Diagnostic ultrasound ( PDFDrive )

CHAPTER 37 The Fetal Heart 1287
RV
LV
RV
RA
LV
LA
RA
LA
SP
SP
FIG. 37.29 Hypoplastic Right Ventricle. Apical four-chamber view
shows small, right ventricular chamber (RV). See also Video 37.11. LA,
Left atrium; LV, left ventricle; RA, right atrium; SP, spine.
FIG. 37.30 Hypoplastic Left Heart Syndrome. The left atrium (LA)
and left ventricle (LV) are small. See also Video 37.10. RA, Right atrium;
RV, right ventricle; SP, spine.
presentation, treatment options, and prognosis are inconsistent,
case-by-case management is variable. 109
Hypoplastic Right Ventricle
In general, hypoplastic right ventricle occurs secondary to
pulmonary atresia with intact interventricular septum. It has
an incidence of 1.1% among stillbirths. 46 Tricuspid atresia may
be associated with a hypoplastic right ventricle, but this is not
as common. 110 Pathophysiologically, hypoplasia of the right
ventricle develops because of a reduction in blood low secondary
to inlow impedance from tricuspid atresia or outlow impedance
from pulmonary arterial atresia. Typical sonographic indings
include a small, hypertrophic right ventricle and a small or absent
pulmonary artery 110 (Fig. 37.29, Video 37.11). Spectral Doppler
ultrasound may be helpful in demonstrating decreased low
through the tricuspid valve or pulmonary artery. Congestive
heart failure and hydrops may develop from tricuspid regurgitation.
Ater birth, closure of the ductus arteriosus frequently results
in neonatal death. Prognosis improves with preoperative prostaglandin
infusion to maintain the patency of the ductus. 111
Hypoplastic Left Heart Syndrome
In hypoplastic let heart syndrome, the let ventricular cavity
is pathologically reduced in size. HLHS constitutes approximately
7% to 9% of all congenital cardiac lesions. 112 It has a 2 : 1 male
predominance and a recurrence risk of 0.5%. 112,113 he small let
ventricle results from decreased blood low into or out of the
let ventricle. he primary abnormalities include aortic atresia,
aortic stenosis, and mitral valve atresia. It is associated with
coarctation of the aorta in 80% of cases. 114 he primary sonographic
feature of HLHS is a small let ventricle (Fig. 37.30,
Video 37.10). he mitral valve is typically hypoplastic or atretic,
as is the aorta. 115 Color Doppler ultrasound is extremely helpful
in the setting of HLHS, usually demonstrating the absence of
low through the mitral and aortic valves. 39
hree decades ago this syndrome had an extremely poor
prognosis, with 25% mortality in the irst week of life and most
untreated infants dying within 6 weeks. 116 Comfort care was
provided, but little could be done to prolong survival. Currently
it is expected that up to 70% of newborns with HLHS may reach
adulthood owing to advancements in surgical techniques,
perioperative management, and postoperative care. 117 Prenatal
diagnosis of HLHS is beneicial for preventing ductal shock and
keeping afected infants stable in the preoperative stage. 118-120
Monophasic blood low across the mitral valve, restricted or
absent low through the foramen ovale, and retrograde low
through the aorta are all considered poor prognostic signs in
utero. Despite signiicant advancements in medical and surgical
management over the past 30 years, follow-up studies indicate
that children with HLHS oten experience major developmental
delays 121 and decreased exercise performance, even ater heart
transplantation. 122 A recent meta-analysis found that although
deicits remain, substantial improvement in neurodevelopment
has occurred over the past 20 years in patients with surgically
corrected HLHS. 123
Univentricular Heart
In univentricular heart, two atria empty into a single ventricle,
via two A-V valves or a common A-V valve. Univentricular heart
is rare, accounting for approximately 2% of CHD. 47 It results
from a failure of the interventricular septum to develop. he
single chamber has a let ventricular morphology in 85% of
cases. 124 Associated cardiac anomalies are common, 125 with
asplenia or polysplenia occurring in 13%. 126 Sonographically,