• Journal of Chest Surgery
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• 제7권2호
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• pp.189-200
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• 1974

The mitral valve replacement with Beall prosthetic valve was performed on three patients, and double valve replacement. aortic and mitral valve, was performed in this department.1) The preoperative studies about the first case were compatible with mitral steno-insufficency.The diseased mitral valve was replaced with the medium sized Beall prosthetic valve under the cardiopulmonary hypass using hypothermic hemodilution technique. The total perfusion time was eighty minutes. Immediate postoperative course was smooth, but this patient was died of asphyxia due to tracheomalacia complicated after tracheostomy 3 months after operation. Autopsy on this patient revealed that no thrombus and no ball variance could be found, and endothelization on the valve cuff was satisfactory. 2) The preoperative studies on the second case were compatible with mitral insufficiency. The diseased mitral valve was replaced with the medium sized Beall prosthetic valve under the cardiopulmonary bypass using hypothermic hemodilution technigue. The total perfusion time was 123 minutes. This patient was discharged in good condition and follow-up study after 16 months revealed the patient had enjoyed healthy life. 3) The preoperative studies about the third case were compatible with aortic insufficiency and mitral stenoinsufficiency. The diseased valves were replaced with type 2 sutureless Magovern aortic valve and the medium sized Beall mitral prosthesis under cardiopulmonary bypass using hypothermic hemodilution technIque and coronary artery perfusion. The total perfusion time was 155 minutes. This patient was discharged in good condition, but thromboembolism was developed 2 months after discharge. 4) The preoperative studies about the fourth case were compatible with mitral insufficiency. The diseased mitral valve was replaced with the medium sized Beall prosthetic valve. The total perfusion time was 132 minutes. The atrioventricular block developed just after operation but converted to normal sinus rhythmn on the third postperative day. The preoperative NYHA functional classification IV was converted to Class 1 or 11 at the time of discharge and this patient enjoyed healthy life. Attendum; The fifth case, nineteen years old male with mital insufficiency underwent Beall valve replacement and his course was uneventful 2 weeks after operation.

• 한국임상수의학회지
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• 제35권1호
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• pp.10-12
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• 2018

Mitral regurgitation is the most frequent cause of cardiac disability and death in dogs. A wide range of medical and surgical treatments have been used for mitral regurgitation. Surgical treatments for complete correction of mitral regurgitation include valve repair and valve replacement, which have the advantages of eliminating or correcting the primary cause. Surgical treatments approach the mitral valve via right- or left-side thoracotomy. Aortic root exposure is needed for cardiopulmonary bypass. To compare right-side and left-side approaches, 10 dog cadavers were used in this study. Subsequently, the left-side surgical approach was used in vivo and in conjunction with cardiopulmonary bypass and cardioplegic arrest. Based on the results, and considering ease of access to the aortic root, valve incision site, and visualization of the surgical field, a left-side approach is recommended.

• Journal of Chest Surgery
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• 제44권2호
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• pp.131-136
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• 2011

Background: We evaluated the surgical results and predictors of long-term survival in patients who underwent coronary artery bypass grafting (CABG) at the time of an aortic valve replacement (AVR) due to aortic stenosis. Materials and Methods: Between January 1990 and December 2009, 183 consecutive patients underwent CABG and concomitant aortic valve replacement for aortic stenosis. The mean follow-up period was $59.8{\pm}3.3$ months and follow-up was possible in 98.3% of cases. Predictors of mortality were determined by Cox regression analysis. Results: There were 5 (2.7%) in-hospital deaths. Follow-up of the in-hospital survivors documented late survival rates of 91.5%, 74.8%, and 59.6% at 1, 5, and 10 postoperative years, respectively. Age (p<0.001), a glomerular filtration rate (GFR) less than 60 mL/min (p=0.006), and left ventricular (LV) mass (p<0.001) were significant predictors of mortality in the multivariate analysis. Conclusion: The surgical results and long-term survival of aortic valve replacement with concomitant CABG in patients with aortic stenosis and coronary artery disease were acceptable. Age, a GFR less than 60 mL/min, and LV mass were significant predictors of mortality.

• Journal of Chest Surgery
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• 제16권3호
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• pp.295-300
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• 1983

Three cases of multiple cardiac valve replacement were done in March 1983 at the department of thoracic and cardiovascular surgery, Chosun University College of Medicine. The patients were moderately symptomatic in all cases, and belonged to the class II and III of the NYHA functional criteria. The diseased valved were replaced with Bjork--Shiley, Ionescu-shiley valve prosthesis under cardiopulmonary bypass using hemodilution technique. The kind of cardioplegic solution used in our institute were Young and GIKs solution with core surface cooling. The average cardiopulmonary bypass time was 251.6 minutes and the average aortic cross clamping time was 223 minutes for aortic and mitral valve replacement. There was no operative morality.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.1083-1084
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• 2010

• Journal of Chest Surgery
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• 제56권6호
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• pp.394-402
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• 2023

Background: The optimal choice of valve substitute for aortic valve replacement (AVR) in pediatric patients remains a matter of debate. This study investigated the outcomes following AVR using mechanical prostheses in children. Methods: Forty-four patients younger than 15 years who underwent mechanical AVR from March 1990 through March 2023 were included. The outcomes of interest were death or transplantation, hemorrhagic or thromboembolic events, and reoperation after mechanical AVR. Adverse events included any death, transplant, aortic valve reoperation, and major thromboembolic or hemorrhagic event. Results: The median age and weight at AVR were 139 months and 32 kg, respectively. The median follow-up duration was 56 months. The most commonly used valve size was 21 mm (14 [31.8%]). There were 2 in-hospital deaths, 1 in-hospital transplant, and 1 late death. The overall survival rates at 1 and 10 years post-AVR were 92.9% and 90.0%, respectively. Aortic valve reoperation was required in 4 patients at a median of 70 months post-AVR. No major hemorrhagic or thromboembolic events occurred. The 5- and 10-year adverse event-free survival rates were 81.8% and 72.2%, respectively. In univariable analysis, younger age, longer cardiopulmonary bypass time, and smaller valve size were associated with adverse events. The cut-off values for age and prosthetic valve size to minimize the risk of adverse events were 71 months and 20 mm, respectively. Conclusion: Mechanical AVR could be performed safely in children. Younger age, longer cardiopulmonary bypass time and smaller valve size were associated with adverse events. Thromboembolic or hemorrhagic complications might rarely occur.

