Custom Made Fenestrated Stent Graft Collapse after Thoracic Endovascular Aortic Repair: A Case Report

We present a case of stent graft collapse after performing thoracic endovascular aortic repair with a custom-made fenestrated stent graft. The patient was a 70-year-old woman with an asymptomatic aneurysm of the distal aortic arch, and thoracic endovascular aortic repair was performed. The patient showed a blood pressure difference between the left arm and the right arm on postoperative day (POD) 17 prompting the performance of a chest computed tomography scan which revealed stent graft collapse. She then underwent staged debranching of thoracic endovascular aortic repair. Stent graft collapse is a rare but well-described complication of thoracic endovascular repair. Therefore, patients who undergo such a procedure should be carefully monitored for signs and symptoms, which suggest the possibility of stent collapse.

Endovascular treatment of aortoiliac aneurysms: From intentional occlusion of the internal iliac artery to branch iliac stent graft

Approximately 20%-40% of patients with abdominal aortic aneurysms can have unilateral or bilateral iliac artery aneurysms and/or ectasia. This influences and compromises the distal sealing zone during endovascular aneurysm repair. There are a few endovascular techniques that are used to treat these types of aneurysms, including intentional occlusion/over-stenting of the internal iliac artery on one or both sides, the "bell-bottom" technique, and the more recent method of using an iliac branch stent graft. In some cases, other options include the "snorkel and sandwich" technique and hybrid interventions. Pelvic ischemia, represented as buttock claudication, has been reported in 16%-55% of cases; this is followed by impotence, which has been described in 10%-17% of cases following internal iliac artery occlusion. The bellbottom technique can be used for a common iliac artery up to 24 mm in diameter given that the largest diameter of the stent graft is 28 mm. There is a paucity of data and evidence regarding the "snorkel and sandwich" technique, which can be used in a few clinical scenarios. The hybrid intervention is comprised of a surgical operation, and is not purely endovascular. The newest branch stent graft technology enables preservation of the anterograde flow of important side branches. Technical success with the newest technique ranges from 85%-96.3%, and in some small series, technical success is 100%. Buttock claudication was reported in up to 4% of patients treated with a branch stent graft at 5-year follow-up. Mid- and short-term follow-up results showed branch patency of up to 88% during the 5-6-year period. Furthermore, branch graft occlusion is a potential complication, and it has been described to occur in 1.2%-11% of cases. Iliac branch stent graft placement represents a further development in endovascular medicine, and it has a high technical success rate without serious complications.

Total endovascular repair of an intraoperative stent-graft deployed in the false lumen of Stanford type A aortic dissection: A case report

BACKGROUND A 46-year-old male underwent ascending aortic replacement,total arch replacement,and descending aortic stent implantation for Stanford type A aortic dissection in 2016.However,an intraoperative stent-graft was deployed in the false lumen inadvertently.This caused severe iatrogenic thoracic and abdominal aortic dissection,and the dissection involved many visceral arteries.CASE SUMMARY The patient had pain in the chest and back for 1 mo.A computed tomography scan showed that the patient had secondary thoracic and abdominal aortic dissection.The ascending aortic replacement,total arch replacement,and descending aortic stent implantation for Stanford type A aortic dissection were performed 2 years prior.An intraoperative stent-graft was deployed in the false lumen.Endovascular aneurysm repair was performed to address this intractable situation.An occluder was used to occlude the proximal end of the true lumen,and a covered stent was used to direct blood flow back to the true lumen.A three-dimensional printing technique was used in this operation to guide prefenestration.The computed tomography scan at the 1stmo after surgery showed that the thoracic and abdominal aortic dissection was repaired,with all visceral arteries remaining patent.The patient did not develop renal failure or neurological complications after surgery.CONCLUSION The total endovascular repair for false lumen stent-graft implantation was feasible and minimally invasive.Our procedures provided a new solution for stent-graft deployed in the false lumen,and other departments may be inspired by this case when they need to rescue a disastrous stent implantation.

