Blood from placenta via umbilical vein -> IVC -> right atrium. Venous return from body -> IVC, mixes with oxygenated blood from placenta. Most oxygenated blood shunted through foramen ovale to left heart -> aorta. Most oxygenated blood goes to brain. Distal to BCS origins, ductus arteriosus feeds deoxygenated blood from lungs into aorta -> mixed blood to body. Umbilical arteries return blood to placenta.
Changes in circulation at birth
SVR increases, PVR drops. Ductus arteriosus closes in first 24 hours. Foramen ovale closes in first month.
What drug keeps ductus arteriosus open?
Prostaglandin keeps open, indomethacin closes it.
Cyanotic congenital heart disease (right to left shunting)
Tetralogy of Fallot, pulmonary stenosis/atresia, tricuspid atresia, Ebstein's anomaly, transposition of great arteries (TGA)
Definition of Tetralogy of Fallot (ToF)
1. VSD 2. Pulmonary atresia 3. Overriding aorta 4. RVH (most common of the cyanotic heart defects). "boot shaped" heart
Pulmonary stenosis/atresia with intact ventricular septum
Stenosis is more common than atresia, which is total obstruction, more severe. Must have PFO or ASD to survive. Tx: stenosis use balloon dilation. Atresia do surgical correction such as valvulotomy PLUS systemic-pulmonary shunt.
Tricuspid atresia features
Tricuspid valve atresia PLUS 1) atresia/hypoplasia of right ventricle 2) ASD, PFO, or VSD. May have TGA or pulmonary stenosis. Most cases have a PDA as well.
Treatment of tricuspid atresia
Emergent systemic-pulmonary shunt or enlargement of PDA/PFO in the newborn for initial palliation. Later, do bidirectional Glenn shunt followed by modified Fontan.
SVC anastamosed to the pulmonary artery
see attached image
Ebstein's anomaly definition
Malformed and downwardly displaced septal and posterior leaflets of tricuspid valve, leading to obstruction. PLUS PFO or ostium secundum defect --> shunting, cyanosis. Arrhythmias common.
Risk factor for Ebsetin's anomaly
Maternal lithium use during pregnancy, esp first trimester
Transposition of Great Arteries (TGA)
Incompatible with life unless PDA, PFO, or VSD exists to allow mixing between the two separate circuits. If septum is intact, have to make emergent balloon septostomy of foramen ovale at birth.
Transection of great vessels just superior to valves, then transfer of vessels to their correct locations. Used for kids with TGA with VSD, within first 2 weeks of life.
Aorta rerouted internally to left ventricle across VSD, pulmonary artery is attached to RV externally (see picture). Used for kids with TGA with VSD plus LVOT obstruction: do a palliative systemic-pulmonary shunt, then Rastelli at age 4-5.
What are the three types of (at least initially) left to right shunt heart defects?
VSD, ASD, PDA
Risk factors for PDA
Shorter gestational age, lower birth weight, female sex
Treatment of PDA
Indomethacin is successful in 90%. Surgery in refractory cases. Unless CHF develops, can do surgery electively anytime between 6 months and 2 years
What is the most common congenital heart defect overall?
Do VSDs close on their own?
90% if small defects close by age 8. Treatment is to medically manage congestive symptoms. surgical closure is indicated if CHF is not controlled medically, or if it does not close by 9 months and pulmonic pressure has reached 2/3 of systemic pressure.
Usually asymptomatic until adult life unless large defect -> growth retardation, fatigue, recurrent PNA. Adults often present with arrhythmia or CHF.
Three types of ASD
Secundum type (middle or lower defect, most common type), sinus venosus (high type assoc with partial anomalous pulmonary venous return), and ostium primum type
Ostium primum type ASD
Endocardial cushion defect, cleft in mitral valve leaflet leading to mitral insufficiency. Uncommon except in Down syndrome
When you have a left to right shunt, increased pulmonary blood flow, PVR increases to the point that shunt becomes right to left -> cyanosis. Only treatment is heart and lung transplant.
What are the obstructive left sided congenital lesions?
Coarctation of the aorta, congenital aortic stenosis, hypoplastic left heart syndrome
Where is aortic coarctation usually located?
Within four cm distal to left subclavian take off
When is surgery done for aortic coarctation?
Neonates with CHF get it right away. Otherwise, ideal time is 3-4 years old
What causes rib notching on CXR in aortic stenosis?
Collateral circulation distal to the coarctation causes marked dilation of intercostal arteries
How do older children with aortic coarctation present?
Hypertensive but asymptomatic. Delayed femoral pulses
What's the deal with hypoplastic left heart syndrome?
Left side of heart is underdeveloped, with ineffective contractility and a valves less aortic remnant. Fetus survives because blood enters systemic circulation via PDA, so when that closes it is incompatible with life. Surgery is 80% survival.