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MMCTS
(August 10, 2006). doi:10.1510/mmcts.2006.001875 Copyright © 2006 European Association for Cardio-thoracic Surgery Procedure SternotomyHôpitaux Universitaires de Strasbourg, Département de Chirurgie Thoracique, Hôpital Civil, 1 Place de l'Hôpital, 67000 Strasbourg, France * Corresponding author: * Tel.: +33-38-811 6202; fax: +33-38-811 6077. E-mail: gilbert.massard{at}chru-strasbourg.fr
Median sternotomy is one of the most frequent accesses in cardio-thoracic surgery. Surgical techniques, indications and pitfalls of this incision are described.
Key Words: Median sternotomy
In 1957, Julian re-introduced Milton's approach, already described in 1897: the median sternotomy [1]. With the subsequent development of cardiac surgery, median sternotomy became the most common thoracic incision. As we will see in the pitfalls section, this incision does not tolerate any mistakes. Adequate performance of sternotomy does not only reduce the risk for complications, but also facilitates a redo operation at a later date.
Indication In general thoracic surgery, sternotomy is mainly used to resect anterior mediastinal tumors. An increasing popularity has been noted for bilateral pulmonary procedures. Bilateral spontaneous pneumothorax is, however, preferably treated with VATS. The ideal approach for bilateral bullae or bilateral volume reduction surgery is still a matter of debate: while sternotomy is an elegant approach, some colleagues would prefer bilateral VATS or bilateral thoracotomy (simultaneous or sequential). Bilateral exploration for pulmonary metastases is an excellent indication for sternotomy [7,8]. Bilateral lobectomy, or pneumonectomy with radical bilateral lymph node dissection are feasible. On a more extremistic position, Urschel recommended sternotomy for all elective pulmonary procedures except left lower lobe resections, arguing that sternotomy is less painful and less deleterious to lung function than lateral thoracotomies [9]. Sleeve lobectomies have been described by this approach. Median sternotomy gives access to the lower trachea and to both main stem bronchi. Baldwin recommended sternotomy for anterior transpericardial repair of bronchopleural fistulas complicating pneumonectomy. Carinal resections and right carinal pneumonectomy can be safely performed through sternotomy [10,11]. Extended tracheal resections require pneumonectomy to mobilize the hila of the lungs. A final ‘pulmonary’ indication is complex completion pneumonectomy. Sternotomy allows for immediate intrapericardial approach of pulmonary vessels which are divided first. The bronchus may then be exposed by transpericardial dissection. Subsequently, removal of the lung can be achieved safely, be it through the sternotomy or a separate lateral thoracotomy. Partial median sternotomy may be used to expose the lower cervical and upper thoracic oesophagus. Sternotomy combined with left cervicotomy is also used to approach the cervico-dorsal part of the spine. Removal of intrathoracic goiters is most often achieved by simple cervicotomy; on rare occasions, sternal split is required to retrieve the intrathoracic part of the growth. While reporting his experience with carinal resection [12], Pearson points out that this approach has several advantages over a right thoracotomy during right tracheal sleeve pneumonectomy: this incision promotes an adequate exposure for intrapericardial mobilization of the right hilum, which is required to release tension on the tracheo-bronchial anastomosis.
Position
The type of description responds to all-day approach for cardiac procedures. The skin incision is median and vertical, starting just below the sternal notch and extending to the tip of the xyphoid process. The skin incision may be reduced for cosmetic reasons. Adequate exposure of the pericardium can be obtained with a small incision limited to 1 cm in length in the upper part of the linea alba. The pectoral fascia is divided and the periosteum is scored with the electro surgical unit (Video 1). It is very important to divide the interclavicular ligament (Video 2).
The tissues just to one side of the xyphoid process are mobilized (Video 3). Some surgeons prefer to resect the xyphoid process. The sternum may be divided by using either an electric or air-powered saw, with either a right blade or a rotative disc. This vertical and strictly median osteotomy may be performed either from above downwards, or from below upwards (our preference) (Video 4). Once the sternum is split, the two verges are retracted and periosteal bleeding points are controlled with cautery (Video 5). Bone wax may be applied to seal the bone marrow, though some surgeons prefer to simply apply towels
To allow a progressive and homogenous retraction of the sternal verges, the pericardium must be freed from the posterior surface of the sternum by dividing the sternopericardial ligaments, which reduces the incidence of inadvertent pericardial or pleural opening (Videos 6 and 7).
At the end of the procedure, mediastinal drainage tubes are placed through separate stab incisions at the epigastrium (Videos 8 and 9). Should the pleural spaces be drained, 24 Fr tubes (MMCTSLink 98) are placed either through the 5th or 6th intercostal spaces, or through a subcostal tunnel created from a stab wound below the costal arch. Sternotomy closure is accomplished with approximately 6 to 8 parasternal sutures utilizing stainless steel wires or heavy polyglycolic acid sutures (Videos 10,11,12,13).
The ends of the wires are securely twisted and buried into the presternal tissues. The two uppermost wires are placed through the manubrium to avoid injuring the subclavian pedicle. Lower sutures taking the body of the sternum are placed through the intercostal spaces. The pectoral fascia is closed with a running suture. Careful repair of the linea alba is mandatory to avoid incisional hernia. The subcutaneous tissues are closed with running absorbable sutures and the skin is closed at the surgeon's preference (Video 14).
