Congenital Heart Defects Flashcards
what is a patent ductus arteriosis (PDA)?
failure of the ductus arteriosus to close
when does ductus arteriosus usually close?
stops functioning within 1-3 days of birth and completely closes within 2-3 weeks of birth
risk factors for PDA?
rubella
prematurity
presenting features of a small PDA
can be asymptomatic causing no functional problems and will close spontaneously
can sometimes be asymptomatic throughout childhood and present in adulthood with sings of heart failure
what is the ductus arteriosus?
connection between the aorta and pulmonary artery which exists during foetal development
function of ductus arteriosus?
foetal blood gets oxygen from the placenta rather than the lungs during development (the lungs are filled with amniotic fluid)
therefore blood does not need to go through the lungs so the ductus arteriosus acts as a shunt to bypass the lungs so it goes straight from pulmonary artery into aorta
why is PDA an issue?
pressure higher in aorta than in pulmonary artery therefore blood will flow from aorta to pulmonary artery
this creates a left to right shunt
this increases pressure in the pulmonary vessels causing pulmonary hypertension and leads to right heart strain as the right side of the heart struggles to contract against the increased resistance in the vessels
pulmonary hypertension and right heart strain lead to right ventricular hypertrophy and increased volume of blood flowing through pulmonary circulation back to left side of heart causes LVH
how does PDA present?
often picked up on newborn examination via machine like murmur can have symptoms of - short of breath - difficulty feeding - poor weight gain - lower resp tract infection
what is the murmur like in PDA?
small PDA might not have any abnormal sounds
larger PDAs cause a normal first heart sounds with a continuous crescendo/decrescendo “machine like” murmur that may continue through second heart sound
how is PDA diagnosed?
echo
doppler during echo can help assess size and characteristics of the left to right shunt
echo can also show any complications like hypertrophy
how is PDA managed?
monitored until 1 year old using ECHO
if still open after 1 year old trans-catheter or surgical closure can be done
(treated earlier if symptomatic or evidence of heart failure due to PDA)
why are babies with PDA only monitored up until 1 year old?
PDA unlikely to close on its own after 1 year
how do atria form?
both atria are connected during development
2 walls grow downwards from top of heart then fuse together with the endocardial cushion in the middle of the heart to separate the atria
(2 walls called septum primum and septum secondum)
what hole exists in the septum secondum during development?
foramen ovale
usually closes at birth
what does an atrial septal defect (ASD) lead to?
shunt of blood between atria (mainly from left to right atrium since pressure is higher in left)
this means blood continues to flow to pulmonary vessels and lungs
this can lead to right heart strain, right heart failure and pulmonary hypertension
what is eisenmenger syndrome?
complication of pulmonary hypertension in ASD where the pulmonary pressure is greater than systemic pressure
this reverses the shunt and forms a right to left shunt across the ASD
this means blood will move from rigth atria to left atria and bypass the lungs causing the patient to become cyanotic
what are the 3 types of ASD?
ostium secondum = septum scondum fails to close
ostium primum = when septum primum fails to close
patent foramen ovale
4 possible complications of ASD?
stroke (in context of venous embolism as DVT can travel to the brain instead of the lungs via the septal defect)
AF or atrial flutter
pulmonary hypertension and right sided heart failure
eisenmenger syndrome
ASD murmur?
mid-systolic, crescendo-decrescendo murmur loudest at the upper left sternal border
fixed split 2nd heart sound
what is a split 2nd heart sound?
where you hear the aortic and pulmonary valves close at slightly different times
can be normal on inspiration but if fixed (there all the time) this can indicate ASD
why do you get a split 2d heart sound in ASD?
bc blood is flowing from left atrium into right atrium across ASD
this increases the volume of blood that the right ventricle has to empty before the pulmonary valve can close
how does ASD usually present?
murmur can be asymptomatic in childhood then present in adulthood with dyspnoea, heart failure or stroke typical childhood symptoms - short of breath - difficulty feeding - poor weight gain - lower resp infections
how is ASD managed?
refer to paeds cardio for ongoing management
if small and asymptomatic watch and wait is enough
can be corrected surgically using transvenous catheter closure via femoral vein or open heart surgery
should give anticoagulants to reduce clot/stroke risk in adults
ventricular septal defect (VSD) is seen more often in which conditions?
down syndrome
turners syndrome
