Congenital Heart Disease - Embryology & Situs Flashcards
The heart is formed between ___ - ___ weeks gestation.
3-7
The truncus arteriosus is is superior and forms what?
The semilunar valves
The aortic root and pulmonary artery form as the truncus separates
Which way should the heart tube fold?
Rightward
What does leftward folding result in?
L-TGA
Stage 1 of atrial septal formation
Septum primum. Foramen primum forms in the lower portion of the IAS
Stage 2 of atrial septal formation
Foramen secundum
Stage 3 IAS formation
Secundum septum. Overlaps the Foramen secundum and forms foramen ovale
What closes the foramen ovale at birth?
Increased pressure in the LA pushes the valve against the septum secundum
Where do the following atrial septal defects occur? Primum ASD, secundum ASD, Sinus venosus ASD
Primum ASD- inferior
Secundum ASD- middle
Sinus venosus ASD- superior
Stage one of IVS formation
Trabecular IVS grows from apex halfway up
Stage 2 IVS formation
Tricuspid and mitral orifice formation
Stage 3 of IVS formation
Truncus formation-> conotruncal septum forms in a spiral fashion to form prox aorta and pulmonary artery
Stage 4 of IVS formation
Membranous septum forms to complete the IVS
What do the 2 medial endocardial cushions form?
Septal leaflet of TV
Anterior MVL
What do the 2 lateral endocardial cushions form?
Anterior and posterior tricuspid leaflets
Posterior MVL
What do the atrioventricular valves form from?
Endocardial cushions
What do the semilunar valves form from?
Truncus arteriosus
There are originally 6 sets of aortic arches in the fetus. Which one develops into the adult aorta?
The 4th
Where does the fetus get its oxygenated blood from?
The placenta -> umbilical vein -> ductus venosus & onward
What are the 3 steps in the segmental approach to CHD?
- visceral atrial situs & atrial connections
- orientation of the ventricles & connections
- orientation of the great vessels & connections
Define dextroposition, mesoposition, levoposition
Dextro: reversed (right)
Meso: middle
Levo: normal (left)
Dextrocardia situs inversus totalis
All organs are mirrored
Describe the 3 visceral situs formats
- situs solitus (normal)
- situs inversus (mirror image)
- situs ambiguous (cant tell)
What are some defining features of the RT atria?
eustachian valve, vena cavae, coronary sinus, Chiari network, RAA
What are some defining features of the LA?
Pulmonary veins, LAA
Defining features of the morphologic RV
-crescent shaped, 3 leaflet valve, larger trabeculations, multiple paps, moderator band, infundibulum, septal leaflet apically displaced
Defining features of the morphologic LV
-bullet shaped, 2 leaflet valve, two paps
