https://orcid.org/0000-0002-7012-1196
Introduction
In modern pancreatic surgery, involvement of the portal vein or superior mesenteric vein (SMV) is no longer considered a contraindication to curative surgery, and venous resection is indicated to achieve negative margins. Resectability is mainly determined by arterial involvement, especially of the superior mesenteric artery (SMA)1,2. The most frequent positive resection margin is around the SMA, which is considered a poor prognostic factor3. Another challenge, particularly after neoadjuvant chemotherapy, is the demanding and inaccurate preoperative resectability assessment based on CT. Pancreatoduodenectomy (PD) with artery-first approaches (AFAs) is characterized by two key aspects: early evaluation of arterial involvement before committing to irreversible steps of the operation; and meticulous clearance of the SMA resection margin to achieve an R0 resection4,5. An AFA is essential to determine whether resection can be performed, and whether sharp clearance of the artery (divestment) is possible or an arterial resection with subsequent reconstruction must be considered.6,7
Approaches
Anterior approach (inferior supracolic)
In the initial report8 of the anterior approach, early division of the gastric antrum and the pancreatic neck is described to access the SMV and subsequently the SMA. More recently, Inoue et al.9 used a wide Kocher manoeuvre, then retracted the stomach and pancreatic body upward without transection to access the SMV. By retracting the SMV to the right side with tape, the SMA is palpated and rotated to the left to detach all soft tissue, lymphatic as well as neural structures (mesopancreas), from the SMA by dividing the inferior pancreaticoduodenal artery (IPDA). Dissection of the mesopancreas continues cranially on the right side of the SMA towards the SMA origin (Fig. 1).
Anterior approach (inferior supracolic)
AO, aorta; IPDA, inferior pancreaticoduodenal artery; IVC, inferior vena cava; PV, portal vein; SMA, superior mesenteric artery; SMV, superior mesenteric vein.
Superior approach
The superior approach provides good exposure for tumours of the superior pancreatic border with suspected common hepatic artery (CHA) involvement. First, the hepatoduodenal ligament is dissected with the gastroduodenal artery and CHA. The pancreas is retracted caudally and dissection continues down along the CHA to the coeliac trunk and the SMA on their origin from the aorta (Fig. 2). In patients with a low origin of the SMA from the aorta, the superior approach might be difficult.
Superior approach
AO, aorta; IVC, inferior vena cava; PV, portal vein; SMA, superior mesenteric artery.
Right posterior approach
The posterior approach is preferred for posteromedial tumours in the head and neck region involving the SMV, and was first described by Pessaux et al.10. The approach begins with a wide Kocher manoeuvre to the left renal vein and aorta. The pancreatic head is rotated to the left to free up the retropancreatic origin of the SMA in its cranial location to the left renal vein. The perivascular tissue is removed along the SMA posterior to the pancreatic head, and dissection continues with removal of the attachments between the SMA and uncinate process. This exposes the SMV from the lateral/posterior side (Fig. 3).
Right posterior approach
AO, aorta; IPDA, inferior pancreaticoduodenal artery; IVC, inferior vena cava; LRV, left renal vein; PV, portal vein; SMA, superior mesenteric artery; SMV, superior mesenteric vein.
Left posterior approach
The left posterior approach was introduced by Kurosaki et al.11, and is indicated for tumours of the uncinate process and posterior pancreatic head. The proximal jejunum is pulled to the left and the first jejunal arteries are divided at the SMA origin, allowing counterclockwise rotation of the SMA. Arising from the posterior segment of the SMA, the IPDA is divided in the next step allowing dissection of the posterior/right side of the SMA. The SMA is further retracted to the right side and the first jejunal branch of the SMV is divided to free up the SMV and separate the uncinate process from the SMA/SMV (Fig. 4).
Left posterior approach
AO, aorta; IPDA, inferior pancreaticoduodenal artery; IVC, inferior vena cava; JA, jejunal artery; PV, portal vein; SMA, superior mesenteric artery; SMV, superior mesenteric vein.
Medial uncinate approach
This approach is indicated for bulky tumours in the uncinate process or pancreatic head12. It starts with a wide Kocher manoeuvre, including opening of the ligament of Treitz from the right side. The proximal jejunum is divided and transposed to the right upper abdomen behind the mesenteric vessels. With the small bowel retracted to the left, the SMA is rotated into view under the SMV. Dissecting the medial aspect of the SMA with division of the IPDA, the mesopancreas is transected from the pancreatic head and uncinate process in a caudocranial direction (Fig. 5).
