© 2006 WebMD, Inc. All rights reserved.                                                       ACS Surgery: Principles and ...
© 2006 WebMD, Inc. All rights reserved.                                                       ACS Surgery: Principles and ...
© 2006 WebMD, Inc. All rights reserved.                                                  ACS Surgery: Principles and Pract...
© 2006 WebMD, Inc. All rights reserved.                                                       ACS Surgery: Principles and ...
© 2006 WebMD, Inc. All rights reserved.                                                     ACS Surgery: Principles and Pr...
© 2006 WebMD, Inc. All rights reserved.                                                         ACS Surgery: Principles an...
© 2006 WebMD, Inc. All rights reserved.                                                                         ACS Surger...
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Acs0415 Diaphragmatic Procedures

  1. 1. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 4 THORAX 15 DIAPHRAGMATIC PROCEDURES — 1 15 DIAPHRAGMATIC PROCEDURES Ayesha S. Bryant, M.S.P.H., and Robert James Cerfolio, M.D., F.A.C.S., F.C.C.P. Although the diaphragm is sometimes thought of as little more drainage occurs via the inferior vena cava and the azygos vein on than a partition between the thoracic organs and the abdominal the right and via the suprarenal and renal veins and the hemiazy- organs, it is in fact a dynamic anatomic structure that plays a piv- gos vein on the left. otal role in the physiology of respiratory mechanics. For example, INNERVATION paralysis of just one hemidiaphragm can lead to the loss of 50% of a patient’s vital capacity.1 Like any other anatomic structure, the The diaphragm receives its muscular neurologic impulse from diaphragm may be affected by either benign or malignant condi- the phrenic nerve, which arises primarily from the fourth cervical tions. Overall, benign diseases of the diaphragm (e.g., paralysis) ramus but also has contributions from the third and fifth rami. are far more common than malignant ones. With either type of The phrenic nerve originates around the level of the scalenus ante- condition, however, the development of a safe surgical treatment rior and runs inferiorly through the neck and thorax before reach- strategy depends on a solid knowledge of diaphragmatic anatomy ing its terminal point, the diaphragm. Because the phrenic nerve and physiology. Accordingly, we begin with a brief review of the follows such a long course before reaching its final destination, a embryology and anatomy of the diaphragm.We then describe the number of processes can disrupt the transmission of neurologic main procedures performed to treat the more common congeni- impulses through the nerve at various points and thereby cause tal diseases (e.g., congenital diaphragmatic hernia [CDH]) and diaphragmatic paralysis [see 4:6 Paralyzed Diaphragm]. acquired pathologic conditions (e.g., paralysis and tumor) that affect this structure. Procedures for Congenital Diaphragmatic Hernia Anatomic Considerations REPAIR OF BOCHDALEK HERNIA Bochdalek hernia, named after the Czech anatomist Vincent DEVELOPMENTAL ANATOMY Alexander Bochdalek, is the most common form of CDH and is The diaphragm is a modified half-dome of musculofibrous tis- also the most common surgical emergency in neonates.1 The usual sue that lies between the chest and the abdomen and serves to sep- presenting symptoms are severe respiratory distress and a scaphoid arate these two compartments. It is formed from four embryolog- ic components: (1) the septum transversum, (2) two pleuroperi- Sternal Portion Esophagus toneal folds, (3) cervical myotomes, and (4) the dorsal mesentery. Inferior Development of the diaphragm begins during week 3 of gestation Vena Cava and is complete by week 8. Failure of the pleuroperitoneal folds to Costal Rib develop, with subsequent muscle migration, results in congenital Portion defects. CLASSICAL ANATOMY The diaphragmatic musculature originates from the lower six ribs on each side, from the posterior xiphoid process, and from the external and internal arcuate ligaments. A number of different structures traverse the diaphragm, including three distinct aper- tures (foramina) that allow the passage of the vena cava, the esoph- agus, and the aorta [see Figure 1].The aortic aperture is the lowest and most posterior of the diaphragmatic foramina, lying at the level of the 12th thoracic vertebra. Besides the aorta, the thoracic duct and, sometimes, the azygos and hemiazygos veins also pass through this aperture.The esophageal aperture is the middle fora- men; it is surrounded by diaphragmatic muscle and lies at the level of the 10th thoracic vertebra.The vena caval aperture is the high- est of the three foramina, lying level with the disk space between T8 and T9. Lumbar Portion Tendon VASCULAR SUPPLY The diaphragm is supplied by the right and left phrenic arter- ies, the intercostal arteries, and the musculophrenic branches of the internal thoracic arteries. Some blood is supplied by small Spine Aorta branches of the pericardiophrenic arteries that run with the phrenic nerve, mainly where the nerves penetrate the diaphragm. Venous Figure 1 Shown is an inferior view of the diaphragm.
