Reconstruction of the chest

10 Reconstruction of the chest






Introduction


Common etiologies for chest wall defects include tumor resection, deep sternal wound infections, chronic empyemas, osteoradionecrosis and trauma. Although each mechanism carries individual nuances, they will all require adequate debridement and, when possible, replacement of like with like. Fundamentally, the chest wall must be restored for the protection of underlying viscera, maintenance of respiratory mechanics, and base for the upper limb and shoulder.


Chest wall reconstruction can be generalized to include skeletal support and soft tissue cover. Skeletal support to prevent paradoxic chest wall motion is usually required when the defect exceeds 5 cm in diameter. Generally, this corresponds to those defects exceeding a two rib resection. This rule of thumb, however, is somewhat region dependent (Table 10.1). Posterior chest wall defects may tolerated up to twice the size of those in the anterior and lateral chest due to scapular coverage and support1,2 Anecdotally, patients who have undergone radiation and have decreased chest wall compliance will tolerate larger resections without skeletal replacement due to an overall fibrosis of their viscera.


Table 10.1 Regions of the chest wall












Anterior Between anterior axillary lines
Lateral Between anterior and posterior axillary lines
Posterior Between posterior axillary lines and the spine

Options for skeletal support include various mesh products including PTFE (Gore-Tex®), polypropylene, Mersilene (polyethylene-terephthalate)/methylmethacrylate,3 and acellular dermal matrix (Fig. 10.1). Furthermore, use of TFL as both graft and flap reconstruction has been described. Little data exists as to outcome comparisons between these options. However, in a retrospective review of 197 patients, PTFE and polypropylene appear to be equivalent in complications and outcomes.1 Another smaller retrospective review of 59 patients prefers Mersilene-methylmethacrylate sandwich to PTFE due of decreased paradoxic chest wall motion.4 As alloplastic implants trend towards an increased infection rate when compared with autogenous material or acellular dermal matrix, the authors prefer to avoid mesh when possible.



Chest wall reconstruction almost always requires some form of soft tissue coverage as very few defects will close primarily. Reconstructive goals include wound closure with maintenance of intrathoracic integrity, restoration of aesthetic contours, as well as minimization of donor site deformity.


Recruitment of local muscles with or without overlying skin is often the first-line of reconstructive offense. These muscles include pectoralis major, latissimus dorsi, serratus anterior, and rectus abdominus. The omentum may also be used. Commonly the ipsilateral latissimus muscle is divided during thoracotomy incisions and the authors encourage early communication between surgeons if there are multiple teams in order to mitigate against routine division. Muscle sparing thoracotomies help to preserve both the latissimus and serratus muscles while providing adequate intrathoracic access (Fig. 10.2).




Common flaps for reconstruction



Pectoralis major


Pectoralis major, a muscle overlying the superior portion of the anterior chest wall, is the workhorse for chest wall reconstruction, especially for defects of the sternum and anterior chest. Its main function is to internally rotate and adduct the arm. Additionally, this muscle serves as the foundation for the female breast and when absent, such as in Poland’s syndrome, reconstruction may be indicated for aesthetic reasons (Fig. 10.3). It originates from the sternum and clavicle and inserts along the superomedial humerus in the bicipital groove. Its dominant pedicle is the thoracoacromial trunk which enters the undersurface of the muscle below the clavicle at the junction of its lateral and middle third. Segmental blood supply is derived from internal mammary artery (IMA) perforators. Based on the thoracoacromial blood supply, it will easily cover sternal and anterior chest wall defects as an island or advancement flap. Division of the pectoralis major muscle insertion can also aid in advancing the muscle flap into a properly debrided mediastinal wound. The muscle can also be turned over based on the IMA perforators and with release of its insertion, cover sternal, mediastinal, and anterior chest wall defects. Importantly, when used as a turnover flap, the internal mammary vessels and their perforators must be examined and deemed intact particularly in the setting of post-sternotomy mediastinitis. This vessel may be absent (left more commonly used than right) due to harvest for coronary artery bypass grafting or damaged during wide debridement of a post-sternotomy wound. The muscle may also be placed intrathoracically, however, this will necessitate resection of a portion of the 2nd, 3rd, or 4th rib (Fig. 10.4). The muscle may be harvested with or without a skin paddle. Donor site deformity including scar placement and loss of anterior axillary fold may be aesthetically displeasing.5





