Objective: Extracardiac total cavopulmonary connection has recently been in
troduced as an alternative to intra-atrial procedures. The purpose of this
study was to compare the hydrodynamic efficiency of extracardiac and intra-
atrial lateral tunnel procedures in total cavopulmonary connections, Method
s: Intra-atrial lateral tunnel, extracardiac tunnel, and extracardiac condu
it with and without caval vein offset were performed on explanted sheep hea
rt preparations and studied in an in vitro flow loop. A rate of fluid-energ
y dissipation analysis was performed for each model using simultaneous meas
urement of pressure acid flow at each inlet and outlet of the right side of
the heart. Preparations were perfused by using a steady flow blood pump at
4 flow indices (1-6 L/min/m(2)) with the inferior vena cava carrying 65% o
f the total venous return. Results: Fluid-power losses were consistently lo
wer for the extracardiac conduit procedure compared with the two tunnel con
figurations (P < .01). A further reduction in energy dissipation of up to 3
6% was noted in the extracardiac procedure, with 5 mm offset of the extraca
rdiac conduit toward the distal right pulmonary, The intra-atrial and extra
cardiac tunnel procedures were least efficient, with losses 73% greater tha
n the optimal extracardiac conduit procedure, Conclusions: The extracardiac
conduit procedure provides superior hemodynamics compared with the intra-a
trial lateral tunnel and extracardiac tunnel techniques. This hydrodynamic
advantage is markedly enhanced by the use of conduit-superior vena cava off
set, particularly at high physiologic flows that are representative of exer
cise. These data suggest additional rationale for the use of extracardiac c
onduit procedures for final-stage completion of the Fontan circulation.