Pediatric Anesthsia.pdf

CHAPTER 61 ■ Anesthesia for Non-cardiac Surgery in Children With Congenital Heart Disease 983
systolic murmur with maximal intensity at the apex in the left
lateral position has to be considered organic. 12 Innocent functional
cardiac murmurs are frequently heard in almost 50% of healthy
children. 13 In all cases, the distinction between organic and func -
tional murmur should be considered in combination with the
clinical assessment. This should include the following four steps:
(1) count heart rate; (2) assess for the color of the nails, lips, and
skin; (3) appreciate the precordial impulse; and (4) evaluate the
amplitude of the pulses at all extremities. 11 Any anomaly that raises
suspicion should have a focused cardiac evaluation by a cardi -
ologist. A diagnosis of an innocent murmur is supported by
a negative clinical history, normal growth and development, the
lack of symptoms related to cardiac failure, normal pulse and
blood pressure in all four extremities, and normal saturation with
normal chest x-ray and electrocardiogram (ECG).
Preoperative Tests
12-Lead ECG
A 12-lead ECG should always be considered, especially in the
presence of an arrhythmia and/or PHTN. Signs of PHTN on ECG
include the presence of a P-wave amplitude greater than 2.5 mm
in II, III, and aVF, and/or greater than 1.5 mm in V1 (reflecting
right atrial enlargement: P pulmonale), right axis deviation greater
than 110, and a dominant R-wave in V1 (>7 mm). As for the
physical examination, it is important to have a systematic approach
to the ECG (rhythm and conduction) to avoid missing subtle
abnormalities that may have clinical importance.
Chest X-Ray
The chest x-ray may be useful in evaluating the importance of the
cardiomegaly and the pulmonary vascularization. In the presence
of pulmonary vascular disease, children will have cardiomegaly
and peripheral pruning of the vascular tree with a hypertranslucent
appearance in association with dilatation of the hilar and proximal
vessels. Whereas in case of hypoperfusion of the lungs, a homo -
geneous translucent appearance is seen such as in TOF with the
abnormal bootlike shape to the heart.
Cardiac Echocardiogram
Cardiac echocardiogram should be reconsidered if there is no
information available or if the last cardiology visit date was more
than 6 to 9 months earlier. Results can be compared with previous
ones and should be discussed with the cardiologist to better
determine ventricular function and cardiac anatomy.
Laboratory Testing
Laboratory testing is more dependent on the presence or absence
of cyanosis and/or the type of surgery that is scheduled.
In the presence of a cyanosis, a hematocrit over 60% is more
likely to be associated with coagulation abnormalities. These
anomalies are related to the degree of chronic hypoxemia as
well as to the degree of hyperviscosity. 14 The most frequently
observed anomalies include thrombocythemia, platelet dysfunc -
tion, hypofibrino genemia, and a deficit in several clot factors.
Aspirin, heparin, oral anti-vitamin K, and other anticoagulation
therapies, frequently prescribed in these children, may worsen
the clotting.
It is crucial to check the electrolytes especially in children
receiving digoxin and/or diuretics and/or angiotensin-converting
enzyme (ACE) inhibitors.
PREOPERATIVE PREPARATION
Preoperative Medication
In general, no medication should be stopped before surgery,
particularly if the child is using diuretics, ACE inhibitors, or
antiarrhythmic agents. Very often, aspirin is prescribed in children
with systemic to pulmonary arterial shunt and its interruption may
lead to a life-threatening thrombosis, particularly if oxygenation
relies on the shunt.
Children with TOFs are often on propanolol to prevent
infundibular spasm of the right ventricle and the occurrence
of a spell. In case of cardiac failure, optimization of the medical
treatment could be required and digoxin concentration levels
should be adapted to reach concentration between 1 and 1.5 ng/
mL (without exceeding 2 ng/mL). 15 The use of diuretics may lead
to hypochloremia, metabolic alkalosis, and hypokalemia that
can potentiate digoxin toxicity. Thus, preoperative administration
of K + to correct hypokalemia may be necessary and should
not exceed 0.5 mmol/kg/h. Although vasodilators such as ACE
inhibitors are of great value in the treatment of cardiac failure, they
might induce arterial hypotension on induction of anesthesia and
may be stopped just the night before surgery. Finally and in very
rare cases, some children with severe cardiac failure may benefit
from a dobutamine infusion or other inotrope or vasodilator
before anesthesia.
Endocarditis Prophylaxis
The incidence of infectious endocarditis with cardiac disorder
is on the order of 35 times higher than that reported in the
normal children. 16 More than half affect those with CHD, with
33% occurring in children with cyanotic complex cardiopathy. 17
As a consequence, the highest incidence of endocarditis is found
in children who have had definitive or palliative surgery for
cyanotic heart disease. 18
The American Heart Association (AHA) has recently revised
the previous complex guidelines. Prophylaxis is now recommended
only for patients with these four conditions 19 : (1) prosthetic cardiac
valve, (2) previous history of infective endocarditis, (3) certain
types of congenital heart disease (unrepaired cyanotic CHD,
including palliative shunts and conduits; completely repaired
CHD with prosthetic material or device, whether placed by surgery
or by catheter intervention, during the first 6 mo after the
procedure; and repaired CHD with residual defects at the site or
adjacent to the site of a prosthetic patch or prosthetic device [which
inhibit endothelialization]),and (4) cardiac transplantation with
valvulopathy.
In addition, the new guidelines restricted the use of prophylaxis
for dental procedures that involve manipulation of gingival tissue
or the periapical region of teeth or perforation of oral mucosa;
incision or biopsy of respiratory tract mucosa; and procedures on
infected skin or musculoskeletal structures. Gastrointestinal or
genitourinary procedures do not require any prophylaxis, but
if the urine is colonized by enterococcus, eradication before
invasive urinary procedures should be considered. Prophylaxis is
based on the administration of a single dose of amoxicillin, 30 to