• Gut and Liver
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• 제12권6호
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• pp.722-727
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• 2018

Background/Aims: Although endoscopic bilateral stent-instent placement is challenging, many recent studies have reported promising outcomes regarding technical success and endoscopic re-intervention. This study aimed to evaluate the technical accessibility of stent-in-stent placement using large cell-type stents in patients with inoperable malignant hilar biliary obstruction. Methods: Forty-three patients with inoperable malignant hilar biliary obstruction from four academic centers were prospectively enrolled from March 2013 to June 2015. Results: Bilateral stent-in-stent placement using two large cell-type stents was successfully performed in 88.4% of the patients (38/43). In four of the five cases with technical failure, the delivery sheath of the second stent became caught in the hook-cross-type vertex of the large cell of the first stent, and subsequent attempts to pass a guidewire and stent assembly through the mesh failed. Functional success was achieved in all cases of technical success. Stent occlusion occurred in 63.2% of the patients (24/38), with a median patient survival of 300 days. The median stent patency was 198 days. The stent patency rate was 82.9%, 63.1%, and 32.1% at 3, 6, and 12 months postoperatively, respectively. Endoscopic re-intervention was performed in 14 patients, whereas 10 underwent percutaneous drainage. Conclusions: Large cell-type stents for endoscopic bilateral stent-in-stent placement had acceptable functional success and stent patency when technically successful. However, the technical difficulty associated with the entanglement of the second stent delivery sheath in the hook-cross-type vertex of the first stent may preclude large cell-type stents from being considered as a dedicated standard tool for stent-in-stent placement.

• International Journal of Vascular Biomedical Engineering
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• 제1권1호
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• pp.32-40
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• 2003

Axillo-bifemoral (Ax-Fem) bypass are now well accepted for bilateral iliac artery occlusion as the second best option. This extra-anatomical (unnatural) bypasses, however, have various hemodynamic liabilities affecting the patency. Hemodynamic conditions of each different type of Ax-Fem bypass were assessed with computer simulation model to determine the hemodynamically more sound type. Simulation models of five different types of Ax-Fem bypass were constructed. Our investigation based on the computer simulation models have shown distinct differences between two most popular Lazy-S type and Inverted-C type on the distribution of flow volume, shear stress and recirculation zone, etc., though both types have shown similar clinical results. Lazy-S type has shown better hemodyanmic status than inverted-C type. The theoretical advantage of "Lazy-S" type has never been adequately proved for its superiority clinically over the inverted-C type. Inverted-C type is now in more favor with clinically better results in spite of many hemodynamic liabilities including retrograde flow to the branching graft. The improvement of over-all long-term patency rate of various extra-anatomical bypasses is still warranted through proper correction of the hemodynamic liability. Even though clinical outcome of the extra-anatomical bypass has been equal regardless of the type of crossover femoral graft configuration, there are distinct differences on the hemodynamic characteristics among various types of configuration. Further hemodynamic study in the pulsatile flow status is warranted to correct hemodynamic defects with proper modification of various hemodynamic factors of each model.

• Archives of Reconstructive Microsurgery
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• 제14권1호
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• pp.57-62
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• 2005

Microvascular anastomosis with suture technique is a basic skill but there are several problems such as stenosis, thrombosis and long operating time. Recently plastic surgeons have developed non-suturing mechanical coupling devices for microvascular anastomosis. The authors applied non-penetrating vascular clips (VCS clips) in the field of free flap surgery of head and neck area. Between August of 2004 and January of 2005, we performed 9 free flaps (16 vessels) using small-sized VCS clips. Four stay sutures were applied first and then VCS clips were placed between sutures about 1 mm apart. Vascular pedicle of free flap included the descending branch of lateral circumflex femoral vessel, thoracodorsal vessel, deep inferior epigastric vessel and cephalic vein. The recipient vessels were the superior thyroid artery, superficial temporal artery, internal jugular vein, external jugular vein, and superficial temporal vein. We performed 13 end-to-end (4 arteries and 9 veins) and 3 venous end-to-side anastomoses. No flap related complication occurred but we applied additional clips or sutures in two cases due to blood leakage after completion of anastomosis. Primary patency rates seemed to be good and more rapid anastomosis could be done than conventional suture technique. Advantages of VCS technique are high patency rate, low thrombogenecity and rapidity. Although the high cost of VCS instrument may be a problem, this clip could be applied safely in microvascular free tissue transfer.

