Fluid-Structure Interaction Simulation of Multiple Overlapping Uncovered Stent Intervention in Aortic Dissection / 医用生物力学

Objective To propose a one-way fluid-structure interaction (FSI) method based on an idealized aortic dissection model, so as to analyze the hemodynamics and wall stress in the false lumen (FL) under the influence of multiple overlapping uncovered stents (MOUS). Methods Upon establishment of the numerical model, the models were divided into two categories according to whether the model involved FL perfused branch artery. The characteristics of hemodynamics and wall stress state in the post-operative scenarios were simulated under different surgical strategies. The wall stress state of the FL before and after thrombosis formation was also compared and analyzed. ResultsThe release process of the stents had little influence on wall stress of the FL. The high velocity and high wall shear stress (WSS) area in the FL could not be reduced by using the MOUS alone. If only the proximal entry tear was blocked with a covered stent-graft, the distal end would maintain a region of high flow rate and high WSS. The combination of covered stent-graft and MOUS would result in a region of low flow rate and low WSS, as well as reduced wall pressure and wall stress in the FL. Compared with the model with FL perfused branch arteries, the model without it was more likely to form a region of low flow rate and low WSS after surgery. However, blood pressure in the FL was relatively higher. The formation of thrombus in the FL could greatly reduce wall stress in the area covered by the thrombus. Conclusions The method proposed in this study can simultaneously investigate hemodynamics and wall stress characteristics of the FL, and provide support for studying mechanical mechanism of FL thrombolysis induced by MOUS and the post-operative aortic expansion.

Stress Analysis of Aortic Vessels under Stent Graft / 医用生物力学

Objective To simulate the interaction between the stent graft (SG) and the aortic wall with finite element (FE) analysis by considering the influence of residual stress field, so as to study the stent influence on stress distributions of the aortic wall. Methods The three-dimensional (3D) residual stress field was generated in an idealized bi-layered thick-wall aortic model via a stress-driven anisotropic growth model by reducing the transmural stress gradient. Upon virtually deploying the SG, the stress on the aortic wall was calculated. Results The 3D residual stress field, corresponding to an opening angle of 117.5°, was shown to reduce the transmural stress gradient in both the circumferential and axial directions. The maximum stress was found at the contact area between aortic wall and wave peak of the stent. At 20% oversize ratio of the stent, the maximum stresses on the aortic wall in circumferential and axial direction were 412 and 132 kPa, respectively, while the in-plane shear stresses σrθ and σrz were both 78 kPa. Under residual stress, the maximum radial, circumferential and axial stresses were decreased by 14.9%, 40.5% and 33.8%, respectively, while the maximum shear stresses σrθ ，σrz，σθz were reduced by 2.5%, 7.1% and 27%, respectively. With the increase of oversize ratio from 10% to 20%, the maximum radial, circumferential and axial stresses were increased by 316%, 129% and 41%, respectively, while the maximum shear stresses σrθ ，σrz，σθz were increased by 661%, 450% and 466%, respectively. Conclusions The residual stress can effectively reduce the transmural stress gradient. Both the residual stress and the oversize ratio of the stent play an important role in modulating the wall stress distribution and the maximum stress.

Management of thoracoabdominal aortic aneurysm: experiences in 39 cases / 中华普通外科杂志

Objective:To compare the efficacy and safety of different treatment methods for thoracoabdominal aortic aneurysm(TAAA).Methods:The clinical data of 39 TAAA patients admitted to our department from Jan 2010 to Feb 2018 were retrospectively analyzed.Results:There were 25 patients in endovascular group, 11 in open group and 3 in hybrid group. The mean age in the endovascular group was significantly higher than that in the open group ( P<0.05). The blood loss and operation time in the endovascular group were significantly lower than those in the open group and the hybrid group ( P<0.05). There was no significant difference in the operation success rate, the complication rate in post-operative 30 days and the rate of re-intervention ( P>0.05) among the three groups. The post-operative 30 days mortality was significantly higher in the hybrid group than that in the endovascular group and open group ( P<0.05). During the follow-up period, the complication rate in the endovascular group was significantly higher than that in the open group ( P<0.05). Conclusion:Endovascular surgery is more suitable for elderly patients because of shorter operation time, less trauma and bleeding.

