Use of Vascularized Posterior Rectus Sheath Allograft in Pediatric Multivisceral Transplantation—Report of Two Cases

Authors


Kadiyala V. Ravindra, kadiyala.ravindra@duke.edu

Abstract

Restoring abdominal wall cover and contour in children undergoing bowel and multivisceral transplantation is often challenging due to discrepancy in size between donor and recipient, poor musculature related to birth defects and loss of abdominal wall integrity from multiple surgeries. A recent innovation is the use of vascularized posterior rectus sheath to enable closure of abdomen. We describe the application of this technique in two pediatric multivisceral transplant recipients—one to buttress a lax abdominal wall in a 22-month-old child with megacystis microcolon intestinal hypoperistalsis syndrome and another to accommodate transplanted viscera in a 10-month child with short bowel secondary to gastoschisis and loss of domain. This is the first successful report of this procedure with long-term survival. The procedure has potential application to facilitate difficult abdominal closure in both adults and pediatric liver and multivisceral transplantation.

Abbreviations: 
HFA

hepatic falciform artery

MMIHS

megacystis-microcolon-intestinal hypoperistalsis syndrome

TPN

total parenteral nutrition

Introduction

Abdominal wall closure is often a challenge in pediatric liver and multivisceral transplantation due to congenital anomalies (e.g. gastroschisis), multiple previous laparotomies, presence of enterocutaneous fistula and size discrepancy between the graft and recipient abdominal cavity. Loss of abdominal domain is common following previous bowel resection and impacts donor selection.

Different techniques have been described to address this unique problem. Loss of domain has been addressed by utilizing smaller grafts (1) or reducing the size of grafts (2). Enlarging the abdominal domain or replacing the damaged or absent abdominal wall is more difficult. Delayed closure (3), closure with mesh or acellular dermal matrix (4), use of flaps (5), donor abdominal rectus fascia as nonvascularized allograft (6) and abdominal wall transplantation (7) have been successfully utilized. The results with these techniques have been encouraging but a high incidence of wound complications in some reports (6) has raised concerns.

Recently, a novel method of using the posterior rectus fascia as a vascularized composite tissue allograft has been described in a pediatric recipient of liver and kidney allografts (8). This technique involves retaining the posterior rectus sheath above the umbilicus attached to the liver by the falciform ligament. The falciform ligament runs from the liver to the umbilicus inferiorly and often carries an arterial branch called the hepatic falciform artery (HFA; Ref. 9). This branch arises from the hepatic artery (most often the left hepatic) and provides some blood flow to the posterior rectus sheath. This forms the anatomical basis for the use of the posterior rectus fascia as a vascularized composite allograft when done in conjunction with a liver graft.

The option of using the vascularized posterior rectus sheath from the donor for these two recipients was considered after personal communication with the senior author (Gottlieb LJ) before the only publication to date (8). As the concept was novel, we performed a human cadaver study in the fresh tissue laboratory to practice the technical performance of procurement of the rectus fascia and to confirm the anatomical basis for vascular supply of the posterior rectus sheath from the falciform ligament. This technique was then successfully applied in our patients. This paper details our experience.

Materials and Methods

Donor procedure

A bilateral subcostal incision was made and the rectus muscle was detached from the costal margin. A midline skin incision was then made from the xiphisternum to the pubic symphysis but the linea alba was left intact. The anterior rectus fascia was incised 1 cm lateral to the midline from the subcostal area to below the umbilicus, thus exposing the rectus muscle. Flaps, including the skin, anterior rectus sheath and the rectus muscle were raised bilaterally and extended beyond the lateral margin of the rectus sheath. This resulted in separation of the posterior rectus fascia from the overlying muscles. An incision was then made laterally in the transversus musculo-aponeurosis beyond the rectus sheath on both sides. The posterior rectus fascia was then incised about an inch inferior to the umbilicus joining the two sides. This step completed the separation of the posterior rectus fascia from the abdominal wall and maintained its continuity with the liver through the falciform ligament (Figure 1). The multivisceral graft was then procured as per standard protocol with a long segment of aorta (10). The Omaha technique is our preferred method of multivisceral transplant—the only difference being the inclusion of the entire pancreas instead of only the head as initially described (10).

Figure 1.

Procurement of the vascularized posterior rectus with the liver (arrow shows the falciform ligament attached to the liver; arrowhead demonstrated the posterior rectus).

