The Studies Of Using The Recanalized Ligamentum Teres Hepatis As Autologous Grafts To Reconstruct Portal Vein And/or Superior Mesenteric Vein

Background and objective:Periampullary carcinoma is a common disease that seriously threatens human health.Locally advanced carcinoma of the pancreatic head or hepatopancreatic ampulla often involves the PV and/or the SMV,increasing the difficulty of tumour resection.Surgical resection is still the main and the most effective treatment method for periampullary carcinoma at present.In recent years,with the continuous improvement of abdominal surgical techniques,pancreaticoduodenectomy combined with PSMV resection is gradually becoming a routin procedure,which greatly improves the surgical resection rate and thus improves the survival rate of patients.During the operation of PD combined with PSMV resection,vascular reconstruction is one of the most key steps,which often determines the success or failure of the operation.According to the International Study Group of Pancreatic Surgery,a patch or interposition graft is necessary if the resection range of the vascular wall was excessive.The choice of vascular graft is particularly important when the portal vein reconstruction is performed with a patch or an interposition vascular graft.At present,from the perspective of domestic and foreign studies,the main kinds of vascular grafts contain autologous grafts,allogeneic grafts and artificial blood vessels prepared using Teflon.In addition,the falciform ligament of the liver,peritoneum and bovine pericardium are also used to reconstruct the PSMV.However,all these different types of grafts have their own advantages and disadvantages.For artificial blood vessels,it is easy to choose the diameter and length matching with the portal vein and superior mesenteric vein,but its long-term patency rate is low,it can cause serious infectious complications,and the price is expensive.For autologous grafts,it has good tissue compatibility,physiological conformity and long-term effect,but it is difficult to obtain the appropriate blood vessels that matching the diameter of portal vein,and the resection of the grafts increased the injury of the body,and even lose the functions of other organs.The source of allogeneic veins is limited,and immune rejection may take place after transplantation.The pantency of the liver falciform ligament and peritoneum were low.There was only a little report of using cattle pericardium as PSMV grafts,needing a further observation.Given the limitations of the above venous grafts,it would be reasonable to identify other materials that would be suitable for the reconstruction of the resected PV and/or SMV.The LTH is derived from the left umbilical vein（UV）in the embryonic period and lies between the umbilical ring and the sac of left portal vein,making it is easily accessible without causing collateral damage during abdominal operations.The using of the LTH as autologous graft to repair abdominal veins avoids the issue of immune rejection.Therefore,the LTH has the potential as PSMV graft.However,as the grafts of PV and/or SMV,the basic and clinical research of the LTH are not adequate,and further research is needed.Our previous studies have confirmed that the diameter of the dilated LTH was similar to the PSMV,which can decrease the chance of thrombosis.In addition,studies have shown that the mismatch compliance of graft and host vessel is an important factor for thrombosis.Therefore,if the LTH is used for the repair and reconstruction of the PSMV,these two types of materials should have similar biomechanical properties to ensure that the LTH can maintain the similar diameter variation with the PV when the luminal pressure changes,so as to avoid increasing the probability of thrombosis.The biomechanical properties of the vessels are determined by the content and function of elastic fibers,collagen fibers and smooth muscles in the vessels wall.Meanwhile,the patency of the reconstructed vascular is colosely related to the content and functions of the elastic fibers,collagen fibers and smooth muscles in the graft wall.Therefore,we studied the biomechanical properties,the histological characteristics and the clinical application of the LTH,in order to provide theoretical basis and clinical reference for the using of LTH as PSMV grafts.This study consists of three parts.The first part is the comparison of the biomechanical properties of LTH and PV.The second part is the histological study of the LTH and PV.The third part is the clinical observation of using the recanalized LTH as autologous