Diagnostic ultrasound ( PDFDrive )

CHAPTER 37 The Fetal Heart 1281
RA
RV
LV
LA RV
RA
Vel 519 cm/s
PG 108 mmHg
R
R
R R R
V V V V PV V V V
A A A PA – A A A A
FIG. 37.15 Using M-Mode Echocardiography to Analyze an
Arrhythmia: Conducted Premature Atrial Contractions. The cursor
is placed simultaneously through the left ventricle (LV) and right atrium
(RA). The M-mode tracing shows normal atrial beats (A) followed by a
premature atrial contraction (PA). The ventricles show normal ventricular
contraction (V) following each atrial beat and a premature beat (PV)
following the premature atrial contraction. LA, Left atrium; RV, right
ventricle.
A
E
A
E
RV
RA
A
E
LV
LA
SP
A
E
A
E
A
E
A
E
FIG. 37.16 Spectral Doppler Ultrasound Used to Interrogate a
Normal Mitral Valve. Spectral Doppler sample volume is placed distal
to the mitral valve in the left ventricle (LV). A normal mitral valve waveform
is appreciated above the baseline, showing the normal early diastolic
(E) and atrial contraction (A) wave points. LA, Left atrium; RA, right
atrium; RV, right ventricle; SP, spine.
T T T T
FIG. 37.17 Tricuspid Insuficiency. Spectral Doppler sample volume
is placed proximal to the tricuspid valve in the right atrium (RA). The
regurgitant low (R) can be seen above the baseline. This implies that
the valve has not closed completely during systole, and therefore blood
low is retrograde into the right atrium. RV, Right ventricle; T, tricuspid
valve.
Ventricular Septal Defect
Isolated VSD is the most common cardiac anomaly, accounting
for 30% of heart defects diagnosed in live-born infants and 9.7%
diagnosed in utero. 46,47,59 VSDs are associated with other cardiac
anomalies in 50% of cases. 60 Of the structural cardiac defects,
VSDs have the highest recurrence rate and the highest association
with teratogen exposure. hey are classiied according to their
position in the interventricular septum (Fig. 37.23) as membranous
or muscular VSD (inlet, trabecular, outlet). 60
About 80% of VSDs occur in the membranous portion of the
septum. 61 However, because most membranous defects also involve
a portion of the muscular septum, they are usually referred to
as perimembranous defects. he subcostal four-chamber view
provides optimal evaluation of the interventricular septum. At
sonography, a VSD appears as an area of discontinuity in the
interventricular septum. When the defect is small, this diagnosis
is problematic, and at least one-third of VSDs are missed on the
four-chamber view. 21,55,62-66 Color Doppler imaging may improve
the diagnostic accuracy for VSD. However, most are missed on
fetal echocardiography. 55,66,67 Small VSDs not detectable on grayscale
echocardiography may be documented with color Doppler
ultrasound in some cases 39 (Fig. 37.24). In the setting of an isolated
VSD, color Doppler ultrasound imaging typically shows bidirectional
interventricular shunting, with a systolic right-to-let
shunt and a late diastolic let-to-right shunt.
he prognosis for an infant with an isolated VSD is excellent,
and many such defects go undetected. he rate of spontaneous
closure of isolated muscular VSDs by 5 years of life is much
higher (65%) than that for isolated perimembranous VSDs (20%). 68
Overall about 40% of VSDs spontaneously close in the irst year