  2. 2. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 4 THORAX 15 DIAPHRAGMATIC PROCEDURES — 2 Preoperative Evaluation abdomen. The primary pathologic condition is the presence of posterolateral defects of the diaphragm, which result either in On chest radiography, a Morgagni hernia appears as a mass at maldevelopment of the pleuroperitoneal folds or in improper or the right cardiophrenic angle [see Figure 2]. Computed tomogra- absent migration of the diaphragmatic musculature. phy of the chest and abdomen, liver scintigraphy, and multiplanar Bochdalek hernias occur in approximately one of every 2,500 magnetic resonance imaging are occasionally helpful in the diag- live births and are twice as common in male neonates as in female nostic process. neonates. Mortality ranges from 45% to 50%. The bulk of the Operative Technique morbidity and mortality of CDH is attributable to the resultant hypoplasia of the lung on the affected side and to various associ- Morgagni hernias can be repaired via a subcostal, a paramedi- ated abnormalities (e.g., malrotation of the gut, neural tube defects, an, or a midline incision. We prefer to use an upper midline and cardiovascular anomalies). abdominal incision. Once the peritoneal cavity is entered, the her- nia sac is identified just posterior to the xiphoid and the posterior Preoperative Evaluation sternal border, then opened. The herniated abdominal viscera are Prenatal ultrasound examination accurately diagnoses CDH in restored to their normal abdominal anatomic positions, and the 40% to 90% of cases.2 In most instances, the examination is per- sac is ligated.The entire hernia sac is defined, resected, and closed. formed to rule out polyhydramnios. It is noteworthy that polyhy- The diaphragmatic defect may be repaired in several different dramnios is present in as many as 80% of pregnant women whose ways, depending on its size and position. Because there is weak tis- fetuses have CDH.3 In neonates with CDH, besides the upper sue in the area of the defect, we generally use a prosthetic patch for gastrointestinal tract, parts of the colon, the spleen, the kidneys, the repair. Either polypropylene mesh (e.g., Marlex; C. R. Bard, and the pancreas may herniate, and the abnormal position of Inc., Murray Hill, New Jersey) or polytetrafluoroethylene (PTFE) these organs can be identified by means of ultrasonography. Mal- mesh (e.g., Gore-Tex; W. L. Gore and Associates, Newark, Del- rotation and malfixation of the small bowel should be ruled out. aware) may be used for this purpose. We prefer PTFE because it Once the diagnosis is confirmed, additional radiographic, echo- may cause fewer adhesions to the underlying abdominal structure, cardiographic, and ultrasonographic studies should be performed which may be an important consideration if further abdominal to rule out associated anomalies. surgery subsequently proves necessary. The prosthetic patch is sewn to the midline abdominal fascia, with wide bites taken to pre- Operative Technique vent an abdominal incisional hernia.The rest of the patch is sewn to the thickened investing fascia that made up the edges of the her- As a rule, neonates with Bochdalek hernias are taken to the oper- nia sac. As noted, the frequently marginal quality of this tissue is ating room immediately after birth. Some studies, however, have the reason why a patch repair is almost always required. shown that delayed surgical repair yields improved survival rates.4 Repair of a Morgagni hernia via a thoracic incision follows the For left-side hernias, a transabdominal subcostal approach is same basic principles.The hernia sac is entered, the visceral con- generally preferred, whereas for right-side hernias, a transthoracic tents are mobilized and reduced into the abdomen, the sac is approach may be more useful.The herniated organs are returned resected, and the diaphragm is repaired. Again, the closure should to the peritoneal cavity. The lung is inspected, but no attempt to be completed without tension. If the defect cannot be closed with expand the hypoplastic lung should be made. If any extralobar horizontal mattress sutures, a prosthetic patch should be used. pulmonary sequestration is present (as is occasionally the case), it should be excised. Most of the defects may be closed primarily Complications with interrupted nonabsorbable sutures; particularly large defects The potential complications of surgical treatment of Morgagni may be closed with a prosthetic patch. The left pleural space is hernia depend to an extent on the type of procedure undertaken drained with a chest tube, which should be placed on water seal. to repair the defect. Laparoscopy may result in failure to reduce the contents of the hernia sac, which