Remote revascularization of abdominal wall transplants using the forearm

Abdominal Wall Closure in Intestinal and Multivisceral Transplantation: A State-Of-The-Art Review of Vascularized Abdominal Wall and Nonvascularized Rectus Fascia Transplantation

Failure to close the abdomen after intestinal or multivisceral transplantation (Tx) remains a frequently occurring problem. Two attractive reconstruction methods, especially in large abdominal wall defects, are full-thickness abdominal wall vascularized composite allograft (AW-VCA) and nonvascularized rectus fascia (NVRF) Tx. This review compares surgical technique, immunology, integration, clinical experience, and indications of both techniques. In AW-VCA Tx, vascular anastomosis is required and the graft undergoes hypotrophy post-Tx. Furthermore, it has immunologic benefits and good clinical outcome. NVRF Tx is an easy technique without the need for vascular anastomosis. Moreover, a rapid integration and neovascularization occurs with excellent clinical outcome.

Acute Rejection Rates in Vascularized Composite Allografts: A Systematic Review of Case Reports

INTRODUCTION

Vascularized Composite Allografts (VCA) are usually performed in a full major histocompatibility complex mismatch setting, with a risk of acute rejection depending on factors such as the type of immunosuppression therapy and the quality of graft preservation. In this systematic review, we present the different immunosuppression protocols used in VCA and point out relationships between acute rejection rates and possible factors that might influence it.

METHODS

This systematic review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. We systematically searched Medline (PubMed), Embase, and The Cochrane Library between November 2022 and February 2023, using following Mesh Terms: Transplant, Transplantation, Hand, Face, Uterus, Penis, Abdominal Wall, Larynx, and Composite Tissue Allografts. All VCA case reports and reviews describing multiple case reports were included.

RESULTS

We discovered 211 VCA cases reported. The preferred treatment was a combination of antithymocyte globulins, mycophenolate mofetil (MMF), tacrolimus, and steroids; and a combination of MMF, tacrolimus, and steroids for induction and maintenance treatment, respectively. Burn patients showed a higher acute rejection rate (P = 0.073) and were administered higher MMF doses (P = 0.020).

CONCLUSIONS

In contrast to previous statements, the field of VCA is not rapidly evolving, as it has encountered challenges in addressing immune-related concerns. This is highlighted by the absence of a standardized immunosuppression regimen. Consequently, more substantial data are required to draw more conclusive results regarding the immunogenicity of VCAs and the potential superiority of one immunosuppressive treatment over another. Future efforts should be made to report the VCA surgeries comprehensively, and muti-institutional long-term prospective follow-up studies should be performed to compare the number of acute rejections with influencing factors.

Closing the abdomen: update on the current surgical toolkit

PURPOSE OF REVIEW

Achieving abdominal wall closure after intestinal transplantation (ITx) is one of the crucial surgical challenges. This problem is present in 25-50% of all transplants due to reduction in abdominal domain, fistulae and extensive adhesions due to previous surgeries. Failure to achieve closure is an independent risk factor for mortality and graft loss. The aim of this paper is to summarize the current options to achieve this.

RECENT FINDINGS

Successful closure of the abdomen requires a tension-free repair. Primary closure of the fascia can be reinforced with synthetic or biological mesh. For more complex fascial defects bridging mesh, nonvascularised or vascularised rectus fascia can be utilised. If all components of the abdominal wall are affected, then a full-thickness abdominal wall transplantation may be necessary.

SUMMARY

A variety of successful techniques have been described by different groups to enable abdominal wall closure after ITx. Emerging developments in preoperative imaging, reconstructive surgery and immunology have expanded the surgical toolkit available. Crucial is a tailor-made approach whereby patients with expected closure issues are identified prior to surgery and the simplest technique is chosen.

Abdominal Wall Vascularized Composite Allotransplantation: A Scoping Review

BACKGROUND

 Abdominal wall vascularized composite allotransplantation (AW-VCA) is a novel reconstructive technique used for large abdominal wall defects in combination with intestinal transplantation (ITx) or multivisceral abdominal transplantation (MVTx). Since the introduction of this procedure, several studies have been published reporting their experience. This study aims to present a scoping review looking at all available evidence-based medicine information to understand the most current surgical techniques and clinical outcomes.

