Intro to Fetal Echocardiography Flashcards
When is the most sensitive period in the 1st trimester for cardiac development?
3.5-6.5 weeks
What is the 1st organ system to reach a functional state?
cardiovascular
What happens at the end of the 3rd week of dev?
circulation of blood has begun
What happens in the 5th week of dev?
heart begins to beat
Blood flow in the fetus varies in what two respects from the neonatal stage?
- communication is open between the right and left sides of the heart through the fossa ovale
- between the aorta and the pulmonary artery via the ductus arteriosus
Where does most of the blood in the right ventricle go?
passes thru the ductus arteriosus into the descending aorta, only a small amount goes to the lungs
How many pulmonary veins are there and where do they enter the LA?
4, posterior wall
What body parts are fed via the three branches off the Ascending Aorita?
head, neck, upper torso
What are the three branches off the AA?
Innominate artery, Left carotid artery, Left subclavian artery
Mixed blood in te descending aorta goes where?
passes into umbilical arteries and is returned to the placenta for reoxygenation
What fetal cardiac structures are no longer necessary after birth?
- foramen ovale
- ductus arteriosus
- ductus venosus
- umbillical vessels
Omission of the placental circulation causes what?
- an immediate fall of BP in iVC and RA
- as lungs expand with air, there is a fall in pulmonary vascular resistance, causing an increase in pulmonary blood flow and thinning of the walls of pulmonary arteries
What causes the foramen ovale to close?
pressure in the LA is higher than that in the RA
When does ductus arteriosus usually constrict?
shortly after birth (within 24-48 hours) once left-sided pressures exceed the right-sided pressures
What is patent ductus arteriosus?
small shunt of blood from the aorta to the pulmonary artery
What constricts after birth to prevent blood loss in neonate?
umbilical arteries
T/F: The umbilical vein may remain patent for some time after birth?
True
Describe normal HR for 1st trimester?
HR begins around 90 bpm and increases to 170 bpm before returning to a normal rate and sinus rhythm
How many bpm qualifies for bradycardia?
<60 bpm
Bradycardia places fetus at high risk for what?
associated heart disease and fetal echocardiography should be performed to rule out the presence of a structural heart defect
What # bpm qualifies as tachycardia?
> 200 bpm
Fetal risk factors indicating echocardiography (8)
- presence of IUGR
- cardiac arrhythmias
- abnormal amniocent. indicating a trisomy
- abnorm. AF collections
- abnorm. HR
- anomalies detected by sonogram (like hydrops fetalis)
- presence of extracardiac abnorm.
- if abnorm. is found in more than one organ system
What issues are frequently associated with congenital heart disease?
- extracardiac abnormalities like renal and GI anomalies, single umbilical arteries, ect
- abnormality located in multiple organ system
Cardiac arrhythmias may be a common finding if they are simply:
extrasystoles, but a very small percentage of arrhythmias are associated with significant heart disease
What are extrasystoles?
premature atrial beats secondary to immature conducting system
What are maternal risk factors indicating fetal echocardiography?
- previous occurrence of congenital heart disease in siblings or parents
- a maternal disease known to affect the fetus, such as diabetes or CT dissease (like lupus)
- maternal use of drugs, such as lithium or alcohol
T/F: The incidence of congenital heart disease in fetuses whose mother have uncontrolled diabetes is much higher than when the diabetes is controlled?
True
What are the most common anomalies stemming from congenital heart disease?
- ventricular septal defect
- transposition of the great arteries
- tetralogy of Fallot
What is the familial risk factor indicating fetal echocardiography?
The recurrence risk cited given a sibling with a common cardiovascular abnormality (ventricular septal, atrial septal defects, patent ductus arteriosus, tetralogy of Fallot) varies from:
2.5-3%
The fetal survey should demonstrate what structures?
- position of fetus
- position of the fetal thorax (spine up or down, which side?)
- position of fetal stomach
- location of apex of heart
- location of the abdominal aorta and IVC
Where should the aorta be found in relation to the spine?
to the left, close to spine
Where should IVC be found in relation to the spine?
to the right, elevated from spine
Obstacles to obtaining an adequate image:
- decreased amniotic fluid (oligohydr.)
- unusual fetal position (spine up, trans,, or low lie in maternal pelvis)
- maternal obesity
8 steps to eval. fetal heart:
- document HR and rhythm
- assess cardiac size
- assess cardiac axis
- assess cardiac position
- determine situs
- eval. the atria
- eval. the ventricles
- eval. the AV valves
Documentation of cardiac activity and rhythm:
- presence of activity should be confirmed via Doppler or M-Mode
- normal ranges from 120-160
When may transient bradycardia be observed?
normal second trimester
Fixed bradycardia may indicate:
heart block
Persistent tachycardia may indicate what?
serious tachydysrhythmias
Fixed brady and persistent tachy would warrant:
fetal echo to rule out structural heart defect
How does the fetal heart lie?
in a horizontal position within the thorax and the apex is directed toward the left hip
The left atrial cavity is the same size as ____
right atrial cavity
The foramen opens which way?
toward the left atrium
Failure of the foramen to close results in
atrial septal defect
Where is the moderator band?
stretches horizontally across the right ventricle near the apex
Normally the tricuspid valve is located just _______ _______ to the mitral valve?
slightly inferior
Which pulmonary vein is NOT imaged in the 4 chamber view?
right lower vein
How does one angle the probe to achieve the 5 chamber view?
angled slightly anterior from the 4 chamber view to include the left ventricular and aortic outflow tract
Describe the criss-cross view:
- probe is angled from the aorta slightly to the left, the pulmonary artery may be seen as it arises from the RV outflow tract
- pulmonary artery normally is anterior and to the left of the aorta
- this “sweep” from the aorta to the pulmonary artery is called criss-cross view…it allows you to see the normal relationship of the great arteries to one another
With careful angulation to an oblique long plane, what may be assessed?
- root of the aorta
- ascending aorta
- arch
- descending aorta
How does one search for the descending aorta and arch?
find the fetal spine in the sag. plane and angle slightly inward toward the left chest
T/F: you should be able to demonstrate the candy cane appearance of ascending aorta, arch, and descending aorta in one plane?
true
What is represented by a second arch-type pattern when probe is angled inferior to from the aortic arch?
patent ductus arteriosus, a communication between the pulmonary artery and the aorta that is patent during fetal life but closes shortly after birth
T/F: The ductus is slightly larger than the aortic arch and has a sharper angle “hockey stick” as it drains into the descending aorta..and has no arterial structures arising from it.
True
