Andersons pediatric cardiology 1903

Abstract The Fontan operation is the treatment of choice for patients with a univentricular heart By directly connecting the systemic veins to the pulmonary circulation, it allows partitioning of the circulation so that systemic oxygen saturation and single ventricle volume are normalized The Fontan circulation has substantially improved the life expectancy in this group of patients However, because there is no subpulmonary ventricle, the “Fontan circulation” comes at the cost of an elevated central venous pressure and a restricted cardiac output In addition to limited functional capacity, the Fontan circulation has an insidious impact on many organ systems, including the liver, gastrointestinal tract, the hematologic and immune systems, and the kidneys Morphologic features such as hypoplastic left heart syndrome are known to impact outcome over the first and second decade As patients survive into their third and fourth decades, the progression of multisystem organ dysfunction has declared itself to be a significant contributor to morbidity and mortality The treatment of problems such as protein-losing enteropathy are evolving, as are surveillance protocols for other abnormalities such as Fontan-related liver or kidney disease The treatment of the “failing Fontan” remains a challenge, particularly in relation to the assessment of suitability for, and timing of, transplantation Many of the disease processes set in motion by the Fontan circulation are untreatable in isolation Standardized lifetime surveillance may play a role improving outcome and attention to the psychological impact of this process, which is similar to that of other chronic diseases, is important There are a number of promising developments aimed at reducing central venous pressure and improving cardiac output reserve, including pulmonary vasodilator therapy and exercise programs that may also improve survival and quality of life in this challenging population Keywords Fontan; univentricular heart; arrhythmia; mortality; risk factors; heterotaxy Evolution of the Fontan Procedure The Fontan operation is the treatment of choice for patients with a single anatomic or functional ventricular chamber From the late 1940s, survivors with a functionally univentricular heart could be palliated with a systemic-topulmonary artery or Glenn shunt, but by the early 1970s, only 50% of those with tricuspid atresia—the most favorable form of functionally univentricular heart— survived 15 years (Fig 73.1).1 In that era, complications of cyanotic heart disease including stroke and cerebral abscess, and progressive ventricular failure and atrioventricular valve regurgitation due to chronic volume loading were the commonest causes of death FIG 73.1 Survival curve and 95% confidence intervals of 101 patients with tricuspid atresia born after 1940 and examined at the Children's Hospital Medical Center, Boston (Modified from Dick M, Fyler DC, Nadas AS Tricuspid atresia: clinical course in 101 patients Am J Cardiol 1975;36[3]:327–337, Fig 5.) The understanding that blood could flow through the lungs without a subpulmonary ventricle led to development of the Fontan operation, first described by Fontan and Baudet as “corrective surgery” for tricuspid atresia in 1971.2 The original procedure consisted of division of the right pulmonary artery from the main pulmonary artery and anastomosis of the superior vena cava to the right pulmonary artery The left pulmonary artery was then anastomosed via a homograft valve to the right atrium, and the main pulmonary artery was disconnected from the hypoplastic ventricle The valve was used to promote the “ventriculization” of the right atrium so that it might generate sufficient pressure to augment pulmonary flow (Fig 73.2) The atrial septal defect was closed and a valve placed at the junction of the inferior vena cava and the right atrium to prevent retrograde flow during atrial contraction Six months later, Dr Guillermo Kreutzer and team carried out their first atriopulmonary Fontan anastomosis This procedure included a 6-mm fenestration in the interatrial septum and as such was the first fenestrated Fontan.3 No valve was positioned in the venous circulation because it was thought that this would result in a degree of obstruction—a hypothesis that was proven correct because it soon became apparent that valves within the Fontan circulation were associated with a high risk of stenosis This technique evolved to generate an atriopulmonary anastomosis as wide as possible without the use of a valved conduit (Fig 73.3) FIG 73.2 First version of the corrective procedure for the treatment of tricuspid atresia, as published by Fontan and Baudet The right pulmonary artery has been anastomosed to the superior vena cava, and the left pulmonary artery to the right atrial appendage Valves were placed between the inferior vena cava and the right atrium and between the right atrium and the left pulmonary artery (Modified from Fontan F, Baudet E Surgical repair of tricuspid atresia Thorax 1971;26[3]:240–248.)