necessitates conversion to an Alternative technique Some surgeons have attempted sur- open procedure. Laparotomy has been associated with postoper- gical correction of severe Bochdalek hernias in the prenatal period. ative pleural effusion,9 wound infection,10 deep vein thrombosis,11 The safety and feasibility of this therapeutic approach continue to and pulmonary embolism.12 Thoracotomy has been associated be debated. Prenatal correction of these hernias poses a risk to both with pneumonia, sepsis, and bowel obstruction in the postopera- the mother and the fetus, with possibly fatal results for both.5 tive period.13 REPAIR OF MORGAGNI HERNIA Outcome Evaluation Morgagni hernias, named after the Italian anatomist and pathol- Most patients do not have any significant postoperative limita- ogist Giovanni Battista Morgagni, are related to maldevelopment tions after repair of a Morgagni hernia, nor are such hernias like- of the embryologic septum transversum and to failed fusion of ly to recur. In one study, 16 patients who underwent transthoracic the sternal and costal fibrotendinous elements of the diaphragm.6 repair of a Morgagni hernia were followed for 5.7 years; no recur- These hernias are generally asymptomatic7 and are usually detect- rences or symptoms related to the operation were reported.14 ed as incidental findings on radiographs. Accordingly, the average age at diagnosis is typically greater for Morgagni hernia than for Bochdalek hernia: in one report, the mean age at which the for- Procedures for Diaphragmatic Paralysis mer was diagnosed was 45 years.8 Morgagni hernias are most The diaphragm is the most important of the respiratory mus- commonly seen on the right side.The hernia sac usually contains cles: diaphragmatic contraction decreases intrapleural pressure dur- omentum, but it may also contain part of the transverse colon ing inspiration, expands the rib cage, and thereby facilitates the move- or, less commonly, parts of the stomach, the liver, or the small ment of gases into the lungs. Accordingly, paralysis of the dia- bowel; almost any upper abdominal structure may herniate in this phragm can have a major adverse effect on respiratory function setting. [see 4:6 Paralyzed Diaphragm]. Diaphragmatic paralysis may involve
  3. 3. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 4 THORAX 15 DIAPHRAGMATIC PROCEDURES — 3 a b Figure 2 Repair of Morgagni hernia. The differential diagnosis of a cardiophrenic-angle mass includes pericardial fat, a lipoma, a pericardial cyst, a Morgagni hernia, and a thymoma. Shown are (a) chest x-rays and (b) chest CT scans from a 33-year-old man with an incidental finding of a Morgagni hernia. either the whole diaphragm (bilateral paralysis) or only one leaflet In most cases, the diagnosis of hemidiaphragmatic paralysis is or hemidiaphragm (unilateral paralysis). The possible causes of suspected on the basis of incidental findings on a chest x-ray. diaphragmatic paralysis are numerous [see Table 1]; the most com- Typically, the roentgenogram reveals an elevated hemidiaphragm, mon causes are phrenic nerve trauma related to a surgical proce- diminished lung volume, and basilar atelectasis. Fluoroscopy may dure (e.g., stretching, crushing, or transection) and invasion by a also be performed. The diagnosis is confirmed by performing a malignant neoplasm. fluoroscopic sniff test, in which paradoxical elevation of the para- lyzed diaphragm is observed with sniffing.15 The sniff test is the DIAPHRAGMATIC PLICATION FOR UNILATERAL PARALYSIS gold standard for the diagnosis of this condition. In certain pa- tients, a chest CT scan may be indicated for evaluating the poten- Preoperative Evaluation tial cause of the paralysis. If an obvious cause is not apparent from With unilateral diaphragmatic paralysis, the paralyzed the history or a previous evaluation, CT scanning of the chest hemidiaphragm paradoxically moves upward on inspiration and should be performed to ensure there is no pathologic process that downward on expiration, passively following changes in is compressing or invading the phrenic nerve. Similarly, MRI of intrapleural and intra-abdominal pressure. Patients with a par- the neck or the spine may be indicated in certain patients to look alyzed hemidiaphragm who are otherwise healthy usually have for conditions that might be causing the diaphragmatic paralysis. no symptoms at rest but experience dyspnea during exertion Two other tests that are also (albeit less commonly) used for the and show a decrease in exercise performance. Physical exami- diagnosis of unilateral diaphragmatic paralysis are electromyogra- nation may reveal dullness to percussion and an absence of phy and transdiaphragmatic pressure assessment. In the first, the breath sounds over the lower chest on the involved side. phrenic nerve is electrically stimulated in the neck in an effort to
