• Journal of Korea Society of Digital Industry and Information Management
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• v.19 no.4
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• pp.97-115
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• 2023

In South Korea, chronic kidney disease(CKD) impacts around 4.6 million adults, leading to a high reliance on hemodialysis. For effective dialysis, vascular access is crucial, with decisions about vascular surgeries often made during dialysis sessions. Anticipating these needs could improve dialysis quality and patient comfort. This study investigates the use of Artificial Intelligence(AI) to predict the timing of surgeries for dialysis vessels, an area not extensively researched. We've developed an AI algorithm using predictive maintenance methods, transitioning from machine learning to a more advanced deep learning approach with Long Short-Term Memory(LSTM) models. The algorithm processes variables such as venous pressure, blood flow, and patient age, demonstrating high effectiveness with metrics exceeding 0.91. By shortening the data collection intervals, a more refined model can be obtained. Implementing this AI in clinical practice could notably enhance patient experience and the quality of medical services in dialysis, marking a significant advancement in the treatment of CKD.

• Journal of Chest Surgery
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• v.31 no.6
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• pp.591-597
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• 1998

Background: The aim of the current study was to analyze the early and intermediate-term performance of aortic valve replacement. Material and Method: Between January 1986 and January 1996, records of 61 consecutive patients who had received aortic valve replacement were reviewed. 38 were male and 23 were female patients, ranging from 10 to 71 years of age(mean: 40.5${\pm}$11.2). Results: The early death rate was 4.9%(3/61). A thorough follow-up rate of 93.1% was accomplished in these 58 patients who left the hospital(mean: 51.5${\pm}$32.0 patient-months) under the assistance of the same operator. Three of these patients who left the hospital died. The late death rate was 5.2%(3/58). Five patients experienced anticoagulant-related hemorrhage(all were minor). Three patients had thromboembolic episodes. There was no clinical evidence of hemolysis and structural failure of valves used. Of those patients who survived, the NYHA functional class improved significantly. Linearized rate were 1.58%/patient-year and 2.0%/patient-year respectively for thromboembolism and anticoagulant-related hemorrhage. The 10 year actuarial survival rate was 83.6%. Conclusion: This early and intermediate-term follow-up suggests that the mechanical valve is a reliable and durable prosthesis with good hemodynamic function and low rate of prosthesis-related complication.

• Korean Chemical Engineering Research
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• v.49 no.2
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• pp.230-237
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• 2011

In this study, the characteristic of fluid flow in the new type lung assist devices has been established using computational fluid dynamics(CFD). For the modeling, the hollow fiber was ignored, and vertical types and tangential types were used for the model. Which was to analyze the flow characteristics of the fluid flow model when there exists 1 and 2 input/output ports, and when the input/output ports is located at the center of the cylinder and at the tangential direction with the cylinder wall. The modeling results showed that it was possible to eliminate no-flow region(stagnant layer) as shown in the vertical type when an inlet and an outlet were installed on the tangential direction of the cylinder as shown in the tangential type. Also, in the tangential type, vortex-type flow appeared as dominant, and it showed a complicated flow not deviated to one side. When the number of input/output was two, there was no deviated flow, and complicated flows were generated all across the tube. From the test result, it was found that input/output of flow was tangential type and complicated flows with no stagnant layer would be generated when there are two inputs/outputs, respectively.

• Journal of Chest Surgery
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• v.32 no.10
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• pp.874-882
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• 1999

