Endothelin-1 may play an important role in the Fontan circulation

Biomarkers for heart failure and prognostic prediction in patients with Fontan circulation

A wide variety of pathologies are involved in heart failure in patients with congenital heart disease (CHD). Specific causes of heart failure after the Fontan procedure include not only single-ventricle circulation, but also the function of the right ventricle as the systemic ventricle, atrioventricular or semilunar valve stenosis or regurgitation, pulmonary hypertension, and left ventricular dysfunction secondary to right ventricular enlargement or dysfunction. As heart failure can occur post-Fontan, for a variety of reasons, clarification of the pathophysiology is the first step in management and treatment. At the same time, it is important to understand each patient's current condition and treatment plan to make an accurate prognosis. Because of the wide variety of pathophysiologies in post-Fontan CHD patients, however, no single biomarker is useful in all situations. Relevant biomarkers must be selected according to each patient's disease state, and combinations of multiple biomarkers should also be considered. In this review, the author describes the clinical importance of various biomarkers for patients who have undergone a Fontan procedure.

Targeted metabolomic analysis of serum amino acids in the adult Fontan patient with a dominant left ventricle

Growing interest lies in the assessment of the metabolic status of patients with a univentricular circulation after Fontan operation, especially in changes of amino acid metabolism. Using targeted metabolomic examinations, we investigated amino acid metabolism in a homogeneous adult Fontan-patient group with a dominant left ventricle, seeking biomarker patterns that might permit better understanding of Fontan pathophysiology and early detection of subtle ventricular or circulatory dysfunction. We compared serum amino acid levels (42 analytes; AbsoluteIDQ p180 kit, Biocrates Life Sciences, Innsbruck, Austria) in 20 adult Fontan patients with a dominant left ventricle and those in age- and sex-matched biventricular controls. Serum concentrations of asymmetric dimethylarginine, methionine sulfoxide, glutamic acid, and trans-4-hydroxyproline and the methionine sulfoxide/methionine ratio (Met-SO/Met) were significantly higher and serum concentrations of asparagine, histidine, taurine, and threonine were significantly lower in patients than in controls. Met-SO/Met values exhibited a significant negative correlation with oxygen uptake during exercise. The alterations in amino acid metabolome that we found in Fontan patients suggest links between Fontan pathophysiology, altered cell energy metabolism, oxidative stress, and endothelial dysfunction like those found in biventricular patients with congestive heart failure. Studies of extended amino acid metabolism may allow better understanding of Fontan pathophysiology that will permit early detection of subtle ventricular or circulatory dysfunction in Fontan patients.