Discussion on the technical details of the controllable fenestrated thoracic aortic endovascular repair / 国际外科学杂志

Fenestrated thoracic aortic endovascular repair (TEVAR), as the most advantageous technique for total endovascular repair of aortic arch lesions, has been widely carried out in China, but the technical level is different, the operation process lacks standardization, and the quality control is insufficient. This article discusses the technical details include how to ensure the controllability of TEVAR in physician-modified fenestration, how to choose indications, select fenestration positions, make fenestration, install preset guide wires, unwind guide wires, accurately position fenestration of the hole, delivery and release of the bridging stent combined with author′s experience.

The treatment of Stanford type B aortic dissection with unhealthy or short anchoring zone using physician-modified fenestration TEVAR / 中华普通外科杂志

Objective:To evaluate the efficacy and safety of physician-modified fenestration TEVAR for treating type B aortic dissection with unhealthy or short anchoring zone.Methods:Clinical data of patients with type B aortic dissection who received TEVAR for left subclavian artery fenesration from May 2016 to Dec 2018 were analyzed prospectively.Results:The technical success rate was 93.2%. One case was converted into chimney stenting. One case suffered type Ⅰendoleak. One case had type Ⅲ endoleak. There were no deaths or neurological complications during the perioperative period, and the mean hospital stay was 9.2 (5-26) days. The median follow-up time was 30 (12-42) months. One case developed type Ⅰ endoleak during follow-up. No retrograde dissection occurred and all LSA stents remained patent.Conclusion:Physician-modified fenestration TEVAR is safe and effective for the treatment of type B aortic dissection with unhealthy or short anchoring zone.

Short-term results of left subclavian artery reconstruction with branched thoracic endovascular aortic repair in the treatment of complex aortic arch lesions / 中华普通外科杂志

Objective@#To evaluate the short-term efficacy of branched TEVAR in the treatment of complex aortic arch lesions.@*Methods@#The clinical data of 18 patients with aortic lesions requiring reconstruction of the left subclavian artery who were treated with branch TEVAR technology in Tianjin Medical University General Hospital from Apr 2016 to Dec 2018 were analyzed retrospectively.@*Results@#There were 16 cases using Castor external branch stent implantation and 2 cases of self-made internal branch stent. The success rate of device release was 100%, the success rate of operation was 100%, and there were no intraoperative deaths. Postoperative complications occurred in 2 cases: one proximal stent tear dissection required open surgery, one died of massive myocardial infarction.Seventeen patients were followed up for 1-8 months. CTA examination in 16 patients 30 days after surgery, found 1 patient with type Ⅲ endoleak. CTA examination done in 8 patients 6 months after surgery found distal occlusion of left subclavian artery stent in 1 patient necess itating distal stent implantation.@*Conclusion@#The branch TEVAR technique is effective method to reconstruct the arch branched artery.

Short-term results of left subclavian artery reconstruction with branched thoracic endovascular aortic repair in the treatment of complex aortic arch lesions / 中华普通外科杂志

Objective To evaluate the short-term efficacy of branched TEVAR in the treatment of complex aortic arch lesions.Methods The clinical data of 18 patients with aortic lesions requiring reconstruction of the left subclavian artery who were treated with branch TEVAR technology in Tianjin Medical University General Hospital from Apr 2016 to Dec 2018 were analyzed retrospectively.Results There were 16 cases using Castor external branch stent implantation and 2 cases of self-made internal branch stent.The success rate of device release was 100％,the success rate of operation was 100％,and there were no intraoperative deaths.Postoperative complications occurred in 2 cases:one proximal stent tear dissection required open surgery,one died of massive myocardial infarction.Seventeen patients were followed up for 1-8 months.CTA examination in 16 patients 30 days after surgery,found 1 patient with type Ⅲ endoleak.CTA examination done in 8 patients 6 months after surgery found distal occlusion of left subclavian artery stent in 1 patient necessitating distal stent implantation.Conclusion The branch TEVAR technique is effective method to reconstruct the arch branched artery.