배경: 체외순환 후의 부종현상 및 이에 따른 여러 장치의 기능 저하를 방지하기 위하여, 최근에 체외 순환 이탈 후 환자의 혈액을 짧은 시간에 관류하여 여과해 주는 변형 초여과법의 사용이 늘고 있다. 이에 대한 긍정적인 임상결과들의 보고도 있으나, 다른 한편 체외 순환 후 염증반응을 포함한 폐손상의 기전에 혈구 성분의 영향이 보고되고 있는 바, 변형 초여과법의 효과, 특히 폐 조직에 대한 영향을 밝혀 보고자 하였다. 대상 및 방법: 몸무게 15에서 22 Kg(평균 16.5$\pm$0.5)의 16 쌍의 잡견을 이용한 정소성 심장이식, 실험에서, 통상적인 인공심폐기 작동군과 인공심폐기 작동 후 변형 초여과 관류를 시행한 군으로 무작위 구분하였다. 변형초여과법은 체외순환 정지 후에 대동맥관에서 나온 혈류를 Roller pump를 거쳐 Amicon Diafilter 초여과 관에 150 mL/m 정도의 속도로 10~15 분 정도 관류시켜 정맥관을 통하여 우심방에 직접 주입하였다. 혈액 채취 및 폐생검은 심폐기 시작 전과 정지 직후, 그리고 변형초여과 시행 군은 초여과 완료 직후에, 대조군은 심폐기 정지 10~15분 후에 각각 시행하였다. 혈류역학 측정요소는 동맥압, 우심방압, 좌심방압 등이었으며, 혈액 검사 항목은 동맥혈 가스분석, 혈색소 농도, 헤마토크릿, 백혈구 수, 혈소판 수, 혈중 단백 성분, 알부민 성분 등이었다. 폐 생검 조직으로는 냉동 건조법을 이용한 수분 함유량을 측정하였고, 광학 및 전자현미경으로 관찰을 하였다. 결과: 변형 초여과 군에서 혈중 혈색소 농도는 수술전 10.3$\pm$1.7 mg/dL, 심폐기 정지 직후 6.3$\pm$1.7 mg/dL, 초여과 직후는 8.3$\pm$2.8 mg/dL의 변화를(p=0.0078, 0.0117), 혈중 총 단백질의 농도 변화는 4.3$\pm$0.9, 3.1$\pm$1.5, 4.1$\pm$1.6 mg/dL, 혈중 알부민의 농도는 1.9$\pm$0.5, 1.4$\pm$0.7, 1.8$\pm$0.8 mg/dL로서, 각각 초여과법의 시행 전후에 유의한 증가를 가져왔고(p=0.0280, 0.0277), 폐조직의 수분 함유량의 변화는 수술전 75.1$\pm$8.6%, 심폐기 정지 직후 82.8$\pm$6.0%, 초여과 직후 77.88%를 보인 반면, 대조군에서는 각각 74.7$\pm$4.9, 82.1$\pm$5.9, 82.3$\pm$5.1%의 변화를 보였다. 미세 구조의 관찰에서, 폐포의 내포세피의 융합 기저막층과 미토콘드리아에서의 부종은 변형 초여과 후에 급격히 감소하였으나, 미토콘드리아내 크리스티의 파괴성 변화와 막성 파괴 성향이 초여과 후에 심화되게 관찰되었고, 세포질 내 소체의 팽창과 공포화 현상도 심폐기 가동 후 발생하여 초여과 후에 더 심화되게 관찰되었다. 세포질 내 소체의 팽창과 공포화 현상도 심폐기 가동 후 발생하여 초여과 후에 더 심화되게 관찰되었다. 폐조직 내의 백혈구는 심폐기 작동 후에 그 수에 있어서 증가하였으며 백혈구의 괴변, 탈과립 정도도 심폐기 작동 후 및 초여과 후에 증가한 소견을 보였다. 결론: 변형 초여과법은 인공 심폐기 후의 혈색소 농도 및 혈중 단백질 농도의 복원에 효과가 있었으며 변형 초여과 관류후 폐의 미세 조직내에서 부종의 급격한 감소 등을 관찰할 수 있었다.

• Journal of Chest Surgery
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• v.36 no.5
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• pp.316-320
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• 2003

Background: The detection of circulating microemboli by transcranial Doppler ultrasonography (TCD) has the potential to select the patients with high risk for future symptomatic brain embolism. We prospectively evaluated the positive rate and the frequency of microembolic signals (MES) before and after the heart valve surgery (HVS). Material and Method: Fifty in-patients with heart valve disease were enrolled in this study. Patients with history of previous stroke or heart valve surgery were excluded. Two unilateral TCD monitoring sessions were peformed from middle cerebral artery for 1-hour, before and after HVS. Result: Mechanical Heart valves were implanted in 28 patients, tissue valves were implanted in 10 patients, and remaining 12 patients received mitral valve repair. Positive rate of MES was significantly increased after HVS (50%), compared to that of before HVS (8%, p=0.00). There was no relation between MES after HVS and intensity of anticoagulation, cardiac rhythm, patients' age, and history of hypertension. The positive rate of MES after implantation of mechanical heart valve (71.4%) was significantly higher than those after implantation of tissue valve or mitral valve plasty (p=0.002). Conclusion: Positive rate of MES was increased significantly after the implantation of HVS. The changes of MES in those with mechanical prosthesis may be related to the increased risk or embolism after Hvs.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.2
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• pp.63-67
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• 2015