Case Reports

Patient 1

A 22-month-old Hispanic male with intestinal failure from dysmotility and resulting total parenteral nutrition (TPN) induced cholestasis was evaluated for multivisceral transplantation. As a neonate, he had been diagnosed with megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS). Shortly after birth, he was also found to have intestinal malrotation and underwent a Ladd's procedure. During this procedure, he was found to have a microcolon, and later developed an intolerance of enteral feeds from a hypo-peristaltic bowel. In addition, he had a very lax abdominal wall contributing to poor truncal strength and delayed physical development, bilateral undescended testis and urinary tract abnormalities requiring placement of a vesicostomy. He had complications of TPN including multiple bacterial and fungal line infections, development of left subclavian vein thrombosis and TPN associated liver disease. A liver biopsy performed at 20 months of age demonstrated bridging fibrosis.

The child was listed to receive a multivisceral graft (combined liver with small bowel and pancreas). Consideration for underlay buttressing of the lax abdominal wall was made in light of concerns that the native abdominal wall may not allow for formation of an ostomy without prolapse and anticipated difficulties with application of the ostomy appliance due to the contour. In addition, the patient had poor physical development believed in part due to severe and disproportionate weakness of the abdominal musculature. Hence, we considered the option of using vascularized donor rectus sheath as an underlay graft to improve abdominal contour. A suitable deceased donor was identified and the posterior rectus fascia was procured along with the donor organs as described above.

Recipient procedure

The multivisceral graft consisting of liver, pancreas and small bowel with the attached vascularized falciform-posterior rectus sheath complex was implanted as previously described (11). Arterial inflow was restored with anastomosis of the donor thoracic aorta to the infrarenal aorta. The liver, bowel and pancreas along with the attached rectus fascia appeared well vascularized. With the abdomen open, intra-operative inspection of the abdominal wall revealed considerably more tone and better developed abdominal musculature to the left of the midline in comparison to the right side. In light of this, the terminal ileostomy was brought out in the left mid-abdomen without traversing the rectus graft. The rectus fascia was utilized as underlay reinforcement to the thin abdominal fascia in the right abdomen using 4-’0’ Prolene suture. The native atrophic abdominal wall was closed in standard fashion over the donor underlay graft.

Result

The postoperative period was uneventful and the child was transitioned to full enteral nutrition in 4 weeks. The surgical site healed and the protuberance of the abdominal wall was considerably less evident than before and the improved contour was maintained at 1 year. Moderate acute cellular rejection of the bowel (postoperative day 17) was successfully treated with intravenous steroid pulse. During the follow up of 16 months, there have been no other major clinical events. No reoperations, radiologic imaging or biopsies to evaluate specifically the rectus fascial graft were performed in the absence of any symptoms.

Patient 2

A 10-month-old girl with intestinal failure secondary to short bowel syndrome from gastroschisis was evaluated for transplantation. The child had severe TPN induced cholestasis and was listed for a liver, small bowel and pancreas transplant. The child had reduced abdominal domain due to neonatal resection of almost the entire small bowel leaving only the duodenum as an end ostomy. She weighed 6 kg and was 62 cm tall.

Recipient procedure

A 7-month-old donor who was of similar size (5.9 kg and 61 cm) as the recipient was identified. The donor posterior rectus fascia was procured in continuity with the liver of this multivisceral graft, in anticipation of potential difficulty with abdominal closure. After revascularization of the multivisceral graft, there was a large defect that could not be bridged. The vascularized donor rectus fascia was used to bridge the defect on the left side. Given the large size of the defect, the fascia proved inadequate to cover the entire defect without tension, so a piece of Goretex dual mesh was utilized to achieve cover of the right lobe of the liver on the right side of the incision (Figure 2).

Figure 2.

Surgical wound on postop day 2. Well vascularized donor rectus sheath covers the left 2/3 of wound and the Goretex mesh is seen in the right 1/3.

Result

In the early postoperative period, the patient underwent reoperation twice (days 3 and 8) to imbricate the donor rectus fascia with interrupted 2–0 prolene sutures. At the second reoperation, the Goretex mesh was completely removed and the linea alba of the donor fascia was approximated to the native rectus fascia above and below as shown in Figure 3. The wound was completely healed by the end of 4 weeks. The child's posttransplant course was complicated by pulmonary infection. Once this resolved, tube feeds were initiated. TPN was weaned by 6 weeks and the follow up has been uneventful for 4 months.

Figure 3.

Wound on postop day 8. The donor rectus sheath has been imbricated with interrupted prolene sutures and the Gortex mesh on the right side has been completely removed.

Discussion

Restoring abdominal wall cover in abdominal organ transplantation is crucial. Approximation of native fascia under tension is associated with abdominal compartment syndrome, break down and infection of the wound site with long-term morbidity including hernia or enterocutaneous fistula formation.

The use of synthetic materials for closure has been described most often and options include the use of synthetic mesh such as polytetrafluoroethylene (PTFE; Ref. 3), polyglactin (Vicryl) or polypropylene (Prolene; Ref. 12). Rarely a silastic patch (13) has been used for a staged abdominal wall closure. However, these methods carry the risk of infection, adhesions and enteric fistula (14). Biological alternatives have also been utilized (5).

