clinical experience in the treatment of patients with functionally univentricular hearts has shown the fontan operation to be much less than a perfect therapy. even in ideal patients, acquired elevation of the venous pressures in the systemic circulation, especially in the regions drained by the inferior caval vein, is only a matter of time. for this reason the treatment of this complex form of congenital heart disease is still the object of active scientific debate, as well as considerable ongoing medical and basic research.