METHODS

 This scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) extension for scoping reviews checklist. A comprehensive research strategy of several databases was conducted.

RESULTS

 A total of 31 studies were included in this review, which comprised animal, cadaveric, and human studies. In human studies, four surgical techniques with high flap survival rates and low complication rates were found. In cadaveric studies, it was shown that the use of iliofemoral cuff-based flaps provided adequate tissue perfusion to the abdominal wall graft. Also, the use of thoracolumbar nerves have been described to provide functionality to the AW-VCA and prevent long-term muscle atrophy.

CONCLUSION

 AW-VCA is a safe and efficient alternative for patients with large and complex abdominal wall defects. The future holds a promising evolution of a functional AW-VCA, though surgeons must face and overcome the challenge of distorted anatomy frequently present in this population. Forthcoming studies with a better level of evidence are required to evaluate functionality and differences between surgical techniques.

Abdominal Wall Transplantation: Indications and Outcomes

Purpose of Review

This article aims to review published outcomes associated with full-thickness vascularized abdominal wall transplantation, with particular emphasis on advances in the field in the last 3 years.

Recent Findings

Forty-six full-thickness vascularized abdominal wall transplants have been performed in 44 patients worldwide. Approximately 35% of abdominal wall transplant recipients will experience at least one episode of acute rejection in the first year after transplant, compared with rejection rates of 87.8% and 72.7% for hand and face transplant respectively. Recent evidence suggests that combining a skin containing abdominal wall transplant with an intestinal transplant does not appear to increase sensitization or de novo donor-specific antibody formation.

Summary

Published data suggests that abdominal wall transplantation is an effective safe solution to achieve primary closure of the abdomen after intestinal or multivisceral transplant. However, better data is needed to confirm observations made and to determine long-term outcomes, requiring standardized data collection and reporting and collaboration between the small number of active transplant centres around the world.

Synchronous Abdominal Wall and Small-bowel Transplantation: A 1-year Follow-up

Abdominal wall-vascularized composite allotransplantation (AW-VCA) has evolved as a technically feasible but challenging option in the rare event of abdominal wall reconstruction in patients whose abdomen cannot be closed by applying conventional methods. The authors conducted the first synchronous child-to-adult recipient AW-VCA using an arteriovenous loop technique. This article presents a 1-year follow-up of the patient's postoperative course. Frequent skin biopsies were performed in accordance with Duke Institutional Review Board protocol, with 3 episodes of rejection treated with high-dose steroids and Thymoglobulin (Genzyme Corp, Cambridge, Mass.). The patient developed an opportunistic fungal brain abscess secondary to immunosuppression, which led to temporary upper extremity weakness. Future considerations for AW-VCA include a modified surgical technique involving utilization of donor vein graft for arteriovenous loop formation. In addition, reduction in postoperative biopsy schedule and changes in immunosuppression regimen may lead to improved outcomes and prevent unnecessary high-dose immunosuppression.

The difficult abdominal closure after paediatric intestinal transplantation: Use of abdominal rectus muscle fascia and literature review

Primary abdominal wall closure after intestinal and multivisceral transplantation may not be possible because of loss of abdominal domain and/or graft size/abdominal cavity mismatch. Traditional closure techniques for the open abdomen may not be valid in these circumstances because of severe scarring of the abdominal wall from multiple previous surgeries in this particular group of patients. We present our initial experience with the use of non-vascularized abdominal rectus muscle fascia in two patients who underwent deceased donation and living-related combined liver and small bowel transplantation, respectively, and who could not be closed primarily. The donor fascia was attached to the recipient fascia in both patients. In either case, there was not enough skin cover for closure, the wound was left open, and a negative pressure dressing was applied. In both cases, over a period of 6 months after placement of the non-vascularized abdominal rectus muscle fascia, the wound contracted, granulation tissue gradually covered the wound, and healing occurred, giving an intact abdominal wall. The abdominal rectus muscle fascia from a deceased donor can be used in a definite procedure for closure of the abdominal wall either at the time of transplant or later when a suitable rectus muscle fascia graft becomes available.

