The fontan procedure: now what?

Abstract

The decision to commit a patient with single ventricle to the Fontan procedure route is made every day by pediatric cardiologists and cardiovascular surgeons. At this point, there is no other viable alternative to the palliative procedure we currently refer to as Fontan Procedure, first described by Francois Fontan in 1971 [1], yet more than four decades later there is concern regarding the long-term outcome of patients with Fontan circulation [4, 11, 13]. Specialists in our field will agree regarding the wisdom of choosing the Fontan procedure for patients with single ventricle (anatomical or physiological due to inability to partition), the alternative is a short and complication fraught life of a systemic-pulmonary arterial shunt. Cardiac transplantation is recommended by a limited number of specialists in this field and deemed by most a fate worse than that encountered through lifelong Fontan circulation and reserved by most cardiologists for those with failed Fontan circulation. The physiological concept behind the Fontan circulation is simple: allow blood to flow from the systemic veins through the pulmonary circulation and beyond to the systemic (single) ventricle without the aid of a pumping (right) ventricle. The flow of blood from the systemic veins to the systemic ventricle is enabled by elevation of the systemic venous pressure, the single ventricle’s diastolic relaxation, and the hopefully low resistance of the pulmonary circulation in between. This achieves separation of the two circulations, thus eliminating cyanosis. It also underloads the single ventricle which after completion of the Fontan procedure would have to deal with the systemic cardiac output alone, therefore, reducing the chances of pump failure. Many Fontan patients are alive in their 3 decade of life, but their wellbeing is challenged by serious complications, many are life-threatening [8]. Fontan procedures completed over the past 3–4 decades were not performed as currently done. It is safe to assume that these surgeries will not be done in the future as currently performed. Surgical techniques coupled with anesthesia and post-operative care allowing safer transition to the new anatomy and physiology of the various phases of the Fontan circulation are constantly improving, therefore, comparing results from yesteryears to current ones is rife with inaccuracies. In addition, interventional cardiac procedures in the cardiac catheterization laboratory currently allow us to improve upon what surgery offers and will certainly add to the better outcome for patients with single ventricle. The fruits of this advancement are noted in many studies of this population of patients assessing ventricular function and cardiac arrhythmias [5, 9], however, the outcome of patients with the Fontan circulation continues to be concerning as unique complications plague these patients, such as heart failure with preserved ventricular contractility, thromboembolism, protein-losing enteropathy, and liver failure. [9, 11, 13] The shortcomings of a Fontan circulation includes: (a) reliance on a single ventricle and (b) alteration of central venous and pulmonary arterial pressures and flow patterns. The single ventricle has to endure the added burden of increase pulmonary blood flow for months as well as the insult from repeated surgical procedures but thereafter assumes a normal volume burden; this is usually well tolerated if it is architecturally a left ventricle. A morphological right ventricle on the other hand may suffer from inefficient muscular design and an incompetent tricuspid valve. The alteration of the central venous and pulmonary arterial circulations is most probably more R. Abdulla (&) Section of Pediatric Cardiology, Rush University, Chicago, USA e-mail: Ra-id_Abdulla@rush.edu