Asian Cardiovasc Thorac Ann 2006;14:e14-e16
© 2006 Asia Publishing EXchange Ltd
Sternotomy Reconstruction With Omentum Followed by Large Diaphragmatic Hernia
Marian Vrtik, MBBS,
David Cameron, FANZCR1,
Mark G Edwards, FRACS
Department of Cardiothoracic Surgery, Department of Radiology, Royal Perth Hospital, Perth, Western Australia
For reprint information contact: Marian Vrtik, MBBS Tel: 61 8 9224 2195 Fax: 61 8 9224 1977 Email: maros96{at}hotmail.com, Department of Cardiothoracic Surgery, Royal Perth Hospital, Wellington Street Campus, Box X2213 GPO, Perth 6847, Western Australia.
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ABSTRACT
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Poststernotomy mediastinitis carries significant morbidity and mortality. Aggressive wound debridement combined with a pedicled omental flap, with or without a pedicled muscle flap, has gained acceptance in the management of difficult sternal wound infections. Two cases of poststernotomy mediastinitis and sternal wound reconstruction with a pedicled omental flap were complicated by a large anterior diaphragmatic hernia containing the large bowel.
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INTRODUCTION
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Poststernotomy mediastinitis poses a difficult therapeutic problem and carries both significant morbidity and mortality. Aggressive wound debridement combined with the use of a pedicled flap has gained acceptance as one of the preferred therapeutic modalities in the management of difficult sternal wound infections. A pedicled omental flap, either alone or together with a pedicled muscle flap, has been shown to be superior to more traditional methods of treatment. The success of this approach is thought to be due to the excellent blood supply provided by the omentum that helps both to resist infection and to encourage expedient wound healing. However, the procedure itself has associated complications. While one case of small bowel herniation has been reported, large bowel herniation has yet to be described as a potential complication after a pedicled omental flap. We report two cases of large anterior diaphragmatic hernia containing colon, which developed after aggressive wound debridement and use of an omental flap in the management of poststernotomy mediastinitis.
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CASE REPORTS
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CASE 1
A 67-year-old Caucasian man underwent emergency coronary artery bypass grafting to the left anterior descending coronary artery. Sternal wound dehiscence was noted on the fifth postoperative day. The sternum was debrided to bleeding bone and reconstructed with multiple steel wires. Despite the initial debridement combined with intravenous antibiotic therapy to treat coagulase-negative Staphylococcus infection, the sternal wound broke down again on the 27th postoperative day. The sternum was resected and all costal cartilages were debrided back to bleeding tissue. The defect was filled with a pedicled omental flap. The omentum was harvested through a midline upper abdominal incision that was in continuity with the median sternotomy wound. The pedicled omental flap was tunneled subcutaneously into the anterior mediastinum. Nineteen months later, during a routine follow-up visit, an asymptomatic upper abdominal incisional hernia was noted. The hernia became symptomatic over the next 6 years, with intermittent dysphagia, aching, and discomfort on coughing. A computed tomography scan showed a large anterior diaphragmatic hernia containing both transverse colon and stomach (Figure 1
). The patient is currently under consideration for operative repair of his diaphragmatic hernia.
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Figure 1. Chest computed tomography scan depicting a large anterior diaphragmatic hernia containing both stomach (thin arrow) and colon (thick arrow) located anterior to the omentum
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CASE 2
A 77-year-old Caucasian man underwent elective coronary artery bypass grafting. On the 11th postoperative day, he became febrile, the sternal skin broke down, and the sternum itself was noted to be unstable. Wound debridement with sternal rewiring was followed by intravenous antibiotic therapy and Betadine wound irrigation. Coagulase-negative Staphylococcus aureus was grown from tissue samples taken intraoperatively. The patient continued to be febrile and the wound broke down again on the 18th postoperative day, necessitating further operative intervention. The sternum was excised and the costal cartilages were debrided back to the costochondral junctions. The defect was reconstructed with an omental flap as described in case 1. Chest computed tomography 12 years later during investigation of bladder transitional cell carcinoma revealed a large anterior diaphragmatic hernia containing colon (Figure 2). The hernia has remained asymptomatic and is not being considered for surgical repair due to the overall deterioration in the patient’s medical condition.
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Figure 2: Chest computed tomography scan showing a large anterior diaphragmatic hernia containing a segment of large bowel (arrow) located anterior to the omentum.
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DISCUSSION
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The incidence of poststernotomy mediastinitis has been widely reported to be between 0.4% and 6.9%.1 Over the years, the management of this complication of cardiac surgery has evolved from wound debridement with healing by secondary intention, to sternal debridement and rewiring followed by closed drainage with or without antibiotic irrigation. In recent years, the use of omentum has significantly reduced both morbidity and hospital stay, particularly in the reconstruction of large and deep chest wall defects.2,3 Omentum can be used either alone or in conjunction with a pedicled muscle flap, such as pectoralis major or a rectus abdominis muscle flap.
The technique of omental flap harvesting and transposition into thoracic wounds has been well described. Following thorough wound debridement and wash out, the abdomen is entered through an upper midline, paramedian, transverse, or left subcostal incision. A bipedicled omental flap, based on both gastroepiploic arteries, can be used to reconstruct lower-third sternal defects. If additional pedicle length is required to cover the upper two thirds of the sternal wound, the omental flap can be based on either of the gastroepiploic arteries. As it is usually the larger of the two vessels, the right gastroepiploic artery is often the vessel of choice.2 It can be transposed into the anterior mediastinum through a small opening in the anterior diaphragm or subcutaneously.4 The subcutaneous approach has been reported to result in the development of incisional hernia in 20% of cases.2 The other rare reported complications associated with omental transposition include one case of fatal cecal volvulus, one case of postoperative peritonitis, and motility disturbance of the stomach and duodenum.5–7
Both of our patients developed complicated sternal wound infections necessitating extensive debridement with sternectomy and cartilage resection back to the costochondral junctions. The chest wall defects were reconstructed with pedicled omental flaps alone, brought up to the anterior mediastinum in front of the diaphragm, with the skin closed directly over the omentum. Both patients developed extensive visceral herniation into the anterior mediastinum on medium-term follow-up, with the hernias located in front of the omentum. To date, one case of small bowel herniation into the anterior mediastinum has been documented on computed tomography scanning.8 However, no case of large bowel herniation into the anterior mediastinum following chest wound reconstruction with a pedicled omental flap has been reported. Due to the size and location of the herniation, it could most likely be ascribed to the extent of debridement as well as to the omentum being tunneled into the anterior mediastinum subcutaneously rather than through a small opening in the diaphragm. A breakdown in the linea alba below the point where the omentum enters the chest could also be an important contributing factor as the subcutaneous method of omental transfer is associated with a high incidence of incisional hernia, which was the case in our first patient. Although reinforcing this area with a synthetic mesh at the time of omental transfer is an option when reconstructing clean chest defects, we do not feel it would be appropriate in the management of poststernotomy mediastinitis as the risk of mesh infection would be very high. Further research is needed to establish the true incidence of this potentially life-threatening complication as well as to further define the factors leading to its development so that it may be avoided in the future.
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REFERENCES
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- Lopez-Monjardin H, de-la-Pena-Salcedo A, Mendoza-Munoz M, Lopez-Yanez-de-la-Pena A, Palacio-Lopez E, Lopez-Garcia A. Omentum flap versus pectoralis major flap in the treatment of mediastinitis. Plast Reconstr Surg 1998;101:1481–5.[Medline]
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ABSTRACT
INTRODUCTION