Role of Grafting Technique on the Success of Stenting Propagation of Two Rose (<i>Rosa</i>sp.) Varieties

The influence of two grafting techniques on the success of stenting (simultaneous cutting and grafting) and some ensuing growth parameters of stentlings were studied under glasshouse conditions. The Avalanch and Peach Avalanch glasshouse rose varieties were utilized as scion and grafted on R. manetti as rootstock. Two grafting techniques namely, splice and omega grafting methods were practiced and graft combinations were inserted in cocopeat-perlit (1:2) medium under mist system. The number of roots, longest root size, shoots and leaf numbers and successful grafting percentage were evaluated after grafting. In Avalanch/R. manetti and Peach Avalanch/R. manetti combinations, higher percentage of successful grafting was observed in the stentlings propagated via omega grafting technique. Furthermore Avalanch/R. manetti stentlings prepared by omega grafting were found to produce more number of roots, shoots and leaves and longest root size as compared to those propagated through splice grafting method. In case of Peach Avalanch/R. manetti combinations propagated via omega grafting more number of shoots was observed as compared to those propagated by splice method. However, these were not significantly different with respect to their leaf numbers. The results showed the superiority of omega grafting procedure.

Stent-grafts for the treatment of TIPS dysfunction:Fluency stent vs Wallgraft stent

AIM:To evaluate the clinical efficacy of an expanded polytetrafluoro-ethylene-covered Fluency stent compared with that of a polyethylene terephthalate-covered Wallgraft stent for the management of transjugular intrahepatic portosystemic shunt(TIPS)dysfunction.METHODS:A retrospective review of patients who underwent TIPS revision with stent-grafts between May 2007 and June 2011 was conducted.The patients were divided into two groups according to the stentgrafts implanted:the Fluency stent(Bard Incorporated,Karlsruhe,Germany)and the Wallgraft stent(Boston Scientific,Galway,Ireland).The primary patency rates were calculated and compared using the Kaplan-Meier method.RESULTS:A total of 73 patients were evaluated in this study:33 with Fluency stents and 40 with Wallgraft stents.The primary patency rates at 12 and 24 mo were 91% and 85%,respectively,in the Fluency stent group and 78% and 63%,respectively,in the Wallgraft stent group.The primary shunt patency rates after TIPS revision were significantly better with the Fluency stent than with the Wallgraft stent(P = 0.033).CONCLUSION:TIPS revision with the Fluency stent has higher medium-term patency rates than that with the Wallgraft stent.

Endovascular stent-grafts for acute and chronic type B aortic dissection: comparison of clinical outcomes

Objective To evaluate the early and mid-term results of endovascular repair for acute and chronic type B aortic dissection, and to compare the clinical outcomes between the 2 groups. Methods From May 2002 to December 2006, 50 patients with type B aortic dissection were treated by endovascular stent-graft. There were 23 patients in the acute aortic dissection (AAD) group and 27 patients in the chronic aortic dissection (CAD) group. All patients were followed up from 1 to 54 months (average, 17±16 months).The immediate and follow-up clinical outcomes were documented and compared between the 2 groups. Results Placement of endovascular stent-grafts across the primary entry tears was technically successful in all 50 patients. Compared to the CAD group, the AAD group had a higher percentage of pleural effusion (17.4% vs. 0%, P=0.04) and visceral /leg ischemia (26.1% vs 3.7%, P=0.04). Procedure related complications, including endoleak and post-implantation syndrome, occurred more frequently in the AAD group than in the CAD group (21.7% vs 3.7% and 30.4% vs 11.1%, respectively; P=0.08 and P=0.04). Kaplan–Meier analysis showed no difference in the survival rate at 4 years between the 2 groups (86.4% vs 92.3%, P=0.42 by log-rank test). However, the event-free survival rate was higher in patients with chronic dissection than in patients with acute aortic dissection(96.2% vs 73.9%; P=0.02 by log-rank test). Conclu- sions Endovascular repair with stent-graft was safe and effective for the treatment of both acute and chronic type B aortic dissection. However, both immediate and long term major complications occurred more frequently in patients with acute dissection than in those with chronic dissection.

Experimental and computational studies on the flow fields in aortic aneurysms associated with deployment of AAA stent-grafts

Pulsatile flow fields in rigid abdominal aortic aneurysm （AAA） models were investigated numerically, and the simulation results are found in good agreement with particle image velocimetry （PIV） measurements. There are one or more vortexes in the AAA bulge, and a fairly high wall shear stress exists at the distal end, and thus the AAA is in danger of rupture. Medical treatment consists of inserting a vascular stent-graft in the AAA, which would decrease the blood impact to the inner walls and reduce wall shear stress so that the rupture could be prevented. A new computational model, based on porous medium model, was developed and results are documented. Therapeutic effect of the stent-graft was verified numerically with the new model.

