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역압력구배하에서 윗벽면 및 평판슬릿흡입이 난류경계층의 구조에 미치는 영향
박계향,이학성,윤명식,유상신 한국항공대학교 1994 論文集 Vol.32 No.-
역압력 구배하에서 벽면흡입과 모델 평판의 슬릿흡입이 난류 경계층구조에 미치는 영향에 대하여 실험적으로 연구하였다. 압력탭이 설치된 평판을 실험부에 설치한 후 평판위에 역압력구배가 작용되도록 하고 경계층 내의 속도 분포와 난류강도를 열선유속계로 측정하였다. 역압력구배가 커지면 경계층의 천이점은 평판의 상류쪽으로 이동하며 평판의 벽면에서 슬릿흡입을 하면 경계층내의 난류강도가 감소하고, 흡입량을 증가하면 난류 강도는 더욱 감소한다. An experimental study on the boundary layer structure on the flat plate with upper wall and slit suction under adverse pressure gradients is presented. Velocity profiles and turbulent intensities in the boundary layer are measured by hot-wire anemometer system. The transition point of a bondary layer moves upstream direction as the adverse pressure gradient increases. Slit suction causes a reduction of turbulent intensity of boundary layer. Reduction of trubulent intensity increases as the suction coefficient increases.
관상동맥 시술 도중 발생한 좌주간부 관상동맥 박리에 대한 스텐트 삽입 치료의 단장기 임상 결과 : acute and long-term results
이세환,이승환,홍명기,김영학,이철환,한기훈,송종민,강덕현,송재관,김재중,박성욱,박승정 대한내과학회 2004 대한내과학회지 Vol.66 No.6
목적 : 심도자 사용 시술과 관련된 좌주간부 관상동맥박리에 대한 적절한 치료는 아직 확실히 정립되지 않은 상태이다. 이에 본 연구는 좌주간부 관상동맥 박리에 대한 스텐트 삽입술의 단장기 임상결과를 후향적으로 분석하였다. 방법 : 좌주간부 관상동맥 박리에 대한 치료로 즉각적인 스텐트 삽입술을 시행하는 것이 안전하고 효과적인 방법임을 가설하였고, 이러한 즉각적인 스텐트 삽입을 시행한 10명의 환자를 대상으로 단장기적 임상경과를 의무기록 고찰과 전화 면담을 통해서 평가하였다. 결과 : 전체 환자 모두 처음부터 좌주간부 관상동맥에 유의한 협착을 가진 환자는 없었으며, 8명의 환자는 심도자의 조작으로 인한 박리가 발생한 경우였고(진단적 혈관 조영술 중에 3명, 유도 도자 조작 중에 5명), 나머지 2명은 다른 병변에 스텐트 삽입시술을 하는 중에 박리가 발생하였다. 이 10명의 환자에서 모두 즉각적인 스텐트 삽입술이 시행되었고, 4명의 환자에서 시술 도중 혈압 저하로 Intra-aortic Ballon Pump (IABP)를 장착하였다. 모든 환자에서 성공적으로 스텐트가 삽입되었고, 병원내 사망은 1명도 없었다. 6개월 추적 관상동맥 조영술은 8명의 환자에서 시행되었다. 혈관 조영상의 재협착(직경 협착 50% 이상)은 8명 모두에게서 관찰되지 않았으며, 퇴원 후 평균 31±25개월의 추적관찰 결과 주요 심장사건은 1건도 발생하지 않았다. 결론 : 비록 대상 환자가 적은 연구였지만 좌주간부 관상동맥 박리에 대한 스텐트 삽입술은 기술적으로 안전하고 빠르게 시행 할 수 있으며, 훌륭한 단장기적인 치료 효과를 보여준다. Background : The optimal treatment of patients with left main coronary artery (LMCA) dissection during catheter-based procedure remains uncertain. We retrospectively analyzed the acute and long-term results of bail-out stenting for LMCA dissection. Methods : In cases with significant LMCA dissection occurring during catheter-based procedure, prompt stent implantation may be safe and associated with favorable clinical outcome. We evaluated the acute and long-term results of bail-out stenting for LMCA dissection occurring during catheter-bases procedure in 1- patients. Results : Initially, there was significant stenosis of LMCA segment in these patients. Catheter-induced dissection occurred in 8 patients (during diagnostic angiography in 3 patients and guiding catheter manipulation in 5 patients). Two patients suffered dissection in the setting of stent deployment in other vessels. Therefore, bail-out stenting LMCA dissection was performed in a total of 10 patients. In 4 patients, hypotension developed and intra-aortic balloon pump was placed during procedure. Stents were successfully deployed in all patients. There was no in-hospital mortality. Six-month angiographic follow-up was performed in 8 patients. Angiographic restenosis(diameter stenosis 50%) was not observed in all patients at follow-up study. During a mean follow-up of 31±25 months after hospital discharge, there was no major adverse cardiac event (death, myocardial infarction, and target lesion revascularization). Conclusion : Bail-out LMCA stenting is technically feasible, and showed good acute and long-term results in a small series of patients.