Medial uncinate approach
IPDA, inferior pancreaticoduodenal artery; PV, portal vein; SMA, superior mesenteric artery; SMV, superior mesenteric vein.
Mesenteric approach (inferior infracolic)
The mesenteric approach is indicated for advanced tumours with suspected SMA infiltration at the origin from the aorta, and tumours of the ventral pancreas or uncinate process. Again, the approach begins with an extended Kocher manoeuvre. Then the peritoneum is incised at the base of the transverse mesocolon and to the left of the duodenojejunal flexure. The inferior mesenteric vein is divided. The left renal vein is identified and the aorta is dissected cranially to the origin of the SMA. The middle colic artery and IPDA are identified and divided. Dissection continues cranially on the posterior and right side of the SMA towards its origin from the aorta13 (Fig. 6).
Mesenteric approach (inferior infracolic)
AO, aorta; IPDA, inferior pancreaticoduodenal artery; IVC, inferior vena cava; LRV, left renal vein; PV, portal vein; SMA, superior mesenteric artery; SMV, superior mesenteric vein.
Clinical outcomes
The most recent meta-analysis14 summarized 18 studies including 1483 patients, and showed less blood loss (weighted mean difference −264 (95 per cent c.i. −336 to −193) ml; P < 0.001) with a similar operating time (−15 (−72 to 41) min; P = 0.58) for AFA-PD. In terms of postoperative outcomes, AFA-PD was associated with a lower overall complication rate (OR 0.62, 95 per cent c.i. 0.47 to 0.81; P = 0.001), a lower pancreatic fistula rate (OR 0.52, 0.37 to 0.73; P < 0.001) and less delayed gastric emptying (OR 0.42, 0.29 to 0.62; P < 0.001). Interestingly, an AFA did not lead to more postoperative bleeding (OR 0.57, 0.19 to 1.73; P = 0.32). However, owing to extensive dissection of lymphatic and neural tissue around the SMA, patients more often developed postoperative diarrhoea (OR 1.91, 1.08 to 3.40; P = 0.03). After AFA-PD, the R0 rate was increased (OR 2.92, 1.72 to 4.96), P < 0.001), resulting in a lower local recurrence rate (OR 0.14, 0.06 to 0.35; P < 0.001) and improved 3-year overall survival (OR 2.15, 1.34 to 3.43; P = 0.001). In subgroup analysis of the different AFAs, the posterior approach showed the most beneficial outcomes and may therefore be the ideal approach. Of note, the quality of the included studies was rated low in 6, medium in 9, and high in only 3 studies.
The only available RCT15 compared 78 patients undergoing AFA-PD with 75 who had standard PD. The results differ from those of the abovementioned meta-analysis of non-randomized studies. Interestingly, the R0 rate was no different between the groups (77 versus 68 per cent; P = 0.194), although there was a trend toward less posterior margin invasion in AFA-PD (88 versus 56 per cent; P = 0.069). Both postoperative complication (73 versus 68 per cent; P = 0.484) and 30-day mortality (4 versus 6 per cent; P = 0.721) rates were similar. The outcomes regarding surgical radicality may of course be debatable as the dissection technique was not described in detail, and not every AFA automatically results in a complete removal of the mesopancreas, unless consciously undertaken.
In the growing field of minimally invasive pancreatic surgery (MIPS), the uncinate approach is most frequently described (16 studies), followed by the posterior AFA (4) and left AFA (3). Of note, adequate working space on the left side of the SMA is difficult to achieve in MIPS, so a right-sided or posterior approach seems more convenient16. Similar to open PD, high-quality comparative studies evaluating AFA-PD in MIPS are lacking.
Conclusions
In modern pancreatic surgery, a thorough understanding of the various AFAs is of paramount importance, especially in advanced pancreatic head cancers or after neoadjuvant chemotherapy. The ultimate goal of an AFA is to increase the R0 resection rate while avoiding ineffectual surgery.
Funding
The authors have no funding to declare.
Author contributions
Philip Müller (Conceptualization, Visualization, Writing—original draft), Beat Müller (Conceptualization, Visualization, Writing—review & editing), and Thilo Hackert (Conceptualization, Visualization, Writing—original draft)
Disclosure
The authors declare no conflict of interest.
