Bovine Pericardium in Complex Abdominal Wall Reconstruction in Patients with Obesity or Morbid Obesity

| September 17, 2014

The Hole in the Wall

Column Editor: Samuel Szomstein, MD, FACS, Associate Director of the Bariatric Institute and Section of Minimally Invasive Surgery, Cleveland Clinic in Weston, Florida, and Clinical Associate Professor of Surgery, Florida International University.

Dedicated to providing a venue for interactive exchange of ideas, interesting topics, and surgical pearls from experts in repair of abdominal wall defects as they relate to bariatric surgery.

This Month’s Featured Expert

Moses K. Shieh, DO, FACOS
Lee Memorial Health System, Fort Myers, Florida; Medical Director, Surgical Healing Arts, Fort Myers, Florida

A Message from the Column Editor
Dear Readers of Bariatric Times:
I would like to welcome you to this installment of “The Hole in the Wall.” We are very pleased to have Dr. Moses Shieh from Lee Memorial Health System in Fort Myers, Florida, as our guest expert. In this issue, Dr. Shieh examines data regarding the overall efficacy and safety of acellular bovine pericardium (ABP) in complex abdominal wall reconstruction in patients with obesity with a focus on recurrence rates.
We welcome Dr. Shieh’s expertise and thank him for this contribution to the column.
Once again, welcome to The Hole in the Wall. We hope you will enjoy this column and we look forward to your questions, comments, and participation in future issues.

Sincerely,
Samuel Szomstein, MD, FACS


 

Abstract
Background: Obesity is a risk factor for hernia development and is associated with hernia recurrence rates of up to 50 percent. Repairing complex abdominal wall defects in patients with obesity, who often have multiple comorbidities, can be challenging. The purpose of this study was to capture data regarding the overall efficacy and safety of acellular bovine pericardium (Veritas Collagen Matrix, Baxter Healthcare Corp., Deerfield, Illinois) in complex abdominal wall reconstruction in patients with obesity with a focus on recurrence rates. Methods: Between 2008 and 2011, a retrospective review of a single general surgeon’s practice identified patients reconstructed with acellular bovine pericardium. Twenty patients with either primary or recurrent ventral hernias were reconstructed with either a components separation technique with acellular bovine pericardium as both an underlay and an onlay in a “sandwich” method, or with acellular bovine pericardium used as an inlay or onlay. Results: In the 20 patients identified (11 women/9 men), there were nine primary (45%) and 11 recurrent (55%) hernias. Thirteen patients (65%) underwent components separation technique with acellular bovine pericardium. Average defect size was 237cm2 (50cm2–800cm2). Approximately 40 percent of patients had a wound class of III (contaminated) or IV (dirty-infected). Complete fascial closure was possible in 15 patients (75%). Recurrence occurred in two patients (10%), both with a body mass index greater than 40kg/m2. Other complications included one seroma, one hematoma, and one disintegration. Conclusions: The use of acellular bovine pericardium in complex abdominal wall reconstruction in patients with obesity was associated with a high rate of complete fascial closure and low rates of recurrence and complications. Bariatric Times. 2014;11(9):14–18.

Funding: No funding was provided.
Financial disclosures: The author reports no conflicts of interest relevant to the content of this article.
Acknowledgments: The author gratefully acknowledges grant support from Baxter Healthcare Corporation for development of study data and figures and assistance with manuscript development. Shireen Dunwoody of Dunwoody Consulting is also gratefully acknowledged for her assistance with development of the manuscript and figures.