Park, Kyoung-Ha,Park, Seong-Wook,Hong, Myeong-Ki,Kim, Young-Hak,Lee, Bong-Ki,Park, Duk-Woo,Choi, Bong-Ryong,Kim, Mi-Jeong,Park, Kyoung-Min,Lee, Cheol Whan,Cheong, Sang-Sig,Kim, Jae-Joong,Park, Seung-J WILEY-LISS 2006 Catheterization and Cardiovascular Interventions Vol. No.
<P>Background: The sirolimus-eluting stent (SES) and the paclitaxel-eluting stent (PES) reduce restenosis in small coronary artery lesions. However, it is not clear which of these stents is superior in terms of clinical outcomes. Methods: The authors retrospectively examined 197 patients with 245 de novo small coronary artery lesions (≤≤2.75 mm) that were treated with either the SES (156 lesions) or the PES (89 lesions). Six-month angiographic restenosis rates and the 9-month target lesion revascularization (TLR) rates were compared between the two groups. Results: In terms of baseline clinical and angiographic parameters, the two groups well matched together. Six-month angiographic follow-up was performed on 170 patients (86.3%), comprising 135 SES lesions (86.5%) and 76 PES lesions (85.4%). At 6-month angiographic follow-up, the late lumen loss was less in the SES group than in the PES group (0.29 ± 0.42 vs. 0.69 ± 0.63 mm, P < 0.01). Therefore, the SES group showed a lower rate of angiographic restenosis than the PES group (6.7% vs. 27.7%, P < 0.01). At 9 months there were no deaths or myocardial infarctions in either group. The 9-month TLR rate was lower in the SES group than in the PES group (3.3% vs. 14.4%, P < 0.01). The Kaplan-Meier estimate of freedom from TLR at 9 months was 96.7% for the SES patients and 86.5% for the PES patients (P < 0.01). Conclusions: The SES treatment may be superior to the PES treatment in terms of long-term clinical and angiographic outcomes in patients with small coronary artery lesions. © 2006 Wiley-Liss, Inc.</P>
Park, Duk-Woo,Yun, Sung-Cheol,Lee, Seung-Whan,Kim, Young-Hak,Lee, Cheol Whan,Hong, Myeong-Ki,Kim, Jae-Joong,Choo, Suk Jung,Song, Hyun,Chung, Cheol Hyun,Lee, Jae-Won,Park, Seong-Wook,Park, Seung-Jung Ovid Technologies Wolters Kluwer -American Heart A 2008 CIRCULATION - Vol.117 No.16
<P>BACKGROUND: Although previous studies have compared the treatment effects of percutaneous coronary intervention and coronary artery bypass grafting (CABG), the long-term outcomes beyond 1 year among patients with multivessel coronary artery disease who underwent percutaneous coronary intervention with drug-eluting stents (DES) or CABG have not been evaluated. METHODS AND RESULTS: Between January 2003 and December 2005, 3042 patients with multivessel disease underwent coronary implantation of DES (n=1547) or CABG (n=1495). The primary end point was all-cause mortality. In a crude analysis, the rate of long-term mortality was significantly higher in patients who underwent CABG than in those who underwent DES implantation (3-year unadjusted mortality rate, 7.0% for CABG versus 4.4% for percutaneous coronary intervention; P=0.01). However, after adjustment for baseline differences, the overall risks of death were similar among all patients (hazard ratio, 0.85; 95% confidence interval [CI], 0.56 to 1.30; P=0.45), diabetic patients (hazard ratio, 1.76; 95% CI, 0.82 to 3.78; P=0.15), and patients with compromised ventricular function (hazard ratio, 1.39; 95% CI, 0.41 to 4.65; P=0.60). In the anatomic subgroups, mortality benefit with DES implantation was noted in patients with 2-vessel disease with involvement of the nonproximal left anterior descending artery (hazard ratio, 0.23; 95% CI, 0.01 to 0.78; P=0.016). The rate of revascularization was significantly higher in the DES than in the CABG group (hazard ratio, 2.81; 95% CI, 2.11 to 3.75; P<0.001). CONCLUSIONS: For the treatment of multivessel coronary artery disease, percutaneous coronary intervention with DES implantation showed equivalent long-term mortality as CABG.</P>
Late target lesion revascularization after implantation of sirolimus-eluting stent
Hong, Myeong-Ki,Mintz, Gary S.,Lee, Cheol Whan,Park, Duk-Woo,Lee, Seung-Whan,Kim, Young-Hak,Jung, In-Hyun,Kim, Sang-Hyun,Cheong, Sang-Sig,Kim, Jae-Joong,Park, Seong-Wook,Park, Seung-Jung Wiley Subscription Services, Inc., A Wiley Company 2008 CATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS Vol.71 No.3
<P>Objectives: We evaluated the incidence, clinical presentation, and angiographic in-stent restenosis (ISR) pattern of late target lesion revascularization (TLR) after sirolimus-eluting stent (SES) implantation. Background: Late TLR is an unusual finding beyond 6–9 months after bare-metal stent implantation. However, late TLR after SES implantation has not been sufficiently evaluated. Methods: The study population consisted of 804 patients with 1,020 native lesions that were patent at 6-month follow-up angiogram after SES implantation. Results: Late TLR was performed in 18 patients with 18 lesions (1.8%) at 24.1 ± 2.6 months (range; 18–30 months) after SES implantation. Clinical presentation of late TLR patients was silent ischemia in eight patients and recurrent angina in 10 patients, but none had an acute coronary syndrome. Angiographic ISR pattern of late TLR lesions were focal ISR in 12 lesions (67%) and diffuse ISR in six lesions (33%). Serial quantitative coronary angiographic analysis of these lesions showed a minimal lumen diameter of 2.6 ± 0.5 mm immediately after SES implantation, 2.4 ± 0.4 mm at 6-month follow-up and 0.7 ± 0.6 mm at 24-month follow-up (ANOVA P < 0.001). By stepwise multiple logistic regression analysis, the only independent predictor of late TLR was stent length (P < 0.001, OR = 1.040, 95% CI = 1.019–1.061). Conclusions: Late TLR was performed in 1.8% of 1,020 native lesions that were patent at 6-month follow-up angiogram. Clinical presentations of late TLR was either silent ischemia or recurrent angina, but not acute coronary syndrome. Two-thirds of late TLR lesions had a focal angiographic ISR pattern. © 2007 Wiley-Liss, Inc.</P>
Hong, Myeong-Ki,Mintz, Gary S,Lee, Cheol Whan,Park, Duk-Woo,Choi, Bong-Ryong,Park, Kyoung-Ha,Kim, Young-Hak,Cheong, Sang-Sig,Song, Jae-Kwan,Kim, Jae-Joong,Park, Seong-Wook,Park, Seung-Jung W.B. Saunders [etc.] 2006 European heart journal Vol.27 No.11