Endovascular treatment for primary infected aortic aneurysms: single center 8-year experience / 中华普通外科杂志

To assess the efficacy and outcome of endovascular aortic repair (EVAR for the treatment of primary infected aortic aneurysms (PIAAs).Methods The clinical data of 15 consecutive patients presenting with PIAA from Apr 2010 to Apr 2018 were retrospectively reviewed.Results 10 were male out of 15 patients ranging from 55 to 80 years old.The aneurysms were located in thoracoabdominal aorta in 1 case,abdominal aorta in 10 cases and left common iliac artery in 4 cases.Positive microbial cultures were reported in 13 patients,including Salmonella species in 12 and Streptococcus in 1.Eleven patients received preoperative antibiotics therapy before elective EVAR for more than 1 week.Four patients underwent emergency EVAR due to ruptured aneurysms.Postoperative antibiotic therapy was given for at least six months.There was no death within 30 days.Mean follow-up time was 44.6 months.Infection relapsed in 6 patients during follow-up.Infection-related death occurred in 3 cases.3 of them were healed.Conclusions EVAR combined with aggressive antibiotic strategy is feasible for the treatment of PIAAs,particularly in high-risk surgical patients or in the acute setting of rupture.

Causes and treatment of intimo-intimal intussusception in endovascular repair of aortic dissecting aneurysms / 中华全科医师杂志

Objective Todiscuss the causes and treatment of intimo-intimal intussusception in endovascular repair of aortic dissecting aneurysms.Methods This retrospective study included 7 patients with intimo-intimal intussusception who underwent endovascular repair of aortic dissecting aneurysms from January 2017 to June 2018.There were 5 males and 2 females aged 34 to 64 years (mean 47.1 years),with a clinical course from 8 hours to 3 months.Six cases presented with acute chest pain and 1 had abdominal pain.Preoperative CTA was performed in all patients to confirm the diagnosis.Six patients received thoracic endovascular aortic repair (TEVAR) and 1 receivedfenestration.Results The endovascular repairs were successful without converting to open surgery in all patients.Pathological classifications were 1 type Ⅰ,5 type Ⅱ and 1 type Ⅲ.Four patients received another aortic stent at distal segment to cover the intimo-intimal intussusception and 1 patient at proximal site.One patients received another bare stent in the superior mesenteric artery,and 1 case received abdominal aortic stent implantation.Balloon was used in 2 cases to dilate the stenosis of aortic stents.The death occurred in 1 case at 3 days after surgery for metadata object description schema,and 1 patient needed continuous renal dialysis after discharge.The postoperative conditions (from 7 to 21 days) of other patients were normal without paraplegia,bowel necrosis,lower limb ischemia or arterial rupture.Conclusions The results indicate that the intimo-intimal intussusception in endovascular aortic dissecting aneurysms repair is rare and it is a severe complication.Re-endovascular aortic repair is a safe and reliable surgical approachbased on the type in early phase.

Fenestrated EVAR using physician-modified stent-grafts for thoraco-abdominal aortic lesions / 中华普通外科杂志

Objective To evaluate fenestrated endovascular aortic repair (FEVAR) using physician-modified stent-grafts (PMSGs) for thoraco-abdominal aortic lesions.Methods Seven cases of thoraco-abdominal aortic lesions (1 type Ⅲ thoraco-abdominal aortic aneurysm,1 type Ⅳ thoraco-abdominal aortic aneurysm,4 chronic thoraco-abdominal aortic dissection and 1 type Ⅰ endoleak after EVAR due to abdominal aortic aneurysm) were treated with FEVAR from Nov 2016 to Nov 2017.Results FEVAR was performed successfully in all cases.Type Ⅱ and Ⅲ endoleak occurred in 4 cases.One died of acute myocardial infarction 2 days postoperatively.Renal dysfunction deterioration occurred in one case of chronic dissection and improved after the medical treatment.Renal subcapsular hematoma was found in 2 cases postoperatively,and resolved after conservative therapy.Mean follow-up period was 7.2 months,target vessel patency was identified in 5 of the 6 cases.Conclusions FEVAR using PMSGs is a viable alternative to treat thoraco-abdominal aortic lesions.

