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Page 8 of 12 Pegoraro et al. Hepatoma Res 2021;7:24 https://dx.doi.org/10.20517/2394-5079.2020.142

[15]
which often lead to intra-abdominal infections) and less adhesions . This results in a double advantage
during the second stage: the liver mobilization results were easier and there was limited blood loss during
the resection thanks to the reduced vascularization of the resection plane guaranteed by the thermal
ablation. At the same time, the ablated plane interrupts collateral blood circulation from the FLR to the liver
segments including the tumor and vice-versa. This allows an increase in the FLR blood flow and the
disruption of all cross-exchanges between neoplastic and healthy liver segments. These advantages add up
to the benefits of a laparoscopic approach, which produces a lower inflammatory response (reducing the
development of adhesions, thus facilitating the second stage), less postoperative pain and shorter length of
stay [26,27] .

Our RALPPS was accomplished by means of several percutaneous and trans-trocar passages of a single
ablation needle under IOUS guidance. Despite causing a certain prolongation of the surgical time compared
to using dedicated ablation devices (such as the Habib 4× bipolar resection device), in our experience, this
®
method represents a valid alternative. In fact, the time of surgery did not exceed 300 min, similarly to the
timings reported in most series describing laparoscopic ALPPS . This is also the “safe limit” above which
[28]
[29]
the number of complications reported start to rise .
We chose not to extend the ablation depth beyond 5 cm along the hypothesized resection shear, applying
the same logic as a partial ALPPS; in fact, there is substantial evidence confirming that a complete resection
plane is not needed to generate a sufficient hypertrophy boost [12,30] . Similarly, a partial ablation is as effective
as a whole-thickness ablation plane and could be more practical and easier. This is because the well-
[15]
known heat-sink effect caused by large vessels (i.e., vena cava) could undermine and/or spread unevenly the
ablation region. Secondly, deepening the ablation plane to the hilum enhances the risk of injuring important
bile ducts that are very sensitive to radiofrequencies.

To further assess the exact limit between left and right hemiliver, ICG fluorescence guidance was used
intraoperatively. This synthetic substance is almost exclusively metabolized by the liver and excreted by
hepatocytes by means of MDR3 channels, which transport bilirubin . For this reason, ICG is extremely
[31]
[32]
well-tolerated and adverse reaction are anecdotal . Its spectrum confers the property of fluorescence when
illuminated with a 1000-1700 nm wavelength light, giving off a bright green light . This technique is
[33]
employed with several purposes in hepatobiliary surgery, such as intraoperative HCC detection after
preoperative i.v. injection, intraoperative cholangiography, and liver vascularization marker. After right
portal vein ligation, a systemic intravenous injection of a 2-mg bolus of ICG was performed. The substance
rapidly spreads in all tissues, which temporarily appear green; after a few minutes, the background
fluorescence vanishes, leaving a strong luminescence in correspondence of the liver parenchyma. With the
right portal vein clamped, only the FLR appeared fluorescent, highlighting the vascular borders of left and
right hemiliver: an electrocautery is then used to mark the limit of the transection/ablation plane. We kept
the ablation passages slightly on the right of the identified plane, as not to affect the FLR (due to the
anticipated expansion of the ablated zone on both sides of the needle).

Following this principle, ICG can be used both for positive staining (when the hemiliver, sector or segment
to be resected is infused and enhanced) and negative staining (when the ICG is injected in the portal system
while the pedicle of the portion to be resected is clamped). The vascular limit between the right and left
anterior sectors is variable and poorly defined macroscopically: this technique allows the preservation of
well-vascularized parenchyma and prevents the formation of ischemic areas.