Liver graft volumetric changes after living donor liver transplantation with segment 2 graft for small infants

Volumetric graft changes after liver transplantation: evidence of adaptation to recipient body size

It is believed that whole liver grafts adjust their size to fit the body size of the recipient after transplantation, despite a lack of evidence. The aim of this study was to test this hypothesis. This was a retrospective cohort study of 113 liver transplantations performed at Karolinska University Hospital. The cohort was divided based on graft volume-to-standard liver volume ratio (GV/SLV) into quartiles of small, mid, and large grafts. Serial volumetric assessment was performed on the day of transplantation and at posttransplant check-ups early (<2 mo) and late (9-13 mo) after transplantation using computed tomography (CT) volumetry. Change in GV/SLV ratio over time was analyzed with ANOVA repeated measures. A multiple regression model was used to investigate the influence of intraoperative blood flow, recipient body size, age, and relative sickness on graft volume changes. Between the three time points, mean GV/SLV ratio adapted to 0.55-0.94-1.00 in small grafts (n = 29, P < 0.001); 0.87-1.18-1.13 in midgrafts (n = 56, P < 0.001); 1.11-1.51-1.18 in large grafts (n = 28, P < 0.001). Regression analysis showed a positive correlation between posttransplant graft growth and portal flow (β = 1.18, P = 0.005), arterial flow (β = 0.17, P = 0.001), and recipient body surface area (β = 59.85, P < 0.001). A negative correlation was observed for graft weight-to-recipient weight ratio (GRWR; β = -33.12, P < 0.001). Grafts with initial GV/SLV-ratio < 0.6 adapt toward the ideal volume for recipient body size 1 year after transplantation. The disparity between graft size relative to recipient body size, and the portal and arterial perfusion, influence volumetric graft changes.NEW & NOTEWORTHY This is the first and largest human study to verify the hypothesis that whole liver grafts adjust their size to match recipient body size 1 year after transplantation-a phenomenon that has previously only been observed in experimental animal studies and human case reports. The direction of volumetric changes is driven by the disparity between graft size relative to recipient body surface area and weight, as well as the intraoperative portal- and arterial graft perfusion.

Hepatic venous reconstruction of the left lateral segment with emphasis on anomalous hepatic vein in pediatric liver transplantation

Left lateral segment grafts have become a suitable option in pediatric liver transplantation (PLT). The correlation between hepatic vein (HV) reconstruction and outcome is relevant when assessing the safe use of these grafts. We retrospectively reviewed the medical records prospectively collected from a pediatric living donor liver transplantation database and conducted a comparative analysis of the different left lateral segment graft types according to HV reconstruction. Donor, recipient, and intraoperative variables were analyzed. Post-transplant outcomes included vascular complications such as hepatic vein outflow obstruction, early (≤30 d) and late (>30 d) PVT, hepatic artery thrombosis, and graft survival. From February 2017 to August 2021, 303 PLTs were performed. According to venous anatomy, the distribution of the left lateral segment was as follows: single HV (type I) in 174 (57.4%), close HVs, simple venoplasty for reconstruction (type II) in 97 (32.01%), anomalous hepatic vein (AHV) with a distance between the HVs orifices that allowed simple venoplasty (type IIIA) in 25 (8.26%) and AHV with a distance between the HVs orifices requiring homologous venous graft interposition (type IIIB) in 07 (2.31%) grafts. Type IIIB grafts came from male donors ( p =0.04) and had a higher mean donor height ( p =0.008), a higher mean graft weight, and a higher graft-to-recipient weight ratio, both p =0.002. The median follow-up time was 41.4 months. The overall cumulative graft survival was 96.3%, and comparative graft survival showed no difference (log-rank p =0.61). No hepatic vein outflow obstructions were observed in this cohort study. There was no statistically significant difference in the post-transplant outcomes between the graft types. The venous reconstruction of the AHV with homologous venous graft interposition had similar outcomes in the short and long term.

Liver Transplantation in Children: An Overview of Organ Allocation and Surgical Management

Liver transplantation is the standard treatment for children with end-stage liver disease, primary hepatic neoplasms, or liver-localized metabolic defects. Perioperative mortality is almost absent, and long-term survival exceeds 90%. Organ shortage is managed thanks to advances in organ retrieval techniques; living donation and partial liver transplantation almost eliminated waiting list mortality, thus leading to expanding indications for transplantation. The success of pediatric liver transplantation depends on the prompt and early referral of patients to transplant Centers and on the close and integrated multidisciplinary collaboration between pediatricians, hepatologists, surgeons, intensivists, oncologists, pathologists, coordinating nurses, psychologists, and social workers.

Serial volumetric assessment of large for size liver grafts after whole cadaveric liver transplant in adults: do large liver grafts shrink in size?

BACKGROUND

After whole graft orthotopic liver transplantation (OLT), adaptation of the large grafts' volume to recipient weight is widely accepted despite the paucity of evidence on this subject.

