Congenital Heart Disease: Fontan Circulation

The Fontan procedure refers to any operation that results in the flow of systemic venous blood to the lungs without passing through a ventricle. Once the procedure is complete the systemic venous blood directly enters the pulmonary circulation, placing the systemic and pulmonary circulations in series driven by a single ventricle. Therefore, the pulmonary vascular resistance (PVR) will control the cardiac output. The procedure is done on patients with a single functioning ventricle, such as in: tricuspid atresia, pulmonary atresia with intact ventricular septum, hypoplastic left heart, and double-inlet ventricle.  Currently, surgeons create Fontan circulation in a series of operations. Complications include exercise intolerance, ventricle failure, right atrium dilatation and arrhythmia, venous hypertension/portal hypertension, coagulopathy, pulmonary AV malformations, venovenous shunts, and lymphatic dysfunction. The major morbidities secondary to these complications include myocardial failure, thromboembolism (PE), and stroke.

  • Supra-ventricular tachycardia in Fontan circulation is usually atrial in origin (ectopic atrial tachycardia or atrial flutter). The faster the rhythm, the poorer the patient’s condition. Adenosine will not work on atrial tachycardias and an anti-arrhythmic will need to be started. Consult the pediatric cardiologist if the patient is stable. Cardioversion is the safest most effective treatment for the unstable patient. New atrial tachycardia may be the only clinical manifestation of conduit obstruction and/or thrombi.
  • Massive pulmonary embolism is the most common cause of sudden out-of-hospital death.
  • Patients in heart failure with Fontan circulation will not respond to traditional heart failure treatment due to the pulmonary vascular resistance controlling the cardiac output. Early pediatric cardiologist consultation is imperative.
  • Positive-pressure ventilation decreases systemic venous return and increases PVR. Avoid placing these patient on positive pressure ventilation, but if needed: minimize plateau pressures, positive end-expiratory pressures, and the rate of inspiratory pressure rise. This can be accomplished by setting a short inspiratory time, prolonged expiratory time, larger tidal volumes, and low respiratory rate.
  • Fluid boluses may be needed to increase the systemic venous return.
Gewillig M. The Fontan circulation. Heart. 2005 Jun;91(6):839-46.
Fredenburg TB, Johnson TR, Cohen MD. The Fontan procedure: anatomy, complications, and manifestations of failure. Radiographics. 2011 Mar-Apr;31(2):453-63.
Leyvi G, Wasnick JD. Single-ventricle patient: pathophysiology and anesthetic management. J Cardiothorac Vasc Anesth. 2010 Feb;24(1):121-30. Epub 2009 Oct 28

 

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