  4. 4. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 4 THORAX 15 DIAPHRAGMATIC PROCEDURES — 4 Operative Technique Table 1 Common Causes of Diaphragmatic Paralysis Diaphragmatic plication may be performed with either sutures or staples; we prefer sutures for this procedure. The chest is Spinal cord transection entered through a thoracotomy in the seventh or eighth intercostal Multiple sclerosis space. Horizontal mattress sutures buttressed with Teflon pledgets Amyotrophic lateral sclerosis are then placed in a lateral-to-medial direction [see Figure 3]. We Cervical spondylosis typically use monofilament nonabsorbable sutures that pass easily Poliomyelitis through the muscle and can be tightened without dragging through Guillain-Barré syndrome tissue. To distribute the tension, multiple sutures must be placed; Phrenic nerve dysfunction Neurologic conditions this is especially important on the right side, where the diaphragm Compression by tumor Cardiac surgery cold injury must be pulled down against the upward force exerted by the pres- Blunt trauma ence of the right hemiliver.When the sutures are tied, the hemidi- Idiopathic phrenic neuropathy aphragm should be almost back to its normal anatomic location. Diabetes mellitus Care must be taken to ensure that the repair is not under undue Postviral phrenic neuropathy (herpes zoster) tension: excessive tension is likely to result in early dehiscence. Radiation therapy Occasionally, a prosthetic patch may be used to buttress the repair Cervical chiropractic manipulation further, but in the majority of cases, this measure should be unnec- Limb-girdle dystrophy essary. If the choice is made to use staples rather than sutures, care Hyperthyroidism/hypothyroidism must be taken to ensure that the underlying abdominal contents Malnutrition are not caught in the staple line. Acid maltase deficiency Connective tissue disease DIAPHRAGMATIC PACING FOR BILATERAL PARALYSIS Myopathic conditions Systemic lupus erythematosus Dermatomyositis Preoperative Evaluation Mixed connective tissue disease Amyloidosis In patients with bilateral diaphragmatic paralysis, the respirato- Idiopathic myopathy ry accessory muscles assume all the work of breathing by con- Muscular dystrophy tracting more intensely. Both hemidiaphragms move upward on Multiple sclerosis inspiration, concomitant with inward (rather than the normal out- ward) movement of the abdominal wall.17 Patients typically pre- sent with severe respiratory failure or with dyspnea (sometimes misinterpreted as a sign of heart failure) that worsens in the supine distinguish between neuropathic and myopathic causes of paraly- position, and they generally exhibit tachypnea and rapid, shallow sis. In the second, transdiaphragmatic pressures are measured by placing a thin-walled balloon transnasally at the lower end of the esophagus in such a way as to reflect changes in pleural pressure; a second balloon manometer is then placed in the stomach in such a way as to reflect changes in intra-abdominal pressure. The dif- ference between the two pressures is the transdiaphragmatic pres- sure. Measurement of transdiaphragmatic pressure can help dif- ferentiate diaphragmatic paralysis from other causes of respiratory failure. Yet another test involves measurement of maximal inspiratory pressures. Patients with diaphragmatic dysfunction and paralysis show a decrease in their maximal inspiratory pressures. These patients cannot generate high negative inspiratory pressures, and thus, their maximal inspiratory pressures will be less negative than –60 cm H2O. Operative Planning Surgical treatment of hemidiaphragmatic paralysis is reserved for symptomatic patients who, after a follow-up period of at least 6 months, have persistent shortness of breath with exertion that is sufficiently pronounced to interfere with lifestyle. For a patient to be considered for operation, the sniff test should show significant paradoxical motion. The basic principle of the surgical procedure is to “reef” (i.e., reduce the surface area of) the redundant floppy diaphragm by plicating it. This measure lowers the resting position of the hemidiaphragm and thus affords the lung the opportunity to expand fully. The effective result is an increase in the functional vital capacity of the ipsilateral lung. A 2002 study found that pli- Figure 3 Diaphragmatic plication. Shown is suture plication of cation of the diaphragm led to long-term improvements in pul- the right hemidiaphragm. Placement of sutures buttressed with monary function test results, as well as reduced dyspnea.16 pledgets extends anteriorly to the level of the vena cava.
