• CARDIAC PROCEDURES AND THERAPY

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.