Small bowel and abdominal wall transplantation: A novel technique for synchronous revascularization

Abdominal wall transplantation (AWT) was introduced in 1999 in the context of reconstruction of complex abdominal wall defects in conjunction with visceral organ transplantation. As of recently, 38 cases of total AWT have been performed worldwide, about half of which were performed in the United States. While AWT is technically feasible, one of the major challenges presenting to the reconstructive surgeon is time to revascularization of the donor abdominal wall (AW), given the immediate proximity of the visceral organ and AWT. The authors report a novel AW revascularization technique during a synchronous small bowel and AWT in a 37-year-old man.

Abdominal wall allotransplantation

Allotransplantation of vascularized composite tissue is a new field of transplantation surgery. One application of this technique is abdominal wall transplantation used as a supplementary procedure to the transplantation of visceral organs in patients with abdominal compartment deficits. As abdominal wall closure problems are experienced in around 30-40% of such patients, peer reviewed conclusions on the viability of various options, are important for an informed choice of possible procedures. This review focuses on the abdominal wall allotransplantion procedure. Our search provided 35 appropriate references which we used to support our findings as follows: abdominal wall transplantation was performed in 33 patients at seven centres. Of these, 30 had a full thickness abdominal wall transplanted from the same donor, 3 from a second donor. Three had visceral organ transplants and in addition, the posterior sheet of the rectus muscle fascia. In summary, our findings were that abdominal wall allotransplantation does not jeopardize the outcome of visceral organs transplantation. There is no higher risk of complications or rejection of the visceral organs. There have been no fatalities as a direct result of complications due to abdominal wall transplantation. Finally, the transplanted abdominal wall may provide an early warning of rejection before diagnostic tests on the bowel are symptomatic.

Innovations in reconstructive microsurgery: Reconstructive transplantation

In the past 20 years, reconstructive transplantation (RT) has emerged as a viable reconstructive option for carefully selected patients. More than 100 upper extremity and 40 face transplants have been performed worldwide to date. Concomitantly, the portfolio of reconstructive transplantation has been extended by additional procedures such as lower extremities, abdominal wall, neck, uterus, genitourinary, and pediatric transplants. In the present review article, we aim to summarize the current state of knowledge about this exciting field.

Small-for-size Syndrome Does Not Occur in Intestinal Transplantation Without Liver Containing Grafts

BACKGROUND

The ideal donor in intestinal transplantation (ITX) is generally considered to be 50% to 70% of recipient body weight. This may be due to concerns for "small for size" syndrome as seen in liver transplantation. We report our experience using smaller donors (donor-recipient weight ratio [DRWR], < 50%) in ITX recipients.

METHODS

We studied a group of ITX recipients with DRWR of 50% or less to unmatched controls who received intestinal allografts with DRWR greater than 50%. We examined patient and graft survival and enteral autonomy from parenteral nutrition as surrogate markers for safety of using smaller donors and ease of abdominal wall closure between groups to determine the value.

RESULTS

There was no difference in overall patient and graft survival, time to enteral autonomy from parenteral nutrition, and weight gain after ITX over time between groups. The need for complicated abdominal closure techniques was significantly more frequent in the control group than in the study group (34.6% vs 6.9%, P = 0.01). Secondary abdominal closure occurred more frequently in the control group (15.4% vs 0%, P = 0.014). Wound revisions also occurred more frequently in the control group (15.4% vs 0%, P = 0.028).

CONCLUSIONS

Our data suggest that ITX using smaller donors (DRWR ≤ 50%) seems to be an acceptable practice without adverse impact on surgical complications, nutritional autonomy, and patient and graft survival. Abdominal wall closure seems easier in recipients of smaller donors and "small for size" syndrome as described in liver transplantation does not occur with intestinal allografts.

The abdominal wall transplant as a sentinel skin graft

PURPOSE OF REVIEW

Abdominal wall transplantation is a technique used to achieve abdominal closure after intestinal and multivisceral transplantation. This review focuses on whether there are additional benefits for the skin component as an immune-monitoring tool.