  5. 5. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 4 THORAX 15 DIAPHRAGMATIC PROCEDURES — 5 External Internal anterior horn cells in the nerve roots, diaphragmatic pacing is fea- Receiver and sible only when the lesion is above the C2-C3 level. Accordingly, Electrode Antenna it is sometimes employed in patients with high spinal cord injuries. Phrenic To date, only one pacing device has been approved by the Food Nerve and Drug Administration: the Mark IV Breathing Pacemaker System (Avery Biomedical Devices, Commack, New York). This device possesses an internal component and an external compo- nent [see Figure 4]. The internal component is surgically placed adjacent to the skeletonized phrenic nerve and is connected to a small, wafer-shaped receiving unit placed under the skin. A bat- tery-powered external transmitting box connected to an antenna is taped over the surface of the skin, just above the subcutaneous receiver. This transmitting box permits adjustment of pulse dura- tion, pulse train duration, respiratory rate, pulse frequency, and current amplitude. In most patients, the only parameters that the clinician adjusts are current amplitude and respiratory rate. Implantation of a diaphragmatic pacer requires significant ex- perience on the part of the surgeon—not so much because of any particular technical demands imposed by the implantation itself but because of the procedures for diaphragm training that must be Diaphragm carried out in the postoperative period. Mark IV Choice of surgical approach Surgical implantation of a diaphragmatic pacer can be done via either a cervical approach or a thoracic approach. The primary advantage of the cervical ap- proach is that it avoids the morbidity associated with bilateral tho- racotomies, which may not be well tolerated in patients who have marginal pulmonary function or a history of severe pulmonary con- tusions. However, there are other ways of avoiding this morbidity, such as using video-assisted thoracoscopic surgery (VATS) or per- forming small muscle-sparing, rib-sparing, nerve-sparing thoracot- Figure 4 Diaphragmatic pacing. Shown are internal and external omies.19 One disadvantage of the cervical approach is that in a small pacer connections. percentage of patients, the current amplitude necessary to stimu- late the phrenic nerve results in transmission of the current through the soft tissues.The transmitted current stimulates the functioning breathing when in the recumbent position. Increased expenditure portions of the brachial plexus, causing rhythmic jerking motions of effort in the struggle to breathe may fatigue the accessory mus- of the upper extremities. Another disadvantage is that there are a cles and lead to ventilatory failure. Patients also report anxiety, number of accessory nerve branches arising distal to the neck. insomnia, morning headache, excessive daytime somnolence, One advantage of the thoracic approach is that inadvertent stim- confusion, fatigue, poor sleep habits, and signs of cor pulmonale.18 ulation of portions of the brachial plexus (as sometimes occurs During physical examination, auscultation of the chest reveals with the cervical approach) may be avoided. Another advantage is limitation of diaphragmatic excursion and bilateral lower-chest that there is some neuroanatomic evidence that a small branch of dullness with absent breath sounds. The finding that establishes the phrenic nerve joins the main nerve trunk only after it enters the diagnosis is a paradoxical inward movement of the abdomen the chest cavity; thus, the thoracic approach may stimulate a larg- with inspiration. As with unilateral diaphragmatic paralysis, how- er portion of the phrenic nerve than the cervical approach would. ever, it is more common for the diagnosis to be suspected on the The disadvantage of the thoracic approach is the preconceived basis of a chest roentgenogram that shows bilateral diaphragmat- notion that entry into the chest is associated with a higher mor- ic elevation, then confirmed by means of the sniff test. bidity than entry into the neck. Operative Planning Operative Technique Treatment depends on the cause and severity of the diaphrag- Cervical placement In the neck, the phrenic nerve runs matic paralysis. Most patients are treated with ventilatory support, between the scalenus anterior and the scalenus medius. A trans- but some are treated with bilateral plication or with pacing. Plica- verse skin incision is made in the midportion of the neck, just lat- tion for bilateral paralysis is performed in the same way as plica- eral to the sternocleidomastoid muscle, and the borders of the two tion for unilateral paralysis [see Diaphragmatic Plication for scalene