Normal Heart and Circulation

How is the heart initially formed?

initially 2 tubes that fuse and fold to form 4 chambers

When does the heart begin to contract?

36 days gestation (5 weeks)

At what CRL is a normal heart definitely detected beating on US?

5 mm

What is the range for the normal fetal heart rate?

120-180 bpm

When is the heart fully formed?

10 weeks

How is the heart situated in the chest?

apex of the heart angled to left of midline at 45 degrees from spine and occupies 1/3 of chest

What is the term for a normally positioned heart in the chest cavity?

levocardia

What is the term for an abnormally positioned heart in the chest cavity?

dextrocardia

Which chamber is closest to spine (posterior) and descending Ao in 4C view?

left atrium

What is the chamber closest to the sternum (anterior) in the 4CH view?

right ventricle

The left and right atria are separated by the atrial septum which opens at ____________

Foramen Ovale

Where is the moderator band located?

right ventricle

How do you confirm a normal cardiac rhythm?

document an atrial and ventricular beat simultaneously

What are the three vessels shown in the 3VV?

PA, Ao, SVC

What connects the PA to the descending Ao?

ductus arteriosus

Why are 3 bypasses needed in fetal circulation?

oxygenated blood comes from the umbilical vein and not the lungs, so the bypasses make sure the oxygenated blood is evenly distributed and not spent on only 1 or 2 organs

What are the 3 bypasses in fetal circulation?

• ductus venosus

• foramen ovale

• ductus arteriosus

What does the ductus arteriosus connect?

umbilical vein to IVC (bypasses liver)

What does the foramen ovale connect?

right atrium to left atrium

What does the ductus arteriosus connect?

MPA to aorta (bypasses lungs)