Unique Aspects of Heart Failure in the Neonate

Neonatal heart failure is characterized by many unique anatomic and physiologic features. Structural and functional differences between the mature and immature myocardium, as well as different etiologies of neonatal heart failure, pose challenges for the clinician when evaluating and treating the clinical syndrome of heart failure. Anatomically, the newborn myocardium is disorganized in its structure and has a lower density of contractile proteins. These features, as well as decreased cellular transport, may play a role in the relatively impaired contractile and relaxation functions of the immature heart. Despite these differences, the Frank-Starling relationship in the neonatal heart is intact and functional as cardiac output can be augmented with increased ventricular filling, as well as higher heart rates and inotropy. The treatment of the clinical syndrome of heart failure depends, in part, on the underlying cause of heart failure. In the presence of depressed myocardial contractility, unloading the myocardium with diuretics and afterload reducing agents often leads to symptomatic relief and improved cardiac output. Understanding the developmental changes in myocardial structure and function will add to the clinician’s ability to provide optimal care of the newborn in the setting of a failing myocardium. The purpose of this chapter is to review the key differences between the neonatal heart failure and heart failure in the older child and adult.