Heartbeat: Focus on the Fontan patient.

Effective surgical palliation for complex congenital heart disease in infancy and childhood allows these patients to live into adulthood but may be associated with adverse outcomes over the longer term. Management of adult patients with “Fontan physiology” is especially challenging. The Fontan operation was first described in 1971 so that the oldest surviving patients with this procedure are only in their 40’s, with most being much younger.The physiology of the Fontan circulation, as elucidated in an elegant review by Gewillig and Brown (see page 1081), is characterized by an obligatory increase in systemic venous pressures because blood flow is directed to the pulmonary circuit without an intervening pumping chamber (e.g. absence of a functional right ventricle). In addition, forward cardiac output is lower than normal and is not responsive to normal physiological stressors, such as exercise (figure 1). In addition, over the long term, the Fontan may “fail” with an inadequate cardiac output to meet metabolic demands even at rest due to increasing pulmonary vascular resistance over time, ventricular dysfunction or refractory arrhythmias, as well as the effects of persistently elevated systemic venous pressure. Over the past 25 year, the Fontan procedure was performed in over 1300 patients in Australia and New Zealand. Using this database, Shi and colleagues (see page 1120) found that freedom from Fontan failure was 74%±3.9% at 20 years. A total of only 34 patients underwent heart transplantation (HTX) and there was significant regional variation in referral for HTX, even though outcomes after HTX in Fontan patients were similar to patients with other types of congenital heart disease (figure 2). In another study of outcomes in Fontan patients (see page 1127), a retrospective analysis of surgical outcomes in 225 patients from 22 medical centers found that after Fontan completion, takedown was the most common procedure in the early postoperative phase whereas late failure (most often manifested as arrhythmias) was treated with Fontan conversion or HTX. At a median follow-up of 5.9 (range 0 to 23.7) years, death or HTX occurred in 44.7% of the 38 Fontan takedown patients, 26.3% of the 137 Fontan conversion patients and 34.0% of the 50 HTX patients (figure 3). In an editorial, Backer (see page 1077) concludes: ‘The high mortality for Fontan takedown reminds us to carefully select our patients for the Fontan operation. The decision of when to proceed with Fontan conversion versus heart transplantation is heavily based on the preservation of ventricular function. Patients with ventricular Figure 1 Exercise and output: normal versus Fontan circulation. Normal subjects with a biventricular circulation can increase their cardiac output up to five times (black line). At rest, patients with Fontan circulation at best already have a cardiac output 80% of normal and with a markedly restricted ability to increase during exercise (green line) allowing only a mild sporting ability. At worst (red line), the output is severely restricted at rest and barely increases during exercise. Adapted with permission from Gewillig and Goldberg. Heart Fail Clin 2014; 10: 105-16.