Heart failure in congenital heart disease—How to manage the Fontan patient

Medical and surgical advances have resulted in excellent midterm survival following the Fontan procedure; however, heart failure has become an important cause of morbidity and mortality as these patients age. The mechanisms of heart failure are multifactorial and include morphologic abnormalities, chronic exposure of the myocardium and pulmonary vascular bed to cyanosis, pathophysiologic volume- and pressure-loads, and myocardial ischemia. Heart failure following the Fontan can be the result of systolic or diastolic ventricular function; equally important is low flow through the Fontan circuit due to abnormalities of the lymphatic or pulmonary vasculature. The hallmarks of a "failing Fontan" circulation include systemic venous congestion and low cardiac output from an underfilled ventricle. Clinical evaluation of the Fontan patient includes evaluation for signs and symptoms of low output and venous congestion along with noninvasive and invasive assessments of hemodynamics and anatomy. Noncardiac comorbidities are common, and laboratory testing is essential for risk stratification. Treatment of heart failure begins with preventive measures to minimize myocardial damage and pulmonary hypertension. Evidence-based medical therapies are lacking, and treatment of ventricular dysfunction is largely limited to Angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. Effective interventions to decrease the consequences of venous congestion have not been identified. Increasing use of ventricular assist devices has been reported, and heart transplantation remains the intervention of choice for end-stage heart failure. Significant knowledge gaps exist regarding the mechanisms of heart failure, the effectiveness and safety of heart failure medications, and the optimal timing and management of ventricular assist devices and heart transplants.