Physiology of Fontan Circulation

Description

In  Fontan circulation  the systemic venous return is connected to the pulmonary arteries without the interposition of an adequate ventricle and all shunts on the venous, atrial, ventricular and arterial level are interrupted. In such a Fontan circuit the postcapillary energy is no longer ‘‘wasted’’ into the systemic veins, but collected and used to push the blood through the lungs. Advantages of a Fontan circuit include near  normalisation of the arterial saturation and abolishment of the chronic volume overload.The cost for such a circulation includes chronic hypertension and congestion of the systemic veins, and decreased cardiac output both at rest and during exercise. Typically for this circuit, cardiac output is no longer determined by the heart, but rather by transpulmonary gradient. Fontan surgery has been carried out to treat patients with tricuspid atresia and univentricular physiology.Understanding the Fontan physiology is the basis of success in the anesthetic management of this patients.The Fontan patients are usually prone for arrhythmia,ventricular dysfunction and thrombosis.Modification of surgical techniques and anesthesia management have improved the outcome of this complex  group of patients.