graft to reconstruct the PV and/or SMV.Part Ⅰ The comparison between the mechanical properties of the ligamentum teres hepatis and the portal vein.Objective:To investigate the mechanical properties of the LTH and PV,providing mechanical theoretical basis for using the LTH as vascular grafts to reconstruct the PV.Methods:1.Twenty-seven adult LTH specimens and 27 PV specimens were obtained.The LTH was dilated with mechanical method combined with water-filling.2.The diameter and wall thickniss of the dilated LTH were measured,and the results were compared with PV.3.The biomechanical test system was used to measure the diameter of the LTH and PV at the pressure of 1kpa,2kpa,3kpa,4kpa,5kpa,6kpa,7kpa and 8kpa,so as to calculate the radius change value of the LTH at different pressures.The corresponding values of the incremental elastic modulus（Einc）,the pressure-strain elastic modulus（Ep）,the volume elastic modulus（Ev）,and compliance（C）of LTH were calculated.The results were compared with PV.Results:1.Eight of the 27 LTH specimens were obtained from liver donors,and 19 obtained from patients who underwent left hemihepatectomy,including 17 males and 10 females,aged 18-78 years.All of the 27 PV specimens were obtained from liver donors,including 13 males and 14 females,aged 18-62 years.2.All of the 27 LTH were successfully dilated and recanalized.After dilated,the diameter of the LTH was 11.98±1.52mm,and the wall thickness was 0.51±0.07mm.The diameter of PV was 11.62±2.45mm,and the wall thickness was 0.50±0.06mm.There was no significant difference in diameter and wall thickness between the LTH and PV group.3.As the intracavitary pressure of LTH and PV increased from 0 kpa to 8 kpa,the Einc,Ep and Ev showed increasing trend,whereas the C value showed downward trend.Statistical analysis showed that there was no significant difference in Einc,Ep,Ev and C values between LTH and PV when the pressure was changed from 0 kpa to8 kpa.Conclusion:The diameter,wall thickness and biomechanical properties of the dilated LTH was similar with PV.The LTH has the biomechanical properties basis as vascular grafts for portal vein reconstruction.Part Ⅱ The histological study of LTH and PV.Objective:To study the composition and function of LTH wall and PV,providing histological theoretical support for the similar biomechanical properties of LTH and PV,and providing histological basis of using LTH as vascular grafts to reconstruct PV.Methods:1.Forty LTH and 40 PV samples were obtained and fixed with 10%neutral formaldehyde solution.Paraffin sections of the specimens were prepared.2.The sections were stained with Verhoeff-Van Gieson（VVG）stain method,the morphology of elastic fibers（EFs）,collagen fibers（CFs）and smooth muscles（SM）were observed under light microscope.Motic medical image analysis software（MMD6.0A）was used for quantitative analysis of the relative content of CFs,EFs and SM in the LTH wall.The stiffness coefficient was calculated,and the results was compared with PV.3,Immunohistochemical staining was performed on the LTH and PV specimens,and the expression of α-smooth mustle actin（α-SMA）and Matrix metalloproteinase-2（MMP-2）in the LTH and PV wall was observed under light microscope.Motic medical image analysis software（MMD6.0A）was used for quantitative analysis of the α-SMA and MMP-2 in the LTH wall.The results were compared with PV.Results:1.Eight of the 40 LTH specimens were obtained from liver donors,and 32 obtained from patients who underwent left hemihepatectomy,including 28 males and 12 females,aged 18-78 years.All of the 40 PV specimens were obtained from liver donors,including 21 males and 19 females,aged 18-62 years.2.After VVG staining,the EFs,CFs and SM were obseveved in the LTH wall,the histological structure of LTH was similar to that of PV.Under microscope,the elastic fibers appeared black,the collagen fibers appeared red,and the smooth muscle appeared yellow.Statistical analysis showed that there was no significant difference in the relative contents of EFs,CFs and SM and the stiffness coefficient between the LTH group and PV.3.After immunohistochemical staining,α-SMA was expressed in the cytoplasm of the smooth muscle cells of LTH and PV,appeared as yellow granules.MMP-2 was expressed in the cytoplasm of the smooth muscle cells and fibroblasts of LTH and PV,appeared as yellowish-brown sheet or granular.Statistical analysis showed that there was no significant difference in the integral optical density value of α-SMA and MMP-2 between the LTH group and PV.Conclusion:The histological structure of the LTH was similar with PV,which provided