Stent-grafts placement for treatment of massive hemorrhage from ruptured hepatic artery after pancreaticoduodenectomy

AIM:To present a series of cases with life-threatening hemorrhage from ruptured hepatic artery pseudoaneurysm after pancreaticoduodenectomy(PD) treated with placement of stent-grafts.METHODS:Massive hemorrhage from ruptured hepatic artery pseudoaneurysm after PD in 9 patients(6 men,3 women) at the age of 23-75 years(mean 48 years),were treated with placement of percutaneous endovascular balloon-expandable coronary stent-grafts.All patients were not suitable for embolization because of a non-patent portal vein.One or more stent-grafts,ranging 3-6 mm in diameter and 16-55 mm in length,were placed to exclude ruptured pseudoaneurysm.Followup data,including clinical condition,liver function tests,and Doppler ultrasound examination,were recorded at the outpatient clinic.RESULTS:Immediate technical success was achieved in all the 9 patients.All stent-grafts were deployed in the intended position for immediate cessation of bleeding and preservation of satisfactory hepatic arterial blood flow.No significant procedure-related complications occurred.Recurrent bleeding occurred in 2 patients at 16 and 24 h,respectively,after placement of stent-grafts and treated with surgical revision.One patient died of sepsis 12 d after the interventional procedure.The remaining 6 patients were survived when they were discharged.The mean follow-up time was 10.5 mo(range 4-16 mo).No patient had recurrent bleeding after discharge.Doppler ultrasound examination verified the patency of hepatic artery and stent-grafts during the follow-up.CONCLUSION:Placement of stent-grafts is an effective and safe procedure for acute life-threatening hemorrhage from ruptured hepatic artery pseudoaneurysm.

Angioscopic Observation of an Endoluminal Stent Graft: CT Imaging versus Angioscopic Imaging

We could observe the endoluminal stent graft (SG) following thoracic endovascular aneurysm repair (TEVAR) by a coronary artery angioscope and establish intravascular visualization of SG. The patient was a 70-year-old woman with the distal aortic arch aneurysm and the descending aortic aneurysm, and debranching TEVAR were performed. After 12 months follow up, urgent hospitalization was required for chest pain, and cardiac catheter examination with a coronary artery angioscope was performed. The endoluminal SG was observed. The observation in angioscope which is a video image is better than CT that is a still image, and observation in blood vessel or SG is possible. It may be possible to observe the endoluminal SG, allowing potential investigation of an endoleak, or the covering status of the SG with the native aortic vessel wall, or the state of intimal membrane formation in the endoluminal graft.

Fatigue Performance of Fabrics of Stent-Grafts Supported with Z-Stents vs. Ringed Stents

Stent-grafts were commercialized rapidly and gained a broad clinical acceptance over the past two decades. However,relatively more recent recognition of particular stent-graft design shortcomings have been identified which need to be addressed. It appears that various stent-graft designs may be more or less resistant to metal fatigue and /or fabric abrasions which can lead to type III and type IV endoleaks over the long term. Therefore,it is necessary to investigate the fatigue performance of the most common stentgraft designs: Z-stents and ringed stents,in a long-term in vitro fatigue simulation environment. This paper aimed to analyze nondestructively( gross observations) and destructively( fabric characteristics,mechanical and chemical properties) in order to put forward suggestions to improve the fabric and stent characteristics that may prevent type III and IV endoleaks. The fabric supported with ringed stent-grafts remained nearly completely intact after 168h. However, the fabric supported with Z-stents demonstrated significant damage. Fabric characteristics and tensile strength of the fibers did not present a significant difference between the control and fatigue simulated specimens. The crystallinity declined for both specimens. The fatigue performance of fabrics supported with ringed stents appears to be superior to that supported with Z-stents. The potential for a dynamic and destructive interaction between the apices of Z-stents which can lead to fraying and /or tearing of the graft fabric must be addressed in future designs.