<P>AIMS: In many countries, drug-eluting stent implantation is the dominant interventional strategy. We evaluated the clinical, angiographic, procedural, and intravascular ultrasound (IVUS) predictors of angiographic restenosis after sirolimus-eluting stent (SES) implantation. METHODS AND RESULTS: SES implantation was successfully performed in 550 patients with 670 native coronary lesions. Six-month follow-up angiography was performed in 449 patients (81.6%) with 543 lesions (81.1%). Clinical, angiographic, procedural, and IVUS predictors of restenosis were determined. Using multivariable logistic regression analysis, the only independent predictors of angiographic restenosis were post-procedural final minimum stent area by IVUS [odds ratio (OR)=0.586, 95% confidence interval (CI) 0.387-0.888, P=0.012] and IVUS-measured stent length (OR=1.029, 95% CI 1.002-1.056, P=0.035). Final minimum stent area by IVUS and IVUS-measured stent length that best separated restenosis from non-restenosis were 5.5 mm2 and 40 mm, respectively. Lesions with final minimum stent area<5.5 mm2 and stent length>40 mm had the highest rate of angiographic restenosis [17.7% (11/62)], P<0.001 compared with other groups. CONCLUSION: Independent predictors of angiographic restenosis after SES implantation were post-procedural final minimum stent area by IVUS and IVUS-measured stent length. The angiographic restenosis rate was highest in lesions with stent area<5.5 mm2 and stent length>40 mm.</P>
Hong, Myeong-Ki,Mintz, Gary S.,Lee, Cheol Whan,Park, Duk-Woo,Park, Kyoung-Min,Lee, Bong-Ki,Kim, Young-Hak,Song, Jong-Min,Han, Ki-Hoon,Kang, Duk-Hyun,Cheong, Sang-Sig,Song, Jae-Kwan,Kim, Jae-Joong,Park Ovid Technologies Wolters Kluwer -American Heart A 2006 CIRCULATION - Vol.113 No.3
<P>BACKGROUND: Late stent malapposition (LSM) after drug-eluting stent (DES) implantation has not been evaluated sufficiently in real-world practice. METHODS AND RESULTS: We evaluated the incidence, mechanisms, predictors, and long-term prognosis of LSM after DES implantation in 557 patients (705 native lesions; sirolimus-eluting stent in 538 lesions and paclitaxel-eluting stent in 167 lesions) in whom intravascular ultrasound was performed at index and 6-month follow-up. LSM occurred in 82 patients with 85 lesions (12.1% overall, 95% CI 9.7% to 14.5%, 71 lesions (13.2%) in sirolimus-eluting stents and 14 lesions [8.4%] in paclitaxel-eluting stents, P=0.12]; the incidence was 25.0% (4/16) after directional coronary atherectomy before stenting, 27.5% (14/51) in chronic total occlusion lesions, and 31.8% (7/22) after primary stenting in acute myocardial infarction (P=0.13, P<0.001, and P=0.001, respectively, versus elective stenting with conventional balloon predilation, 9.7% [60/616]). There was an increase of external elastic membrane area (from 17.1+/-3.6 to 21.4+/-4.8 mm2, P<0.001) that was greater than the increase in plaque area (from 9.3+/-2.5 to 10.5+/-2.7 mm2, P<0.001). Independent predictors of LSM were total stent length, primary stenting in acute myocardial infarction, and chronic total occlusion lesions. Except for 1 death in the non-LSM group, there were no major adverse cardiac events in either LSM or non-LSM patients during a mean 10-month follow-up after detection of LSM. CONCLUSIONS: LSM occurs in 12% of cases after DES implantation. The predictors of LSM are total stent length, primary stenting in acute myocardial infarction, and chronic total occlusion lesions. LSM after DES implantation was not associated with any major adverse cardiac events during a subsequent 10-month (mean) follow-up.</P>