The bony thorax with its overlying muscles and integument creates a cage that protects the relatively fragile heart, great vessels, lungs, esophagus, and large lymphatic vessels. Disruption of the thorax by trauma, tumor, congenital anomaly, infection, or surgical intervention can have potentially lethal consequences. Advances in cardiac and thoracic surgery have enabled surgeons to operate safely within these cavities. Positive-pressure ventilation with the use of selective tubes and bronchial blockers permits surgeons to open the pleural spaces and continue respiration while the pleural cavity is disrupted. Technological advances in cardiac surgery include cardiopulmonary bypass, intraaortic balloon pumps, and ventricular assist devices that permit continued or augmented perfusion with oxygenated blood. These advances combined with a better understanding of biomaterials,^1–3 tissue-engineered solutions, and advances in plastic and reconstructive surgery^4–6 have permitted more complex sternal and chest wall defects to be reconstructed successfully. In this chapter we focus on a multidisciplinary approach to reconstruction of the chest and highlight the three most common flaps used for large defects: the latissimus dorsi muscle, pectoralis major muscle, and omentum.

SURGICAL PRINCIPLES

The chest wall has a robust blood supply provided anteriorly by the internal mammary vessels that are connected via intercostals to the aorta. Multiple other arteries, including the thoracoacromial trunk, transverse cervical artery, and thoracodorsal artery, provide the blood supply to muscles around the upper chest, back, and shoulders. Thorough understanding of the intricacies of the chest wall vasculature, including angiosomes, allows the surgeon to design reliable flap coverage for most defects. Occasionally, if regional flaps are insufficient or unavailable, free-tissue transfer may be necessary to close selected defects.

Large chest wall defects may benefit from a stable reconstruction of the ribs or rib cartilages to maintain adequate pulmonary function. This is generally performed with a variety of materials, including synthetic and biologic implants. An understanding of the biomaterial-tissue interface is critical to planning a reconstructive operation. In addition, the stiffness of the biomaterial should optimally match that of the region being replaced to avoid stress concentrations at the junction between the biomaterial and normal tissue. Meticulous surgical technique is essential to ensure that the flap will survive after transfer. Because of the robust blood supply to the chest skin, many wounds can be closed using moderate tension without tissue breakdown. Many chest wall reconstructive procedures occur before or after radiation therapy. Radiated tissues can be difficult to work with because of increased stiffness and susceptibility to infection.

PATIENT SELECTION

The reconstructive surgeon must carefully match the many possible solutions to a thoracic defect with the needs of the specific patient. Chest wall compliance is a function of age. Older patients have barrel chest development and stiffening of the costochondral junction. These patients often can tolerate more options for chest wall reconstruction than a younger patient, in whom movement may result in chest wall instability. Younger patients require careful attention to the donor site and ultimate functional and aesthetic outcome and can tolerate longer, more complicated procedures to achieve these goals. Older, more debilitated patients are better served by a more expeditious and reliable operation that also might involve more visible scarring. Chest wall reconstruction is performed optimally in a multidisciplinary setting that often includes reconstructive, thoracic, and cardiac surgery, as well as an experienced anesthesia team. A team that works together frequently will soon develop a sense for what operations can be performed safely in which patients.

PREOPERATIVE ASSESSMENT

The reconstructive surgeon must evaluate the patient in conjunction with a cardiac or thoracic surgeon to coordinate each portion of the procedure. The nutritional status of the patient, as defined by albumin and prealbumin levels, can be an important predictor of successful wound healing.⁷ Careful history and examination of the patient with regard to previous surgeries are essential to eliminating flaps that may not be useful based on previous incisions. Ideally, flaps should come from areas that have not been heavily irradiated, making assessment of previous radiation delivery sites an important issue. Since many cancer patients may be receiving chemotherapy, the operative timing should be coordinated to avoid periods of neutropenia.

SURGICAL TECHNIQUE

Most thoracic reconstructions can be accomplished with one or a combination of the latissimus dorsi, pectoralis major, and omental flaps. Flaps have an independent blood supply and can be transposed into the defect. They fill dead spaces and allow a three-dimensional vascularized surface ideal for wound healing and antibiotic delivery.

Latissimus Dorsi Muscle Flap

The latissimus dorsi muscle is the largest muscle in the body. It has its origin from the thoracic spine and thoracolumbar fascia to the iliac crest and inserts into the humerus (Fig. 117-1). Its major blood supply comes off the thoracodorsal system. The muscle can be accessed through a vertical, horizontal, or oblique incision or endoscopically.⁸ The skin and subcutaneous tissues are dissected off the muscle, and the muscle is dissected off the chest wall. Large perforators from the paraspinous and thoracolumbar area can be divided with clips or ties. The thoracodorsal pedicle is identified and preserved. The nerve can be left intact, divided, or crushed depending on the desired function of the muscle. For additional pedicle flap reach, the insertion to the humerus can be divided. This large muscle reaches nicely into the chest cavity after a portion of the second rib is removed, and it easily covers the hilum. This muscle also easily reaches the anterior mediastinum to cover the heart. When a skin paddle is included with the tissue, it can be a useful flap for breast reconstruction or chest wall reconstruction. The distal portion of the flap sometimes can be unreliable as a result of vascular insufficiency, and therefore, caution needs to be taken when the flap is harvested for defects that are distal to the costal margin. For many patients who have undergone a standard posterolateral thoracotomy, this muscle is divided, and only the superior portion can be used based on the thoracodorsal blood system. Closure of this defect generally is accomplished with deep dissolvable sutures. Quilting sutures are preferred by many surgeons to reduce the size of the cavity to minimize the risk of postoperative seroma, which has been reported to occur in 20–80% of patients.