Long term outcomes of drug-eluting stent versus coronary artery bypass grafting for left main coronary artery disease： a meta-analysis

BackgroundIt 仍然是争论的有 drug-eluting stent ( DES )的经皮的冠的干预是否与冠的动脉相比安全、有效为没有防卫的左主要冠的动脉( ULMCA )绕过接枝外科( CABG )疾病在长期列在后面在上面( 3 年) .MethodsEligible 研究被寻找 PubMed 选择， EMBASE ，并且 Cochrane 图书馆直到2016年12月6日。主要端点是一死亡，心肌的梗塞(MI ) 或在最长的后续期间的击合成。死亡，心脏的死亡， MI，击和重复 revascularization 是第二等的 outcomes.ResultsFour 使随机化的控制试用和包含 14,130 个病人的 12 调整观察研究被包括。DES 比得上关于主要端点的出现的 CABG (HR = 0.94， 95% CI：0.86-1.03 ) 。而且， DES 显著地与 MI 的更高的发生被联系(HR = 1.56， 95% CI：1.09-2.22 ) 并且重复 revascularization (HR = 3.09， 95% CI：2.33-4.10 ) 当没有差别在二策略之间被发现时，与 CABG 相比认为是死亡，心脏的死亡和击的率。而且， DES 能减少死亡， MI 或击的合成端点的风险(HR = 0.80， 95% CI：0.67-0.95 ) 因为有句法的 ULMCA 损害与重复 revascularization 的更高的风险获得 32 .ConclusionsAlthough，有 DES 的一种总线标准看起来象为 ULMCA 疾病在的 CABG 一样安全长期列在后面起来。另外，有 DES 的治疗能是到为 ULMCA 损害与的 CABG 的其他的 interventional 策略对中间的解剖复杂性低。

Role of Second-Generation Drug-Eluting Stents and Bypass Grafting in Coronary Artery Disease:A Systematic Review and Meta-analysis

Background:The safety and efficacy of coronary artery bypass grafting(CABG)and second-generation drug-eluting stents(DESs)in patients with coronary artery disease(CAD)remain controversial.Therefore we aimed to compare the outcomes of CAD patients treated with CABG and second-generation DESs.Methods:We systematically searched the PubMed,Cochrane Library,Ovid,and Elsevier databases.Studies comparing second-generation DESs with CABG in CAD patients were included.RevMan 5.3 was used to extract and pool the data from the applicable studies.Results:Six trials(N=6604 participants)were included in this meta-analysis.Among all of the CAD patients,second-generation DESs were associated with no differences in the risks of all-cause death[risk ratio(RR)1.18,95% confi dence interval(CI)0.98–1.43,P=0.09],cardiovascular death(RR 1.14,95% CI 0.81–1.59,P=0.45),myocardial infarction(RR 1.22,95% CI 0.98–1.54,P=0.08),and stroke(RR 0.83,95% CI 0.59–1.17,P=0.29),but increased the risks of revascularization(RR 1.95,95% CI 1.66–2.30,P<0.001)and major adverse cardiac and cerebrovascular events(RR 1.72,95% CI:1.31–2.26,P<0.001)when compared with CABG.Conclusions:In the treatment of CAD patients,second-generation DESs was not associated with increased risks of all-cause death,cardiovascular death,myocardial infarction,and stroke,but increased the risks of revascularization and major adverse cardiac and cerebrovascular events when compared with CABG.

Which Offers the Best? Stent Graft or Bare Metal Stent for Endovascular Treatment of Aortoiliac Disease

Background: In the present study, it was aimed to compare the stent grafts and bare-metal stents in terms of post-procedural patency, clinical recovery and complications in the subjects with symptomatic aorto-iliac arterial disease. Methods: A total of 79 subjects with symptomatic aorto-iliac arterial disease treated with endovascular methods were included in the present study. Forty three subjects received self-expendable bare metal stent (ev3 Protégé stent system, Endovascular Inc., Plymouth, Minnesota, USA) and 36 subjects received PTFE-covered stent graft (Fluency Plus Stent Graft, Bard Peripheral Vascular, Tempe, Arizona). The subjects were compared after and at Months 1, 6, and 12 following the procedure in terms of Rutherford’s classification, ankle-arm index (AAI), patency rates, and complications. Results: The subjects receiving bare metal stent and stent graft for aorto-iliac arterial disease were followed for averagely 15 months. For the subjects receiving bare metal stent, primary patency rates at months 1, 6, and 12 were 98%, 81%, and 70%, respectively, while secondary patency rate at month 12 was found to be 84%. For the group of stent graft, primary patency rates were found as 97%, 97%, and 92%, respectively and secondary patency rate at month 12 was found to be 94%. Stent grafts were applied at the same time in 2 patients who had metal bare metal because the rupture occurred during the procedure. In the comparison between two groups, the group of stent graft was found to be statistically superior to the other in terms of patency, clinical and post-procedural complications. Conclusion: In conclusion, it was found that the stent grafts were superior to the bare metal stents in terms of patency and complication rates in the subjects with symptomatic aortoiliac disease.