Purpose Among various causes that influence image quality degradation, various methods for decrease in Artifact occurred by respiration of patients are being used. Among them, this study intended to evaluate CTAC Shift correction method and additional scan compare to the Scan(Q static scan) using respiratory gated system. Materials and Methods This study was conducted on 10 patients, and used PET-CT Discovery 710 (GE Healthcare, MI, USA) and Varian's RPM system. 5.18 Mbq per kg of $^{18}F$-FDG was injected on patients, asked them to take a rest for 1 hour in the bed, and conducted test after urination. Images were visualized through Q static scan, CTAC Shift correction method, Additional scan based on the Whole body scan(WBS) with Artifact. Decrease in Artifact was compared in each image, conducted Gross Evalution, and measured changes of SUVmax. Results For image obtained through the CTAC Shift correction method through WBS with Artifact, 12~56%, Q static scan image showed 17~54% of change rate and Additional Scan showed -27~46% of change rate. In Blind Test, the CTAC Shift correction image showed the highest point with 4 points, Q static scan image showed 3.5 points, and Additional scan image showed 3.4 points. The standardized WBS scan through Oneway ANOVA and three types of Scan method showed significant difference(p<0.05), and did not show significant difference between the three Scan methods(p>0.05). However, the three Scan methods showed significant difference in Blind test. Conclusion Additional scan and Q static scan require more time than the CTAC Shift correction method, there is concern about excessive exposure to patients by CT rescan and Q static scan is difficult to apply on patients with inconsistent respiration or irregular respiration cycle due to pain. For CTAC Shift correction method, limited correction is possible and the range is limited as well. It is considered as a useful method of improving diagnostic value when hospitals use the system appropriately and develop various advantageous factors of each method.

• Journal of Chest Surgery
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• v.35 no.4
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• pp.274-282
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• 2002

Background: Paravalvular leakage or false aneurysm developed after isolated aortic valve replacement(AVR) for aortic regurgitation(AR) associated with Behcet's disease is one of the most serious complications, and requires subsequent reoperations. We describe the surgical result of homograft aortic root replacement(ARR) for AR associated with Behcet's disease. Material and Method: From January 1992 to December 2001, 6 patients with AR associated with Behcet's disease underwent 7 ARR with homograft and 1 Ross operation. Five patients were male and one was female. The grafts used for ARR were 5 aortic and 2 pulmonic homografts. Ages at operation ranged from 27 to 51 years(mean, 37$\pm$9 years). Two patients underwent ARR with aortic homograft at the first operation. In the remaining 4 patients, ARR using a homograft was performed for paravalvular leakage that developed after AVR, and the mean interval from AVR to ARR was 21 $\pm$29 months(range, 5 to 73.3 moths, median, 7.6 months). Result: There was no early death. All patients were followed up for an average of 18.9$\pm$24.0 months(range, 1.9 to 68.9 months, median, 8.4 months). Two of 4patients who had undergone ARR after AVR required subsequent reoperations for false aneurysm of the ascending aorta and failure of pulmonary homograft. One patient underwent re-replacement of the aortic root, ascending aorta and partial aortic arch with an aortic homograft, the other underwent Ross operation. Conclusion: This study suggests that aortic root replacement using a homograft in aortic regurgitation with Behcet's disease may provide good clinical results and decrease the incidence of paravalvular leakage or false aneurysm after aortic valve replacement. However, the adequate perioperative management and complete removal of the inflarrunatory tissue at operation were also important for the good long-term results.