Introduction
Obesity is considered a risk factor for the development of primary and incisional ventral hernias.[1–7] Repairing complex defects in patients with morbid obesity with a body mass index (BMI) greater than 40kg/m2 who often present with comorbidities (e.g., diabetes, hypertension, poor vascular bed perfusion/circulation, severe wound infections) is challenging. In the obese population, one of the most significant challenge is recurrence, with rates as high as 50 percent.[8] The factors that predispose patients with obesity to development of hernia may also be a factor in recurrence. Sauerland et al[9] reported obesity to be the greatest risk factor for hernia recurrence. Hernia recurrence, especially in morbidly obese patients, is also often complicated by infection or extrusion of mesh.[10]

The high recurrence rate is in part caused by the lack of autogenous tissue to repair the initial defect. Therefore, the use of prosthetic mesh to assist in closure was developed to attempt to reduce the high rate of recurrence, but mesh is associated with its own complications including infection, extrusion, adhesions, and enterocutaneous fistulae.[11,12] These complications led to the search for alternative biologic graft materials as well as new methods of closure to reduce recurrence rates and minimize complications.

An alternative repair technique incorporating the use of autogenous tissue with minimum donor site morbidity is the components separation technique (CST) as described by Ramirez et al.[13] The goals of abdominal wall reconstruction are to restore function and integrity, provide stable skin and soft tissue coverage, maintain a tensionless coaptation, and preserve the vasculature and innervation.[14] However, because of the large defect size in the patient population with obesity, tensionless coaptation with CST alone is often not possible. In these instances, use of a suitable biologic material for closure, such as acellular bovine pericardium (ABP) may increase the chance of successful recovery and reduce or alleviate recurrence. The purpose of this study was to capture data regarding the overall efficacy and safety of ABP in complex abdominal wall reconstruction in patients with obesity with a focus on recurrence rates.

Materials and Methods
Between 2008 and 2011, a retrospective review of a single surgeon’s practice was conducted to identify patients reconstructed with ABP (Veritas Collagen Matrix, Baxter Healthcare Corp., Deerfield, Illinois). Inclusion criteria for the study was the use of ABP for repair of large abdominal defects in patients with obesity (BMI >30kg/m2) and morbid obesity (BMI>40kg/m2). Patients reconstructed with ABP who had a BMI below 30kg/m2 were excluded from the study. Clinical follow up on all patients was complete through December 2012.

The study protocol was submitted to the Western Institutional Review Board (WIRB) with a request for exemption determination. The WIRB IRB Affairs Department reviewed and granted the exemption under criteria 45 CFR §46.101(b)(4):
“Research, involving the collection or study of existing data, documents, records, pathological specimens, if these sources are publicly available or if the information is recorded by the investigator in such a manner that subjects cannot be identified, directly or through identifiers linked to the subjects.”

Patients with primary and recurrent hernias were reconstructed with either CST with ABP as both an underlay and an overlay or with ABP used as an inlay or onlay. In patients reconstructed ABP, either a large sheet (12cm x 25cm) or multiple large sheets were quilted together to form a biologic graft of the appropriate size. In patients reconstructed with CST with ABP, a unique “sandwich” technique was used for reconstruction. The first sheet was used as an underlay below the musculofascial layer with appropriate overlap (4–5cm) of the hernia defect to protect the peritoneum and its visceral contents. A second sheet of ABP was then used as an overlay on top of the myofascial separation component (Figure 1).

When using the CST with ABP reconstructive method, after defining the edges of the fascia, the components separation was performed. Skin and subcutaneous tissue were elevated in the prefascial plane above the anterior rectus sheath and external oblique fascia. The external oblique muscle was then incised lateral to the anterior rectus sheath to facilitate mobilization of the rectus-internal oblique-transversus abdominis unit. When appropriate, suction drains were placed subcutaneously. In several patients, late incisional wound debridement was required to keep the wound clean. Once viable tissue was established, negative pressure wound therapy (V.A.C., Kinetic Concepts, Inc., San Antonio, Texas) was applied.

Abdominal reconstruction in a contaminated field is one of the most significant challenges to a successful hernia reconstruction and plays a significant role in recurrence.[15,16] Infection, once triggered, profoundly changes the entire healing process. Virulent bacteria reduce the phagocytic ability of leukocytes and macrophages and prevent them from reclaiming their role in the inflammatory focus, an indispensable condition for the appearance of granulation tissue and synthesis of normal, healthy collagen. Even if collagen is subsequently normalized (or is in excess), fiber quality remains inferior and has inadequate orientation, especially after prolonged suppurations or in the presence of chronic infection.  Wounds were classified using guidelines from the Centers for Disease Control and Prevention (CDC)(Table 1).[17]

Results
The data results are summarized in Table 2. A total of 20 patients with 20 hernias were treated. There were 11 women and 9 men ranging in age from 31 to 78 years (mean age 53 years). Fourteen of the patients (70%) had a BMI greater than 40kg/m2 and six of the patients had a BMI greater than 30kg/m2.

