Hepatectomy combined with the simultaneous resection of the IVC and three major hepatic veins represents one of the most complicated and challenging procedures in hepatobiliary surgery. An “ex vivo” or “ante situm” technique is often required to resect the tumor followed by reconstruction of the IVC and one of the major hepatic veins. However, the presence of the IRHV can circumvent RHV reconstruction even in cases of such an extended hepatectomy. In 1987, Makuuchi et al. mentioned the theoretical feasibility of an IRHV-preserving left hepatic trisectionectomy with resection of the RHV . Thereafter, several authors reported this type of extended hepatectomy in patients having the IRHV [4, 5]; in these reports, RHV embolization was unnecessary because the IRHV was originally “thick.” On the other hand, in patients with a “thin” IRHV like that in the present case, omitting reconstruction of the RHV may be risky due to possible congestion of the remnant liver. To avoid this potential risk, in 2003, one of the present authors (MN) introduced RHV embolization , which can help to develop collaterals from the RHV to the IRHV; in that previous case, the tumor involved the RHV but not the IVC; thus, the IVC was not resected. In the present case, the IVC was extensively involved, requiring IVC resection with reconstruction. If the IRHV had been absent, or if the RHV had not been embolized, a curative en bloc resection would have been very difficult.
After RHV embolization, we should wait at least 2 weeks to develop enough collaterals from the RHV to the IRHV. The previous experimental study reported that adequate intrahepatic collaterals develop rapidly after hepatic vein occlusion and are established within 2 weeks in large animals .
RHV embolization has a potential risk of coil migration leading to pulmonary embolism. To date, however, no serious procedure-related complications were reported [7, 8]. We thought that use of Amplatzer vascular plug could reduce the risk of such migration, providing the plug is oversized by at least 50%.
An important topic of discussion is the definition of “thin” or “thick,” which is vague and based on an empirical impression. In other words, to what extent does the diameter of the IRHV guarantee the safety of this extended hepatectomy? Although this issue is still unclear, one previous study classified a large-caliber IRHV as a vein with a diameter of > 18 mm and a medium-sized IRHV as a vein with a diameter of 5 to 18 mm . Accordingly, the IRHV in the present case is apparently defined as “thin.”