The abdomen is incised in the midline as for a standard laparotomy approach (Fig. 2.1). Adherence to the linea alba makes abdominal closure easier. To minimize the likelihood of bowel injury secondary to abdominal wall adhesions, select a site in the upper abdomen or away from any prior incision sites to enter the peritoneum sharply. Digital exploration ensures that no bowel is adherent to the abdominal wall prior to extending the laparotomy incision along the length of the abdomen from xiphoid to pubis. The falciform ligament should be divided between ties. Exposure of the infrarenal aorta begins with mobilization of the small bowel to the right of the midline (Fig. 2.2). When taking down the attachments at the ligament of Treitz and opening the retroperitoneum, care should be taken to incise slightly to the left of the midline. This technique leaves an adequate margin of tissue for suture closure of the retroperitoneum at the end of the case without risking inadvertent bowel injury.

Once the retroperitoneum has been opened, clamp sites for proximal and distal vascular control should be exposed as soon as possible. Distal control can be obtained at the level of the common iliac arteries or by isolating each external and internal iliac artery separately, if common iliac aneurysmal or occlusive disease is present. Circumferential control of the iliac arteries is not necessary and should be avoided to minimize the risk of iliac vein injury. Surgical dissection at the aortic bifurcation should also be avoided to prevent injury to the sympathetic nerve plexus at that location.

Proximal dissection in the retroperitoneum begins by exposing the left renal vein as it crosses anterior to the aorta. Failure to find the left renal vein indicates the presence of a retroaortic left renal vein which passes posterior to the abdominal aorta. This relatively common anomaly highlights the importance of avoiding unnecessary circumferential dissection of the abdominal aorta (Fig. 2.3). A slight cephalad retraction of the crossing renal vein usually exposes the bilateral renal arteries.

If suprarenal aortic clamping is required, exposure between the SMA and renal arteries is sometimes adequate. Exposure between the SMA and celiac artery is rarely needed, and a clamp in this location leads to ongoing blood loss secondary to SMA backbleeding via collateral pathways fed by the celiac trunk. To avoid this problem, the next level of exposure obtained via a transperitoneal approach is the supraceliac aorta. Exposure in this location is facilitated by having a nasogastric or orogastric tube in place. In emergent situations, pulling the cardia of the stomach downward allows for manual palpation of the gastric tube. The aorta is then located where it crosses the diaphragmatic hiatus. The left anterior crus of the diaphragm should be sharply divided, and planes on each side of the aorta can be digitally developed enough to place a clamp in this location. Being able to palpate the spine on each side usually indicates that the aorta has been adequately cleared for clamping. Attempts to clamp the aorta before incising the periaortic tissues down to the spine will fail as the clamp slips off anteriorly. The most common error in this location is inadvertent clamping of the esophagus, typically caused by forgetting that the aorta is the more posterior structure and the vertebral bodies are directly deep to it. Palpation of the gastric tube in the esophagus provides a constant reminder of its location and helps avoid esophageal injury and inadvertent clamping.

When exposure of the visceral segment of the aorta is needed, for example, in the setting of type IV thoracoabdominal aneurysm repair, we recommend a retroperitoneal approach to avoid obscuration by the overlying viscera.

Retroperitoneal aortic exposure has the advantages discussed previously (Table 2.1). The key steps in positioning prior to this exposure are as follows:

A curvilinear incision begins lateral to the rectus sheath, approximately 2 in. anterior to the anterior superior iliac spine (ASIS) and extends superiorly to the appropriate rib space as determined by the proximal extent of the aneurysm. For most abdominal aortic pathology, the incision is carried through the 10th interspace (the highest unattached rib) (Fig. 2.5).

Careful attention to the layers of the abdominal wall in this location can help avoid inadvertent entrance into the peritoneum (Fig. 2.6). The first layer encountered is the external oblique aponeurosis. Incising this layer with electrocautery exposes the fibers of the internal oblique. Using a blunt-tipped instrument in this location allows for spreading and exposure of the transverse abdominal muscular fibers, behind which lays the fatty tissue of the retroperitoneum. Digital exploration confirms access into the retroperitoneum not the peritoneum and allows for manual separation of the peritoneum from the abdominal wall layers to allow the remainder of the incision to be opened. Beginning this manual dissection laterally and extending it superiorly to the diaphragm helps maximize exposure.

Once the retroperitoneal space has been developed, manual displacement of the left kidney anteriorly allows for identification of the left renal artery and exposes the left diaphragmatic crus if needed. A self-retaining retractor assists with the exposure and can also be positioned to keep the left ureter out of the operative field. Exposure of the left renal artery and dissection proximally to its origin from the aorta takes the surgeon across an accessory lumbar vein that drains into the left renal vein. This vein should be preemptively divided to avoid avulsing it (Fig. 2.7). The aortic bifurcation can be located by palpation, and the bilateral common iliac arteries are usually bluntly exposed to minimize iliac vein injury while creating isolated clamp locations. If additional proximal exposure above the renal arteries is required, the right renal artery is usually lower than the left, and exposing above the left renal artery with a combination of blunt and sharp dissection allows the SMA pulsation to be appreciated. If space to clamp in this location is not adequate, the left crus can be divided which quickly exposes the supraceliac aorta. In emergent situations, the initial incision through the 10th intercostal space allows manual palpation of and clamp placement on the thoracic aorta until further exposure can be obtained. Thoracic aortic clamping is a temporary, salvage maneuver, and the clamp should be moved distally as soon as possible.

When planned intervention requires a supraceliac aortic clamp, the incision is often through the 9th interspace which requires division of the costochondral cartilage. If planned intervention is on the descending thoracic aorta primarily, or in addition to abdominal aorta, incision through the 6th rib space, with or without division of the diaphragmatic fibers, allows for proximal thoracic aortic clamping (Fig. 2.8). These procedures are typically performed with sequential clamp techniques and left heart bypass if the situation demands.

Descriptions of exposures to gain access to the aortic arch and the origin of the great vessels can be found in any cardiac or thoracic surgical atlas. Exposure of the ascending aorta, aortic arch, innominate artery, and left common carotid artery origin is obtained by way of a median sternotomy. To expose the origin of the left subclavian artery, a left anterior thoracotomy is performed through the fourth intercostal space.