Ch 8 Normal Heart Flashcards
Blood starts to circulate within the embryo by how many weeks gest age?
5 weeks
The heart begins as a set of paired tubular structures known as what?
Cardiogenic cords
The cardiogenic cords begin to fuse on what day?
22nd day
What do the cardiogenic cords form after they fuse?
Forms the single heart tube
At approx what day does the endocardial cushions begin to develop + separate the atria from ventricles?
Day 27
What does the endocardial cushions separate?
Atria + ventricles
By what day post-conception are the mitral + tricuspid valves formed?
Day 33
B/w what days does the septum primum form?
25th-28th day post conception
What does the septum primum create an initial division b/w?
The right + left portions of the atrium
Once the septum secundum is formed, why does the foramen ovale remain?
Remains to allow the right to left shunting until birth
Where do the great vessels (AO/PAs) arise from?
The common vessel of the truncus arteriosis
Swellings in the truncus arteriosus form + twist around each other during what week? What does this form?
-7th week
-Forms the aorticopulmonary septum
The pulmonary channel is contiguous/touching the RV or LV?
RV
The systemic (aortic) channel is contiguous/touching the RV or LV?
LV
The AO + pulmonary arches arise from what? When does this occur?
-Series of primitive aortic arches
-B/w 19-30 days post conception
By the beginning of what week has the heart fully formed + placental circulation has begun?
Start of 8th week gestation
The majority of the blood from the umbilical vein is shunted into what?
The ductus venosus
What does the majority of the blood from the umbilical vein bypass + enter?
Bypasses the hepatic circulation + enters the IVC
Where does the remainder of blood flow through?
The hepatic circulation prior to entering into the IVC via hepatic veins
Blood enters the RA from what vessels?
IVC + SVC
How does oxygenated blood get into the LA from the RA?
Oxygenated blood is directed by the eustachian valve through the foramen ovale into the LA
The remained of blood in the RA (plus returning blood from SVC) pass through which valve to enter the RV?
TV
From the RV, blood passes through which valve into the PA?
PV
The majority of blood that enters the PA is diverted through what?
The ductus arteriosus into the AO + systemic circulation
Blood in the LA comes from 2 places, what are they?
-From pulmonary circulation
-Gets shunted through foramen ovale (from RA)
Blood in LA passes through what valve to get into LV?
MV
The highly oxygenated portion of blood is shunted mainly to what portion of the fetus?
The cranial portion
Highly oxygenated blood gets shunted mainly to the cranial portion of the fetus via what arteries?
Brachiocephalic arteries (which arise from the prox portion of the AO arch)
What are the brachiocephalic arteries?
Right subclavian artery + right carotid artery
The remainder of blood goes where after it reaches the cranial portion of the fetus?
Spreads to distal portion of fetus through abdominal AO
The remainder of blood goes where after it reaches the distal portion of the fetus?
Returns to the placental circulation through the umbilical arteries
Does the MCA + umbilical artery have opposite or the same dopplers in regards to diastolic flow?
Opposite (MCA wants low, UA wants high)
Difference b/w MCA + umbilical artery dopplers?
MCA: higher peaks, lower diastolic flow
UA: lower peaks, higher diastolic flow
The location + orientation of the heart can be evaluated once what is determined?
Fetal position
The heart should occupy how much of the left side of the fetal chest?
The majority of it
Should the apex normally point to the left or right?
Left
What is the normal angle of the heart in degrees?
45 degrees to left of midline
(plus/minus 20 degrees)
What is the term that represents a normal sided heart?
Levocardia
(levo = left side)
What is dextrocardia?
When the heart is on the right side of chest, with apex also pointing to right
(fully flipped)
What is dextroposition?
When the heart is on right side of chest, with apex pointing to left
(apex still in right position, but wrong side chest)
What is mesocardia?
When heart is in middle portion of chest, with apex pointing along midline
(meso = middle)
Dextroposition + mesocardia occur m/c due to what?