• Clinical and Experimental Pediatrics
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• v.46 no.6
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• pp.554-560
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• 2003

Purpose : To investigate the teratogenic effect of gamma-ray on the heart of chick embryo. Methods : 50 rad, 100 rad, 150 rad, 200 rad, 250 rad, and 300 rad of gamma-ray were used to irradiate three days old chick embryos. The control group was not irradiated. After three weeks, the embryos were sacrificed and examined for cardiovascular malformation. Results : The survival rate of the gamma-ray irradiated group was significantly lower than that of the control group(33.3-63.3% vs 76.4%, P=0.001). The cardiac malformation rate of the experimental group was 11.0%. In the control group, no congenital cardiac malformations were observed. The experimental groups had a significantly higher malformation rate(P=0.001). The types of malformation were ventricular septal defect, tricuspid atresia, Ebstein anomaly and aortic arch anomaly. In the gamma-ray irradiated group, the cardiac malformations were : 14 small ventricular septal defects (VSDs), five large VSDs, two tricuspid atresias, and one Ebstein anomaly. The higher the dose of radiation applied, the higher the incidence of cardiac malformation was noted. Conclusion : Gamma-ray irradiation of 3 days old chick embryos increased the rate of death and the rate of cardiac malformation significantly.

• Journal of Chest Surgery
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• v.41 no.4
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• pp.417-422
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• 2008

Background: The aim of this study is to evaluate the long term results of creating various right ventricle to pulmonary artery conduits for treating complex congenital heart disease. Material and Method: Between June 1986 and July 2006, we retrospectively reviewed 245 patients who underwent reconstruction of the right ventricular outflow tract with various kinds of conduits. 410 operations were done in 245 patients, the mean age at operation was $3.2{\pm}4.9$ years (range: 7 days$\sim$45 years) and the mean body weight was $12.5{\pm}8.7\;kg$ (range: $2.4\sim76.3\;kg$). Result: We used the following conduits: Polystan conduit, Shelhigh conduit, Carpenter-Edward conduit, Dacron graft with an artificial valve, valveless Gore Tex vascular graft, homograft and hand-made bovine or autologous pericardial conduit. The mean follow up duration was $6.3{\pm}5.2$ years. Redo operation for RV-PA conduit dysfunction was performed in 131 patients, a second redo was done in 31 and a third redo was done in 3. The reoperation free rates were 67.3%, 48.5% and 39.4% for 5 years, 10 years and 15 years, respectively. The homograft showed the best durability, followed by the Dacron graft with artificial valve and the Carpentier-Edward conduit. The larger sized conduit showed better durability. Conclusion: The homograft showed lowest reoperation rate and a smaller size of conduit showed the highest reoperation rate. The reoperation rate for the RV-PA conduit was about 35% at 5 years, so it is mandatory to develop the more durable conduit for RV outflow.

• Journal of Chest Surgery
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• v.40 no.2 s.271
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• pp.83-89
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• 2007

Background: The surgical repair of an isolated coarctation of the aorta, without complex cardiac anomalies, has improved, with very good results. However, despite the success of surgical repair, many long-term complications, such as hypertension, re-coarctation and an aortic aneurysm, still exist. Material and Method: Between 1991 and 2006, 50 patients diagnosed with an isolated coarctation of the aorta were reviewed retrospectively. The incidence of re-coarctation and hypertension were compared with respect to age and surgical methods. Result: There were no early & late mortality, or post operative aortic aneurysms. Hypertension developed in 11 patients (22%). A greater number of patients in the child/adult group had hypertension (52.4%) than in the neonate/infant group (0%). With respect to the surgical methods, the patients in the graft interposition group suffered more hypertension (88.9%) than those in the EEEA (extended end to end anastomosis) group (5.3%). Post operative re-coarctation developed in 2 out of the 29 patients (6.9%) in the neonate/infant group and 2 out of the 21 patients (9.5%) in the child/adult group, but without any statistical difference. There were no statistical differences between the operative type-related groups. Conclusion: Even though the surgical outcomes have greatly improved, an isolated coarctation of the aorta still has many long-term problems, such as hypertension and re-coarctation. An isolated coarctation is accepted as a systemic vascular dysfunction, and often progresses to other cardiovascular diseases. Therefore, patients with a coarctation of the aorta have to be carefully followed-up, and aggressive management must be given when required.