Anatomical Thorax Structure
What is the normal orientation/angle of the fetal cardiac axis relative to the fetal midsagittal line (interventricular septum to anteroposterior midline)?
45 degrees (plus or minus 20 degrees) (pointing toward the fetal left side).
What are the main differences anatomically in the Ductal Arch vs. the Aortic Arch?
Ductal Arch: Hockey-Stick Shaped, no head vessels
Aortic Arch: Candy-Cane shaped, 3 Head Vessels
What is the relation of the Tricuspid Valve to the Mitral Valve? Which is left and right?
The Tricuspid Valve inserts more apically than the mitral valve (meaning it is closer to the apex of the heart)
Tricuspid - Right
Mitral - Left
How many pulmonary veins are there usually?
4
In what embryonic week does the primitive heart tube begin beating, and by what week is structural cardiac septation and four-chamber development essentially complete?
Begins beating during the 4th week (around day 21–22); structural development and septation are completed by the end of the 8th embryonic week (10 weeks gestational age).
What is the medical term for a heart located within the left hemithorax with the apex pointing toward the left?
Levocardia.
What are the three head branches of the aortic arch?
Brachiocephalic (right common carotid and right subclavian artery)
Left Common Carotid
Left Subclavian
Where is the moderator band located?
In the right ventricle of the heart
Which valves are open in systole in the fetal heart?
The Semilunar Valves (Aortic and Pulmonary) open in systole- the Atrioventricular Valves open in Diastole.
During normal embryonic development, in which direction does the primitive heart tube loop to establish normal levocardia, and what abnormality results if it loops in the opposite direction?
It loops to the right (D-looping or Dextro-looping). If it loops to the left (L-looping), it results in L-transposition (corrected transposition) or dextrocardia.
How much of the chest cavity does the fetal heart occupy?
1/3
What are the three most important sonographic views of the fetal heart, which rules out most structural pathology?
4 Chamber Heart, 3VV, Pulmonary Veins
The flap of the foramen ovale (valve of the foramen ovale) normally opens into which cardiac chamber in utero?
The valve opens into the LEFT ATRIUM.
What are the three fetal shunts in the cardiac system? What happens to them after birth?
Foramen Ovale, Ductus Arteriosus, Ductus Venosus- they all close off after birth.
What adult cardiovascular structures are formed by the partitioning of the Truncus Arteriosus and the Bulbus Cordis?
Truncus Arteriosus: Divides into the Ascending Aorta and the Main Pulmonary Artery (separated by the spiral aorticopulmonary septum).
Bulbus Cordis: Forms the smooth outflow tracts of both ventricles (conus arteriosus/infundibulum in the right ventricle and the aortic vestibule in the left ventricle).
What structures allow you to confirm fetal situs?
What structure shunts blood to the fetal brain, bypassing the liver in utero?
Ductus Venosus
What chamber of the heart do pulmonary veins drain into?
Left Atrium
Which valve corresponds to the left side of the heart (LVOT)? Which corresponds to the right (RVOT)?
Aortic is Left
Pulmonary is Right
What is the normal physiological baseline range for fetal heart rate in the second and third trimesters?
120-160
In the normal fetal chest, which cardiac chamber lies most anteriorly (closest to the anterior chest wall), and which chamber lies most posteriorly (closest to the spine)?
Most Anterior: Right Ventricle (RV)
Most Posterior: Left Atrium (LA)
In the fetus, which vessels carry oxygen rich blood from the placenta to the fetus? How does this change after birth?
In utero, veins carry oxygen rich blood through the fetus. After the shunts close and pressure changes, arteries take over oxygenated blood because it now can pass through the lungs to obtain oxygen (via pulmonary respirations).
Which chamber of the heart do the SVC and IVC drain into?
Right Atrium
Which view can be imaged more cranially in the fetus:
3VV
3VTV
What is the difference between them?
The 3 Vessel Trachea view is more cranial than the 3VV. The 3VTV shows the connection between the Ductus Arteriosus and the Aorta near the posterior region (spine) of baby.
What Structures form systemic venous circulation in the fetus (3)?
Vitelline duct, umbilical veins, and cardinal veins