muscles are dissected.The scalene muscles are then divid- Unilateral Paralysis, above], except that both hemidiaphragms are ed, and the phrenic nerve is identified lying in a layer of fascia just lowered. Diaphragmatic pacing is not useful in the treatment of anterior to the anterior surface of the scalenus medius. unilateral diaphragmatic paralysis, because of the difficulty of syn- Identification of this nerve is often facilitated by the use of a hand- chronizing the contractions of the normal hemidiaphragm with held nerve stimulator. Intraoperative fluoroscopy allows observa- those of the paralyzed hemidiaphragm. However, it is sometimes tion of diaphragmatic contraction in response to phrenic nerve an appropriate choice for the treatment of bilateral paralysis, espe- stimulation, which confirms that pacing is successful. cially in patients who have a central condition that is causing their Once the phrenic nerve is identified, it is carefully dissected free apnea. Because the phrenic nerve stimulates the C3, C4, and C5 of its investing fascia, and the Y-shaped electrode is placed under
  6. 6. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 4 THORAX 15 DIAPHRAGMATIC PROCEDURES — 6 a b Right Lower-Lobe Tumor Invading Gore-Tex Patch Diaphragm Figure 5 Resection of diaphragmatic tumor. The patient has a right lower-lobe bronchogenic malignancy with erosion into the right hemidiaphragm. (a) The tumor is resected en bloc with the diaphragmatic fibers; the electrocautery is used to achieve clear surgical margins and hemostasis. (b) The defect in the right hemidiaphragm is closed with a mesh patch. it and secured with sutures. Care must be taken to ensure that the there are several specific complications associated with diaphragmat- nerve is not injured during this step.The connecting wire from the ic pacing.The most common of these are dislodgment of the pacer electrode is then tunneled subcutaneously to a subcutaneous pock- electrode, transmission of pacer impulses to the brachial plexus with et that is created just below the ipsilateral clavicle.The connections resultant rhythmic jerking of the upper extremity (seen with cervical are made and sealed, and the small incisions are closed. placement of the electrode), and hardware malfunction. Thoracic placement In the thoracic approach, the chest is Outcome Evaluation entered through a high thoracotomy (usually over the fourth inter- Retrospective analysis of the collective experience at a single cen- space), and the proximal phrenic nerve is identified. On the right ter between 1981 and 1987 suggested that long-term pacing did not side, the nerve lies along the mediastinum, situated just anterior to lead to progressive diaphragmatic dysfunction.23 Six of the 12 patients the vena cava and coursing along the pericardial surface. On the in this cohort continued to undergo diaphragmatic pacing on a full- left side, it lies on the pericardium for most of its length.The prox- time basis for a median period of more than 14 years. Pacing was imal nerve is freed of its fibrous investments, and the electrode is well tolerated in this group; the reasons for discontinuance included placed under it and secured with sutures. The electrode is con- intercurrent medical illness and lack of social support. Concerns nected to the receiver, which is placed in a subcutaneous pocket. have been raised that prolonged diaphragmatic pacing might dam- As noted (see above), there are alternative approaches to pacer im- age the phrenic nerve. In the series cited, however, the ability to pace plantation that avoid the cervical approach but also do not involve stan- the phrenic nerve was not lost in any of the patients, and the mean dard thoracotomies. For example, there is limited (but growing) ex- threshold currents for pacing did not change significantly over time. perience with thoracoscopic placement of phrenic nerve pacing leads.20 In addition, laparoscopic implantation of intramuscular pacing elec- trodes onto the inferior aspect of the diaphragm has been reported.21 Resection of Diaphragmatic Tumors Taking into account all the advantages and disadvantages of each Primary tumors of the diaphragm are extremely rare. Benign approach to pacer implantation, we generally prefer the thoracic tumors (e.g., lipomas and cystic masses) are more common than approach, either via VATS or via a thoracotomy.20,22 The evolution malignant tumors, which mostly are sarcomas of fibrous or muscu- of less invasive surgical techniques may allow the thoracic approach lar origin.Thoracic and abdominal tumors (e.g., bronchogenic car- to be employed in patients who are unable to tolerate thoracotomy. cinomas, pleural malignancies, and chest wall malignancies [see 4:3 Chest Wall Mass]) may involve the diaphragm secondarily through Complications direct extension. Malignant pleural mesothelioma represents a dif- Besides the usual complications associated with any thoracic pro- ferent scenario and is not discussed here. Schwannomas, chondro- cedure (i.e., infection, bleeding, atrial fibrillation, and pneumonia), mas, pheochromocytomas, and endometriomas have all been re-