RECENT FINDINGS

The largest series of abdominal wall transplants has recently been published. Alongside the physiological advantage gained in abdominal closure, the authors describe the immunological insight that the skin component can provide and how this contributes to the management of patients. The skin appears to develop a rash with early rejection, which facilitates early systemic treatment before significant visceral rejection occurs. It can also help in cases in which there is diagnostic doubt regarding the cause of bowel dysfunction such as in instances of intestinal infection. Despite the additional immunological burden of donor tissue, there appears to be no requirement for increased immunosuppressive therapy.

SUMMARY

The technical and immunological feasibility of abdominal wall transplantation has now been demonstrated by several centres. Skin transplanted as part of the abdominal wall or as a separate vascularized sentinel skin flap may aid in the diagnosis of rejection. This has the potential to improve graft survival and reduce immunosuppressive morbidity.

Role of “reduced-size” liver/bowel grafts in the “abdominal wall transplantation” era

The evolution of multi-visceral and isolated intestinal transplant techniques over the last 3 decades has highlighted the technical challenges related to the closure of the abdomen at the end of the procedure. Two key factors that contribute to this challenge include: (1) Volume/edema of donor graft; and (2) loss of abdominal domain in the recipient. Not being able to close the abdominal wall leads to a variety of complications and morbidity that range from complex ventral hernias to bowel perforation. At the end of the 90’s this challenge was overcome by graft reduction during the donor operation or bench table procedure (especially reducing liver and small intestine), as well as techniques to increase the volume of abdominal cavity by pre-operative expansion devices. Recent reports from a few groups have demonstrated the ability of transplanting a full-thickness, vascularized abdominal wall from the same donor. Thus, a spectrum of techniques have co-evolved with multi-visceral and intestinal transplantation, ranging from graft reduction to enlarging the volume of the abdominal cavity. None of these techniques are free from complications, however in large-volume centers the combinations of both (graft reduction and abdominal widening, sometimes used in the same patient) could decrease the adverse events related to recipient’s closure, allowing a faster recovery. The quest for a solution to this unique challenge has led to the proposal and implementation of innovative solutions to enlarge the abdominal cavity.

Current state of abdominal wall transplantation

PURPOSE OF REVIEW

Primary closure of the abdominal wall remains one of the early challenges of intestinal transplantation. Our aim is to review the role of abdominal wall transplantation in achieving tension-free closure of the abdomen.

RECENT FINDINGS

In total, 38 full-thickness vascularized abdominal wall transplants, six partial-thickness vascularized and 17 partial-thickness nonvascularized rectus facia grafts have been reported worldwide. Different techniques have been described. The most popular choice seems to be the full-thickness vascularized abdominal wall allograft, where the anastomosis is performed either in a micro- or macrovascular fashion. Temporary 'remote' revascularisation of the allograft has been performed in some cases onto the recipient's forearm vessels when there is a long anticipated cold ischaemia time (>5 h). Preliminary data suggest that the abdominal wall skin rejection might be an early predictor of intestinal rejection. Vascularized and nonvascularized rectus fascia may be effective when there is inadequate healthy muscle/fascia but sufficient skin cover.

SUMMARY

Several centres have already proved the technical and immunologic feasibility of partial or full-thickness abdominal wall transplantation. It is an effective option to achieve primary abdominal closure following intestinal transplantation and in its full-thickness form, it may be useful for monitoring rejection in visceral organs.

Abdominal Wall Transplantation: Skin as a Sentinel Marker for Rejection

Abdominal wall transplantation (AWTX) has revolutionized difficult abdominal closure after intestinal transplantation (ITX). More important, the skin of the transplanted abdominal wall (AW) may serve as an immunological tool for differential diagnosis of bowel dysfunction after transplant. Between August 2008 and October 2014, 29 small bowel transplantations were performed in 28 patients (16 male, 12 female; aged 41 ± 13 years). Two groups were identified: the solid organ transplant (SOT) group (n = 15; 12 ITX and 3 modified multivisceral transplantation [MMVTX]) and the SOT-AWTX group (n = 14; 12 ITX and 2 MMVTX), with the latter including one ITX-AWTX retransplantation. Two doses of alemtuzumab were used for induction (30 mg, 6 and 24 h after reperfusion), and tacrolimus (trough levels 8-12 ng/mL) was used for maintenance immunosuppression. Patient survival was similar in both groups (67% vs. 61%); however, the SOT-AWTX group showed faster posttransplant recovery, better intestinal graft survival (79% vs. 60%), a lower intestinal rejection rate (7% vs. 27%) and a lower rate of misdiagnoses in which viral infection was mistaken and treated as rejection (14% vs. 33%). The skin component of the AW may serve as an immune modulator and sentinel marker for immunological activity in the host. This can be a vital tool for timely prevention of intestinal graft rejection and, more important, avoidance of overimmunosuppression in cases of bowel dysfunction not related to graft rejection.