All patients were repaired using ABP (Figure 2). Thirteen patients (65%) underwent CST. Hernias ranged in size from 50cm2 to 800cm2 (mean: 230cm2). For those undergoing CST, hernias ranged in size from 100cm2 to 800 cm2 (mean: 315cm2). Nine of the hernias were primary (45%) and 11 were recurrent (55%). Complete fascial closure was possible in 15 patients (75%)(Figure 3). Eight of the patients (40%) presented with Class III (contaminated) or Class IV (dirty-infected) wounds.

The mean follow up was 28 months (range 4–42 months). There were two recurrences (10%) and one disintegration of the graft (5%).  It is important to note that both recurrences and the disintegration of the graft occurred in patients with BMIs greater than 40kg/m2. Minor complications included one seroma (5%) and one hematoma (5%).

Discussion
Patients with obesity and morbid obesity are predisposed to developing abdominal wall hernias with the potential complication of small bowel obstruction and other morbidity.[18] Prevention of hernia is ideal; however, in this patient population in particular, it may often be unavoidable. In many complicated cases, the surgeon is presented with a patient who may have undergone several previous surgeries, leaving skin and fascia that are attenuated, unreliable, or missing. More often than not, the patient requiring complex hernia repair has local and systemic issues that place them at risk for complications and recurrences, such as the presence of infection, previous mesh, an enterostomy, enterocutaneous fistulae, diabetes, cancer, and other comorbidities that complicate reconstructive planning.[20]

As one can see in this report, the hernias tend to be very large, on average, in this patient population. For this reason, the use of prosthetic mesh to assist in closure is often used. Unfortunately, complications associated with mesh include infection, extrusion, adhesions, and enterocutaneous fistulae.[11,12] These complications led to the search for alternative biologic materials.

Several studies have examined the use of human acellular dermal matrix (H-ADM [Alloderm, Lifecell, Branchberg, New Jersey]) in abdominal wall repair.[21–28] The incidence of complications after abdominal wall reconstruction using H-ADM has been reported to be 20 to 60 percent in several retrospective studies.[21,23,24] Based on their experience with H-ADM, Schuster et al[24] suggested that having an open wound with exposed H-ADM in the postoperative period following repair of contaminated fascial defects was associated with a high probability of hernia recurrence.

In 2009, Limpert et al[10] reported on the use of ABP in abdominal wall repair in 26 patients with successful results. They were also able to show a considerable cost benefit when using ABP for abdominal repair versus H-ADM.[10] However, little specific data exist on the efficacy of ABP in complex abdominal repair in patients with obesity and morbid obesity. The authors’ experience with ABP suggests that its use for complex repairs of large defects in patients with obesity and morbid obesity is safe, effective, and feasible in the setting of contaminated fields, especially in patients who may also have comorbidities that adversely affect positive outcomes, such as diabetes and poor vascular bed perfusion/circulation.

Commonly accepted advantages of biologic grafts are their infection tolerance, inherent ability to minimize infection, and the ability to place the material in a contaminated wound.[10,29,30] Infection frequently requires removal of synthetic mesh and attendant morbidity.[30] Wound infection also appears to significantly increase the risk for hernia recurrence.[15,16,31] In a study by Luijendijk et al,[32] the rate of recurrence among patients with postoperative infection was 80 percent, compared with 34 percent for those without infection. Awad et al[33] estimated that more than 75 percent of all recurrence is due to infection and inadequate repair material fixation and/or overlap.

