fetal echocardiography
TRANSCRIPT
Why
•Commoner than most realize
• 1% in all live births
• Approximately 5% in all pregnancies
•The incidence increases if there is a positive family history
•if sibling affected incidence is 2 – 4%
•if mother affected incidence is 10-12%
Indications
•Family history
•Exposure to known cardiac teratogens
•Chromosomal abnormalities (trisomy 21, 50%; trisomy 13 and 18, almost 100%)
•Maternal disease (diabetes, collagen disease, phenylketonuria, infections)
•Non-cardiac abnormalities detected on US
•Polyhydramnios
Weeks Length mm
Event`
1-2 1.5 No heart or great vessel
4 2 Single median cardiac tube, ineffective contraction
5 4 Bilobed atrium
5 4 Begining of circulation
5 7.5 AV orifices, 3 chamber heart
6 8.5-13 Septum secundum, complete inferior septum, divided truncus arteriosus,
7 20 4 chamber heart
Cardiac embryology
Cardiac Size
20 week fetus’heart comparedwith an American quarterUsual HR120-160/min
Time
•The best time to do a fetal cardiac exam is 18-22 weeks
•Later exams may show anatomy better but might be difficult because of rib shadowing
•Adequate exam depends on fetal position and maternal habitus
•Some pathologies become obvious with fetal age
Fetal Circulation
Fetal circulation is
complex and different
from adult blood flows
with three major shunts:
Ductus venosus
Forman ovale
Ductus arterosus
Rate and rhythm
•The heart rate is usually 120-160/min,
the rhythm is regular but transient
bradycardia is normal in the 2nd
trimester but not in the 3rd
First assess fetal position
Acquire a four chamber view
•Transverse section through the fetal thorax
•Corresponds to the 4 chamber apical view in the adult
•The atrium nearest the spine is the left atrium
•The atrium nearest the fetal anterior thoracic wall is the right
Axis
•45+20o towards the left
•Abnormal axis increases the risk of a cardiac malformation
•The heart may also be displaced from its normal position in dipaphragmatic hernia or cystic adenomatoid malformation
•Fetus cephalic
•Probe marker to mother’s left
•Fetal spine posterior
•Fetus breech
•Probe marker normal
•Fetal spine posterior
Basic fetal cardiac examination
•Done on a 4 chamber view
•Heart mostly in left chest
•Occupies 1/3rd of thoracic area
•Normal cardiac situs, axis and
position
•No pericardial effusion
General
Basic fetal cardiac examination
•Both of same size
•Foramen ovale flap in
left atrium
•lower end of atrial septum
(septum primum) present
Atria
Atria
•Lower end of septum
•Foramen ovale
•Flap of foramen ovale
in LA
Basic fetal cardiac examination
•Equal size
•Intact septum
•Moderator band
identifies right ventricle
Ventricles
Ventricles
•Both of same size
•Moderator band identifies rightventricle
Basic fetal cardiac examination
•Both valves move freely
•Tricuspid valve inserted
more apically than mitral
AV Valves
Extended basic cardiac examination
•The outflow tracts are imaged by tiltingthe probe towards the fetal head
•The great vessels should be of equal size and should cross at approximately 90o as they emerge from their respective ventricles
Look for these:
•The outflow tracts cross each other at about 90o
•The anterior aortic root wall is continuous with the
Inter Ventricular Septum
•The pulmonary artery bifurcates
•The aortic and pulmonary valves move freely
•Both great vessels are of similar size but the
pulmonary artery tends to be slightly bigger
The aortic arch
•The aortic arch canbe identified
•The aortic cusps can be seen
The pulmonary artery bifurcates
The outflow tracts cross at around 90o
Pulm trunk Aortic arch
Cases
Echogenic Intracardiac Focus (EIF)
•Can be seen in up to 6%of normal pregnancies
•Highly operator and machine dependant
•Associated with cardiacand extracardiac anomalies
•Bilateral EIF is moresignificant
EIF
Biventricular EIF are more significant
this patient was 47XY
Normal nuchal translucency