Hybrid Procedure Utilizing Stent Grafts to Stabilize Distal Flaps after Common and Superficial Femoral Endarterectomy

Background: Endarterectomy has long been the standard for common femoral artery (CFA) occlusive disease. Hybrid procedures utilizing endovascular and open techniques have recently been used for revascularization. The purpose of this study was to evaluate the effectiveness of the use of a stent graft to stabilize the distal flap and prevent further dissection after extensive endarterectomy. Methods: All patients from Monmouth Medical Center in Long Branch, NJ from September 2008 to March 2013 who underwent an extensive common and superficial femoral (SFA) endarterectomy combined with the use of a Viabahn (Gore Medical) stent graft to stabilize the distal flap were included in the study. These stents were deployed in the proximal SFA after extensive endarterectomy, under direct visualization, without the aid of fluoroscopy. Due to the location in the SFA, these flaps were not amenable to suture tacking. Results: Fifteen patients met these criteria and were included in our study. Twelve patients underwent femoral endarterectomy for severe claudication and three patients for limb salvage. Technical success was achieved in all 15 patients. Five patients also had stents placed proximally to increase inflow and one patient had an additional stent placed distally to improve outflow. There were no intraoperative or postoperative complications. Conclusion: Stent graft placement allows a more extensive endarterectomy to be performed by stabilizing the distal flap allowing a safe transition into the true lumen that is not possible with suture tacking.

Endovascular stent graft repair of abdominal aortic aneurysms:Current status and future directions

Endovascular stent graft repair of abdominal aortic aneurysm(AAA)has undergone rapid developments since it was introduced in the early 1990s.Two main types of aortic stent grafts have been developed and are currently being used in clinical practice to deal with patients with complicated or unsuitable aneurysm necks,namely,suprarenal and fenestrated stent grafts.Helical computed tomography angiography has been widely recognized as the method of choice for both pre-operative planning and post-operative followup of endovascular repair(EVAR).In addition to 2D axial images,a number of 2D and 3D reconstructions are generated to provide additional information about imaging of the stent grafts in relation to the aortic aneurysm diameter and extent,encroachment of stent wires to the renal artery ostium and position of the fenestrated vessel stents.The purpose of this article is to provide an overview of applications of EVAR of AAA and diagnostic applications of 2D and 3D image visualizations in the assessment of treatment outcomes of EVAR.Interference of stent wires with renal blood flow from the hemodynamic point of view will also be discussed,and future directions explored.

Viabahn Stent Graft for Inadvertent Insertion of a Central Venous Catheter in the Subclavian Artery

Subclavian artery (SCA) injuries associated with central venous catheter (CVC) insertion are uncommon yet lethal complications that typically require surgical treatment. This case report presents the case of a 94-year-old man with an iatrogenic right SCA injury resulting from a misplaced CVC. Computed tomography revealed the catheter piercing the right internal jugular vein to enter the right SCA and then reaching the aortic arch. Emergent endovascular treatment was performed, and a 13-mm × 50-mm self-expanding Viabahn stent graft (W.L. Gore & Associates, Flagstaff, AZ, USA) was placed via the right brachial artery. The misplaced catheter was successfully removed under simultaneous postdeployment balloon dilatation. This case highlights the utility of the Viabahn stent graft for iatrogenic right SCA injury caused by a misplaced CVC and presents some insights and tips for a safer procedure.

