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To avoid the cumulative morbidity and mortality associated with
initial palliative procedures followed by later repair, primary
corrective surgery has become increasingly common for patients with
congenital heart disease. One result of this trend is that an increasing
number of cardiac surgery procedures are performed on neonates and
even on premature infants. Optimal care of these infants requires
specialized knowledge of the unique structural and functional characteristics
of neonatal organ systems and is best accomplished by a multidisciplinary
team including cardiology, cardiac surgery, neonatology, anesthesia,
and critical care. The purpose of this chapter is to review general
principles of care for these infants. The physiology and surgical
procedures pertinent to specific defects are discussed in Chapters 6, 7, and 8.
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Cardiac surgery procedures are classified as to whether they
are open or closed and whether they are corrective or palliative
(Table 13-1). “Open” refers to those procedures
in which cardiopulmonary bypass is used; bypass is not used in “closed” procedures.
Palliative procedures are performed in patients in whom complete
correction of the cardiac defects is not possible or not feasible
because of comorbidities. Palliated patients have residual intracardiac
shunting or other hemodynamic abnormalities. In most institutions,
palliative procedures are only performed for infants with a functional
single ventricle (eg, hypoplastic left heart syndrome, tricuspid
atresia) or for those with poorly developed pulmonary arteries.
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Most corrective procedures, for example, for truncus arteriosus
or transposition of the great arteries, are performed by use of
cardiopulmonary bypass. Venous blood is siphoned to a reservoir
of the heart-lung bypass machine, which also collects blood drained
from the operative field by suction catheters. Blood is pumped through
an oxygenator, a heat exchanger, and a filter and then returned
to the patient’s ascending aorta through an aortic cannula.
The patient is always fully anticoagulated with heparin while on
bypass.
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Hypothermia extends the safe duration of cardiopulmonary bypass
in neonates and infants. Metabolic activity and thus, oxygen consumption,
are decreased. “Deep” hypothermia involves cooling
to about 18°C. For many years surgeons combined deep hypothermia
with either low-flow bypass (25%-50% of normal
flow) or more commonly, with no bypass flow, arresting the heart
(deep hypothermic circulatory arrest). Deep hypothermic circulatory
arrest provided the surgeon with a bloodless and relaxed heart not
attached to multiple cannulas that may distort the surgical field.
This technique allowed intricate surgical procedures to be ...