• Journal of Chest Surgery
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• 제53권1호
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• pp.28-33
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• 2020

Background: When an arteriovenous fistula (AVF) is created using the basilic or deep cephalic vein, it is additionally necessary to transfer the vessels to a position where needling is easy; however, many patients develop wound-related postsurgical complications due to the long surgical wounds resulting from conventional superficialization of a deep AVF or basilic vein transposition. Thus, to address this problem, we performed videoscopic surgery with small surgical incisions. Methods: Data from 16 patients who underwent additional videoscopic radiocephalic superficialization, brachiocephalic superficialization, and brachiobasilic transposition after AVF formation at our institution in 2018 were retrospectively reviewed. Results: Needling was successful in all patients. No wound-related complications occurred. The mean vessel size and blood flow of the AVF just before the first needling were 0.73±0.16 mm and 1,516.25±791.26 mL/min, respectively. The mean vessel depth after surgery was 0.26±0.10 cm. Percutaneous angioplasty was additionally performed in 25% of the patients. Primary patency was observed in 100% of patients during the follow-up period (262.44±73.49 days). Conclusion: Videoscopic surgery for AVF dramatically reduced the incidence of postoperative complications without interrupting patency; moreover, such procedures may increase the use of native vessels for vascular access. In addition, dissection using a videoscope compared to blind dissection using only a skip incision dramatically increased the success rate of displacement by reducing damage to the dissected vessels.

• Journal of Chest Surgery
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• 제38권3호
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• pp.191-196
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• 2005

서울대학교병원 흉부외과에서 시행한 관상동맥우회술 환자에서 수술 후 1년 및 5년째에 관상동맥조영술을 시행하여 문합 부위의 형태학적 변화를 분석하였다 대상 및 방법: 1995년 1월부터 1997년 12월 사이에 관상동맥우회술만을 시행한 219예 중 수술 후 1년 및 5년째 추적 관상동맥조영술을 시행한 149예($75.3\%$) 및 115예($58.1\%$)를 대상으로 문합 부위의 변화 및 개존율을 FitzGibbon 등급을 사용하여 분석하였다. 결과: 동맥도관을 이용한 문합은 수술 후 1년 및 5년 개존율은 각각 $96.5\%$ (192/199), $93.1\%$ (134/144)로 복재정맥도관의 개존율 $82.9\%$ (224/270), $77.5\%$ (141/182)보다 유의하게 높았다(p<0.01). 동맥도관 및 복재정맥도관 각각의 개존율은 수술 후 1년 및 5년 사이에 유의하게 감소하였으나, 복재정맥도관의 경우에서는 FitzGibbon 등급 B의 비율이 1년째의 $5.2\%$에서 5년째에 $8.2\%$로 증가하여 정맥도관질환의 더 빠른 진행을 시사하였다(p<0.01). 결론: 관상동맥우회술 후 동맥도관의 개존율은 수술 후 1년 및 5년째에 모두 복재정맥의 개존율보다 우수하였다. 복재정맥도관은 동맥도관에 비해 협착 진행의 비율이 수술 후 1년에서 5년 사이에 유의하게 높았다.

• 대한영상의학회지
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• 제84권6호
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• pp.1339-1349
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• 2023