Pectoralis Major Muscle Flap

The pectoralis major muscle is the largest anterior chest muscle and is very versatile for treating a variety of chest defects (Fig. 117-2A ). Its primary blood supply is from the thoracoacromial trunk. Access to the muscle can be accomplished through an incision concealed in the inframammary fold. The skin and subcutaneous tissues are dissected off the muscle, and the muscle is taken off the chest wall with electrocautery. The perforating vessels off the internal mammary artery are coagulated or ligated, and the thoracoacromial trunk is identified and preserved (see Fig. 117-2B ). For additional length, the medial and lateral pectoral nerves as well as the insertion into the humerus can be divided. To cover the hilum, the muscle can be brought through a second rib resection anteriorly (see Fig. 117-2C ). For cervical esophageal reconstruction, overlying skin can be taken with the muscle and tubed. For anterior mediastinal reconstructions, the muscle can be transposed over the ribs, easily filling the superior portion of the anterior mediastinum. For lower defects, the muscle is often more efficiently transposed on the perforators from the internal mammary artery system. In this case, the thoracoacromial vascular pedicle and humeral insertion are divided, and the muscle is "turned over" medially to fill the defect. Since there is usually a perforator between each costal cartilage, it is possible to divide the muscle along its fibers and use multiple small segments of the muscle to fill complex defects of the anterior mediastinum.

Omental Flap

The omentum is a large, vascularized fatty structure in the abdominal cavity that originates from the greater curvature of the stomach. It adheres to and drapes over the transverse colon (Fig. 117-3) and connects to the spleen on the left side. Access to the omentum is achieved most easily through a small upper midline incision, although it is possible to reach it from the anterior mediastinum, through the diaphragm, or endoscopically. The first step in harvest is to release any existing abdominal adhesions to the omentum. Making counterincisions over previous scars, such as an appendectomy incision, can facilitate the dissection. The omentum and transverse colon are then brought into view, and the omentum is meticulously dissected off the transverse colon, preserving both the vasculature to the colon and the vasculature to the transverse colonic mesentery. After some dissection, the lesser sac is entered. Generally, the omentum is less adhered to the transverse colonic mesentery on the left side than on the right, and this generally makes it easier to begin the dissection on the left side. Extensions to the spleen are divided with clamps and ties or with an advanced coagulation method.

For anterior mediastinal defects, this amount of dissection may be sufficient. If additional length is needed, it can be based on either the right or left gastroepiploic system, which needs to be assessed for patency. Each of the gastric perforators is ligated individually while checking the pulse within the gastroepiploic system. Releasing the gastric perforators in this fashion adds several inches of length to the omentum and permits large segments of vascularized material to be placed virtually anywhere within the chest cavity. Closure of the abdominal cavity needs to be performed with care to avoid undue compression on the pedicle.

POSTOPERATIVE CARE

Initial care of complex reconstructions of the chest is delivered most reliably in an intensive care setting with staff experienced in the treatment and care of thoracic surgical patients. Invasive hemodynamic monitoring, ventilatory support, and monitoring of fluids and renal function are essential to avoiding morbidity and mortality. Pain relief using narcotics, nonsteroidal anti-inflammatory agents, and regional epidural blocks can greatly aid patient recovery. Deep venous thrombosis prophylaxis is essential. For free-tissue-transfer operations, a monitoring system that is well understood in the hospital is essential for flap success. Even in the best centers, 5–10% of patients with free-tissue transfers will need to return to the OR for potential vascular thrombosis and revision of the microanastomosis. If discovered early, there is a high likelihood of correcting the problem.

PROCEDURE-SPECIFIC COMPLICATIONS

The latissimus dorsi muscle flap will weaken arm adduction but is generally tolerated well. Seroma is common after latissimus dorsi muscle transposition and is best treated with serial aspiration and/or drain reinsertion. Pectoralis muscle flaps will cause some weakness in adduction and internal rotation of the arm. The turnover flap can cause a significant contour deformity. Because of the nature of omental flaps, bowel obstruction, herniation, and abdominal dehiscence can occur. For infections of the chest, the most common complication seen is inadequate debridement of necrotic bone or cartilage fragments, which leads to recurrent infection.

SUMMARY

Chest wall reconstruction requires a multidisciplinary approach to patient selection and operative intervention, as well as close postoperative monitoring. Thoracic reconstruction allows treatment of large and complex defects. The combination of new technology such as advanced biomaterials, free-tissue transfer, advanced wound care modalities, and vascularized tissue transfer has allowed these defects to be treated routinely with low morbidity and mortality. The complexity of these operations requires a team approach including a cardiac or thoracic surgeon, a plastic surgeon, and intensive care specialists to provide advanced life support measures in the postoperative period. Advances in plastic surgery, including better understanding of anatomy, improved biomaterials, and tissue-engineered solutions, have made pedicled flap closure of most of these defects quite reliable. Free-tissue transfer is sometimes needed but generally can be avoided by using local or regional flaps.

CASE HISTORY

A 57-year-old woman presented with hemoptysis of 4 months' duration after an extrapleural pneumonectomy for malignant pleural mesothelioma. Findings on bronchoscopy and chest radiography were consistent with a small bronchopleural fistula (Fig. 117-4A ). The patient was able to tolerate a single-stage procedure using a combination of latissimus dorsi, serratus anterior, pectoralis major, and omental flaps that were used to fill the cavity (see Fig. 117-4B, C ).

EDITOR'S COMMENT

Many thoracic surgeons choose to do their own muscle or omental flaps and plastic surgery consultation may not be necessary. At the end of the day, regardless of who harvests the flaps, the goals are the same: total coverage of the defect with a viable flap that provides coverage, support, cosmesis, function, and decreased infection risk. When more complex flaps are needed, as is the case for esophageal reconstruction, plastic surgery participation is mandatory.

–LZ

REFERENCES