Truncus arteriosus gives rise to
Ascending aorta and pulmonary trunk
Bulbus cordis gives rise to
Smooth parts (outflow tract) of left and right ventricles
Primitive ventricle gives rise to
Trabeculated left and right ventrciles
Primitive atria gives rise to
Trabeculated left and right atria
Left horn of sinus venosus gives rise to
Coronary sinus
Right horn of sinus venosus gives rise to
Smooth part of right atrium
Right common cardinal vein and right anterior cardinal vein gives rise to
Superior vena cava
How is truncus arteriosus formed
Neural crest migration –> truncal and bulbar ridges that spiral and fuse to form the aorticopulmonary (AP) septum –> ascending aorta and pulmonary trunk
Pathology of truncus arteriosus failure to spiral
Transposition of great vessels (or due to improper neural crest migration into the TA)
Pathology of truncus arteriosus skewed AP septum development
Tetralogy of Fallot
Pathology of truncus arteriosus partial AP septum development
Persistent TA (or due to improper neural crest migration into the TA_
Three steps of interventricular septum development
- muscular ventricular septum forms with the opening called interventricular foramen
- AP (aoritcopulmonary) septum rotates and fuses with muscular ventricular septum to form membranous interventricular septum - closing interventricular foramen
- Growth of endocardial cushions separates atria from ventricles and contributes to both atrial separation and membranous portion of the interventricular septum
Eisenmenger’s syndrome
Membranous septal defect causes an initial left-to-right shunt which later reverses to a right-to-left shunt due to the onset of pulmonary hypertension
Interarterial septum development eight steps
- Foramen primum narrows as septum primum grows toward endocardial cushions
- Perforations in septum primum form foramen secundum (foramen primum disappears)
- Foramen secundum maintains right-to-left shunt as septum secundum beings to grow
- Septum secundum contains a permanent opening (foramen ovale)
- Foramen secundum enlarges and upper part of septum primum degenerates
- Remaining portion of septum primum forms valve of foramen ovale
- Septum secundum and septum primum fuse to form the atrial septum
- Foramen ovale usually closes soon after birth because of increase left atrial pressure
Patent foramen ovale
Caused by failure of septum primum and septum secundum to fuse after birth
Fetal erythropoiesis sites at: 3-10 week 6 week to birth 15 to 30 week 22 week to adult
Yolk sac - 3 to 10 week Liver - 6 week to birth Spleen - 15 to 30 week Bone marrow - 22 week to adult Young Liver Synthesizes Blood - fetal Hb of alpha 2 and gamma 2, adult Hb of alpha 2 and beta 2
Fetal Circulation pathway
Blood (oxygenated from placenta) enters fetus though umbilical vein through ductus venosus into IVC (bypass hepatic circulation) –> heart –> foramen ovale –> out the aorta –> head and body
Deoxygenated blood entering RA from SVC –> RV –> pulmonary artery –> ductus arteriosus –> descending aorta –> umbilical arteries –> placenta
When infant takes first breath what happens?
Decreased resistance in pulmonary vasculature causes increase LA pressure vs. right atrial pressure –> foramen ovale closes (fossa ovalis) –> increase in O2 leads to decrease in PG –> closure of ductus arteriosus
What drug is used to close PDA?
Indomethacin
What can keep PDA open?
Prostaglandins (PG) E1 and E2
Umbilical vein postnatally turns into
Ligamentum teres hepatis - in the falciform ligament
Umbilical arteries postnatally turn into
Medial umbilical ligaments
Ductus arteriosus postnatally turns into
Ligamentum arteriosum
Ductus venosus postnatally turns into
Ligamentum venosum