histological theoretical support for the similar biomechanical properties of LTH and PV,and provided histological basis of using LTH as vascular grafts to reconstruct PV.Part Ⅲ The clinical study of using LTH as autologous grafts to reconstruct PV and/or SMV.Objective:To observe the clinical application effect of using the LTH as autologous graft in the reconstruction of PV and/or SMV,providing clinical evidence of using the recanalized LTH to reconstruct the PV and/or SMV.Methods:1.Patients who underwent opened PD in Binzhou Medical University Hospital were selected from January 2003 to December 2019.The patients who underwent PD combined with PV and/or SMV resection and reconstruction with LTH were defined as PD-VR group,while the patients who underwent PD with none vascular reconstruction were defined as PD-NVR group.Retrospective reviews of the patients’medical and radiological records were performed.2.The age,operation time and intraoperative blood loss of the patients in the two groups were analyzed and compared.The time of vascular occlusion and the way of vascular reconstruction in PD-VR group were analyzed.3.The incidence of postoperative complications,postoperative 30-day mortality and postoperative hospital stay of the patients in the two groups were compared and analyzed.4.The thrombosis rate and vascular patency rate of the patients in the PD-VR group were analyzed.Results:1.There were 23 patients in the PD-VR group,including 13 males and 10 females,with an average age of 60±9.13（46-74）years,including 3 patients with cholangioma,17 patients with pancreatic tumor,and 3 patients with ampullary tumor.There were 209 patients in the PD-NVR group,including 135 males and 74 females,with an average age of 59.83±10.14（25-79）years,including 64 patients with cholangiocarcinoma,42 patients with pancreatic tumor,48 patients with duodenal tumor,and 55 patients with ampullary tumor.Statistical analysis showed that there was no significant difference in age between the two groups（P=0.96）.2.Among the 23 patients in the PD-VR group who underwent PV and/or SMV resected,the LTH was used for PV reconstruction in 13 cases,for SMV reconstruction in 9 cases,and for PSMV reconstruction in 1 case.The LTH was used as a patch in 4 cases and as an interposition vascular graft in 19 cases.In the PD-VR group,the operative time was 482.26±93.13（310-630）min,the vascular occlusion time was 50.83±14.35（25-85）min,and the intraoperative blood loss was 244.78±146.28（80-800）ml.In the PD-NVR group,the operative time was 362.36±112.61（170-715）min,and the intraoperative blood loss was 249.76±190.68（50-1500）ml.Statistical analysis showed that the operation time of patients in the PD-VR group was significantly longer than that in the PD-NVR group（P<0.001）.There was no significant difference in intraoperative blood loss between the two groups（P=0.69）.3.For the patients in the PD-VR group,the average postoperative hospital stay was 20.57±6.39（9-34）days,the incidence of postoperative complications was 39.13%,and the mortality within 30 days after surgery was 8.70%.In the PD-NVR group,the average postoperative hospital stay was 20.00±9.20（1-54）days,the incidence of postoperative complications was 40.19%,and the mortality within 30 days after surgery was 7.18%.After statistical analysis,there were no significant differences between the two groups in postoperative hospital stay,incidence of postoperative complications and the mortality within 30 days after operation.4.In the PD-VR group,a total of 4 patients had thrombosis,and the range of thrombosis was less than 1/2 of the lumen circumference,the lumen was not blocked,the vascular patently rate was 100%.The clot-free patencies at 2 weeks,1 month,3 months and 6 months after operation were 91.30%,91.30%,86.96%and 82.61%,respectively.The median postoperative survival was 5 months（9 days--104 months）.Conclusion:Using the recanalized LTH as autologous grafts to reconstruct PV and/or SMV in PD is safe and feasible.This operation does not increase the blood loss during operation,the incidence of postoperative complications,postoperative 30-day mortality and postoperative hospital stay.The reconstructed vessels had high vascular patency rate.Good clinical results were obtained.To summarize,we found that the biomechanical properties and histological characteristics of the LTH are similar to those of PV.In clinically,we successfully reconstructed the PV and/or SMV using the recanalized LTH,and received a good clinical effect.Thus,we recommend the use of the recanalized LTH as autologous graft to reconstruct the PV and/or SMV.