Chamber dilation Cirrhotic cardiomyopathy Cyanosis Valvar heart disease Shunts: Intracardiac (baffle leaks) an extracardiac (atrioventricular collaterals and venovenous collaterals) Thrombi and cardioembolic events Peripheral Elevation in central and peripheral venous pressure veins Varicose veins Neurologic Increased risk of cerebrovascular events including ischemic and hemorrhagic strokes Reduced executive functioning skills Sleep-disordered breathing Lymphatics Impaired lymphatic circulation Protein losing enteropathy Plastic bronchitis Metabolic Increased risk of obesity and deconditioning Hematologic Erythrocytosis (due to cyanosis) Thrombocytopenia (due to cyanosis and/or portal hypertension) Gastrointestinal Gastroesophageal varices and risk of bleeding Diarrhea and protein losing enteropathy Reproductive Increased maternal and fetal risks of pregnancy Fontan Failure Phenotypic Classification Because of the phenotypic heterogeneity of Fontan failure and the complexity of the interaction of the cardiovascular system with other organs, a classification system has been proposed360 based on hemodynamic phenotypes of Fontan failure (Table 73.5) Arrhythmias, valvar disease, and obstructions within the Fontan or pulmonary arteries should be excluded as causes of Fontan failure before assigning a phenotype These potentially reversible causes of Fontan failure should be prioritized in the treatment strategy Arrhythmias should be treated with restoration of sinus rhythm or device therapy, if indicated Any valvar or obstructive lesions should be treated percutaneously and/or surgically depending on the clinical circumstances (Videos 73.7, 73.8 and 73.9).358,361 Despite the overlap between these Fontan failure phenotypes, this classification is useful to guide therapy based on the predominant pathophysiology Table 73.5 Fontan Failure Phenotypic Classification Type I Type II Type III Type IV Fontan failure with reduced systemic ventricle ejection fraction Fontan failure with preserved systemic ventricle ejection fraction Fontan failure with normal pressures Fontan failure with abnormal lymphatics Type I: Fontan Failure With Reduced Systemic Ventricle Ejection Fraction This phenotype is the most common in children and more often associated with non–left ventricle morphology Clinical features may include pulmonary venous congestion, hepatic congestion, ascites, and peripheral edema Elevated CVP can lead to the creation of venovenous collaterals and cyanosis Thromboembolic events and arrhythmias are also common in this phenotype Because of the neurohormonal activation associated with systolic dysfunction, treatment strategy is similar to that of acquired cardiomyopathy and heart failure βBlockers, ACE inhibitors, angiotensin receptor blockers (ARBs), and aldosterone antagonists, in addition to newer agents such the angiotensin receptor–neprilysin inhibitor (valsartan/sacubitril), have been shown to improve mortality in large clinical trials in adults with acquired left ventricle systolic heart failure.362–373 Caution is advised when attempting to extrapolate from these data for the treatment of patients with a functionally univentricular heart who have undergone with Fontan failure because there is little information demonstrating the efficacy of these therapies in the Fontan population.248,306–308,320 Loop diuretics and aldosterone antagonists are commonly used to relieve congestion and for symptomatic improvement, while monitoring renal function and electrolytes β-Blockers are also used in these patients to help improve ventricular remodeling and systolic function, in addition to their role in arrhythmic suppression To date, carvedilol, metoprolol succinate, and bisoprolol are the only β-blockers with proven benefit in systolic heart failure and should be used in first-line therapy, when possible β-Blockers should generally be used with caution in the presence of bradycardia or conduction abnormalities ACE inhibitors and ARBs are also used, particularly in the pediatric population However, these medications can result in excessive vasodilation, especially if there is cirrhosis and portal hypertension Similarly, angiotensin receptor–neprilysin inhibitors can cause excessive vasodilation and should probably be avoided or used with extreme caution until more experience and data are available Advanced heart failure is an indication for heart transplantation, with special attention to the liver because advanced liver disease may preclude heart-only transplantation and necessitate consideration for combined heart and liver transplantation Left ventricle assist device therapy has been used as a bridge to transplant,374 and temporary percutaneous mechanical support for cardiogenic shock with the Impella device as a bridge to transplant375 has been reported in the literature, but experience is limited Type II: Fontan Failure With Preserved Systemic Ventricle Ejection Fraction This phenotype resembles heart failure with preserved ejection fraction It should be noted that normal ejection fraction is not synonymous with normal systolic function Abnormal strain imaging and cardiac fibrosis are common features in this subtype Patients with normal ejection fraction can have abnormal systolic function and invariably also have diastolic dysfunction as measured by echocardiography In the Fontan circulation the systemic ventricle pulls blood from the pulmonary vasculature during early diastole Suction is reliant on the process of active relaxation As relaxation becomes impaired, central venous and pulmonary artery pressures rise and cardiac output falls Hence these patients typically have elevated pressure in the Fontan pathway and hepatic congestion as a consequence of pulmonary venous congestion and elevated systemic ventricle filling pressures Although unusual in Fontan patients, coronary disease should be considered in patients with heart failure and preserved ejection fraction The mainstay of treatment is relief of pulmonary venous and peripheral congestion with loop diuretics, aldosterone antagonist, sodium restriction, and antihypertensive therapy in hypertensive patients Type III: Fontan Failure With Normal Fontan Pressures Patients with this phenotype are symptomatic despite apparently normal left ventricle systolic and diastolic function, as well as acceptable Fontan pressures Although echocardiographic measures of diastolic function are helpful, invasive hemodynamics are often necessary to distinguish type II from type III phenotypes, with the former having elevated ventricular filling pressures and the latter having normal ventricular filling pressures Right heart failure symptoms such as dyspnea, edema, ascites, hepatomegaly, splenomegaly, and varicose veins predominate and appear to be out of proportion to the hemodynamics Pulmonary vascular changes are invariably associated with the Fontan circulation and can lead to increased pulmonary vascular resistance However, the calculated pulmonary vascular resistance may be erroneously normal due to the decompressing effect of venovenous collaterals, even in the absence of ... generally be used with caution in the presence of bradycardia or conduction abnormalities ACE inhibitors and ARBs are also used, particularly in the pediatric population However, these medications can result in excessive vasodilation, especially if there is cirrhosis and portal hypertension