to L in ASD
clot from DVT bypasses lungs and can go straight to head causing stroke
What investigations need to be done is ASD
What can be seen on an ECG in ASD
tall p wave - due to right atrial enlargement
right axis deviation
What can be seen on a CXR in ASD
enlarged RA and RV
increased pulmonary markings
How is ASD managed
diuretics if causign HF
surgical closure - open or transcatheter
What are the complications for women of child bearing age with ASD
increased risk of pre-eclampsia, low birth weight and fetal loss
if pulmonary HTN, significant increases risk of mortality in pregnancy - AVOID!!!
Describe the formation of the ventricular septum
membranous portion grows down from endocardial cushions
muscular portion grows up from base of heart - accounts for majority of septum
How can VSDs be classified
subarterial infundibular - adjacent to the arterial valves
Inlet or AV canal - lie beneath the septal leaflet of the tricuspid valve
What conditions are associated with VSD
Down's - trisonomy 21
Patau's - trisonomy 13
Edward's - trisonomy 18
Di george - 22q11 deletion
Turner's - 45X
diabetes in pregnancy
fetal alcohol syndrome
What are the symptoms of VSD
asymptomatic at birth
if moderate to large: excercise intolerance - feeding affected - increased RR, slow feeding, increased effort of breathing. leads to poor weight gain
if very large: pulmonary HTN, leads to R to L shunt. causes Eisenmenger's cyanosis
What are the signs of VSD
mild: child well developed and pink, harsh systolic murmur at lower left sternal edge
moderate to large: parasternal heave, grade 2-6 systolic murmur at lower left sternal border
State the grading of murmurs
1 - The murmur is only audible on listening carefully for some time.
2 - The murmur is faint but immediately audible on placing the stethoscope on the chest.
3 - A loud murmur readily audible but with no thrill.
4 - A loud murmur with a thrill.
5 - A loud murmur with a thrill. The murmur is so loud that it is audible with only the rim of the stethoscope touching the chest.
6 - A loud murmur with a thrill. The murmur is audible with the stethoscope not touching the chest but lifted just off it.
What investigations should be done in VSD