Cavopulmonary connections (CPC) have been extensively used in the palliation of complex forms of congenital heart disease requiring some form of right heart bypass. The concept has evolved from unilateral CPC to total CPC (TCPC) in an attempt to prolong the palliated state, but the physiological implications remain only partially understood. We summarize some of the modifications and experimental data and their impact on flow distribution after the Fontan procedure. Copyright 1998 by W.B. Saunders Company