Anterior Mediastinal Herniation of the Transverse Colon After an Omental Flap Transposition

By Halldorsson, Ari Meyerrose, Gary; Griswold, John

Poststernotomy mediastinitis continues to be an infrequent but serious complication after cardiac surgery. We present a case of a 59-year-old man who developed a deep sternal wound infection after an emergency cardiac surgery. Omental transposition flap was used to cover the sternal defect. Several days later, the patient developed a transverse colon herniation into the anterior mediastinum that required emergency exploration and colon resection. The patient survived after a difficult hospital course. Indications, technical points, and possible complications of using omental flap transposition are discussed. A DEEP STERNAL WOUND infection is a relatively rare but serious and life-threatening complication of open heart surgery. Although mediastinitis after a sternotomy is reported to be only 0.4 per cent to 6 per cent in most series, it is associated with a mortality rate of 14 per cent to 47 per cent.1″3 This complication is also associated with high morbidity, prolonged intensive care and hospital stays, and the need for repeated surgical procedures. Although more superficial sternal infections can be treated with drainage and sometimes closed irrigation, most of the deeper infections require aggressive debridement, including sternectomy followed by appropriate wound care and subsequent closure of the large defect, most commonly using omenturn or pectoral muscle flaps.1″3 Recent reports have advocated very aggressive early treatment for this complication with excellent short- and long-term results.2,3

Case Report

A 59-year-old man was admitted to the hospital with unstable angina. Attempts at angioplasty and stenting were complicated by coronary artery perforation, mandating an immediate surgical intervention. An on-pump three-vessel bypass was performed. On postoperative Day 7, the patient was diagnosed with a deep sternal infection, and was taken to the operating room where a thorough sternal debridement was carried out. The wound was initially managed by negative pressure wound therapy. When the base of the wound was clean and granulating, the patient was taken to the operating room for closure. The omentum was mobilized from the transverse colon and a large omental flap ,was developed based on the right gastroepiploic artery. The omentum was tunneled into the anterior mediastinum through the sternal reflection of the diaphragm. The skin was closed primarily over closed system suction. Approximately 2.5 weeks after the omentoplasty, the patient developed sudden onset abdominal pain, nausea, vomiting, and increased shortness of breath. An abdominal CT scan was performed that showed herniation of the transverse colon into the anterior mediastinum (Figs. 1 and 2). The patient was taken to the operating room where he was found to have herniation of the transverse colon into the anterior mediastinum through a defect anterior and to the right of the omental stalk (Fig. 3). The colon was deemed not viable and a complete transverse colectomy was performed with a rightsided colostomy and a left- sided mucous fistula. After confirming independent blood supply to the omentum from the wound bed by gently clamping the stalk, the omentum was divided at the level of the hernia. The hernia defect was then closed primarily using interrupted sutures. The patient did well postoperatively and was discharged on the 56th hospital day and has since resumed normal activities.

Comments

The greater omentum has been used for a long time in reconstructive surgery to fill large defects, help clean contaminated wounds, and speed up the healing process. Its versatility has expanded to use in cosmetic surgery, revascularization, and to reinforce tissue healing after surgery in previously radiated areas. Although initially limited to intra- abdominal use, further understanding of its anatomy, specifically its blood supply, has made it possible to form long omental flaps that will reach almost any area of the body.4,5 The omentum has unique characteristics that make it especially appealing for the reconstruction of large contaminated spaces. Its excellent blood supply derived from the right and left gastroepiploic arteries make it possible to structure a very large flap to either side of the body. Its large size (300-500 cm2) and amorphic shape allow it to fill very deep irregular spaces or to be spread over a broad flat area. The omentum has been used extensively in chest wall reconstruction and in the management of complex thoracic wounds.6 Deep wounds after poststernotomy infection are currently treated aggressively with debridement and wound care followed by coverage as soon as the patient’s condition permits. Most commonly, omental or pectoral flaps are used. Recent comparison of the two methods seems to favor using omental flap for the best short-term infection control, wound healing, and long-term results.7

FIG. 1. Scout film from the abdominal CT showing the transverse colon herniating into the mediastinum.

FIG. 2. Midthoracic cut from the abdominal CT demonstrating the transverse colon in the anterior mediastinum.

FIG. 3. Schematic illustration of the intraoperative findings.

