Congenital heart diseases that decrease cardiopulmonary reserve include intracardiac shunting, hypoxemia from inadequate pulmonary blood flow or intracardiac shunting, congestive failure from volume or pressure overload, vascular obstructive disease from excessive pulmonary blood flow, various kinds of stenoses, and occasional coronary ischemia.
Many of the determinants of shunting (its magnitude and direction) may change considerably during anesthesia and operative manipulations.
There are simple shunts, bidirectional shunts, and occasionally complex shunts. The key for anesthesia providers is to understand the effects of vasodilators, cardiac depressants, and surgical manipulation on these various shunts.
"Bubble discipline" is an important concept for patients with congenital heart disease.
Chronic hypoxia leads to polycythemia, which in turn leads to dramatic increases in blood viscosity.
The anesthesia provider should understand the hemodynamic consequences of pulmonary vascular hypertrophy, the end stage of which is the Eisenmenger syndrome.
Even though a child with congenital heart disease may not have frank failure, cardiac reserves may be dramatically decreased, especially if episodes of prolonged congestive failure have been a part of the patient's history and have resulted in cardiomegaly or ventricular hypertrophy.
"Transitional circulation" keeps neonates with severe life-threatening congenital heart disease alive. In this context, therapy with prostaglandin E1 infusion should be understood, especially the possibility of side effects such as apnea and major vasodilatation.
The functional capacities of the immature heart should be of particular interest to anesthesia providers. The immature noncompliant ventricle is extraordinarily sensitive to increases in volume and is considerably restricted in its ability to respond to the same by increasing stroke volume. The Starling curve plateau in neonates is reached at left ventricular end-diastolic pressures of 4 mm Hg. Therefore, cardiac compliance values in neonates do not correspond to values for adult patients.
Adult arterial pressures, especially during bypass, do not apply to neonates and infants.
The procedures for weaning from bypass and using deep hypothermic circulatory arrest or low-flow hypothermic bypass are important and should be reviewed in detail.
The anesthesia provider should fully understand the hemodynamic consequences and purpose of various pulmonary artery banding procedures and various kinds of transcatheter management of congenital lesions. Transcatheter procedures require anesthetic care in the interventional cardiac catheterization laboratory.
Halothane has been a successful induction anesthetic in children with various kinds of transcatheter treatment of congenital lesions.
Intravenous anesthetics, including high-dose opioids and ketamine, may provide increased margins of safety in some infants with congenital heart disease.
Intramuscular ketamine 3 to 5 mg/kg is reasonably well tolerated, even in sick children with cyanotic congenital heart disease.
Inhaled nitric oxide is a clinically useful and efficacious selective pulmonary vasodilator for many, but not all, patients with congenital heart disease.
The goal of anesthetic management in the treatment of patients with congenital heart disease (CHD) is maintenance of circulatory homeostasis despite the destabilizing events accompanying therapeutic procedures. Anesthesia for management of CHD is complicated by the diversity of lesions and the variety of therapeutic approaches. Congenital cardiac defects vary widely in severity, ...