ReviewRole of comprehensive care in Fontan survivors: A multidisciplinary team approach☆
Introduction
The current standard management strategy for patients born with single ventricle heart disease includes a series of palliative surgeries, culminating in the Fontan operation [1]. This procedure was first described by François Fontan in 1971 [1], yet more than four decades later we continue to uncover a variety of comorbidities in Fontan survivors involving multiple organ systems. Although the Fontan operation is successful in eliminating the mixing of desaturated systemic venous return from ventricular output, thus eliminating cyanosis, the desaturated systemic venous blood has to flow passively through the lungs, resulting in an obligate elevation in central venous pressure (CVP), typically in the range of 10–15 mmHg [2,3]. Apart from this elevation in CVP, in patients who have undergone Fontan operation, relative pulmonary hypertension, lack of pulsatile pulmonary blood flow and chronic low cardiac output state contribute to an unfavorable hemodynamic milieu. The comorbidities resulting from this disadvantageous physiology, including cardiac, pulmonary, gastrointestinal, hepatic and renal issues are thought to be related in large part to the chronic elevation in CVP [4]. In the early years of Fontan palliation, the primary focus of medical community was on optimizing the flow dynamics of the Fontan circuit by modifying the surgical approach. Currently, the extracardiac conduit Fontan is the most common variation of the Fontan surgery performed. More recently, the medical community has shifted its focus to long-term evaluation and management of late, multisystem complications associated with Fontan physiology. Many of these complications develop in the second decade of life [5], which has been unmasked in recent years due to a decrease in early mortality [[5], [6], [7], [8], [9]]. With the recognition that survivors of Fontan palliation are at risk for developing a wide breadth of complications, spanning multiple different organ systems, interest in developing multidisciplinary teams dedicated to the care of these patients has emerged [9].
Section snippets
Cardiac
Ventricular pump function has been demonstrated to be strong predictor of outcomes after Fontan operation [10]. Although ventricular systolic function is usually well preserved, relaxation abnormalities of the ventricular myocardium and diastolic dysfunction are thought to be common and often progressive. Atrioventricular valve regurgitation is another common issue that requires close attention and follow-up in Fontan patients. A dominant right ventricular morphology is more commonly associated
Protein-losing Enteropathy
Protein-losing enteropathy (PLE) is one of the dreaded complications following Fontan operation. The development of PLE, similar to plastic bronchitis, results from a breakdown in the integrity of the intestinal mucosa and leakage of protein-rich fluid into the bowel lumen, resulting in significant loss of protein [16]. An association with resistive indices in the superior mesenteric artery has been demonstrated [17], suggesting a role for gut hypoperfusion as well. The pathophysiology of PLE
Pulmonary
Plastic bronchitis, the formation of exudative airway casts [27,28], is a rare complication seen after Fontan operation. The casts can partially or completely obstruct the lower airways and can lead to life threatening hypoxemia. The cause of plastic bronchitis remains uncertain, but the commonly accepted working theory involves high lymphatic pressures leading to fibrin-rich fluid entering the airspace and solidifying to form casts. The incidence is 4–16% in post-Fontan patients [29]. The link
Bone Health, Growth and Puberty
Fontan survivors have multiple risk factors for abnormal growth and bone abnormalities. Compromised somatic growth and bone demineralization have both been documented after Fontan operation [[33], [34], [35]]. These problems are compounded in the setting of other comorbidities, such as PLE, where therapies often include systemic corticosteroids [36]. Chronic heart failure, nutritional deficiencies, vitamin D deficiencies, malabsorption, increase protein loss, chronic medication use (diuretics,
Development and Mental Health
With the increase in survival after staged palliation, developmental challenges have been widely recognized and phenotyped as patients with Fontan circulation interact more frequently with the school system [[38], [39], [40]]. Common abnormalities identified on neuropsychological assessment include problems with attention and executive functions, such as processing speed and impulsivity [39,41]. Patients with cyanotic heart disease are at risk for stroke [42], which adds an element of possible
Other Organ Systems
Children who have undergone serial operations involving cardiopulmonary bypass are also at risk for the development of acute kidney injury [45]. The etiologies of acute kidney injury after cardiac surgery include hemodynamic, inflammatory and nephrotoxic insults [46]. These episodes are a risk factor for the development of chronic kidney disease [45,47].
The Multidisciplinary Approach
Given the increasing evidence for the broad range of pathology spanning nearly every organ system, it seems less a question of whether or not a multidisciplinary approach is warranted for Fontan patients, but what testing and sub-specialists referrals are most vital to include in a multidisciplinary approach to long-term care of Fontan survivors [2]. The key element of this approach at the outset is recognition that the care paradigm in which Fontan patients simply see their cardiologist
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Authors declare there is no conflict of interest.