What are
the general anesthetic considerations for the common cardiac lesions?
Associated extracardiac defects are present in
5–50% of children with congenital heart disease. In 17–18%, the defect is part
of a syndrome or chromosomal anomaly. Genitouri-nary tract anomalies are among
the most common lesions and are present in 4–15% of patients with congenital
heart disease. Major chromosomal anomalies with associated car-diac lesions of
anesthetic significance are Down (trisomy 21), Turner, Noonan, and DiGeorge
syndromes.
All patients with shunt lesions are at risk for
air emboli to the systemic circulation irrespective of their usual shunting
pattern. A left-to-right shunt may transiently reverse due to the earlier
relaxation of the left ventricle compared with the right ventricle.
Additionally, upon sud-den obstruction to right ventricular output due to an
air embolus, a left-to-right shunt will convert to a right-to-left shunt
pattern. Therefore, the intravenous (IV) line should be meticulously debubbled
and then rechecked after warming of the operating room, since this may have
caused nitrogen to come out of solution in the IV fluid, forming additional
hazardous bubbles. All IV lines should be con-nected while the IV fluid is
flowing freely. In addition, all syringes should be cleared of air. Prior to
injecting into an intravenous line, a small amount of fluid should be
aspi-rated into the syringe to clear any air that may be in the needle or
injection port. A recommended technique is to dilute any given medication such
that 1 mL consists of a unit dose. With this technique, aspiration of IV fluid
into the syringe will not significantly change the drug concen-tration. These
precautions are important in any patient in whom a communication exists between
the systemic and pulmonary circulations, regardless of the presence or absence
of pulmonary outflow obstruction.
The majority of patients with congenital heart
disease, pre- or post-correction or palliation, require antibiotic prophylaxis
for the prevention of bacterial endocarditis prior to any surgical, diagnostic,
or dental procedure that may result in bacteremia. Routine oral endotracheal
intu-bation and flexible bronchoscopy do not require prophy-laxis. However,
manipulation of the genitourinary tract does. Current recommendations as
published by the American Heart Association are listed in Table 69.2.
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