Andersons pediatric cardiology 1735

Abstract For centuries heart failure was considered to result from an injury to the heart, leading to an abnormality of the ventricle's systolic function It is now recognized that heart failure is more complex, dynamic, and progressive; it affects not only on the heart itself but also a myriad of extracardiac processes and cannot be defined in simple hemodynamic terms The current framework posits a primary insult to the heart that results in a cascade of secondary responses within the heart and related organs These secondary responses may, at least initially, be adaptive and designed to preserve blood flow to the vital organs With time, however, they become maladaptive as the patient progresses into decompensated heart failure In view of these observations, a complete evaluation of the patient with heart failure would require not only an assessment of cardiac function (including ventricular systolic and diastolic performance, myocardial oxygen consumption, and the relationship between ventricular performance and cardiac load) but also an assessment of the function of other organs, including the sympathetic nervous system and kidneys, as well as symptoms and quality of life With increased understanding of the complexity of heart failure, treatment strategies have expanded beyond increasing pump function to addressing systemic maladaptive responses In fact, no positive inotropic medication has been shown to increase survival in heart failure Most recent recommendations suggest that there are few data to support or refute the use of digoxin in pediatric heart failure Although diuretics have never been shown (and possibly never will be) to improve survival in heart failure, their use is considered important because of the need for anticongestive measures Angiotensin converting enzyme inhibitors are widely used, although data on their efficacy in children are limited Despite positive initial reports of the use of β-blockers in children with heart failure, the only multicenter prospective randomized double-blind trial of carvedilol failed to detect a benefit of carvedilol over placebo The newest pharmacologic strategy in the treatment of heart failure in adults is a combination of an angiotensin receptor blocker with a neprilysin inhibitor, which has been shown to provide survival benefit compared with angiotensin converting enzyme inhibitor therapy Pediatric trials are under way The use of an implantable cardioverter-defibrillator is widely recommended for selected adults with heart failure Thus appropriate application of cardioverterdefibrillator therapy to children could clearly save lives, although there are few data regarding their use As with virtually all other treatments for heart failure in children, the indications for resynchronization therapy are unclear and its potential risk-benefit ratio is still to be determined Keywords Heart failure; ventricular function; angiotensin-converting enzyme inhibitors; β-blockers; implantable cardioverter-defibrillator Introduction Chronic heart failure has long been recognized as a cause of considerable mortality and morbidity in adults The early recognition of heart failure in the 17th and 18th centuries was that of edema, anasarca, and dyspnea, which was appropriately attributed to blood “backing up” behind an impaired pump, the heart.1 Early descriptions of heart failure in children were usually in the setting of rheumatic fever It was not until 1936 that Abbott mentioned “isolated” cardiac insufficiency as a cause of death in children,2 although we now recognize that chronic heart failure and cardiomyopathy are indeed important causes of morbidity and mortality in children Among children with cardiomyopathy who entered a national population-based registry in Australia between 1987 and 1996, freedom from either transplant or death at 5 years after diagnosis was only 83% for those with the hypertrophic3 and 63% for those with the dilated4 form of the disease The concepts that underlie our understanding of chronic heart failure in both children and adults have changed considerably in recent years This chapter summarizes some current concepts related to key pathophysiologic processes in chronic heart failure and examines the outcomes of its treatment