Leveraging Aberrant Vasculature in Celiac Artery Stenosis: The Arc of Buhler in Pancreaticoduodenectomy

Abstract Background: Celiac artery stenosis and occlusion have been described rarely in patients undergoing pancreaticoduodenectomy (PD), although it occurs relatively frequently in this group. An arterial connection between the celiac and superior mesenteric arteries, known as the Arc of Buhler, provides alternative flow to the celiac distribution once the gastroduodenal artery (GDA) is ligated in PD. Case Presentation: A 69-year-old man, in whom pre- and intraoperative efforts to stent an occluded celiac artery failed, had sufficient retrograde flow from an unrecognized Arc of Buhler to maintain adequate hepatic arterial perfusion after ligation of the GDA during a PD. Conclusions: Although there are several case reports and case series regarding the management of celiac stenosis in PD, the impact of an Arc of Buhler variant in this setting has been rarely reported. This case report demonstrates the ability of an intact Arc of Buhler to maintain adequate hepatic perfusion after ligation of the GDA and avoid the potential morbidity of a hepatic artery bypass procedure.


Background
Celiac artery stenosis and occlusion (CAS) are described infrequently in pancreaticoduodenectomy (PD), despite being a relatively common variant (2-7.6%). 1 The largest American series of patients undergoing PD for periampullary cancer reports rates of 4%. 2 Identification preoperatively requires consideration of vascular intervention or alternative approaches, since PD involves ligation of vessels connecting the celiac and superior mesenteric axes. Arterial reconstruction or bypass, however, increases the PD complications significantly; in one institution it was responsible for one-third of perioperative deaths. 3 An aberrant arterial arc between the celiac and superior mesenteric arteries (SMAs), identified in 1904 by Buhler, can provide collateral flow to the celiac axis in CAS. Case reports have further named it a potential arterial supply to the foregut once the gastroduodenal artery (GDA) has been ligated during PD. [4][5][6] Presentation A 69-year-old man with chronic pancreatitis, presenting with epigastric pain and jaundice, was found to have biliary obstruction. CT demonstrated pancreatic head mass with abutment/impingement of the superior mesenteric and portal veins, but no evidence of distant metastases. Endoscopic ultrasound locally staged it as T3N0, and fine needle aspiration biopsy found it to be adenocarcinoma. CT also noted short-segment celiac occlusion. Given the borderline resectability, the patient underwent preoperative chemoradiation. During unsuccessful attempt at endovascular stenting of the celiac artery, the GDA was found to be the main supply of the hepatic artery and the rest of the celiac axis. The origin of the SMA was also stenotic. A plan was made for intraoperative stent or arterial bypass.
Intraoperatively, the celiac artery was unable to be stented retrograde, so the decision was made to perform bypass after tumor resection. The entire dissection was completed before GDA ligation. After GDA ligation, however, persistent hepatic arterial Doppler signal was appreciated, originating from a presumed SMA collateral vessel on completion of angiography (Fig. 1). No further intervention was performed, and the procedure was completed without signs of ischemia or loss of flow.
He was discharged to home on postoperative day 7 after a course notable only for a transient transaminitis of 1324/1145U/L (aspartate aminotransferase/alanine aminotransferase) on the first day. These elevated liver enzymes resolved in 2 days and have not recurred, so no further imaging of the hepatic vessels has been made. Another complication was Klebsiella bacteremia of uncertain etiology but without signs of abscess, which resolved with brief hospitalization and antibiotics. Diagnosed with intraductal papillary mucinous neoplasm on final pathology, he remains without evidence of disease 1 year later.
Reanalysis of the preoperative angiography identified the collateral vessel as an Arc of Buhler (Fig. 2). However, due to the concomitant occlusion of the celiac axis and stenosis of the SMA, the arc also filled retrograde through the GDA. Division of the GDA intraoperatively had allowed for antegrade flow through the arc from SMA to celiac trunk.

Conclusions
Preoperative identification of CAS in PD is of utmost importance to prevent unexpected foregut ischemia. 4 Routine angiography was once advocated, but many authors only perform one now if prompted by CAS on CT imaging. The latter imaging is recommended routinely. 2 Intraoperatively, test clamping the GDA before ligation is also recommended to evaluate hepatic arterial flow. 2,3 To avoid the documented ischemia after GDA ligation in this setting, 1,2,5 CAS identification pre-or intraoperatively can avoid complications through bypass, reimplantation, stent, GDA preservation, or median arcuate ligament release. 2,3 Preoperative imaging is, therefore, vital to plan appropriate intervention and resection strategy. In cases of aberrant arterial anatomy, such as this one, preoperative identification of potential collateral flow to the liver can help preserve these  vessels and avoid the need for costly reconstruction, multiple interventions, and/or surgical delay.