Latissimus dorsi


Latissimus dorsi, a large, flat muscle covering the mid and lower back is often recruited for chest wall reconstruction especially when significant bulk and mobility is required. It is easily placed into the chest for intrathoracic space-filling. It is known as the climbing muscle and adducts, extends, and internally rotates the arm. It originates from the thoracolumbar fascia and posterior iliac crest and inserts into the superior humerus at the intertubercular groove. Superiorly, it is attached to the scapula and care must be taken to carefully separate this muscle from the serratus at this point to avoid harvesting both muscles. Its dominant blood supply is the thoracodorsal artery which enters the undersurface of the muscle five centimeters from the posterior axillary fold.6 Segmental blood supply is derived from the posterior intercostals arteries as well as the lumbar artery. Based upon its thoracodorsal pedicle, the muscle can easily reach the ipsilateral posterior and lateral chest wall, including those defects involving either the anterior chest wall, sternum, or mediastinum. It can also be turned over and based upon the lumbar perforators. In this fashion, it can reach across the midline back. Again, it can be moved intrathoracically with rib resection. Donor site morbidity can include shoulder dysfunction, weakness and pain, as well as unattractive scarring.7 However, our experience suggests these concerns are minimal. Also, transposition of this muscle can blunt or obliterate the posterior axillary fold, resulting in some asymmetry (Figs 10.5, 10.6).5 Care must be taken to properly drain the donor site, as seromas are common. Quilting or progressive tension sutures may mitigate against seroma formation.







Omentum


The omentum is comprised of visceral fat and blood vessels which arises from the greater curve of the stomach and is also attached to the transverse colon. This flap can easily cover wounds in the mediastinum, anterior, lateral and posterior chest wall. It has two dominant pedicles, the right and left gastroepiploic arteries. The greatest benefit of this flap is the pedicle length, which can be easily elongated with division of internal arcades. The flap is mobilized onto the chest or into the mediastinum through the diaphragm or over the costal margin. Ideally, the flap is mobilized through a cruciate incision in the right diaphragm as the liver helps to buttress the incision and prevent diaphragmatic hernia. Furthermore, right-sided transposition obviates the need to navigate the flap around the heart. Care must be taken when interpolating the omentum as it is often of very little substance and can easily be avulsed during passage through the diaphragm. Strategies to protect the omentum during transposition include placing the omentum into a bowel bag. The empty bag can be passed from the mediastinum into the abdomen via the diaphragm incision, past the left lobe of the liver. The omentum is then gently packed into the bowel bag with tension transferred to the bowel bag rather than the omentum during interpolation. Caution is again advised for patients with prior laparotomy incisions as the omentum may have significant intra-abdominal adhesions or have been previously resected (Figs 10.9–10.11).5






History


Throughout history, the ability to perform surgical resections has been limited by their survivorship. Chest wall resections, in particular, were difficult given the intimate relationship of the chest to vital structures beneath – the heart, lungs, and great vessels. In particular, sequelae such as pneumothorax were exceptionally challenging for surgeons in the era preceding positive pressure ventilation and tube thoracostomy.


Despite adversity, however, and as early as 1906, the latissimus dorsi was used for chest wall coverage following radical mastectomy.8 This was similarly performed by Campbell in 1950.9 The earliest use of fascia lata grafts appears in 1947.10 Axially-based flaps regained popularity in the 1970s and in 1986, Pairolero and Arnold published their series of 205 patients managed with muscle flaps purporting their safety and durability.11


As surgical advances and innovations were made, the sequelae of postoperative infection followed close behind. Interestingly, the treatment of mediastinal infection has changed dramatically since the first description of the sternotomy incision in 1957.12 Open chest drainage fell out of favor quickly due to exposure of heart and mediastinum and subsequent risk of rupture. Mortality rates were as high as 50% with open packing.13 Throughout the 1960s, closed chest drainage with antibiotic catheter irrigation was advocated as the first-line therapy for deep sternal wound infections.14,15 This innovative technique reduced mortality to approximately 20%.16 Then, in 1980, Jurkiewicz published a landmark paper revealing debridement and muscle flap coverage was significantly more successful than antibiotic catheter drainage alone.17 This advancement further reduced mortality rates to 10%.18 In recent times, mediastinitis treatment has advanced to include subatmospheric pressure wound therapy and rigid fixation of residual sternal bone. These techniques address the loss of chest wall integrity, paradoxic chest wall motion, and chronic pain.19,20



Patient selection/approach to patient


The importance of a multidisciplinary approach to chest wall reconstruction cannot be underestimated. These patients, whether suffering from malignancy, infection, or trauma, are often also plagued with cardiac or respiratory insufficiency, diabetes, obesity, malnutrition, and generalized deconditioning. Thorough work-up including pulmonary function testing, physical therapy and nutritional assessment, and preoperative control of blood sugar may optimize outcomes. Furthermore, communication between referring surgeon and reconstructive plastic surgeon is crucial for properly defined preoperative reconstructive expectations as well as incision planning. For example, it may be advantageous to spare chest wall musculature, such as the latissimus dorsi, during thoracotomy.


Acquired chest wall deformities are commonly the result of iatrogenic injury. Usually encountered in conjunction with cardiac or thoracic surgery, wound infections, mediastinitis, osteoradionecrosis, refractory empyema and bronchopleural fistulas, can all necessitate chest wall reconstruction.

Feb 21, 2016 | Posted by in General Surgery | Comments Off on Reconstruction of the chest
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