  Fontan patients often develop circulatory failure and are in desperate need
of a therapeutic solution. A blood pump surgically placed in the cavopulmonary
pathway can substitute the function of the absent sub-pulmonary ventricle by
generating a mild pressure boost. However, there is currently no commercially
available device designed for the cavopulmonary application; and the risks and
benefits of implanting a ventricular assist device (VAD) originally designed
for the left ventricular application on the right circulation of failing Fontan
patients is not yet clear. Moreover, further research is needed to compare the
hemodynamics between the two clinically-considered surgical configurations
(Full Support and IVC Support) for cavopulmonary assist, with Full and IVC
Support corresponding to the entire venous return or only the inferior venous
return, respectively, being routed through the VAD. In this study, we used a
numerical model of the failing Fontan physiology to evaluate the Fontan
hemodynamic response to a left VAD during the IVC and Full supports. We
observed that during the Full support the VAD improved the cardiac output while
maintaining blood pressures within safe ranges, and lowered the IVC pressure to
<15mmHg; however, we found a potential risk of lung damage at higher pump
speeds due to the excessive pulmonary pressure elevation. IVC support the other
hand, did not benefit the hemodynamics of the example failing Fontan patients,
resulting in the superior vena cava pressure increasing to an unsafe level of
>20 mmHg. The findings in this study may be helpful to surgeons for recognizing
the risks of a cavopulmonary VAD and developing coherent clinical strategies
for the implementation of cavopulmonary support.
