Extraanatomic Repair for Renovascular Disease




Historical Background


Extraanatomic revascularization of the renal arteries using the splenic or hepatic branches of the celiac trunk for inflow generally yields inferior results when compared with traditional aortorenal bypass. These procedures are usually reserved for patients in whom exposure of the aorta is considered difficult or dangerous. Splenorenal revascularization was initially described by Thompson and Smithwick in 1952 as a splenic artery transposition in a patient with hypertension secondary to unilateral renal disease, and successful bypass with autogenous grafts was reported later in the same decade. The use of the hepatic circulation for revascularization of the right renal artery was not described until 1977, and since then, there have been several larger series detailing both procedures. Extraanatomic renal artery bypasses continue to be used as component hybrid endovascular approaches to abdominal aortic aneurysm repair where revascularization of the renal arteries from the hepatic and splenic circulation allowed extension of an endovascular seal zone to the superior mesenteric artery. In addition, extraanatomic renal artery bypass has been described as a salvage maneuver for inadvertent coverage of the renal arteries during endovascular aneurysm repair.




Preoperative Preparation





  • Imaging. Variable anatomy of the arterial branches of the celiac artery and, in particular, the hepatic arterial circulation is observed in up to 40% of patients, making preoperative imaging essential. The increased fidelity of fine-cut helical computed tomography or magnetic resonance angiography has led to these modalities being used as first-line studies.



  • Renal insufficiency. The presence of renal insufficiency as determined by a low glomerular filtration rate may preclude the use of gadolinium-based contrast agents, and hydration with sodium bicarbonate may be necessary to decrease the risk of contrast nephropathy.





Pitfalls and Danger Points





  • An anomalous origin of the right hepatic artery off the gastroduodenal artery precludes the sacrifice or use of the gastroduodenal artery during right renal artery revascularization.



  • The gastroduodenal artery is a critical collateral in patients with occlusive disease or superior mesenteric artery disease and cannot be used for right renal artery revascularization.



  • Significant occlusive disease at the origin of the celiac artery precludes splenorenal or hepatorenal bypass.



  • A heavily calcified splenic artery cannot be easily mobilized, and a tortuous splenic artery may be subject to kinking during transposition. A bypass graft with an end-to-side anastomosis off the splenic artery is an alternate approach.



  • Hepatic insufficiency precludes the use of the hepatic artery for right renal artery revascularization. Despite hepatic blood supply from the portal vein, diversion of even a fraction of hepatic artery flow may prove detrimental.



  • The common hepatic artery lies anterior to the portal vein and to the left of the bile duct. Both the vein and the duct, as well as the duodenum, are at risk of injury during exposure of the hepatic artery.



  • The splenic artery travels along the superior border of the pancreas, where it gives off multiple small-branch vessels. The pancreas is at risk of injury during mobilization of the splenic artery.



  • The spleen is at risk of injury during a splenorenal bypass.





Operative Strategy


Surgical Anatomy of the Hepatic and Splenic Arteries


The celiac trunk originates from the anterior surface of the aorta at the T12-L1 interspace and consists of three branches: the left gastric artery, the splenic artery, and the common hepatic artery. The common hepatic artery courses anterior of and to the right along the superior border of the pancreas. It then runs along the right side of the lesser omentum, entering the hepatoduodenal ligament cranial to the pylorus. The common hepatic artery almost always lies anterior to the portal vein and to the left of the bile duct. Because it courses toward the hilum of the liver, it gives off the gastroduodenal artery, which is an important collateral between the celiac and the superior mesenteric artery circulation. The hepatic artery travels toward the liver, superior and cephalad to the common bile duct, and terminates at the liver hilum as the right and left hepatic arteries. The splenic artery travels along the superior border of the pancreas, where it gives off the dorsal pancreatic artery and several small branches and terminates at the spleen ( Fig. 37-1 ).




Figure 37-2


Exposure for a hepatorenal bypass. A, Patient positioning for a right subcostal incision. B through D, Exposure of the hepatic and right renal arteries for hepatorenal bypass.

