Heart Embryology Flashcards
Folds that yield foregot and myocardium
The conotruncus develops into . . .
. . . the great vessels and their associated semilunar valves
aka truncus ateriosus
Components of heart tube
Stages of Looping in Cardiac Dev
28 Day vs 8 Week hearts
Foramenae and Septae of developing heart
Both foramenae link the R and L atria.
The first septum to develop is the septum primum. This septum has two holes: the foramen primum and the foramen secundum.
As the heart grows, the septum primum eventually grows around the foramen primum, until it disappears, leaving the foramen secundum as the only communication between atria.
Eventually, the septum secundum grows from the right atrium and covers over the foramen secundum, leaving no communications between atria.
How the septa separate the heart into four chambers
When the foramen ovale forms, the SVC/IVC bloodflow may be summarized as. . .
Blood from the IVC (containing nutrients from placental interface) is preferentially directed through the foramen ovale to the left ventricle and to developing organs.
Blood from the SVC (deoxygenated and nutrient depleted) is preferentially directed to the right ventricle.
Locations where developmental abnormalities most often occur
Ostium primum and ostium secundum
Primum:
Secundum: For whatever reason, the limbus-primum septum flap valve fails to close properly, letting blood from the right atrium into the left atrium. Usually this is because the endocardial cushions fail to form and thus the septum primum fails to form properly.
The limbus and septum primum together effectively function as ___.
The limbus and septum primum together effectively function as a flap valve.
When there is not much return to the left atrium (as per normal in-utero circulation), this flap valve stays open. But, once blood starts pouring into the left atrium, the flap is forced closed. (As long as L atrium hydrostatic pressure > R atrium hydrostatic pressure, it stays shut)
The ___ give rise to the AV valves
The endocardial cushions give rise to the AV valves
Endocardial cushions separating L and R canals
What is the consequence of endocardial cushions being involved in both canal formation and AV valve formation?
If one cushion is absent, the leaflets of the AV valves that it gives rise to in each valve will both be missing.
This is why certain congenital AV valve defects often travel in pairs.
Note that this is true for superior and inferior cushions, but not lateral cushions, which are only used in one valve each.
Closing of interventricular septum between weeks 6 and 8
The most common place for septal defects is . . .
. . . right at the junction of the three parts of the wall that meet to close the septum: the inferior muscular portion, the superior conotruncal portion, and the endocardial cushion portion in the middle.
Simple diagram of the tube heart
Conotruncus shift diagram
Conotruncus twist diagram
Diagram showing canal formation, twist, and membranous septum formation stages together
Double Outlet Right Ventricle conotruncal defect
Cause: Improper regulation of conotruncal twist
Result:
Transposition conotruncal defect
Cause: Failure to initiate conotruncal twist
Result:
Truncus arteriosus conotruncal defect
Cause: Failure to septate the conotruncus
Result: (aorta and PA arise from same vessel)
Tetralogy of Fallot conotruncal defect
Cause: Unbalanced segmentation of conotruncus
Result: Tiny pulmonary artery and huge aorta and hole between ventricles
Primary and Secondary Heart Fields
Neural crest cell migration in cardiac embryology
Development of asymmetry in embryologic great vessels
Development and destruction of aortic arches
Developmental origin of important vasculature
The most imporant developmental aortic arches to adult human circulation
Arches III, IV, and VI
Double aortic arch diagram
This exists, at least theoretically, during development. Where the cut-off point is determines which parts of the circle regress, and this determines where the carotid and subclavian arteries arise from (normal positions or from the descending aorta)
Esophagus and trachea in relation to double aortic arch