METHODS

Thirty nine patients with GRWR > 2.5% were included in this study and subsequently divided into two groups with 3 ≥ GRWR > 3%. Patients had CT scans at three predetermined time points after OLT used for measuring the liver volume. The objective of this study is to evaluate the volumetric changes of whole large liver grafts after adult OLT.

RESULTS

At LT, the mean graft recipient body weight ratio (GRWR) was 3.1 ± 0.4%. The mean liver weight was 1881 ± 68 g at LT, 2014 ± 99 ml at one week, 1725 ± 126 ml at 3 months, and 1632 ± 117 (ml) at >6 months. There is an initial increase at 1 week after LT and a subsequent decrease of liver volume on later measurements. None of the late volume measurements were significantly different from the initial graft volume at liver transplant in pair wise comparisons ANOVA repeated measures (p > 0.05). Similarly, the mean GRWR did not change significantly between the initial calculation at transplantation date and the subsequent measurements during the different study time points (F = 0.04, p = 0.96) with a mean of 3.1% (95% CI = 2.2-4.2). AUC ROC discriminated a cutoff of 3% for the initial GRWR above which grafts tend to decrease in size over time (c statistics = 0.74, p = 0.036). In a Clustered ANOVA repeated measures, there was no significant difference in the changes of liver volume between both groups. However, patients with GRWR > 3 showed a trend towards a latent reduction in volume over the tracing period. There was a tendency, but none significant; towards a higher bilirubin, AST, ALT levels over the first postoperative days in recipients with GRWR > 3.

CONCLUSION

Large grafts do not significantly decrease in size. Nonetheless, grafts weighing >3% of the GRWR show a different trend towards decrease in size over time.

Selection of living donor liver grafts for patients weighing 6kg or less

In the field of pediatric living donor liver transplantation (LDLT), physicians sometimes must reduce the volume of left lateral segment (LLS) grafts to prevent large-for-size syndrome. There are 2 established methods for decreasing the size of an LLS graft: the use of a segment 2 (S2) monosegment graft and the use of a reduced LLS graft. However, no procedure for selecting the proper graft type has been established. In this study, we conducted a retrospective investigation of LDLT and examined the strategy of graft selection for patients weighing ≤6 kg. LDLT was conducted 225 times between May 2001 and December 2012, and 15 of the procedures were performed in patients weighing ≤6 kg. We selected S2 monosegment grafts and reduced LLS grafts if the preoperative computed tomography (CT)-volumetry value of the LLS graft was >5% and 4% to 5% of the graft/recipient weight ratio, respectively. We used LLS grafts in 7 recipients, S2 monosegment grafts in 4 recipients, reduced S2 monosegment grafts in 3 recipients, and a reduced LLS graft in 1 recipient. The reduction rate of S2 monosegment grafts for use as LLS grafts was 48.3%. The overall recipient and graft survival rates were both 93.3%, and 1 patient died of a brain hemorrhage. Major surgical complications included hepatic artery thrombosis in 2 recipients, bilioenteric anastomotic strictures in 2 recipients, and portal vein thrombosis in 1 recipient. In conclusion, our graft selection strategy based on preoperative CT-volumetry is highly useful in patients weighing ≤6 kg. S2 monosegment grafts are effective and safe in very small infants particularly neonates.

Segment 4 architecture and proposed parenchyma-wise technique for Ex vivo graft procurement and implantation

A parenchyma-wise technique for the ex vivo procurement of segment 4 (S4) grafts, based on the detailed architecture of the segment, is proposed. Eighteen normal, fresh livers from adult cadavers were injected differentially with colored latex; dissection casts were prepared; and the intricate architecture of S4 was studied. The portal vein elements of the sheath forming most of the inferior part of S4 (S4b) and the superficial major fraction of its superior part (S4a) arose constantly from the medial aspect of the umbilical part of the left portal vein branch. The arterial elements arose constantly from a branch, whose diameter ranged from 2.00 to 3.35 mm (mean = 2.61 ± 0.54 mm) and whose length ranged from 15.15 to 45.65 mm (mean = 27.98 ± 12.13 mm). The biliary elements coalesced as a single duct at the corner, which was formed from the umbilical and transverse parts of the left portal vein branch; the duct's diameter ranged from 2.90 to 6.85 mm (mean = 3.90 ± 1.34 mm). Theoretically, this parenchymal mass-S4b and the superficial fraction of S4a-could be procured for implantation in an infant, and the rest of the liver could be split for an adult and a child. The portal vein branches of the graft would be procured with a patch from the medial aspect of the donor's umbilical portion of the left portal vein branch. This umbilical portion would be reconstructed with a patch from the donor's round ligament. The recipient's portal vein would be reconstructed through the fashioning of a conduit anastomosed with the graft's venous patch.