  7. 7. © 2006 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 4 THORAX 15 DIAPHRAGMATIC PROCEDURES — 7 ported. Bilateral occurrence, calcification, sharp margins, and flat- the edges of the defect; this prevents the edges from retracting, tened contours are indicative of a malignant process, such as pleur- helps keep the defect as small as possible, and keeps abdominal al metastases, mesothelioma, or a primary diaphragmatic tumor. contents from interfering with the resection. In addition, we place The most common indication for diaphragmatic resection is clips on the edges for guidance purposes, in case adjuvant radio- mesothelioma. This remains true even though mesothelioma is therapy is delivered after the operation. If adequate margins are relatively uncommon in comparison with bronchogenic malig- obtained, which is usually relatively easy in a diaphragmatic resec- nancy and even though few patients with mesothelioma are actu- tion, postoperative radiotherapy should be unnecessary. If, how- ally candidates for resection. Again, resection of a mesothelioma is ever, the tumor abuts vital structures (e.g., the suprahepatic vena not addressed here. The ensuing operative description focuses on cava), postoperative radiotherapy may have a useful role to play. diaphragmatic resection to treat either a lung cancer invading the Once the entire tumor has been resected and clear margins diaphragm or a primary diaphragmatic tumor [see Figure 5]. have been confirmed by frozen-section examination, the diaphragm is reconstructed. Primary repair is rarely indicated, because in most OPERATIVE TECHNIQUE cases, the defect is too large and the tension on the repair would Once the decision is made to resect a tumor involving the be too great. Moreover, the tissue in the anterior aspect of the diaphragm, the key considerations are (1) the surgical approach to diaphragm is thin and is likely to tear under tension. Accordingly, be taken and (2) the placement of the incision in the diaphragm. repair with a prosthetic patch is the usual choice. Infection of such We prefer a skin incision that is lower and slightly more anterior a patch is exceedingly rare, and with the exception of the cost, than a normal posterolateral thoracotomy; such an incision allows there is little downside to the use of prosthetic material in this set- easy entry over the top of the seventh rib. After entry into the chest, ting. As in the repair of a CDH, we prefer PTFE mesh [see Figure the lung, the pericardium, and the pleural surface are carefully vis- 5b] to polypropylene mesh because it is less likely to adhere to ualized and palpated to search for any signs of metastatic disease. underlying abdominal structures. Next, the incision in the diaphragm is planned. Ideally, the inci- The mesh patch is sewn to the edges of the defect (preferably sion should be made anterior or lateral to the tumor so that a hand with nonabsorbable suture material, such as 0 polypropylene), can be placed easily into the peritoneal cavity [see Figure 5a]. Intra- starting at the most anterior and inferior portion of the opening abdominal palpation confirms that the tumor has not extended and continuing toward the surgeon [see Figure 5].The inferior half into underlying structures. This information is almost always of the repair is done with a continuous suture.The repair is com- gleaned from the preoperative CT scan, but if any uncertainty pleted with two or three sutures, which are tied circumferentially. remains after the scan, diagnostic laparoscopy may be performed To prevent paradoxical motion, the diaphragm must not be too before the thoracotomy to look for possible tumor extension. redundant or floppy. It should remain in the normal anatomic The tumor is then resected with 2 to 4 cm margins. The large position so that the remaining lung can expand completely. In arteries that course through the diaphragmatic fibers are ligated. general, however, it is best to keep the repair taut so as to optimize It is our practice also to place a few silk sutures (stay stitches) in pulmonary mechanics after the procedure. References 1. Kirks DR, Caron KH: Gastrointestinal tract. 9. Jani PG: Morgagni hernia: case report. East Afr 18. 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