There being a mass lesion in the left chest
(ex. mass causes heart to shift over onto wrong side of chest)
Is dextrocardia usually a congenital condition?
Yes
List the heart protocol?
-4 ch view
-LVOT + RVOT
-SAX
-AO + ductal arch
-Bicaval
-3 vessel view
-Cine sweep from stomach to 3VV (with + w/o CD)
-Split screen/cine showing axis of heart relative to stomach
Is the heart often a reason why moms comes back for a repeat u/s?
Yes!
How is the apical 4 ch view obtained?
-From TRV image of fetal chest
-Apex points either directly towards or away from probe
-Ventricular + apical/atrial septa is parallel to probe
-Ensure valves are on the same level
Should the RA + LA be approx equal size?
Yes!
Does the RV or LV appear slightly larger?
RV (remember is opposite of adults)
The MV + TV valves (AV valves) are located where?
B/w atria + ventricles
What do we have to watch out for when imaging the 4 ch view in regards to the ventricular septum?
-Watch out for drop out (as the septum is parallel to the beam)
-Ensure septum is continuous w/o any disruption
What should the atrial septum contain in fetuses?
The normal opening of the foramen ovale
What is the foramen ovale?
-Hole in b/w RA + LA
-Foraminal flap should be seen opening into the LA
Are the 2 superior pulmonary arteries or veins seen entering into the LA in the 4 ch view?
Veins
How do we angle the probe to get LVOT?
Angle towards the fetal right shoulder from the 4 ch view
If a VSD is present, how would it appear in LVOT?
As a break in the continuity of the IVS
Is PLAX in adults the same view as LVOT in fetuses?
Yes!
How do we angle the probe to get RVOT?
Angle further toward the fetal right shoulder while in LVOT
Should RVOT + LVOT cross when switching/angling back and forth b/w them?
Yes!! Should show AO crossing anteriorly to the PA
How do we angle the probe to get SAX?
Angle slightly towards fetal left shoulder
Is PSAX - AoV level in adults the same as SAX in fetuses?
Yes!
What structures are seen in SAX?
-AO appears as central circular structure
(encircled by surrounding PA)
-RA, RV + PA seen
-AoV, PV + TV seen
-Size of AO + PA can be directly compared here
How do we angle the probe to get the AO arch?
Angle from left shoulder to right hemithorax while in a longitudinal/SAG view of fetus
How can we distinguish the AO arch from the ductal arch?
-By identifying the head + neck vessels
-Ductal arch is more caudal
AO arch has what appearance?
Candy cane
Ductal arch has what appearance?
Hockey stick
(think dudes = play hockey = ductal)
How do we angle the probe to get the ductal arch?
Remaining in longitudinal/SAG view from the AO arch, but rotating back to a straighter anterior-posterior view
What structures are seen in the ductal arch?
PA (top) , ductus arteriosus (middle) + descending AO (bottom)
What 3 vessels come off the Ao arch?
-Left subclavian artery
-Left common carotid artery
-Brachiocephalic trunk
How do we angle the probe to get the 3 vessel view?
Apical 4 ch view obtained, then probe is moved cephalad
List the structures in the 3VV?
From midline to lateral: acronym PASS
-PA
-AO
-SVC
(can compare size of AO to PA here)
Why does the PA appear more elongated in the 3VV compared to the AO + SVC?
B/c the PA is being imaged at the level of the ductus arteriosus
What is the ductus arteriosus?
-A blood vessel that connects the fetal PA to the AO, it closes after birth
-It allows oxygenated blood to bypass pulmonary circulation + go right into AO, since the lungs aren’t being used yet
How can we obtain the bicaval view?
Go oblique, SAG view through heart
What structures are seen in the bicaval view?
-SVC entering RA superiorly
-IVC entering RA inferiorly
(make sure we image IVC and not accidentally AO)
What is SAX short for?
Short Axis
The smallest vessel on the 3V view is the?
SVC
The heart should point 45 degrees to the left, +/- this many degrees?
20 degrees
Levocardia is defined as?
A normal heart
