#{149}.:..:;,.I
Consultation

I

with

Complications
of Polycythemia
Patients
Who
Have Cyanotic
Congenital
Heart
Disease
William

B. Strong,

A 13-mo-old

child

in

MD*

is brought

to his pediatrician

following

sudden

onset

of left-sided

hemiplegia.
The pediatrician
accompanies
the child and family to the emergency
room.
The pediatrician
has been following
the child, who has a diagnosis
of possible cyanotic congenital
heart disease. The child has never been known to have had a hypercyanotic

range

episode.

Oxygen

of 84% to 88%.

saturation

determinations

5

ordered.

On one occasion,

It demonstrated

when

by pulsed

oximeter

had

been

in the

was very upset, a reading of
78% was observed.
At his 1-year visit, his hemoglobin level was 13 g/dL.
On admission
to the emergency
department,
a computed
tomographic
scan of the
head was
lesion.

a right-sided

What is the likely pathophysiology
of
this event?
What are the more cornmon complications
of hypoxemia
in
the older infant and young
child?
This clinical
scenario
is uncommon,
but it represents
one of the two
feared
central
nervous
system
complications
of cyanotic
congenital
heart disease,
(ie, cerebrovascular
accident
and brain abscess).
A uniform
response
to hypoxemia
of cardiac
etiology
is the production
of erythropoietin
to produce
more red
blood cells. This is a compensatory
mechanism
to maintain
oxygen
delivery to the peripheral
tissues.
Normally,
hemoglobin
is about 96%
saturated
with oxygen.
Therefore,
the
oxygen-carrying
capacity
of blood
with a normal
hemoglobin
concentration of 15 g/dL is approximately
20.3 mL of oxygen
per 100 mL of
blood (ie, 15 g of hemoglobin
x
1.35 mL of 02 per g of hemoglobin
=
20.3).
The oxygen
content
of
blood equals
the oxygen-carrying
capacity
multiplied
by the oxygen
saturation.
At a normal
oxygen
saturation
of 96%, the 02 content
of arterial
blood (Hgb 15 g/dL) equals
19.5

*Edigoria!

Board

Pediatrics

in Review

I

VoL

13

No.

10

October

the child

nonhemorrhagic

cerebrovascular

mLJdL
(96%
x 20.3 mm3/dL)
or
195 mL per liter of cardiac
output.
The arterial
02 content
of this
child,
assuming
an average
arterial
saturation
of 85%, will be 1 1 1 mL/
dL. Therefore,
every liter (10 dL) of
cardiac
output
will carry 1 1 1 mL of
02 or 84 mL of 02 less than the
child with a 15 g/dL hemoglobin
level. The normal
compensation
for
this deficit
is either to increase
cardiac output
(to deliver
more blood
with less 02) or to increase
the red
blood cell mass so that every 100 mL
of blood has more hemoglobin
and is
able to carry more 02. A fairly typical hemoglobin
level for a child with
an 02 saturation
of 85% would
be
17 g/dL. This would
provide
an 02
content
of 19.5 mLIdL
(17 x 1.35
x .85), which
is similar
to the normal child’s
oxygen
content.
So why was this patient’s
hemoglobin
only 13 g/dL? Investigation
of
the child’s
hematologic
status revealed a mean corpuscular
volume
of
66 fL, mean corpuscular
hemoglobin
concentration
of 29.8 g, a zinc protoporphyrin
level of 105 mg/dL,
a
transferrmn
saturation
of 4%, and a
serum ferritin
of 2.8 ng/mL,
indicating significant
iron deficiency
anemia.
.

Children
who have cyanotic
heart
disease
and iron deficiency
anemia
are especially
susceptible
to cerebrovascular
accidents
secondary
to the
decreased
deformability
of the red
blood cells as they traverse
the cerebral microcirculation.
Therefore,
even though
this 13-mo-old’s
hemoglobin
value would
be normal
for a
normal
child,
it is insufficient
for a
hypoxemic
child.
Children
who have cyanotic
heart
disease
may have hemoglobin
levels
in the range of 16 to 17 g/dL and
still be iron-deficient.
Therefore,
every hypoxemic
child should
have
his or her iron status evaluated
routinely.
Many of these infants
and
young
children
are poor eaters because of their disease
and may require substantial
iron and vitamin
supplementation
as well as caloric
supplementation
if they are not growing well. Therefore,
infants
and
young
children
who have cyanotic
congenital
heart disease
are at risk
for polycythemia,
iron deficiency
anemia,
and cerebrovascular
accidents.
Interestingly,
children
who have
pulmonary
parenchymal
disease,
especially
cystic fibrosis,
seem to
have an inadequate
erythroid
response
to hypoxemia.
It has been
demonstrated
that the inadequate
erythroid
response
is secondary
to a
disturbance
of erythropoietin
regulation and iron availability.
Older children
who have congenital heart disease
and are cyanotic
because of an inoperable
defect
or because of the development
of pulmonary vascular
obstructive
disease
(ie,
Eisenmenger
syndrome)
may become

1992

Downloaded from http://pedsinreview.aappublications.org/ by guest on June 22, 2016

379

#{149}.3.’.

.

;

:

#{149}..,:

:

.