On table fenestrated stent graft in zone 0 and zone 1 for aortic arch diseases / 中华普通外科杂志

Objective To evaluate fenestrated thoracic endovascular aortic repair (f-TEVAR) using fenestrated stent graft on table in zone 0 and zone 1 for aortic arch diseases.Methods 13 patients undergoing f-TEVAR by using physician modified fenestrated stent grafts (PMSGs) on table in zone 0 and zone 1 for aortic arch diseases between Nov 2015 and Mar 2018 were retrospectively reviewed.Results The median age was 59 years(range,33-81 years).PMSGs were deployed from Z0 in 5 patients and Z1 in remaining 8 patients.All but 3 patients underwent elective procedure.The technical success rate was 92.3％.Overall mortality was 7.7％ (1/13).There were no perioperative neurologic complications and paraplegia.One patient suffering from acute left leg ischemia and renal failure recovered after openembolectomy and dialysis.Median length of stay was 9.0 days (range,4-35 days).12 patients were survival at a median follow-up of 11.5 months (range,1.0-19.0 months).Retrograde dissection occurred in one patient and resolved after open repair.During follow up,all target vessels remained patent,with no fenestration-related type Ⅰ or Ⅲ endoleaks.Conclusions f-TEVAR using modified fenestrated stent grafts on table in Z0 and Z1 is feasible for the treatment of aortic arch diseases.

The value of contrast enhanced ultrasound in diagnosing type Ⅰ and Ⅱ endoleaks after endovascular abdominal aortic aneurysm repair / 中华超声影像学杂志

Objective To investigate the role of contrast enhanced ultrasound (CEUS) in detecting type Ⅰ and Ⅱ endoleaks after endovascular abdominal aortic aneurysm repair (EVAR).Methods PostEVAR patients who met the inclusion criteria were enrolled.All of patients underwent CEUS and computer tomography angiography (CTA) examination.The following parameters were evaluated:ultrasound contrast agent within aneurysmal sac,location and source of endoleaks,wash-in time of endoleaks and stentgraft since contrast agent injection.Analysis was performed to observe different types of endoleak features in CEUS.Results Nine cases were enrolled and all the cases had endoleaks.Three cases were type Ⅰ,6 cases were type Ⅱ.The wash-in time of type Ⅱ endoleaks delayed 9.8 seconds compared to type Ⅰ,and the results of CEUS diagnosis were consistent with CTA.Conclusions CEUS is an effective way to detect endoleaks.This technique can be used as a supplement for CTA in follow-up of post-EVAR patients.

Diagnosis and management of Stanford B aortic dissection / 国际外科学杂志

Type B aortic dissection is a life-threatening aortic disease.With the development of clinical classification and diagnostic method,the mortality of type B aortic dissection has been greatly decreased.In respect of treatment,endovascular repair due to minimally invasive advantages become the first choice for the treatment of complicated type B aortic dissection.For non-complicated type B aortic dissection,endovascular repair also gradually replace drug treatment,and showed good efficacy.Open surgery is only available for patients who ate not suitable for endovascular repair or repair failure or patients with connective tissue disease.

Human telomerase reverse transcriptase-mediated effects on biological characteristics of rat fetal liver stem cells / 中国组织工程研究

BACKGROUND:Studies have shown that stem cels transfected with human telomerase reverse transcriptase (hTERT) gene can stably express high-level telomerase activity and strengthen cel proliferation, which lays the foundation to establish geneticaly engineered immortalized stem cel lines. OBJECTIVE:To explore the effects of hTERT transfection on proliferation and cel cycle of rat fetal liver stem cels in vitro. METHODS:Rat fetal liver stem cels culturedin vitro were transfected by recombinant adeno-associated virus carrying hTERT genes. RT-PCR and western blot assay were used to detect the expression of hTERT mRNA and protein, respectively. Cel Counting Kit-8 method and cel growth curve were used to detect cel growth and proliferation. Changes in cel cycle distribution were determined by flow cytometry. RESULTS AND CONCLUSION:Compared with the control group and empty virus group, in the hTERT infection group, hTERT expressed at gene and protein levels, the growth rate of the cels increased, and the number of cels at G0/G1 phase and S phase was decreased and increased, respectively. The results show that recombinant adeno-associated virus as a vector of hTERT gene used for gene transfection can promote the in vitro proliferation of rat fetal liver stem cels and play an optimal role in cel culture.

