Parametric investigation of an injection-jet self-powered Fontan circulation

Abstract

Approximately $$1/2500$$ 1 / 2500 babies are born with only one functioning ventricle and the Fontan is the third and, ideally final staged palliative operation for these patients. This altered circulation is prone to failure with survival rates below $$50\%$$ 50 % into adulthood. Chronically elevated inferior vena cava (IVC) pressure is implicated as one cause of the mortality and morbidity in this population. An injection jet shunt (IJS) drawing blood-flow directly from the aortic arch to significantly lower IVC pressure is proposed. A computer-generated 3D model of a 2–4 year old patient with a fenestrated Fontan and a cardiac output of 2.3 L/min was generated. The detailed 3D pulsatile hemodynamics are resolved in a zero-dimensional lumped parameter network tightly-coupled to a 3D computational fluid dynamics model accounting for non-Newtonian blood rheology and resolving turbulence using large eddy simulation. IVC pressure and systemic oxygen saturation were tracked for various IJS-assisted Fontan configurations, altering design parameters such as shunt and fenestration diameters and locations. A baseline “failing” Fontan with a 4 mm fenestration was tuned to have an elevated IVC pressure (+ 17.8 mmHg). Enlargement of the fenestration to 8 mm resulted in a 3 mmHg IVC pressure drop but an unacceptable reduction in systemic oxygen saturation below 80%. Addition of an IJS with a 2 mm nozzle and minor volume load to the ventricle improved the IVC pressure drop to 3.2 mmHg while increasing systemic oxygen saturation above 80%. The salutary effects of the IJS to effectively lower IVC pressure while retaining acceptable levels of oxygen saturation are successfully demonstrated.

Characterization of baseline hemodynamics after the Fontan procedure: a retrospective cohort study on the comparison of 4D Flow MRI and computational fluid dynamics

“…First, the fluid was assumed to be Newtonian. While many studies on Fontan circulation have considered non-Newtonian fluid models for CFD analysis ( Wei et al, 2020 ; Frieberg et al, 2022 ; Prather et al, 2022 ), the Newtonian model was used in this study to ensure consistency in calculating viscous dissipation between 4D Flow MRI and CFD. Second, the vessel wall was assumed to be rigid.…”

In Vitro Hemodynamic Performance of a Blood Pump for Self-powered Venous Assist in Univentricular Hearts

“…However, when the same shunt was positioned within the ECC lumen with fenestration, computational simulations reported a reduction in IVC pressure [41]. Despite this potential bene t, the proposed solution lacks clinical feasibility, as the unsupported shunt inside the ECC lumen is susceptible to pronounced oscillations due to highly pulsatile aortic ow and strong jet ow momentum.…”

“…Correspondingly, a 4 mm aortic graft inlet size was deemed congruent with established clinical practices pertaining to aortopulmonary shunts [45]. In accordance with prior studies [40,41,43], a range of aortic nozzle sizes spanning from 2.0 mm to 3.5 mm was taken into consideration.…”

“…While in vitro experiments have demonstrated the ability of the system to provide proper venous support, the presence of turbine-to-pump leakage poses a signi cant challenge, affecting the system's overall performance. Computational simulations have suggested that an alternative approach, such as a shunt that injects a portion of aortic ow into either the pulmonary arteries [40] or inferior vena cava (IVC) [41], can reduce IVC pressure. However, unsupported shunts are highly susceptible to uctuations due to the pulsatile nature of the aortic ow, which may signi cantly affect the system's clinical feasibility and performance.…”

Narrative review of single ventricle: where are we after 40 years?

“…Investigative collaboration with bioengineers and mathematicians has opened a new horizon in the research for mechanical circulatory support even in Fontan circulation, resulting in a large number of publications on the topic ( 177 , 238 , 246 - 251 ).…”