PAEDIATRIC CARDIOLOGY
NORMAL FOETAL CIRCULATION:
STEP 1: Cord clamping
1) immediate vasoconstriction (areterial vasospasm) due to
cold exposure
2) ↑ systemic vascular resistance
STEP 2: Baby Cries / 1st breath (secs)
1) Alveoli expands = amniotic fluid pushes into pulmonary
vessels
2) ↓ pulm. vascular resistance
3) Reduced RA pressure and high LA pressure squashes
atrail septum
4) Mechanical pressure closure of foramen ovale
STEP 3: Ductus venosus closes (mins)
1) absent flow through umbilical veins
2) closure occurs days later to become ligamentum
venosum
STEP 4: Ductus Arteriosus closes (>1o hrs)
1) increased blood O2 causes prostaglandin drop
2) Keep patent using prostin (PGE analog) for cyanotic HD
(e.g. trcicuspid atresia) - enable L --> R shunting
3) NSAIDs for closure
HEART EMBYROLOGY
Foetal structure Adult Derivative
1. sinus venosus forms SVC and part of the right atrium
2. primordial atrium forms the anterior parts of the right and left atria
3. primordial ventricle forms most of the left ventricle
4. bulbus cordis forms most of the right ventricle and parts of the
outflow tracts for the aorta and pulmonary trunk
5. truncus arteriosus form the pulmonary trunk and aorta
NORMAL FOETAL CIRCULATION:
STEP 1: Cord clamping
1) immediate vasoconstriction (areterial vasospasm) due to
cold exposure
2) ↑ systemic vascular resistance
STEP 2: Baby Cries / 1st breath (secs)
1) Alveoli expands = amniotic fluid pushes into pulmonary
vessels
2) ↓ pulm. vascular resistance
3) Reduced RA pressure and high LA pressure squashes
atrail septum
4) Mechanical pressure closure of foramen ovale
STEP 3: Ductus venosus closes (mins)
1) absent flow through umbilical veins
2) closure occurs days later to become ligamentum
venosum
STEP 4: Ductus Arteriosus closes (>1o hrs)
1) increased blood O2 causes prostaglandin drop
2) Keep patent using prostin (PGE analog) for cyanotic HD
(e.g. trcicuspid atresia) - enable L --> R shunting
3) NSAIDs for closure
HEART EMBYROLOGY
Foetal structure Adult Derivative
1. sinus venosus forms SVC and part of the right atrium
2. primordial atrium forms the anterior parts of the right and left atria
3. primordial ventricle forms most of the left ventricle
4. bulbus cordis forms most of the right ventricle and parts of the
outflow tracts for the aorta and pulmonary trunk
5. truncus arteriosus form the pulmonary trunk and aorta
