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FOCUS POINTS
Fetal cardiac development begins at approximately 22 days of gestation. The fetal circulation allows for preferential shunting of oxygenated blood to the brain and heart.
Beginning at birth, the cardiovascular system undergoes drastic physiological changes as it transitions from a parallel to a series circulation. In the transitional circulation, the fetal shunts (ductus arteriosus, ductus venosus, and foramen ovale) close functionally and eventually, anatomically.
Normal vital signs value change with age, reaching adult values in adolescence.
Congenital heart disease is the most common form of birth defect with an incidence of between 4 and 7 per 1000 live births. Patients with congenital heart disease may have associated extracardiac anomalies and genetic syndromes.
Congenital heart disease (CHD) can be classified as cyanotic or acyanotic, depending on the presence or absence of right-to-left shunting.
The magnitude of shunting and its hemodynamic significance depends on the location and size of the shunt as well as the pressure gradient across the shunt and the relative compliances of the downstream chambers or resistances of the downstream vessels.
Pediatric heart failure can be related to volume- or pressure-overload. It can occur in structurally normal heart with primary cardiomyopathy (dilated, hypertrophic, or restrictive) or secondary cardiomyopathy due to arrythmia, ischemic, toxicity, infection, or infiltrative diseases.
The approach to the patient with CHD undergoing noncardiac surgery should be systematic and team-based.
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A thorough understanding of cardiovascular physiology and pathophysiology is an unequivocally essential component of the practice of anesthesiology. Pediatric anesthesiologists must be cognizant of the normal physiologic changes that the cardiovascular system undergoes during growth and development, from fetal through adult life. They must be familiar with the broad spectrum of pathophysiology that accompanies congenital, and, to a lesser extent, acquired heart disease and its management. In this chapter, we will review the most salient aspects of this expansive subject and provide a basic framework for the clinical management of the patient with cardiac disease presenting for noncardiac surgery.
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DEVELOPMENTAL PHYSIOLOGY
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Fetal cardiac development begins at approximately 22 days’ gestational age. Several intrauterine shunts form to divert blood away from the fetal lungs, which do not participate in gas exchange. These shunts also help optimize oxygen delivery to the developing brain and heart. Blood that has been oxygenated in the maternal circulation crosses the placenta and enters the fetal circulation via the umbilical vein with an oxygen saturation of 70% to 80%. The umbilical vein enters at the level of the liver, where a portion of the blood provides perfusion to the hepatic circulation and the rest is shunted across the ductus venosus toward the heart. This blood travels toward the right atrium (RA) independently from inferior vena cava (IVC) blood. The blood from the ductus venosus enters the RA and is shunted across the foramen ovale to the left atrium (LA), where it mixes with the small amount of blood that made it through ...