Vascularized composite allograft-specific characteristics of immune responses

Vascularized composite allograft (VCA) transplantation, or reconstructive transplantation, has revolutionized the treatment of complex tissue and functional defects. Despite arriving during an age in which the immunology of solid organ transplant rejection has been investigated in much detail, these transplants have offered new perspectives from which to explore the immunobiology of transplantation. VCAs have a number of unique molecular, cellular, and architectural features which alter the character and intensity of the rejection response. While much is yet to be clarified, an understanding of these distinct mechanisms affords new possibilities for the control of immune responses in an effort to improve outcomes after VCA transplantation.

Reconstruction of Large Abdominal Wall Defects Using Neurotized Vascular Composite Allografts

BACKGROUND

Abdominal wall vascularized composite allotransplantation is the second most common form of vascularized composite allotransplantation. Sensory and functional recovery are expected in other forms but have never been demonstrated in abdominal wall vascularized composite allotransplantation. The authors hypothesize that coaptation of two thoracolumbar nerves will result in reinnervation of the alloflap and maintenance of the muscle component.

METHODS

Adult, male, 10-week-old Brown Norway and Lewis rats were used for experiments. The rat donor's common iliac vessels were anastomosed to the recipient's femoral vessels. Intercostal nerves T10/L1 were coapted. Four groups (n = 5 per group) were included for study: group 1, Lewis, intercostal nerves cut, not repaired; group 2, Lewis intercostal nerves cut, T10/L1 repaired; group 3, allogeneic Brown Norway-to-Lewis abdominal wall vascularized composite allotransplantation, T10/L1 repaired; and group 4, syngeneic Lewis-to-Lewis abdominal wall vascularized composite allotransplantation, T10/L1 repaired. Animals were killed on postoperative day 60. Nerve regeneration was assessed using muscle weight analysis, myofibril cross-sectional area, nerve histomorphometry, and neuromuscular junction percentage reinnervation.

RESULTS

Groups 2, 3, and 4 maintained a significantly greater percentage of postharvest weight compared with group 1 (p < 0.05). Group 1 had significantly decreased myofibril cross-sectional area compared with controls (p < 0.05). There was no significant difference in myofibril cross-sectional area in groups 2 through 4 compared with controls (p > 0.05). Group 1 had significantly decreased percentage reinnervation of the alloflap compared with controls (p < 0.05). There was no significant difference when comparing group 2 through 4 with internal, contralateral controls (p > 0.05).

CONCLUSION

In a murine model for abdominal wall vascularized composite allotransplantation, coaptation of T10/L1 will allow for reinnervation of the alloflap and maintenance of the muscle component.

Procurement strategies for combined multiorgan and composite tissues for transplantation

PURPOSE OF REVIEW

The purpose of this article is to identify the unique aspects of combined multiorgan and vascularized composite allograft (VCA) procurement from deceased donors and outline the steps essential for success.

RECENT FINDINGS

Transplantation of nonsolid organ composite tissues is becoming a viable option for reconstruction of massive tissue defects. With the United Network for Organ Sharing designation of VCAs as organs, placing them under the domain of the Organ Procurement and Transplantation Network, a systematic method for combined solid organ and VCA procurement is required. Several centers have reported experience with successful procurement strategies including sequential and simultaneous retrievals. The published literature describing donor screening, sequence of procurement with relation to solid organs and allocation is reviewed.

SUMMARY

With the 2013 classification of VCAs as organs, the Organ Procurement and Transplantation Network and United Network for Organ Sharing are better suited to aligning procurement and allocation policies. As VCA transplantation becomes more commonplace, protocol guidelines will ensure smooth integration with existing procurement infrastructure.