-

#{149}
.

.
.

.

..

.

.

.

excessively
polycythemic.
These
adolescents
become
symptomatic
because of increased
blood viscosity.
The symptoms
most frequently
described
are decreased
exercise
tolerance, headache,
and chest pain,
which
are observed
most commonly
when the hematocrit
exceeds
65%.
These youngsters
frequently
will benefit from an erythrophoresis,
which
removes
erythrocytes
and replaces
the volume
extracted
with a similar
volume
of colloid
(fresh frozen
plasma,
dextran,
hetastarch).
As with
the younger
child,
iron deficiency
may occur because
of the removal
of
erythrocytes
and their iron content.
It is important
not to perform
a
simple
phlebotomy,
which would
reduce
intravascular
volume,
decrease
systemic
resistance,
and promote a larger right-to-left
shunt.
This
would
increase
hypoxemia
further,

,

.

resulting
in systemic
vasodilatation
that would
increase
the right-to-left
shunt,
furthering
hypoxemia
and resuIting
in acidosis
and potential
cardiovascular
collapse.
The pathophysiology
of the vascular system
in cyanotic
congenital
heart disease
is simple:
flow goes
where
resistance
is least. It is important for all pediatricians
to have an
understanding
of this mechanism
and
potential
complications.
Any procedure that has the potential
to reduce
blood pressure
should
be avoided
unless the child is in a well-supervised
and monitored
situation.
One final caution
in managing
children
who have right-to-left
intracardiac
shunts
is the potential
for
paradoxical
systemic
embolus.
Any
intravenous
fluids or medications
must be given with scrupulous
attention to avoiding
injection
of any air

.

.

.

.

.

.

.

or foreign
material.
In the normal
child,
these minute
particles
would
be filtered
in the pulmonary
circuit.
The patient
who has an intracardiac
right-to-left
shunt is at high risk for
those particles
entering
the systemic
circulation,
especially
the cerebral
circulation.
The risk can be reduced
substantially
by incorporating
an air
filter into all intravenous
systems
and
giving
medications
distal to the filter.
In summary,
attention
to detail
is
critical
in the care of children
who
have cyanotic
congenital
heart disease to avoid preventable
complications.
Oxygen
saturation
may be
monitored
transcutaneously
with
pulsed
oximetry
and iron status by
blood count and indices.
Intravenous
fluids and medications
should
be administered
through
a system
that contains an air filter.

S

S

I.’

Subscriptions

are now being

accepted

for the

1993 PREP curricular year (January-December
1993). This includes twelve issues of Pediatrics
Review, the Self-Assessment
Exercise
(available
in CompuPREP
format also), the 1 993 Content
Specifications
booklet,
and binder.
Individuals

are

eligible

to receive:

In

PREP

subscription

AAP

.

are:

FelIow/CPS

$150

$195

AAP Candidate
Fellow
Allied Health/Resident
AAP Non-member/institution
Group Subscribers

$100
$100
$215

today

$ 85
for more information
charge orders at

0004330010
Extension

for anyone

for 1993

AAFP Member

Call the PREP office
and for VlSNMastercard

40 AMA Category
1 credits
40 AAFP Prescribed
credits
. 28 AOA
category
2-B credits
. 40 NAPNAP
contact hours
for participation
in PREP.
.

An excellent
value
pediatric
care.

fees

involved

S

7912

in
Note:

Enrollments

will receive

in the PREP office after November
of Pediatrics In Review.

received

back issues

380

15, 1992

i992

Downloaded from http://pedsinreview.aappublications.org/ by guest on June 22, 2016

Consultation with the Specialist: Complications of Polycythemia in Patients Who Have
Cyanotic Congenital Heart Disease
William B. Strong
Pediatrics in Review 1992;13;379
DOI: 10.1542/pir.13-10-379

Updated Information &
Services

including high resolution figures, can be found at:
http://pedsinreview.aappublications.org/content/13/10/379

Permissions & Licensing

Information about reproducing this article in parts (figures, tables) or in its
entirety can be found online at:
http://beta.pedsinreview.aappublications.org/site/misc/Permissions.xhtml

Reprints

Information about ordering reprints can be found online:
http://beta.pedsinreview.aappublications.org/site/misc/reprints.xhtml

Downloaded from http://pedsinreview.aappublications.org/ by guest on June 22, 2016

Consultation with the Specialist: Complications of Polycythemia in Patients Who Have
Cyanotic Congenital Heart Disease
William B. Strong
Pediatrics in Review 1992;13;379
DOI: 10.1542/pir.13-10-379

The online version of this article, along with updated information and services, is located on
the World Wide Web at:
http://pedsinreview.aappublications.org/content/13/10/379

Pediatrics in Review is the official journal of the American Academy of Pediatrics. A monthly
publication, it has been published continuously since 1979. Pediatrics in Review is owned, published, and
trademarked by the American Academy of Pediatrics, 141 Northwest Point Boulevard, Elk Grove
Village, Illinois, 60007. Copyright © 1992 by the American Academy of Pediatrics. All rights reserved.
Print ISSN: 0191-9601.

Downloaded from http://pedsinreview.aappublications.org/ by guest on June 22, 2016