• 설비공학논문집
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• 제25권3호
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• pp.137-142
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• 2013

A small air-conditioner or chiller for a constant temperature bath normally uses a constant speed compressor. The constant speed compressor is relatively inexpensive, but it uses on/off control for capacity modulation. The on/off control has several disadvantages, specifically energy loss and large temperature fluctuation. Continuous operation with a bypass system can be an alternative to on/off control, for capacity modulation. In this study, a heat pump system having a hot-gas bypass and a liquid bypass was adopted. The performance of the bypass-type heat pump was measured, by varying the bypass valve opening. The differences of the COP between the hot-gas bypass and the liquid bypass, in the cooling and heating operations, were within 2% and 1%, respectively. The liquid bypass showed a wider range of capacity control in the cooling operation but the hot-gas bypass showed a wider range of capacity control in the heating operation.

• Journal of Advanced Marine Engineering and Technology
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• 제40권7호
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• pp.663-670
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• 2016

본 논문은 심해저 채광시스템 중 심해저 광물자원의 안전한 양광을 위한 바이패스 밸브의 개념 소개 및 CAE 기반의 바이패스 밸브 요소 설계 기술을 고찰하고 있다. 바이패스 밸브는 다른 해양의 기자재와 같이 고장예방과 안정성 확보를 위해 간단한 구조로 제안되었으나, 유체, 구조, 동적 거동 등의 다양한 영향으로 인해 설계는 복잡하고 어렵다. 설계가 복잡한 바이패스 밸브를 개발하기 위해서 본 연구에서는 CAE 기반 설계 기술을 활용하였다. CAE 기반 설계 기술은 설계, 설계검증, 가상의 실험 등을 한 번에 할 수 있어 바이패스 밸브와 같이 복잡한 설계 문제 해결에 효과적이다. 특히, 바이패스 밸브에 사용되는 스프링은 밸브 특성에서 가장 중요한 응답 성능에 관련된 부품으로 유체력, 동역학을 이용한 CAE 기반 설계 기술을 적용하는 것이 효율적이며, 이를 위해 각 학제들을 연동한 통합설계 모델을 개발하였다. 이러한 통합설계 모델을 바탕으로 바이패스 밸브의 설계 및 설계에 대한 검증을 수행하였으며, 이러한 일련의 과정을 통하여 바이패스 밸브를 개발하였다.

• 설비공학논문집
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• 제16권4호
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• pp.390-396
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• 2004

A double-inlet pulse tube refrigerator was fabricated as a U-shape with $\Phi$19.0 mm${\times}$125 mm regenerator packed by #200 stainless steel mesh and $\Phi$12.7 mm${\times}$125 mm pulse tube. A pressure sensor was installed at the inlet of the regenerator and a differential pressure sensor was installed across the bypass. Amplitude of the pulsating pressure was independent of the opening of the orifice and the bypass valves. Helium flow through the orifice and the bypass was calculated based on the measured pressure. Energy loss through the orifice and the bypass was evaluated with the measured pressure and the calculated helium flow rate. The energy loss, which is equivalent to the refrigeration capacity at the cold end of the ideal pulse tube refrigerator, was mainly generated through the orifice. It was proportional to the opening of the orifice valve, but the real refrigerator displayed the best performance at the optimized opening of the orifice valve. This optimized performance of the tested pulse tube refrigerator can be explained by additional refrigeration losses. As an example, the shuttle heat transfer loss of the pulse tube was calculated from the measured experimental data.

• Journal of Chest Surgery
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• 제56권3호
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• pp.197-203
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• 2023

Background: The survival benefit of coronary artery bypass grafting (CABG) using the bilateral internal thoracic arteries (BITA) is well known; however, the role of BITA in concomitant aortic valve replacement (AVR) and CABG has not been studied. Methods: We retrospectively reviewed patients who underwent concomitant AVR and CABG. Cases not using an internal thoracic artery and less than 2 bypass grafts were excluded. We enrolled 114 patients in this study. The mean follow-up duration was 61.5±43.5 months. Results: Forty patients (35.1%) underwent CABG with a single internal thoracic artery (SITA) and 74 patients (64.9%) underwent CABG with BITA. The preoperative clinical characteristics were not significantly different between the 2 groups, with the exception of a higher prevalence of atrial fibrillation in the SITA group. Postoperative mortality and morbidity were not significantly higher in the BITA group than in the SITA group. In the univariable analysis, the survival of the BITA group was similar to that of the SITA group (p=0.157). Multivariable analysis showed that only mean age was a predictor of death (p=0.042), but using BITA was not an independent predictor (p=0.094). In low-risk patients whose preoperative ejection fraction was >45%, the survival of the BITA group was significantly better than that of the SITA group (p=0.043). Conclusion: BITA use in concomitant AVR and CABG showed no difference in mortality compared to using SITA. Although its impact on long-term survival was inconclusive, BITA use can be considered for low-risk patients.