Long-Term Patency of Hemashield Vascular Grafts Used for Middle Hepatic Vein Reconstruction During Living-Donor Liver Transplantation: A Single-Center Korean Experience

Introduction

Middle hepatic vein (MHV) reconstruction using vascular graft interposition has become a standard practice during living-donor liver transplantation (LDLT) with modified right-liver grafts. While large-caliber vein allografts from deceased donors are considered the gold standard for MHV reconstruction, their limited supply remains a major constraint. As an alternative, prosthetic vascular grafts demonstrate comparable patency rates, offering a practical substitute. Various synthetic grafts are available; therefore, careful selection is essential for optimizing the surgical outcomes. Previously, we reported that Hemashield vascular grafts had short-term patency rates comparable to those of ringed expanded polytetrafluoroethylene (ePTFE); however, long-term performance was less favorable. This underscores the need for further evaluation of Hemashield graft durability. Accordingly, the present study aimed to assess the long-term patency of MHV reconstructions using Hemashield grafts, as well as their impact on patient survival following LDLT.

Material and Methods

STUDY DESIGN:

This retrospective observational study evaluated the patency of MHV reconstruction, as well as patient survival after adult LDLT, specifically utilizing Hemashield graft interposition for MHV reconstruction.

PATIENT SELECTION:

The institutional liver transplantation (LT) database was reviewed to identify adult recipients who underwent primary LDLT between January 2018 and December 2022. The inclusion criteria were limited to patients who received Hemashield grafts for MHV reconstruction. To ensure homogeneity, re-transplantation cases and dual-donor LDLT recipients were excluded. Additionally, only Korean citizens were included to enable consistent long-term follow-up. In total, 149 patients met the eligibility criteria and were included in the final analysis.

The medical records and imaging studies of all eligible patients were retrospectively reviewed. Follow-up data were obtained until September 2024 or until patient death, using both institutional records and data from the National Health Insurance Service. The study protocol was approved by the Institutional Review Board (IRB No. S2025-1547). The requirement for informed consent was waived owing to the retrospective nature of the study. All procedures were performed in accordance with the ethical principles of the Declaration of Helsinki, as revised in 2013.

SELECTION OF PROSTHETIC VASCULAR GRAFTS AND SURGICAL TECHNIQUES FOR MHV RECONSTRUCTION:

Following the establishment of standardized techniques for MHV reconstruction, MHV tributaries measuring ≥5 mm in diameter, including segments V (V5) and VIII (V8) veins, were reconstructed routinely. The criteria for MHV reconstruction are described in previous publications [1–8]. MHV interposition was performed using Hemashield vascular grafts measuring 10 mm or 12 mm. The surgical methods used for MHV reconstruction with Hemashield grafts have been described previously [8].

EVALUATION OF MHV-INTERPOSED HEMASHIELD GRAFT PATENCY, AND INDICATIONS FOR INTERVENTIONAL STENTING:

Dynamic computed tomography (CT) was performed weekly during the initial hospitalization period, followed by imaging at 3- to 6-month intervals during outpatient visits for the first 3 years. Thereafter, annual CT scans were conducted for up to 5 years after transplant and biannually thereafter. Imaging studies were performed more frequently based on the clinical necessity for patients with hepatocellular carcinoma (HCC) [9–11].

MHV conduit occlusion was defined as the absence of detectable blood flow within the Hemashield graft between V8 or V5 (when only V5 was reconstructed) and the inferior vena cava (IVC) on liver dynamic CT. When CT was contraindicated because of renal dysfunction, liver magnetic resonance imaging (MRI) or Doppler ultrasonography was used as an alternative.

Interventional stenting of a thrombosed MHV conduit was considered when significant perfusion abnormalities were identified in the graft liver [12,13]. Regardless of the post-stenting patency, the need for conduit stenting was classified as evidence of graft occlusion.

STATISTICAL ANALYSIS:

Quantitative variables were expressed as either medians with ranges or means with standard deviations, according to the data distribution. Survival outcomes, including recurrence and overall survival, were evaluated using the Kaplan-Meier method, and intergroup comparisons were conducted using the log-rank test. A P value <0.05 was considered indicative of statistical significance. Analyses were performed using SPSS version 22 (IBM Corp., Armonk, NY, USA) and MedCalc (version 23.2.1; MedCalc Software Ltd., Ostend, Belgium).

