480
U N I T 5
Circulatory Function
In coarctation, the pressure in the legs is lower and may
be difficult to obtain. Patients with coarctation are often
identified during a diagnostic workup for hypertension.
Most patients with moderate coarctation remain other-
wise asymptomatic owing to collateral vessels that form
around the area of narrowing. Left untreated, however,
coarctation will result in left ventricular hypertension
and hypertrophy and significant systemic hypertension
(see Chapter 18). Infants with severe coarctation dem-
onstrate early symptoms of heart failure and may pres-
ent in critical condition upon ductal closure. Reopening
of the duct with prostaglandin E
1
, if possible, and emer-
gent surgery are needed in this subgroup.
88
Children with coarctation causing a blood pressure
gradient between the arms and legs of 20 mm Hg or
greater should ideally be treated by 2 years of age to
reduce the likelihood of persistent hypertension.
88
A sur-
gical approach typically involves resection of the nar-
rowed segment of the aorta and end-to-end anastomosis
of healthy tissue. This can usually be accomplished
without cardiopulmonary bypass, with a mortality rate
near zero. Balloon angioplasty with or without stent
placement has also been used, although the presence
of residual gradients and the reliability of the surgical
approach have limited this technique.
88
Functional Single-Ventricle Anatomy.
Several forms
of complex congenital heart disease result in only one
functional ventricle. Functional single-ventricle anat-
omy is the most common form of congenital heart dis-
ease diagnosed on routine prenatal ultrasonography.
There may be a single right or a single left ventricle, or a
ventricle of indeterminate morphology.
89–92
Hypoplastic
left heart syndrome, a term used to describe a group of
closely related cardiac anomalies characterized by under-
development of the left cardiac chambers, is the most
common form of this disorder.
92
Several other forms of
double-inlet ventricle have been described; however, all
forms of this disease result in similar pathologic effects
and follow a common pathway of intervention.
89–93
All forms of single-ventricle anatomy result in a
common mixing chamber of pulmonary and systemic
venous return and cause varying degrees of cyanosis
(Fig. 19-23). The single ventricle must pump blood
to both the pulmonary and systemic circulations, and
thus the flow to each circulation is determined by the
resistance in each system.
89–92
As pulmonary vascular
resistance falls, flow to the pulmonary circulation will
be preferential and systemic circulation will be compro-
mised. In some defects, such as hypoplastic left heart
syndrome, systemic flow depends on a patent ductus
arteriosus. Neonates with this lesion typically present
with extreme cyanosis and symptoms of heart failure as
the ductus begins to close.
92
Although functional single-ventricle anatomy cannot
be completely repaired, the surgical palliation of these
defects has been one of the most innovative interven-
tions for congenital heart disease. The goal of surgical
palliation is to redirect systemic venous return directly
to the pulmonary arteries and allow the single ventricle
to deliver oxygenated blood to the systemic circulation.
This is accomplished in a series of two to three staged
surgical palliation interventions during the child’s first
years of life. Stage one palliation is designed to ensure
unobstructed systemic blood flow and adequate flow to
the pulmonary circulation. Stage two, a bidirectional
cavopulmonary shunt, redirects systemic venous return
from the superior vena cava directly to the pulmonary
arteries. Stage three connects flow from the inferior
vena cava directly into the pulmonary arteries so that
the pulmonary and systemic circulations are effectively
separated.
93
Cardiac transplantation is also used as
an intervention for the most complex forms of single-ventricle congenital heart disease.
Survival rates for children with complex forms of
single-ventricle heart disease have improved markedly,
but long-term outcomes remain uncertain. Ventricular
dysfunction, arrhythmias, and thromboses plague this
population of patients. Defining the optimal medical
and surgical management strategies for these patients
remains an active area of research in pediatric cardiol-
ogy and cardiac surgery.
89–93
Kawasaki Disease
Kawasaki disease is an acute vasculitis (i.e., inflamma-
tion of the blood vessels) with potential for involvement
of the coronary arteries. The disease occurs predomi-
nantly in young children; about 80% of patients are
younger than 5 years of age.
94,95
First described in
Japan in 1967 by Dr. Tomisaku Kawasaki, the disease
is the leading cause of acquired heart disease in North
America and Japan.
35,36,67,68
Although most common in
Very small
ascending aorta
Atrial
septal
opening
Right
atrium
Right
ventricle
Ductus arteriosus
Underdeveloped
left ventricle
Left atrium
Pulmonary
artery
FIGURE 19-23.
Functional single-ventricle anatomy with
an underdeveloped left ventricle and small ascending aorta.
Because of the markedly decreased left ventricular compliance,
most of the pulmonary venous blood returning to the left
atrium shunts left to right at the atrial level. Pulmonary arterial
blood flows into the pulmonary arteries as well as right to left
across a patent ductus arteriosus into the aorta.
