Heart failure (or congestive heart failure) is defined as the inability of the myocardium to meet the metabolic requirements of the body. This may arise as a consequence of excessive work or volume load imposed on the myocardium, primary alterations in myocardial performance, metabolic derangements, or a combination of these elements. Heart failure leads to a neurohormonal response, which contributes to the symptoms associated with heart failure and increased morbidity and mortality.
In the pediatric age group, the underlying abnormality is often a large left to right intracardiac shunt, most commonly a ventricular septal defect, or an obstructive lesion, such as an aortic coarctation. In contrast to heart failure in adults, pediatric patients often have normal left ventricular function. Exceptions to this may include patients with myocarditis, dilated cardiomyopathy, ischemia-reperfusion injury following cardiopulmonary bypass, or a congenital coronary artery anomaly.