Results

PATIENT PROFILES:

Table 1 summarizes the clinical characteristics of the 149 recipients who underwent LDLT using modified right liver grafts with MHV reconstruction using Hemashield vascular grafts. The mean recipient age was 56.2±7.7 years. Hepatitis B virus (HBV) infection was the predominant etiology (76 patients; 51.0%). The mean Model for End-Stage Liver Disease (MELD) score at transplantation was 15.2±8.6. ABO-incompatible LDLT was performed in 37 patients (24.8%). The mean graft-to-recipient weight ratio was 1.06±0.25.

CONFIGURATIONS OF MHV RECONSTRUCTION USING HEMASHIELD VASCULAR GRAFTS:

V5 reconstruction was achieved using a single anastomosis, occasionally incorporating unification venoplasty, in 111 patients (74.5%), whereas 32 (21.5%) and 2 (1.3%) patients underwent double and triple anastomoses, respectively (Table 2). Similarly, V8 reconstruction involved a single anastomosis in 116 cases (77.9%, including those with unification venoplasty), double anastomoses in 20 (13.4%), and triple anastomoses in 1 (0.7%). The Hemashield grafts used had an internal diameter of 10 mm (100 patients; 67.1%) or 12 mm (49 patients; 32.9%).

SEQUENCES OF HEMASHIELD GRAFT CONDUIT OCCLUSION:

Serial follow-up CT scans revealed that occlusion within the Hemashield vascular grafts typically began near the V5 anastomotic site. A gradual decline in V5 outflow was observed, accompanied by progressive concentric thrombus formation within the graft lumen. As a result, the original wide conduit, measuring 10 mm or 12 mm of the internal diameter, narrowed progressively, resulting in a significant reduction in the inner caliber. Subsequently, complete luminal occlusion developed in the segment of the graft between the V5 and V8 orifices. In contrast to V5, V8 outflow tended to persist longer. These sequential changes leading to MHV conduit occlusion following Hemashield graft placement were presented in Figure 1.

LONG-TERM PATENCY OF HEMASHIELD GRAFT CONDUITS:

Over the post-transplant follow-up period of up to 74 months, luminal occlusion of the Hemashield graft conduits was identified in 76 patients (51.0%).

Early thrombosis of the MHV conduit occurred in 3 patients (2.0%) on post-transplant days 1, 3, and 18, respectively. In all 3 cases, severe anastomotic stenosis at the junction between the Hemashield graft and the IVC was determined to be the underlying cause. Endovascular stenting re-established conduit patency in these patients (Figure 2).

The cumulative rates of freedom from Hemashield graft conduit occlusion were 81.0% at 3 months, 65.8% at 6 months, 57.9% at 12 months, 48.7% at 3 years, and 43.8% at 5 years (Figure 3). Notably, MHV conduit occlusion occurring beyond the first postoperative month did not result in clinically significant hepatic venous congestion in the modified right liver grafts.

PATENT SURVIVAL:

During the follow-up period of up to 74 months after transplantation, 22 patients (14.8%) died. The causes of death included HCC recurrence (n=9), pneumonia (n=5), alcohol relapse-associated graft failure (n=1), brain hemorrhage (n=1), de novo pancreas cancer (n=1), and an unidentified cause (n=5). The Hemashield graft conduit was occluded in 8 of these 22 patients at the last imaging study prior to death, but no patient showed graft dysfunction associated with occlusion of the Hemashield graft conduit. None of the patients underwent re-transplantation. The overall survival rates were 97.3% at 6 months, 95.3% at 1 year, 89.1% at 3 years, and 85.7% at 5 years (Figure 4).

COMPLICATIONS ASSOCIATED WITH THE HEMASHIELD VASCULAR GRAFT:

No accidental migration of the Hemashield graft conduit into the adjacent visceral organs, or Hemashield graft-related infections, were observed during a mean follow-up period of 56.3±6.5 months.

