Surgical resection with complete tumor clearance improves patient survival and is superior to palliative therapy with regard to long-term outcome in cases with locally advanced tumors [
1,
3,
9]. As a result of improved operative techniques, venous resection is a feasible, standard procedure in high-volume centers [
10,
11,
12]. The reconstruction techniques follow the principles of vascular surgery. If primary anastomosis is not possible, a tube graft interposition or patch is applied for reconstruction.
Decision for the type of interponate
The decision for the graft is made depending on the vessel lumen, the type of vascular reconstruction (patch plastic or a tube substitute) and the septic contamination of the surgical procedure, the availability of the graft, and the individual expertise.
In HPB surgery, conventional alloplastic materials such as polyethylene terephthalate (PET) grafts (Dacron®) and (ringed) polytetrafluoroethylene (PTFE) grafts (Gore-Tex®, Gore, USA) are the ones most often used for vascular replacement. In case of high probability for local septic complications such as biliary leakage or pancreatic fistula, autologous material is preferred for the reconstruction. Cryopreserved homografts are mostly used in vascular surgery for reconstruction in the presence of infections for example in abdominal aortic surgery. Data from the literature show comparable rate of graft thrombosis and long-term graft patency for cryopreserved homografts as other biological grafts. However, the need of postoperative immunosuppression and ABO group compatibility is still controversial. We did not use allogenic material since in our collective the reconstruction could be performed, in the majority of cases, with autologous tissue. While autologous venous grafts are suitable and often used, either an additional incision is frequently needed for extraction and/or operation time is longer. In case of a tube graft interposition, we still prefer to harvest an autologous vessel like the saphenous or the jugular vein, which is more suitable for the reconstruction in terms of lumen size as the ovarian or spermatic vein.
For reconstruction with autologous parietal peritoneum, patches can be harvested from the abdominal wall through the same laparotomy without additional incisions. Compared to autologous venous grafts, this technique has several other advantages. The material is easily available, without a considerable increase of the operation time and additional surgical procedure as in case of harvesting another vessel like ovarian/spermatic, saphena, and left renal vein and there is no size limitation. Furthermore, the risk of infection is lower, PPP`s are less expensive and there is no need for postoperative anticoagulation as in the case of synthetic materials [
5,
11,
13,
14]. Given all these advantages, vascular reconstruction with peritoneal patches has gained more acceptance in the last decade.
After initial encouraging reports in preclinical studies [
15,
16], several case reports followed [
16,
17,
18]. The results of a small patient cohort of six patients with PPP reconstruction of the IVC during liver resection were published by the Australian study group of Chin et al. in 1999 [
19]. The outcome was encouraging with no mortality or obstruction of the IVC reported postoperatively. The largest series was published in 2015 by the French study group of Dokmak et al. [
5]. They reported 52 cases and were the first to use peritoneal patches during pancreatic resection for reconstruction of the portal vein and superior mesenteric vein. Their results showing a patency rate of 97% after application of lateral PPPs are encouraging. The mean follow-up of 14 months for the postoperative CT scan evaluation was nearly comparable to our average time frame of 17 months. However, the majority of the literature still consists of case reports and to the best of our knowledge, there are only four retrospective studies available [
6]. In particular, data for pancreatic resections and reconstruction of the portal vein are scarce, which may be one of the reasons for the lack of widespread application yet [
20].
In our cohort, PPPs were used in both liver and pancreatic surgery for reconstruction of the IVC and PV. We started using PPPs for IVC reconstruction during paraaortic lymphadenectomy in 2017, with one patient undergoing the procedure. In 2020, we applied this technique in eight patients. Although not included in this paper, we have also used PPPs for reconstruction of the external iliac vein in sarcoma resections with good postoperative results.
Data for the use of PPP for tube graft interposition in literature is even more scarce. A systemic review showed in 2021 three studies with seven interposition of PPP tubes after PV resection. Obstruction was reported in four cases (71%) in the follow-up, and one patient presented with stenosis [
6]. These results are somehow disappointing, but the number of patients is limited and therefore not representative. Some better data were obtained on the replacement of the vena cava with PPP tube. In 2013, a study group from Australia performed over 15 tubular interpositions with PPP with no signs of obstruction in the follow-up [
21].
Very recent results, reported by the study group of Balzan et al., showed in a small cohort of 8 patients promising results after application of falciform ligament tubular graft for the reconstruction of PV/VMS during Whipple procedure with vascular resection [
22]. Seven of the 8 patients showed non-altered vascular patency in CT 6 months postoperatively and a partial thrombosis, clinically inapparent, was diagnosed in one patient. These data are encouraging and the falciform ligament can be used as an alternative to the PPP. However, clinical outcome from prospective studies in larger cohorts of patients is still missing.
Stenosis and obstruction
Clinical symptoms may indicate the presence of vascular stenosis or obstruction. The symptoms of PV obstruction are initially non-specific as fever, abdominal pain, diarrhea, or ileus and can increase to clinically relevant portal hypertension syndromes presented with ascites and haematemesis. The symptoms of IVC obstruction result from a reduced venous return to the heart. This causes hypotension, tachycardia, edema of the low extremities, elevated liver enzymes, and further organ failure. Diagnostic is accomplished by doppler ultrasound or CT angiography.
According to the French study group, patency rates after PPP reconstruction in liver surgery were better than those observed after pancreatic resection [
5]. Our results are in line with these findings. In our small cohort, there were no cases of clinically relevant stenosis postoperatively in patients with reconstruction of the IVC. Two patients developed portal vein obstruction after distal pancreatectomy and hemihepatectomy, respectively (Figs.
5 and
6).
One possible explanation for maintaining postoperative patency after PPP usage could be the inherent fibrinolytic properties of the mesothelium. This aspect was examined in preclinical studies and needs to be studied further [
23]. The morbidity rate in our cohort of 24% for patients with CDC ≥ 3b is high but within the reported range for complex multivisceral resections in malignant tumors. Postoperative morbidity was due to sepsis as a result of biliary leakage, pancreatic fistula, or insufficient anastomosis and not related to the patches used.
Anticoagulation after vascular reconstruction
Although there are no guidelines for the postoperative anticoagulation after venous reconstruction, we defined a standard approach for our institution according to the general guidelines for perioperative venous thromboembolism prophylaxis in general and visceral surgery and the available literature based mainly on case reports [
8,
11]. After IVC reconstruction with autologous material, patients receive pharmacological prophylaxis with heparin (low-molecular-weight LMWH or unfractionated UFH) for 4 weeks postoperative if no complication occurs.
After PV reconstruction with autologous graft, prophylactic LMWH doses are applied for a normal diameter ≥ 1.0 cm after reconstruction and half-therapeutic doses of LMWH are applied if the venous diameter was < 1.00 cm.
Our study has some limitations because of its retrospective nature, the heterogeneity of the surgical procedures and the lack of structured follow-up regarding patency rates of vessel reconstructions with PPP. However, it was designed to describe the indications and technical aspects of this still rare procedure. Although data were collected from a small patient cohort, it still represents one of the largest patient cohorts investigated to date. By describing the surgical technique and highlighting important operative steps, we aim to encourage to apply this safe and cost-effective procedure in high-volume centers and further push the borders in surgery of complex multivisceral resections in malignant tumors.