목적 단일 기관에서 7년간의 장골 분지 장치 사용 경험을 바탕으로 그 효과와 안전성을 확인하고 효용성 및 한계를 고찰하고자 하였다. 대상과 방법 이 연구는 단일 기관에서 총장골동맥류에 장골 분지 장치 삽입술을 받은 환자들을 대상으로 시행했다. 추적 컴퓨터단층촬영 스캔을 분석하고, 내장골동맥의 개방성 및 장골분지 장치 사용과 관련된 합병증을 검토했다. 후향적 분석을 시행하였으며 전체 생존율과 재시술이 필요 없는 환자의 비율을 Kaplan-Meier method에 따라 분석했다. 결과 38명의 총장골동맥류가 있는 환자들 중에서 10명의 환자(12개의 총장골동맥류)만이 해부학적으로 장골 분지 장치 사용에 적합했다. 5명의 환자는 반대측 내장골동맥 색전술과 함께 장골 분지 장치 삽입술을 받았으며, 이 중 3명의 환자(60%)는 합병증으로 파행을 보였으나 모두 6개월 만에 증상이 호전되었다. 또한 7년 후 장골 분지 장치 사용 관련 재시술이 필요없는 환자의 비율은 77.8%였으며 시술과 관련된 사망은 없었다. 결론 장골 분지 장치는 높은 기술적 성공률과 장기 개통률을 보이지만, 아시아인의 경우 해부학적 요인으로 인해 적용이 제한되는 경우가 많다. 또한 단측 내장골동맥 색전술을 시행한 경우에도 경미한 합병증과 좋은 예후를 보였으므로, 해부학적으로 복잡한 총장골동맥류에서 단측 장골 분지 장치 삽입술 및 반대측 내장골동맥 색전술을 선택하여 시행할 수 있다.

• Journal of Chest Surgery
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• 제28권11호
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• pp.983-988
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• 1995

From January 1983 to December 1994, 48 cyanotic patients were underwent a subclavian artery-pulmonary artery shunt using polytetrafluoroethylene[PTFE for the purpose of improvement of reduced pulmonary blood flow. The diameters of the PTFE used were 4mm[4 cases , 5mm[36 cases , and 6mm[8 cases sizes. The effectiveness of modified Blalock-Taussig shunts was evaluated clinically and angiographically. There were 5 early deaths and 2 late deaths. There were 3 early shunt failures and 5 late shunt failures. The overall graft patency rate was 83.3%. Postoperative hemoglobin was reduced significantly[p = 0.0011 in comparison of the preoperative and postoperative hemoglobin, SaO2, PaO2, and cardiothoracic ratio.

• Journal of Chest Surgery
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• 제20권1호
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• pp.187-190
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• 1987

The Saphenous vein is still the graft of choice for bypass of small calibered peripheral arteries, and many recent studies revealed that the "In Situ" technique had higher rate of long term patency than the conventional "reversed" one. A 71-year-old male who had atherosclerotic obstruction in the superficial femoral and popliteal trifurcation underwent In Situ saphenous vein arterial bypass. The saphenous vein is exposed by a long medial skin incision over the course of the vein. All branches of vein are ligated. A olive-tipped metal needle is introduced into the vein from above and everts the valves. The patient has been followed for 2 months after operation. The graft remained pulsatile and the gangrenous areas on the toe proceeded to heal. We think In situ vein bypass offers an excellent and safe method of revascularization of the arterial occlusion below the knee although it is technically demanding and the time consuming. time consuming.

• 한국전산유체공학회지
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• 제16권4호
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• pp.84-91
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• 2011

Hemodialysis is essential for patients with end stage renal failure. It is important to improve the patency rate and to minimize occurrence of the stenosis. Also, the blood flow to the artificial kidney can affect the blood flow characteristics through arteriovenous graft. Thus, the delivered dose are important factors for analyzing hemodynamic characteristics during hemodialysis access. In this study, the numerical analysis was performed for the effect of the delivered dose during hemodialysis access on the blood flow through the graft. As a result, The adverse pressure gradient occurred in case of a larger delivered dose through a catheter than standard dose and the flow instability increased. Also the circulation flow appeared largely at anastomotic site of the vein when the delivered dose was exceeded about half blood flow of inlet blood flow.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1919-1922
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• 2003

Bypass anastomosis are frequently adopted for surgical treatments. After the bypass grafting, the bypass artery is often occluded due to restenosis and/or anastomotic neointimal fibrous hyperplasia phenomena. Optimal coronary bypass anastomosis should be investigated to improve the patency for the arterial bypass techniques. The objective of this study is to investigate the influence of bypass with sequential bypass effects in the stenosed coronary artery. Numerical analyses are focused on the understanding of the flow patterns for different sequential anastomosis techniques. Blood flow field is treated as two-dimensional incompressible laminar flow. The finite volume method is adopted for discretization of the governing equations. The Carreau model is employed as the constitutive equation for blood. To find the optimal sequential bypass anastomotic configurations, the mass flow rates at the outlet of different models are compared quantitatively.