Levi reported transplantation of the full thickness of the abdominal wall in eight patients undergoing intestinal transplantation (7). The graft blood supply was based on inferior epigastric vessels left in continuity with the donor iliac and femoral vessels. Of the 15 grafts reported (15), five were still viable in the survivors. Morbidity included graft loss from vascular thrombosis in two and acute rejection of the abdominal wall graft in three that was treated with steroids. The limited application of the technique probably reflects the complexity of this procedure.

Another novel biologic alternative technique for abdominal closure is the use of fascia of the rectus muscle (FoRM) as a free nonvascularized graft (6). The rectus sheath (either anterior alone or both layers) was harvested from the donor and used as a nonvascularized allograft for abdominal wall closure. The occurrence of wound infection in 7 of 16 patients (with loss of graft in two) raises concern with the use of this technique in immunosuppressed patients.

The most recent biologic innovation to assist in closure of the abdomen after pediatric abdominal transplantation describes use of vascularized posterior rectus sheath fascia from the donor (8). The success of this graft in liver transplant recipients is based on the presence of blood supply to the posterior rectus and falciform ligament from the hepatic artery.

Hepatic falciform artery

The falciform ligament is the embryological remnant of the ventral mesentery and marks the separation of the left lobe of liver into the medial and lateral segments. Blood vessels in the falciform ligament are now called the “hepatic falciform artery” (HFA). The HFA arises as a terminal branch of either the middle or left hepatic artery (9). It runs in the falciform ligament to the umbilical vein to the umbilicus. It provides some blood supply to the tissues around the umbilicus and communicates with the branches of the internal thoracic and superior epigastric arteries. The presence of HFA was reported in 39 of 58 (67.2%) postmortem anatomic dissections. In contrast, its detection on angiography has been lower, varying between 2 and 24.5% (16, 17).

The University of Chicago case involved (8) a 3-year-old who underwent a combined liver and bilateral kidney transplant for hereditary oxalosis. Size mismatch led to difficulty in abdominal closure and this was achieved with the help of the vascularized donor rectus sheath which had been procured attached to the liver. The child underwent re-exploration three times and was found to have a viable fascia. Unfortunately, the child succumbed to fungal infection 51 days after surgery.

The technique was used by us in two children for different reasons. The first child had an extremely lax and protuberant abdomen and the vascularized rectus fascia was used as an underlay graft with the aim of improving the abdominal contour. The child likely benefitted from improved contour of the abdomen leading to improved balance and physical rehabilitation. The second child underwent the same procedure to enable utilization of a graft that would normally have been turned down for size. The vascularized rectus fascia not only provided cover for the multivisceral graft in the absence of native skin coverage, but occurred without complication (infection or fistula) and healed quickly with development of granulation and wound contraction.

Here, we confirm the feasibility of vascularized posterior rectus fascia as a biologic “mesh” with no demonstrable morbidity in two cases of combined liver, small bowel and pancreas transplantation. The simplicity of the procedure is a major advantage over full thickness abdominal wall transplantation and the presence of vascularity appears likely to diminish the risk of infection and delayed wound healing often associated with nonvascularized rectus fascia graft and other biologic mesh (such as Alloderm).

Most small bowel transplant programs are highly selective with respect to donor selection in pediatric patients with short bowel syndrome and a small abdominal domain. In this subset of patients, the general rule is to use organs from donors who are considerably smaller (50–75% of weight). Application of this procedure has the potential to help relax these restrictions and expand the donor pool potentially leading to decreased waitlist mortality in patients requiring a combined liver-small bowel transplant.

Limitations in our current knowledge regarding this procedure include the unknown long term viability of this fascial allograft, the potential impact of short- or long-term immunological changes in the transplanted rectus fascia, and lack of demonstration of venous drainage of the graft. The ability to visualize the graft during the first eight days in the second patient, allowed confirmation during the short-term follow-up of good vascularity of the fascia and the absence of congestion. The ease of the technique and lack of complications associated with other biologic and mesh materials justifies further consideration of the procedure for difficult abdominal closure or abdominal wall defects.

Conclusion

The posterior rectus fascia derives demonstrable blood supply from the hepatic artery through the hepatic falciform artery. It may be recovered in continuity with the liver and has the potential to be used to achieve abdominal wall cover in pediatric liver and multivisceral transplantation. This has great potential for permitting the use of larger grafts in pediatric recipients and, thus, shorten waitlist times. Further studies are required to define the role of this procedure in transplantation.

Disclosure

The authors of this manuscript have no conflicts of interest to disclose as described by the American Journal of Transplantation.

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