Sternotomy is a risky thoracic incision: there are several pitfalls in this approach because of its role of angle-stone of the chest. Healing of the bone incision occurs under the shearing stress of multiple respiratory movements, culminating with a cough. The skin scar of the usual vertical median sternotomy is a source of concern to some patients, especially young women. Various alternatives have been proposed and the transverse submammary skin incision, described by Laks [13], appears to offer the best cosmetic advantages despite the potential complications originating from a large skin flap (necrosis, seroma). In a straightforward procedure, the skin incision may be reduced to 7 cm, while exposure of the ends of the bone is obtained with a good Farabeuf's retractor (and a strong assistant!) – MMCTSLink 105. The lower extension of skin incision adds few to exposure, but adds a potential for incisional hernia. The first classic pitfall is to leave the midline: cutting the sternochondral cartilage or ribs will be difficult to repair and lead to complex wound complication. Adequate identification of the midline is easy: the surgeon palpates the lateral sternal borders by placing the thumb and the index finger into either intercostal space and marks the periosteum with the cautery in the midline (Video 15).
Special attention must be given to the interclavicular ligament. If one decides to saw from above downwards, it must be divided with the cautery or the scissors before starting to saw. Care must be taken to avoid injury to the classic and annoying jugular veinous arch (a vein of varying size that joins the two anterior jugular veins across the midline) lying in the sternal notch (Video 16). There is the similar vein crossing the upper part of the xyphoid cartilage which will be controlled and sectioned. It seems, therefore, easier to saw from below upwards, and to transect the ligament under smooth retraction of the verges of the sternum that have been cut.
Injury to the inomminate vein or brachiocephalic artery should be avoided by carefully pulling upwards the sternal saw. The same accounts for an ectatic aorta. In case of any doubt, we advise to slide a finger behind the sternal notch for exploratory purposes (Video 17).
Before dividing the sternum with the saw, the anesthetist should stop ventilation to avoid damage to the lung. Some investigations identified the use of bone wax as a risk factor for sternal wound infections. It can be considered as a foreign body with deleterious effects on wound healing [14]. Periosteal hemostasis must be elective: excessive use of cautery leads to necrosis which may jeopardize healing of the sternum and favor infection. Special attention must be taken by retracting edges. Once the sternum is split, the two verges are retracted progressively. Rib fractures and stretching injury of the brachial plexus may occur if the sternal spreader is opened without caution. When opening the retractor, the surgeon should observe tension applied to the innominate vein. Accurate approximation of the bone edges is essential to minimize sternal dehiscence and postoperative pain. The aim is to reduce postoperative override and shift of the sternal verges, and sternal wound complications. Many various recommendations have been published. The best material is the one the surgeon is used to, and the best method is the one which works in the hands of the surgeon. Robicsek proposed to insert one suture per ten kilograms of weight and recommended special maneuvers in risky patients. To be sure to avoid hurting the right ventricle with wires, we always use a surgical towel to protect any risky involuntary wound (Video 18).
When inserting wires in a parasternal fashion, one should be aware of the presence of the internal thoracic pedicle. Any injury must be immediately recognized and controlled because of the risk for postoperative bleeding (and tamponade if the pericardium has been opened). Wires should be embedded into the sternal periosteum to avoid progressive skin erosion. Sternal dehiscence is not exclusively the result of poor operative technique! Poor quality of the bone, as with osteoporosis, is a classic cause of dehiscence [15]. If this type of ‘soft sternum’ is recognized at the time of operation, closure may be reinforced using the Robicsek technique (a vertical wire placed alongside the sternum and woven around the ribs provides additional support). The additional manipulation necessary through the sternotomy approach may cause a hemodynamic problem in elderly patients and those with heart disorders. In the special case of tracheal surgery through median sternotomy, movement of the head and neck should not be restricted by the operative drapes or anesthesia equipment so as to prevent extension or flexion; it is particularly important in the case of tracheal resections in which mobilization of the head may be required. When anatomic lung resections are performed through a sternotomy, it may be helpful to lift up the hilum by packing some gauze pads into the posterior gutter. On the right side, care must be taken to avoid compression of the right atrium. However, both lower lobes, and especially the left, are difficult to handle. In the case of repeat sternotomy, it is preferable to use an oscillating saw. This allows a progressive control of the depth of the sternal bone incision. For the same reason, it is recommended to leave the wires until the bone is transected.
Median sternotomy as a mean of access to the pulmonary hilum was first described by Padhi [16]. Most surgeons are familiar with the surgical technique of sternotomy. The main advantages of median sternotomy are its speed in opening and in closing, its outstanding exposure for all anterior mediastinal lesions. The major problem of this incision in thoracic surgery is the poor exposure of posterior hilar structures, especially those of the left lower lobe. For a long time, sternotomy is renowned to be less painful and to cause a lower decrease of pulmonary function postoperatively in comparison to thoracotomy. In 1978 Cooper and Pearson reported already the usefulness of sternotomy to treat minor bilateral resections, and pointed out a quicker recovery [17]. Pulmonary resection can be performed electively through a median sternotomy. Some authors report a shorter operative time, a decreased postoperative pain and an earlier discharge from the hospital. Urschel [9] identified specific pulmonary procedures for which a lateral thoracotomy remains preferable: resection of a superior sulcus carcinoma, pulmonary resection with chest wall extension, and left lower lobe resection in particular patient populations (obese, cardiomegaly, elevated diaphragm). Recently, the safety and efficacy of median sternotomy in patients with decreased lung function has been evaluated by the NETTRG (National Emphysema Treatment Trial Research Group). In this randomized study, conclusions were that morbidity and mortality were comparable after lung volume reduction surgery by VATS or sternotomy as were functional results. VATS seemed to allow an earlier recovery at a lower cost [18]. However, air-leak persisting for more than 7 days occurred in approximatively half of the patients [19,20,21] and its incidence was higher in VATS patients. Presumably, intraoperative identification of air-leak is more difficult during VATS approach.
"To be well exposed, it's the half of the success of a surgical procedure"
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Introduction