( C, From Benjamin ME, Dean RH: Techniques in renal artery reconstruction: Part II, Ann Vasc Surg 10:409-414, 1996.)


Selection of Conduit


For hepatorenal bypasses, a reversed saphenous vein is preferred. Because this bypass lies close to the duodenum, an autogenous conduit should be more resistant to infection. However, when the saphenous vein is less than 4 mm in caliber or absent, a 6-mm polytetrafluoroethylene or polyester graft can be used. For splenorenal bypasses, transposition of the splenic artery is preferred; alternatively, a saphenous vein graft or, if necessary, a synthetic graft can be used.




Operative Technique of Hepatorenal Bypass


Incision


The patient is supine, and a roll is placed longitudinally to elevate the right flank. The right arm is extended on an arm board. The abdomen and thigh are prepped and draped. A right subcostal incision, two finger’s breadths or 4 to 5 cm below and parallel to the inferior costal margin that extends from the midline to the eleventh rib, affords access to both arteries and limits bowel manipulation. This incision can be extended across the midline to improve exposure in larger patients. The three muscle layers of the abdomen are divided, the peritoneum is entered, and a self-retaining retractor is placed. In most patients adequate exposure can be obtained with minimal or no division of the rectus muscle ( Fig. 37-2 , A ).




Figure 37-1


Anatomy of the celiac trunk and its branches. IVC, Inferior vena cava.


Exposure of the Right Renal Artery


The small intestines are wrapped in a moist towel and packed inferiorly and to the left. The right colon is then freed from its lateral peritoneal attachments in an avascular plane from the hepatic flexure to the cecum. The mobilized colon and mesentery can then be retracted to an inferior and medial position. The second portion of the duodenum is mobilized with an extended Kocher maneuver, and the duodenum and pancreas are reflected to the left. This exposes the inferior vena cava and the right renal vein, which is anterior to the artery in this position. The right renal vein is dissected free and circled with a vessel loop or thin Penrose drain. The inferior vena cava should be mobilized at the level of the renal artery to allow access to the origin of artery at the aorta. This occasionally requires ligation of a lumbar vein to ensure safe mobility in both directions. The gonadal vein enters the inferior vena cava on the anterior surface, inferior to the renal veins, and care should be taken to avoid avulsion during inferior vena cava mobilization. The right renal vein can be retracted either superiorly or inferiorly to expose the underlying renal artery. The renal artery should be freed from its aortic origin to the first renal branch of surrounding nerve and lymphatic tissue, which can be quite thick. Gentle rightward traction of the inferior vena cava allows direct access to the aorta and right renal artery origin (see Fig. 37-2 , D ).


Exposure of the Hepatic Artery


The right lobe of the liver is gently retracted superiorly to expose the hepatoduodenal ligament. The hepatic artery can be located by dividing the lesser omentum and is located to the left of the common duct. The common hepatic, gastroduodenal, and proper hepatic arteries are circled with vessel loops.


Proximal Anastomosis


After systemic administration of heparin, the proximal and distal hepatic arteries are controlled with small, atraumatic clamps. The anastomosis to the hepatic artery is performed from end to side. The location of the anastomosis depends on the patient’s anatomy and the need to avoid graft kinking. An inferior arteriotomy either proximal or distal to the gastroduodenal artery is generally used, and the gastroduodenal artery may be sacrificed if it is not an important collateral. The conduit is spatulated to provide a generous opening for the anastomosis, and the graft should be oriented with the heel toward the patient’s right. The running anastomosis is created with 5-0 or 6-0 polypropylene, and it is technically easier to begin the suture line in the center of the back wall of the arteriotomy and run the inferior suture line in both directions ( Fig. 37-3 , A ). In some instances the right renal artery may be of adequate length to anastomose directly to the hepatic artery, thus avoiding the need for a conduit.


Mar 13, 2019 | Posted by in VASCULAR SURGERY | Comments Off on Extraanatomic Repair for Renovascular Disease
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