When the omentum is used to cover a large poststernotomy wound, it can be harvested open or laparoscopically, and the flap can be based on the right, left, or both gastroepiploic vessels, depending on the size of the omentum and the amount of tissue needed for coverage (Fig. 4). Most authors have abandoned tunneling the omentum through the midline incision in favor of a direct tunneling through the sternal portion of the diaphragm into the anterior mediastinum (Fig. 5). The omentum is tacked to the wound area with sutures and/ or tissue glue, and is then covered by approximating the skin edges or split-thickness skin graft at the initial operation or a few days later. Excellent cosmetic and functional results have been reported.8^10

Complications directly related to the omental harvest and transpositions are relatively low and most of them are minor: ileus, wound infection, and incisional hernias are most common. Shrager9 reported only 3.5 per cent donor site complication rate in 85 patients where the omentum was used in chest reconstruction with no herniation. Hultman et al.5 in a recent study reported 18.5 per cent donor site complications in 135 omentoplasty patients, including symptomatic hernias in 8 (6.7%) patients. Several studies have confirmed this very low rate of tunnel defect hernias after mediastinal omentoplasties.5-10 When the transposed omental flap is exteriorized from the abdominal cavity, a hernia defect has been created by definition. To avoid herniation of intra-abdominal structures through the defect along side the omental stalk, the surgeon has to create an abdominal defect large enough to accommodate the omental stalk without the risk of vascular compromise, but not so large that a herniation of intraabdominal organs is likely. A common practice is to tag the omentum to the edges of the defect to seal it and to make sure that the omentum has been thoroughly freed from the surrounding abdominal structures to decrease the likelihood of herniation. If a hernia occurs around the omental stalk, several methods have been recommended for repair using natural tissues, if possible, or prosthetic material for larger defects. The best way to repair a hernia defect is to verify that the omental flap is receiving adequate blood supply from the wound bed to sustain its viability, and then to divide the omentum at the level of the defect and close it primarily, as was done in this case. Most authors feel that this neovascularization takes several weeks, although in this case, that period was much shorter.

FIG. 4. Omental transposition flaps based on (A) the right gastroepiploic artery and (B) The left gastroepiploic artery. (C) Both gastroepiploic arteries.

FIG. 5. TransDiaphragmatic tunneling route from the abdomen into the anterior mediastinum.

We present a case of near fatal complication after using omental flap for wound coverage after poststernotomy infection. Although herniation through abdominal wall defects created when performing exteriorization of omental flaps is well known, colon herniation into the anterior mediastinum of this magnitude has not been previously reported to our knowledge.

REFERENCES

1. El Oakley RM, Wright JE. Postoperative mediastinitis: Classification and management. Ann Thorac Surg 1996;61:1030-6.

2. De Feo M, Gregorio R, Delia Corte A, et al. Deep sternal wound infection: The role of early debridement surgery. Eur J Cardiothorac Surg 2001;19:811-6.

3. Losanoff JE, Richman BW, Jones JW. Disruption and infection of median sternotomy: A comprehensive review. Eur J Cardiothorac Surg 2002;21:831-9.

4. Liebermann-Meffert D. The greater omentum: Anatomy, embryology, and surgical applications. Surg Clin North Am 2000;80: 275-93.

5. Scott Hultman C, Carlson CW, Losken A, et al. Utility of the omentum in the reconstruction of complex extraperitoneal wounds and defects donor-site complications in 135 patients from 1975 to 2000. Ann Surg 2002;235:782-95.

6. Arnold PG, Pairolero PC. Chest wall reconstruction: An account of 500 consecutive patients. Plast Reconstr Surg 1996;98:804-10. 7. Milano CA, Georgiade G, Muhblaier LH, et al. Comparison of omental and pectoralis flaps for poststernotomy mediastinitis. Ann Thorac Surg 1999;67:377-81.

8. Yasuura K, Okamoto H, Morita S, et al. Results of omental flap transposition for deep sternal wound infection after cardiovascular surgery. Ann Surg 1998;227:455-9.

9. Shrager JB, Wain JC, Wright CD, et al. Omentum is highly effective in the management of complex cardiothoracic surgical problems. J Thorac Cardiovasc Surg 2003; 125:526-32.

10. Krabatsch T, Hetzer R. Poststernotomy mediastinitis treated by transposition of the greater omentum. J Card Surg 1995; 10: 637- 43.

ARI HALLDORSSON, M.D.,* GARY MEYERROSE, M.D.,t JOHN GRISWOLD, M.D.*

From Texas Tech University Health Sciences Center, Department of Surgery, *Division of Cardiothoracic

Surgery and [dagger] Division of Cardiology, Lubbock, Texas

Address correspondence and reprint requests to Ari Halldorsson, M.D., Chief, Division of Cardiothoracic Surgery, Texas Tech University Health Sciences Center, 3601 4th Street, M.S. 8312, Suite 3A159, Lubbock, TX 79430.

Copyright Southeastern Surgical Congress Apr 2007

(c) 2007 American Surgeon, The. Provided by ProQuest Information and Learning. All rights Reserved.