Discussion

MHV reconstruction with a modified right liver graft during LDLT increases recipient survival rates while minimizing donor-related risk. Since MHV reconstruction has become a routine practice for adult LDLT at our institution, the demand for large-caliber vein allografts has increased markedly. However, the limited number of deceased organ and tissue donors in Korea means that there is a significant shortage of these allografts. By contrast, prosthetic vascular grafts are not subject to supply constraints and are readily available. Ringed ePTFE grafts, previously used in our practice, demonstrate satisfactory long-term patency [5,8] and were the preferred choice when vein allografts were unavailable. However, following discontinued production of ringed Gore-Tex grafts, we adopted Hemashield grafts as the primary alternative [6–8]. During the study period of this study, homologous vascular grafts including cryopreserved iliac vein and aorta grafts were also used for MHV reconstruction [14].

Hemashield grafts bear a close resemblance to ringed ePTFE grafts in terms of their structure, featuring circular pleats that resist external compression and prevent collapse. Flexible, woven, double-velour polyesters are easy to handle and suture. The pleated design allows for longitudinal adjustment during anastomosis, thereby accommodating graft remodeling. Impregnation with bovine collagen reduces needle-hole bleeding and early thrombus formation, thus allowing the use of standard Prolene sutures. A colored alignment stripe assists in proper positioning. The diameter (10 or 12 mm) and length (25 cm) of Hemashield Platinum grafts makes them well-suited for use as MHV conduits [8].

This study demonstrated that Hemashield grafts maintain favorable long-term patency rates that are comparable to those of ringed ePTFE grafts [6,8]. To the best of our knowledge, this is the first report to provide real-world data on the long-term performance of Hemashield grafts used for MHV reconstruction. Several factors likely contribute to their high patency rate, including their wide internal diameter, compression-resistant pleated design, and use of a bridging allograft patch to mitigate tissue reactivity, coupled with a low-thrombogenic, bovine collagen-impregnated lumen that promotes gradual formation of an endothelialized internal channel within the thrombus [5–8].

No routine thromboprophylaxis protocol was implemented for patients undergoing MHV reconstruction with Hemashield grafts, as the gradual occlusion of the reconstructed conduit is typically offset by the development of intrahepatic collateral venous pathways [15]. When intraluminal stent placement within the MHV graft was performed, anticoagulation with warfarin over 1 year was instituted only in cases where substantial hepatic venous congestion attributable to MHV deprivation was anticipated.

Accidental migration of ePTFE grafts into hollow viscera such as the stomach or duodenum has been reported, and can lead to life-threatening complications, necessitating surgical removal [8,16–19]. When thrombosed, the ringed ePTFE grafts often become rigid and retain their tubular shape, thereby increasing the risk of accidental migration. Previously, we reported a 5-year migration rate of 1.6% [6], which is consistent with a Taiwanese study that reported 1.5% [18]. A study from Turkey documented 13 instances of prosthetic graft migration involving 10 ePTFE grafts and 3 polyethylene terephthalate (Dacron) grafts. Of these cases, 7 grafts were retrieved via endoscopy, while 6 required surgical removal [20].

In contrast, there were no cases of Hemashield graft migration in the present study. Morphological analysis revealed that thrombosed Hemashield grafts tended to collapse into a flattened shape, unlike the persistent rigidity seen with ringed ePTFE grafts. This structural difference may explain the lower risk of erosion of adjacent organs. Overall, our findings suggest that Hemashield grafts is preferable for MHV reconstruction, given their comparable patency and lower complication rates. However, the inadvertent migration of Dacron grafts suggests that similar incidents could occur during LDLT procedures using Hemashield grafts, as Hemashield grafts are derived from Dacron vascular materials [20].

This study had some limitations. First, it was a single-center study, which may have contributed to selection bias. Moreover, despite the extended follow-up period, it may still be insufficient to fully capture lifelong complications related to Hemashield grafts.

Conclusions

MHV reconstruction using Hemashield vascular grafts demonstrated acceptable short-term and long-term patency, with no incidences of migration or infection. These findings support the use of Hemashield vascular graft as a reliable and effective prosthetic option for MHV reconstruction during LDLT.