Studies have shown that crosslinked biologic materials are more prone to encapsulation and potential infection, and it may not be prudent to place crosslinked biologic graft material within a contaminated surgical field as the subsequent lack of cellular infiltration may render the body incapable of clearing the infection.[30,34,35] In contrast, ABP (specifically, Veritas, which was used in the patients in this study) is non-crosslinked. Non-crosslinking has been shown to facilitate native tissue ingrowth and neovascularization.[30] In addition, non-crosslinking technology has been shown to facilitate earlier[36] host cell migration between graft and native tissue, providing a healthy source of host cell response to prevent or minimize infections better than other crosslinked biologic grafts.[37]

An additional benefit to the use of ABP in large, complex abdominal wall defects is the ability to easily quilt multiple sheets together to provide adequate coverage. The material is supple and compatible with a variety of fixation techniques including suturing, stapling, tacking or other methods. In the author’s opinion, the bioengineered contouring of the non-crosslinked ABP material provides the most natural feel among all the biologic grafts and makes it easy to handle. In addition, non-crosslinked ABP does not require product-specific preparation or reconstitution with saline prior to use. This can improve intraoperative efficiency and reduce surgical time, thereby decreasing accumulation of inflammatory mediators and edema in the soft tissue of a patient with an exposed abdomen under anesthesia and can improve the quality of tissue approximation in closing the abdomen.

The current series of patients is small; a larger study may have shown increased complications and recurrence rates in this particular patient population. However, it is the authors’ experience that ABP may have a role in the repair of large abdominal wall defects in patients with obesity and morbid obesity, especially when prosthetic mesh is contraindicated. It is important to note that ABP is relatively inexpensive compared with other available biomaterials used in abdominal wall reconstruction.[10]

Conclusion
In conclusion, the use of acellular bovine pericardium in complex abdominal wall reconstruction in patients with obesity in this series was associated with a high rate of complete fascial closure and low rates of recurrence and complications.

References
1.    Sarr M. Abdominal wall reconstruction in the morbidly obese patient. In: M Nahabedian, P Bhanot, eds. Abdominal Wall Reconstruction. Woodbury, CT: Cine-Med, Inc.; 2013.
2.    Heniford BT, Park A, Ramshaw BJ, Voeller G. Laparoscopic repair of ventral hernias: nine years’ experience with 850 consecutive hernias. Ann Surg 2003;283:391–399.
3.    Datta T, Eid G, Nahmias N, Dallal RM. Management of ventral hernias during laparoscopic gastric bypass. Surg Obes Rel Dis. 2008;4:754–758.
4.    Eid GM, Mattar G, Hamad G, et al. Repair of ventral hernias in morbidly obese patients undergoing laparoscopic gastric bypass should not be deferred. Surg Endosc. 2004;18:207–210.
5.    Herbert GS, Tausch TJ, Carter PL. Prophylactic mesh to prevent incisional hernia: a note of caution. Am J Surg. 2009;197:595–598
6.    Newcomb WL, Polhill JL, Chen AY, et al. Staged hernia repair preceded by gastric bypass for the treatment of morbidly obese patients with complex ventral hernias. Hernia. 2008;12:465–469.
7.    Raghavendra SR, Gentileschi P, Kini SU. Management of ventral hernias in bariatric surgery. Surg Obes Rel Dis. 2011;7:110–116.
8.    Schuster R, Curet MJ, Alami RS, et al. Concurrent gastric bypass and repair of anterior abdominal wall hernias. Obes Surg. 2006;16:1205–1208.
9.    Vilallonga R, Fort JM, Gonzalez O, et al. Management of patients with hernia or incisional hernia undergoing surgery for morbid obesity. J Obes. 2011;86092. Epub 2010 Dec 5.
10.    Downey SE, Morales C, Kelso RL, Anthone G. Review of technique for combined closed incisional hernia repair and panniculectomy status post open bariatric surgery. Surg Obes Rel Dis. 2005;1:458–14461.
11.    Foutopoulos K, Kehagias I, Kalfarenzos F. Dermolipectomies following weight loss after surgery for morbid obesity. Obes Surg. 200;10:451–459.

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