PMC6343381_01
Schematic representation of the relevant anatomy and physiology. Interlobar hepatic venous collaterals have developed between the hepatics connected to the inferior vena cava (*) and the atrial-draining hepatic vein. Given the lower resistance in the atrium, the result is massive right-to-left shunting of inferior vena cava blood directly into the atria via these hepatic venous collaterals (broad arrow)
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F1
Subsequent catheterization diagnosed massive right-to-left shunting via hepato-hepatic venous collaterals-allowing systemic venous blood to bypass the PAs and flow directly into the atrium-with little-to-no effective antegrade pulmonary blood flow [Figures 1 and 2].
Power injection in anteroposterior (left) and lateral (right) projections within the inferior vena cava limb of the Fontan pathway. Note the dextrocardia and mid-line liver. (a) The normally connecting hepatic veins (*) backfill early after contrast injection into the inferior vena cava. (b) A complex meshwork of interlobar hepatic collaterals (#) connects the inferior vena cava-hepatics to an anomalous hepatic that drains directly into the atrium ( ). No contrast is seen within the inferior vena cava stent since all inferior vena cava flow is directed right-to-left into the atrium via the hepatic venous connections. Also seen is the vascular plug device in a previously occluded anomalous atrial-draining hepatic vein
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F2
Subsequent catheterization diagnosed massive right-to-left shunting via hepato-hepatic venous collaterals-allowing systemic venous blood to bypass the PAs and flow directly into the atrium-with little-to-no effective antegrade pulmonary blood flow [Figures 1 and 2]. A second, smaller, and unrecognized anomalous hepatic vein was present, which slowly enlarged resulting in fairly rapid regression to the same degree of preocclusion cyanosis [Figure 2].
Fenestrated covered stent delivery. (a) A 4 Fr catheter is positioned in the hepatic vein via the inferior vena cava and an exchange length 0.014" wire is advanced as distally as possible. (b) The 0.014" wire has been inserted through the covered stent (outside the body) which was then hand-mounted and advanced into position on a wire coursing from the inferior vena cava to superior vena cava. (c) The covered stent has been deployed and a 6 mm balloon was advanced over the 0.014" wire and into the hepatic vein, dilating the fenestration
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SVC, and then stent was deployed. Sterling balloons  (Boston Scientific, Marlborough, MA, USA)-4 and 6 mm-were next used to dilate the side hole, creating a functional "fenestration" [Figures 3 and 4].
Final inferior vena cava angiogram (top) and echocardiogram (bottom) after fenestrated covered stent placement. Top: Contrast now flows through the inferior vena cava stent and into the branch pulmonary arteries. The fenestration is patent with filling of the hepatic vein, but only the inferior vena cava-connecting hepatic vein has opacified. The interlobar connections and anomalous atrial-draining hepatic vein have not filled secondary to flow restriction through the controlled fenestration. Bottom: The inferior vena cava and stent (*) are widely patent with red fenestration flow visible into the hepatic vein ( )
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SVC, and then stent was deployed. Sterling balloons  (Boston Scientific, Marlborough, MA, USA)-4 and 6 mm-were next used to dilate the side hole, creating a functional "fenestration" [Figures 3 and 4]. Follow-up echocardiography demonstrated a 4 mmHg fenestration gradient and normal hepatic venous Doppler signals [Figure 4].