Partial diaphragmatic resections are necessary to remove tumors that have invaded a portion of the diaphragm. The redundancy of the muscle frequently permits primary repair for small to modest resections. Larger defects are easily repaired with the use of a mesh or impermeable graft sutured to the remnant of muscle. We use mesh for patients with lung tissue remaining in the ipsilateral hemithorax, but impermeable grafts for patients who have had a pneumonectomy. The impermeable patches prevent fluid shifts between the thorax and abdomen.
Complete diaphragmatic resection may be required for large tumors invading the diaphragm, such as lung cancer of the lower lobe or sarcomas of the chest. We have gained extensive experience with complete diaphragmatic resection in the course of developing the extrapleural pneumonectomy for mesothelioma.5
An extrapleural pneumonectomy is the complete removal of the pleural envelope and all its contents, including the ipsilateral lung, lateral pericardium, and underlying diaphragm. Because the pleura cannot be separated from the central tendon of the diaphragm, the diaphragm must be resected if the pleural envelope is to be kept intact during removal.
Diaphragmatic resection begins with the traction of the pleura away from the chest wall deep into the diaphragmatic sulcus. This exposes the bare area of the lateral diaphragm where the pleura folds off the ribcage and back onto the upper surface of the diaphragm (see Fig. 149-11). The division of these lateral radial bands of the fan-shaped portion of the diaphragm is started at the most anterior portion of the chest close to the pericardium. The fingers of the surgeon bluntly dissect the peritoneum from beneath the muscle, then pull the fibers taut to facilitate visualization. The muscle is generally divided with cautery. It is not unusual for the posterolateral portion of the diaphragm to be beyond the direct vision of the surgeon. Fibers in this area can be bluntly avulsed with minimal risk of bleeding. Once the ligamentum arcuatum externum (external arcuate ligament) is reached in the paravertebral sulcus, the perinephric fat of Gerota fascia, and not the peritoneum, is directly beneath the fan-shaped muscle. This part of the dissection quickly progresses to the lateral margin of the crus. The diaphragm can then be separated from the peritoneum up toward the lateral border of the pericardium. Defects in the peritoneum are closed as they are recognized.
The phrenic nerve is divided. The trileaflet of the diaphragmatic tendon is divided along the line demarcating the central tendon of the ipsilateral muscle from the tendon lying beneath the pericardium. This cut is made medial to the insertion of the phrenic nerve into the anterior muscle. This medial cut is extended along the fused portion of diaphragmatic tendon and pericardium to the inferior vena cava on the right, or the esophageal hiatus on the left.
The only attachment of the diaphragm remaining is the crus. Blunt dissection of the pleura of the deep diaphragmatic sulcus needs to be completed before division of the crus to prevent buttonholing the inferior extent of the posterolateral pleura.
The superior phrenic arteries are surgically inconsequential and rarely identified. The inferior phrenic vessels, however, lie on the deep surface of the crus and are easily seen and ligated. These vessels may bifurcate low over the crus, and a second branch may therefore be found after ligation of a branch thought to be the main trunk. The left inferior phrenic vein usually has two branches, one of which drains into the left renal or suprarenal vein and another that passes anterior to the esophageal hiatus and empties into the inferior vena cava. The right inferior phrenic vein empties directly into the inferior vena cava and therefore requires careful dissection and ligation. Vigorous lateral traction can avulse this vessel from the inferior vena cava, close to the insertion of the hepatic veins. Once these vessels have been divided, the crus is easily divided. This completes the diaphragmatic resection.
The postpneumonectomy space fills with fluid. To prevent fluid shifts between the thorax and abdomen, we use a 2-mm impermeable Gore-Tex prosthetic patch to reconstruct the resected diaphragm. This patch prevents herniation of abdominal contents into the chest, holds the abdominal viscera out of the thoracic radiation field, and also bolsters the contralateral diaphragm by fixing the medial edge of the fan into place. This then facilitates the function of the opposite diaphragm by allowing its central tendon to become the anchor point for the lateral fan fascicles. Without patching the ipsilateral diaphragmatic defect, the contralateral muscle function is compromised.
After the patch has been cut to the shape of the removed diaphragm, the medial edge is sewn to the pericardial tendon with a soft nonabsorbable stitch. We prefer 0-Ethibond for this suture. This suture line runs from the free edge of the divided anterior fan muscles, along the pericardial edge, to either the inferior vena cava or esophageal hiatus. A reliable lateral anchorage system has been devised, requiring a sterilized leatherworking awl. Loops of suture material that have been passed through the lateral edge of the patch are then brought through the chest wall with the awl. The sutures are then passed through a small postage stamp–sized patch of the same material, as well as a sterile plastic button, with the assistance of two angiocaths. The loop of suture is then tied down to itself onto the button, resulting in excellent lateral displacement of the patch.
The posterior mediastinum between the thoracic spine and the inferior vena cava or esophagus is the area where patch ruptures occur, with abdominal contents herniating into the chest. This is due to a lack of strong mediastinal tissue available to anchor the patch. Our group of surgeons have developed the following three potential solutions: (1) a suture anchoring the patch to the anterior spinal ligament, (2) a tongue of extra patch material folded inferiorly along the lumbar spine in simulation of the diaphragmatic crus, and (3) a composite of two patches of 2-mm Gore-Tex stapled together in the middle with a thoracoabdominal (TA) stapler to create a dynamic patch at the center with less tension at the lateral suture lines. The first technique uses the dense spinous ligament to anchor the posterior mediastinal portion of the patch and decreases the free defect between the anterior suture line at the inferior vena cava and the thoracic spine to a few centimeters. The second technique allows the medial portion of the patch to partially displace into the chest, but prevents visceral herniation unless the entire tongue becomes displaced into the chest. The last technique allows the prosthetic patch to “give” without rupture if the patient experiences abdominal distention.