Research on the suppressive effect on transplantation rejection by indoleamine 2, 3-dioxygenase / 中华外科杂志

<p><b>OBJECTIVE</b>To study the suppressive effect of indoleamine 2, 3-dioxygenase on transplantation rejection in mice heterotopic cardiac transplantation.</p><p><b>METHODS</b>Adenovirus vector containing IDO gene was used to infect donor (C57BL/6) DC to obtain IDO(+)DC. Mouse heterotopic cardiac transplantation models were established (C57BL/6-BALB/c) and the following groups were set up, including the control group, DC injection group, TC injection group, IDO(+)DC injection group and co-injection group of IDO(+)DC and TC, 12 donors and 12 recipients in each group.Survival time of the donor heart in every group was observed. Meanwhile, donor hearts were harvested 7 days post transplantation for different examinations, including pathological examination, mRNA expression of IDO through real-time PCR, IDO protein expression through Western blot. Peripheral blood of recipients was also harvested for CD3(+)T lymphocyte apoptosis rate examination through fluorescence-activated cell sorting.One-way ANOVA and Kaplan-Meier Survival Analysis were used for statistic analysis of IDO expression, CD3(+)T lymphocyte apoptosis rate and survival time of the donor heart respectively.</p><p><b>RESULTS</b>Cadiac allograft median survival time of each group were 7.0, 7.5, 11.0, 17.5, 24.0 days respectively. Compared with control and DC injection group, IDO(+)DC, TC and co-injection group significantly prolonged the survival time of donor hearts (t = 3.523-8.449, P < 0.01). Both IDO mRNA and protein expression showed significant increase(t = 5.974-16.176, P < 0.01). The CD3(+)T lymphocyte apoptosis rate was also significantly increased (t = 6.324-38.120, P < 0.01). Compared with IDO(+)DC or TC group alone, co-injection group significantly prolonged the survival time of the donor heart (t = 5.971 and 2.831, P < 0.05). Both IDO mRNA and protein expression showed significant increase (t = 2.853-15.194, P < 0.01).Furthermore, the CD3(+)T lymphocyte apoptosis rate was significantly increased as well (t = 26.069 and 7.643, P < 0.05).</p><p><b>CONCLUSIONS</b>Suppressive effect of co-injection of IDO(+)DC and TC is much more effective than administration of IDO(+)DC or TC alone, which suggests that IDO achieved immune suppressive effect through the pathway of tryptophan depletion and accumulation of TC.</p>

Inhibitory effect of high expression of IDO from donor DCs on allograft rejection in mice heterotopic cardiac transplantation model / 中华器官移植杂志

Objective To investigate the effect of high expression of functional IDO trom donor DCs on transplantation rejection in mice heterotopic cardiac transplantation.Method Adenovirus vector containing IDO gene was used to infect donor (C57BL/6) DCs to obtain IDO+ DCs.Mouse heterotopic cardiac transplantation models were established (C57BL/6-BALB/c) and the following groups were set up:control group,DCs injection group and IDO+ DCs injection group.Survival time of the donor heart in all groups was observed.Meanwhile,donor hearts were harvested at 7 th day post-transplantation for different examinations,including pathological examination,mRNA expression of IDO by real-time PCR,and IDO protein expression by Western blotting.Peripheral blood of recipients was also harvested for T lymphocyte apoptosis rate examination by FACS.Result Cardiac allograft median survival time in control group,DCs injection group and IDO+ DCs injection group was 7,7.5,and 17.5 days respectively.IDO+ DCs treatment significantly prolonged the survival time of donor hearts (P＜0.01).Pathological grading was significantly decreased (P＜0.01).The CD3+ T lymphocyte apoptosis rate in peripheral blood of recipients in IDO+ DCs injection group was (46.50 + 5.02)％,significantly higher than the other two groups (P＜0.01).Both IDO mRNA and protein expression showed significant increase (P＜0.01).Conclusion The preoperative medication with IDO+ DCs injection to the recipients could induce T lymphocyte apoptosis and significantly suppress the rejection in mice heterotopic cardiac homotransplantation.