Inverted Y‐shaped technique for complex superior mesenteric / portal vein reconstruction in pancreatoduodenectomy for locally advanced pancreatic head ductal adenocarcinoma

Abstract Most pancreatoduodenectomy (PD) procedures for locally advanced pancreatic head adenocarcinoma (PDAC) require superior mesenteric/portal vein (SMV/PV) axis resection and reconstruction. Here we describe the inverted Y‐shaped as a new technique for complex SMV/PV reconstruction and aimed at evaluating its safety and effectiveness. Among 287 patients who underwent PD for locally advanced PDAC from April, 2007 to December, 2020 at our hospital, 11 patients (3.8%) who underwent PV/SMV reconstruction with this technique were enrolled. Briefly, two distal veins were slit‐wedged, sutured, resulting in one orifice, then reconstruction was completed with (n = 6) or without (n = 5) interposed autologous right external iliac vein (REIV) grafts, respectively. Operation time and blood loss were 649 (502–822) min and 1782 (475–6680) mL, respectively. The median length of resected SMV/PV was 40 (20–70) mm, 50 (50–70) mm for REIV grafts, and the splenic vein was resected in eight patients. No patient developed pancreatic fistula; mild leg edema was observed in the six graft patients and the median hospital stay was 36.0 d. PV patency rate at 2 mo after PD was 91% (10/11) and no 90‐d mortality was recorded. R0 resection rate was 91% (10/11). It is feasible to safely reconstruct the SMV/PV using the inverted Y‐shaped technique in appropriately selected PDAC patients.

negative (R0) resection, the only cure that leads to improved patients' overall survival. 3 When PDAC of the pancreatic head infiltrates the SMV/PV axis, pancreatoduodenectomy (PD) combined with SMV/PV resection and reconstruction is performed, a procedure first reported by Fortner et al. 4 Based on the International Study Group of Pancreatic Surgery (ISGPS) classification, 5 there are four vascular reconstruction types (venorrhaphy, venoplasty with a patch, primary veno-venous anastomosis, and anastomosis with an interposed venous graft).
This study aimed at evaluating the safety and efficacy of reconstructing the SMV/PV axis following PD for locally advanced PDAC with an inverted Y-shaped (double-single orifice) technique. Surgical steps for this technique are described.

| Patients
Of 287 patients who underwent PD for locally advanced PDAC, 11 (3.8%) who had SMV/PV axis resection and reconstruction with the inverted Y-shaped technique between April 2007 and December 2020 at our hospital were enrolled. Table 1 shows their characteristics.

| Surgical procedure of SMV/PV axis resection and reconstruction with the inverted Yshaped technique
After an upper-midline incision, our standard anterior approach to the SMA was used as described by Mizuno et al. 6 After measuring the involved length of the SMV/PV axis, the pancreatic head together with the tumor-involved SMV/PV segment was resected (Video S1). Figure 1 highlights the steps of the vascular reconstruction. In six patients, sufficient lengths of autologous right external iliac vein (REIV) grafts were harvested for inter-positioning (Video S1 and Table 2). Two distal branches of SMV (DV1 and DV2) were each held by a vascular clamp apposed side-to-side (Step 1), then, depending on the diameter of the veins, slit-wedges of no longer than 3 mm were made on their medial (DV1) and lateral (DV2) opposite sides to increase the size of the anastomosis diameter (Step 2). To avoid tearing the thin walls of distal veins and minimize forceps-handling of the veins, three stay sutures were gently placed (posterior, central, and anterior) of the apposed orifices for traction, then an intraluminal suture technique using 6-0 vascular sutures from the posterior to the central side was employed. Upon reaching the central side, the needle-thread and posterior stay suture were gently pulled in opposite directions, allowing for the growth factor of the new orifice. The same procedure was repeated from the central to the anterior side (Step 3). Finally, the needle thread was secured in a knot with the anterior stay suture and the venoplasty of DV1 and DV2 was completed (Step 4). Depending on the surgeon's preference, the venoplasty can be performed from the anterior to posterior side, Following vascular reconstruction, the digestive tract and biliary tree were reconstructed using a modified Child method by performing endto-side pancreatojejunostomy, end-to-side hepaticojejunostomy, and end-to-side or side-to-side gastrojejunostomy. In the postoperative period, anticoagulant therapy was not routinely used.

| Assessing SMV/PV anastomosis patency
Portal vein patency was assessed on postoperative dynamic computed tomography (CT)-scan imaging done 6 d after surgery and in the follow-up period.

| Patients
As summarized in Tables 1 and 2

Proximal vein
Step 1

| DISCUSS ION
Pancreatic head cancer easily invades the PV/SMV axis due to its anatomical relationship; therefore, resection and reconstruction of PV/ SMV is an essential technique to achieve R0 resection in some PD cases. 3   (54.5%) of our patients had >1500 mL blood loss, but only Case 1 had massive bleeding, and the operating time in this one was more than in the other five patients. Even though most post-PD complications are managed conservatively, they impact patient recovery, length of hospital stay, and medical costs. 10 The three most common include POPF, DGE, and PPH with incidence rates of 22%-26%, 14%-30%, and 3%-10% respectively. 11 In this study, POPF was not encountered; Short-and long-term outcomes were comparable between the two groups, but PV thrombosis within 30 d post PD was observed in both end-to-end (2/97) and graft (1/25) patients, respectively.
However, since direct end-to-end anastomosis is linked to better R0 resections, 18 it is preferred even for up to 50-mm resections by mobilizing the liver or performing a Cattell-Braasch maneuver. 19 In this study, direct end-to-end anastomosis was done for However, our technique has some shortcomings that include risk for increased intraoperative bleeding, small intestinal veins' congestion, and microthrombosis in the distal veins due to prolonged venous clamping time, PV thrombosis or stenosis, and leg swelling.
As a limitation, it may not be applied in PDAC patients where more than two distal branches of the SMV are involved. The main pitfalls include easy tearing of the fragile walls of the distal veins and increased operation time due to the surgical steps needed to complete the reconstruction.
Nonetheless, based on the overall perioperative outcomes of our 11 patients, which are comparable to previous reports, 11,17,18 it is feasible to safely reconstruct the SMV/PV using the inverted Yshaped technique during PD for PDAC.

| CON CLUS ION
The inverted Y-shaped technique can safely be used to reconstruct the SMV/PV in appropriately selected PD cases involving longsegment SMV/PV axis encasement.

FU N D I N G I N FO R M ATI O N
This research did not receive any specific grants from funding agencies in the public, commercial, or not-for-profit sectors.

CO N FLI C T O F I NTE R E S T
The authors declare no conflicts of interest for this article.

DATA AVA I L A B I L I T Y
Data supporting the findings of this study are available from Naohisa Kuriyama upon reasonable request.