Cardiovascular- Embryology and anatomy Flashcards
EMBRYONIC STRUCTURE GIVES RISE TO…
- Truncus arteriosus
- Bulbus cordis
- Endocardial cushion
- Primitive atrium
Ascending aorta and pulmonary trunk
Smooth parts (outflow tract) of left and right ventricles
Atrial septum, membranous interventricular septum; AV and semilunar valves
Trabeculated part of left and right atria
EMBRYONIC STRUCTURE GIVES RISE TO…
- Primitive ventricle
- Primitive pulmonary vein
- Left horn of sinus venosus
- Right horn of sinus venosus
- Right common cardinal vein and right anterior cardinal vein
Trabeculated part of left and right ventricles
Smooth part of left atrium
Coronary sinus
Smooth part of right atrium (sinus venarum)
Superior vena cava (SVC)
Heart morphogenesis
First functional organ in vertebrate embryos; beats spontaneously by week 4 of development
Defect in left-right Dynein
(involved in L/R asymmetry) can lead to Dextrocardia, as seen in Kartagener syndrome (1° ciliary Dyskinesia).
Cardiac looping
Primary heart tube loops to establish left-right polarity; begins in week 4 of gestation
Septation of the chambers Atria
Septum primum grows toward endocardial cushions, narrowing foramen primum.
Foramen secundum forms in septum primum (foramen primum disappears).
Septum secundum develops as foramen secundum maintains right-to-left shunt.
Septum secundum expands and covers most of the foramen secundum. The residual foramen is the foramen ovale.
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 LA pressure.
Patent foramen ovale
caused by failure of septum primum and septum secundum to fuse after birth; most are left untreated.
Can lead to paradoxical emboli (venous thromboemboli that enter systemic arterial circulation), similar to those resulting from an ASD.
Septation of the chambers Ventricles
Muscular interventricular septum forms. Opening is called interventricular foramen.
Aorticopulmonary 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 septation and membranous portion of the interventricular septum
Ventricular septal defect
most common congenital cardiac anomaly, usually occurs in membranous septum.
Outflow tract formation
Neural crest and endocardial cell migrations
- truncal and bulbar ridges that spiral and fuse to form aorticopulmonary septum
- ascending aorta and pulmonary trunk.
Conotruncal abnormalities associated with failure of neural crest cells to migrate:
Transposition of great vessels.
Tetralogy of Fallot.
Persistent truncus arteriosus.
Valve development
Aortic/pulmonary: derived from endocardial cushions of outflow tract.
Mitral/tricuspid: derived from fused endocardial cushions of the AV canal
Ebstein anomaly
Valvular displacement
Fetal circulation
Blood in umbilical vein has a Po2 of ≈ 30 mm Hg and is ≈ 80% saturated with O2. Umbilical arteries have low O2 saturation.
3 important shunts:
Blood entering fetus through the umbilical vein is conducted via the ductus venosus into the IVC, bypassing hepatic circulation.
Most of the highly Oxygenated blood reaching the heart via the IVC is directed through the foramen Ovale and pumped into the aorta to supply the head and body.
Deoxygenated blood from the SVC passes through the RA to RV to main pulmonary artery to Ductus arteriosus to Descending aorta; shunt is due to high fetal pulmonary artery resistance (due partly to low O2 tension).