Biocompatibility between stent graft and abdominal aorta

To evaluate the biocompatibility between the domestic stent-graft and abdominal aorta.Methods We made stent-graft with felting of expanding-polytetra- fluroethylene (ePTFE) graft and nitinol stent.They were implanted in the subrenal abdominal aorta.The specimes were taken out 2,4,12 weeks afterwards and underwnet HE/special pigmentation of collagen and elastin,immunohistochemistry of α actin from vascular smooth muscle cells(VSMC),in-situ apoptosis detection and scan of electromicroscopy.The comparison between them and normal abdominal aorta in intimal thickness,relative content of collagen and elastin,density and apoptosis ratio of VSMC in medium was made through the image analysis.Results The stent-graft was covered with intima as early as 2 weeks but suffered more severe intimal hyperplasia all the time (P<0.01).The morphology and distribution of collagen and elastin were generally normal in the experimental group (P>0.05).However,its density and apoptosis ratio of VSMC in medium were significantly higher than in the normal ones (P<0.01) in 2,4 weeks.Conclusion The stent-graft shared fine biocompatibility with the abdominal aorta except for the significant intimal hyperplasia.3 refs.

Case Report of a Pseudoaneurysm of Ascending Aorta Treated by Stent

Pseudoaneurysms of the ascending aorta are a rare complication of aortic and cardiac surgery. In this article, we present a clinical case of a 56-year-old patient with a fortuitous diagnosis of a pseudoaneurysm of ascending aorta that was treated by an endovascular stent-graft. We discuss in this article the diagnostic and therapeutic aspect of the case and the place of endovascular treatment for the ascending aorta.

颈动脉狭窄合并冠心病同期外科治疗的疗效分析:单中心经验

目的总结同期颈动脉血运重建手术及冠状动脉血运重建手术治疗颈动脉狭窄合并冠心病患者的单中心临床经验。方法回顾性分析2008年1月至2020年1月中日友好医院心脏血管外科收治的54例颈动脉狭窄合并冠心病患者资料,其中同期行颈动脉内膜剥脱术(carotid endarterectomy,CEA)+冠状动脉搭桥术(coronary artery bypass grafting,CABG)38例,同期行颈动脉支架植入术(carotid artery stenting,CAS)+CABG 16例。结果手术成功率100%。围手术期内出现小卒中3例,短暂性脑缺血发作4例,术后短暂低血压8例,术后高灌注综合征3例,二次开胸3例,心肌梗死4例;无围手术期死亡病例。同期CEA+CABG组与同期CAS+CABG组的手术时间、术中出血量、围手术期输血量、神经系统并发症和循环系统并发症发生率差异均无统计学意义(P>0.05)。48例患者获得随访,随访时间29~140个月,平均(89.8±35.6)个月,因心肌梗死和心功能不全死亡患者各1例。结论同期CEA+CABG与同期CAS+CABG治疗颈动脉狭窄合并冠心病患者均安全有效。

血管通路顽固性狭窄病变递进处置策略及临床分析

目的对于动静脉内瘘顽固性狭窄病变,采取递进处置策略进行干预治疗,分析该方案治疗的预后,旨在探讨更为有效合理的动静脉内瘘维护手段。方法回顾性分析2020年6月—2021年6月在南京医科大学第二附属医院血液净化中心因高位自体动静脉内瘘(autologous arteriovenous fistula,AVF)头静脉弓狭窄和人工血管动静脉内瘘(arteriovenous graft,AVG)静脉吻合口区域狭窄首次行超声引导经皮腔内血管成形术(percutaneous transluminal angioplasty,PTA)治疗,并采取递进处置策略维护的患者,随访24个月观察内瘘的通畅和再干预情况,另与南京医科大学第二附属医院血液净化中心同类病变单纯以高压球囊维护的随访数据比较得出结论。结果高位AVF头静脉弓狭窄采取递进处置策略维护的患者31例,单纯以高压球囊扩张规律维护的患者16例,随访24个月,两者在再干预次数(t=4.461,P<0.001)、再干预后平均通畅时间(t=3.550,P<0.001)及PTA辅助通畅率(χ^(2)=5.562,P=0.021)方面比较差异有统计学意义;AVG静脉吻合口区域狭窄采取递进处置策略维护的患者68例,单纯以高压球囊扩张规律维护的患者58例,随访24个月,两者在再干预次数(t=5.094,P<0.001)及再干预后平均通畅时间(t=3.251,P=0.002)方面比较差异有统计学意义。结论采取递进处置策略,循序渐进地使用各种介入治疗器械以及手术方案处置动静脉内瘘顽固性狭窄病变可以提高PTA的通畅性,减少干预频次,改善预后。