Diagnostic ultrasound ( PDFDrive )

1282 PART IV Obstetric and Fetal Sonography
A
B
FIG. 37.18 Using Color Doppler Ultrasound to Access Normal Blood Flow. (A) Dual screen three-vessel view (3VV) image with color
Doppler ultrasound shows normal low through the pulmonary artery (P), the aorta (A), and the superior vena cava (S). (B) Color Doppler ultrasound
shows normal blood low through the aortic arch.
4 wk
4 1 /2 wk 4 1 /2 – 5 wk
Septum primum
A
RT LT
Atrium
Ostium primum
Endocardial
cushion
B
RT
LT
Developing
ostium secundum
Ostium primum
Endocardial
cushion
C
RT
LT
Ostium secundum
Ostium primum
5 wk 8 wk
Septum secundum
RT LT
Septum primum
RA LA
Ostium secundum
Septum secundum
Foramen ovale
Foraminal flap
D
E
FIG. 37.19 Development of Intraatrial Septum (Viewed Facing Patient). (A) At 4 weeks’ gestation the septum primum is small. A large
ostium primum is present. (B) At 4 1 2 weeks, enlargement of the septum primum results in reduction in size of the ostium primum. Perforations
in the septum primum develop. (C) Perforations in the septum primum coalesce to form the ostium secundum. (D) At 5 weeks the septum primum
has fused to the endocardial cushions, and the septum secundum begins to develop to the right of the septum primum. (E) At 8 weeks the septum
secundum has enlarged, now covering the ostium secundum. Blood lows from the right atrium through the valve mechanism (foraminal lap) of
the foramen ovale.
SVC
SVC
SVC
RA
RV
RA
RV
RA
RV
IVC
IVC
IVC
A
Ostium secundum ASD B Ostium primum ASD C Sinous venosus ASD
FIG. 37.20 Types of Atrial Septal Defect (ASD). Schema of the atrial septum viewed from the right atrium (RA). (A) Ostium secundum ASD.
(B) Ostium primum ASD. (C) Sinus venosus ASD. IVC, Inferior vena cava; RV, right ventricle; SVC, superior vena cava.