• 대한의용생체공학회:의공학회지
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• 제35권5호
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• pp.119-124
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• 2014

A Ventricular assist device (VAD) is one of the most efficient treatments to raise the survivability of the end stage heart failure patient. However, some of LVAD patients have died for the failures and improper control of LVAD. To detect critical dangers in LVAD, the monitoring methods of LVAD outflow have been requested, because it can be affected by patient's hemodynamic states and abnormal conditions of LVAD. In the case of an external pulsatile LVAD, the air movement through the air line can be used to estimate LVAD outflow. In this study, the air movement in the air-line of the extracorporeal pulsatile LVAD was measured with a differential pressure sensor between different points. The precise estimation of air movement could be achieved by additional measurement of air pressure. In a series of in-vitro experiments, the LVAD outflow were changed according to the afterload of LVAD and the differential pressure of LVAD didn't have close correlation with the LVAD outflow that were measured with an ultrasonic flowmeter at the same time. However, new precise estimation with the data from differential pressure and one point pressure in the air-line showed higher correlations with LVAD outflow.

• 임상간호연구
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• 제28권2호
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• pp.167-176
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• 2022

Purpose: Driveline infection (DLI) is one of the major adverse events of Left Ventricular Assist Device (LVAD). The purpose of this study was to explore the incidence of DLI according to the driveline dressing methods. Methods: This study was a retrospective cohort study that investigated the medical records of 75 patients who implanted LVAD from January 2015 to December 2020 at a hospital in Seoul, Korea. Traditionally, sandwich dressing method was applied until October 2019, after which newly winded dressing method was adopted for driveline dressing to LVAD patients. The outcome variables were compared between sandwich dressing method applied group (n=41) and winded dressing method applied group (n=34). The follow-up period for DLI was 1 year. Results: When compared participants' characteristics, there was no difference between the two groups, except the type of LVAD device. The incidence of DLI was 17.1% in sandwich dressing group, while no infection was found in winded dressing group (p=.011). Conclusion: Although there were difference in the LVAD devices, it is considered that winded dressing contributed to the reduction of DLI. Further research on standardized dressing methods was required for DLI prevention in Korea.

• Journal of Chest Surgery
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• 제36권3호
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• pp.123-130
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• 2003

배경: 공압식 심실보조기의 실험을 위한 심부전 모델을 개발하는 데 있어서 사람의 심장구조와 유사하고 저렴하며 일관되게 반복적으로 급성심부전을 유발할 수 있는 방법을 찾기 위해 본 연구진은 사람의 심장구조와 가장 유사하며 저렴한 돼지를 사용하여 관상동맥의 좌전하행지를 결찰하는 방법으로 급성심부전을 유발시키고자 하였다. 대상 및 방법: 성인의 몸무게에 해당하는 5마리의 돼지를 사용하여 전신마취 후 좌측개흉술을 통하여 심장을 노출시키고 관상동맥의 좌전하행지의 원위부에서 시작하여 근위부로 올라오면서 결찰, 재관류, 결찰의 방법으로 심부전을 유발시켰다. 각 과정의 전, 후에 좌심실확장기말기압력, 동맥압, 심박출계수를 측정하였고, 심외막 심에코도를 통하여 좌심실확장기내경, 좌심실수축기내경, 분획단축, 심구혈률을 측정하였다. 이와 같은 과정을 좌전하행지의 원위부부터 근위부까지 충분한 심부전이 달성될 때까지 반복하였으며 목표달성 후 심실보조기를 장착하여 구동시켰다. 결과: 5마리 중 3마리에서 안정적인 심부전을 달성할 수 있었으며 3마리 모두에서 심외막 심에코도상 심구혈률을 기준으로 관상동맥 결찰 전에 비하여 50% 정도의 심기능 저하를 유지 할 수 있었다. 또한 결찰, 재관류, 결찰의 방법을 통하여 심근에 대해 허혈성 전처치를 시행한 후 완전 결찰을 시행하였을 때 대동물의 관상동맥 결찰 시 흔히 발생하는 심실성 부정맥이나 심관기절에의한 심정지도 관찰되지 않았으며 병리조직학적 소견상 심근허혈을 유발시킨 좌, 우심실의 심첨부에서 중간부위까지 광범위한 허혈성 손상을 입은 심근세포들을 확인할 수 있었다. 결론: 허혈성 전처치의 개념을 관상동맥 결찰을 통한 심부전 모델에 적용하여 좌전하행지의 원위부에서부터 근위부 까지 순차적으로 결찰, 재관류, 결찰을 시도한 결과 안정적이고 반복 가능한 급성 심부전 모델을 얻을 수 있었다.

• 대한의용생체공학회:의공학회지
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• 제22권5호
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• pp.449-458
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• 2001

한국형 양심실 보조 인공 심장의 효율 측정 방법과 측정 결과이다. 한국형 양심실 보조 인공 심장은 에너지 변환기로 브러시 없는 직류 모터를 사용한다 이 브러시 없는 직류 모터가 기어 열을 따라 원추운동을 하며 혈액주머니에 힘을 가하게 되고. 이 힘에 의해 혈액주머니 안의 혈액이 박출하게 된다. 효율 측정을 위하여 제어기 및 모터부, 기어부 및 작동기부. 혈액주머니 및 기타부 등 크게 세 부분으로 나누었으며. 각각을 다시 소자별로 나누어 입. 출력의 효율을 측정했다. 부하의 토크, 분당 회전수 각속도, 인가되는 전압 등을 바꾸어 가면서 시스템의 효율을 측정했고. 이 측정을 통해서 모터 운동시의 전체적인 효율과 부분별 효율을 알 수 있었다. 특히 양심실 보조 장치의 모터부와 작동기부의 효율측정에 중점을 두었다. 측정 결과 이동 작동기형 양심실 보조 장치의 평균 동작 영역인 4$\ell/min$ 박출량에서, 전체 효율은 8 %정도이며 구체적으로는 모터부 50 %, 작동기부 85 % 혈액주머니부 19 %정도의 효율을 보였다. 또한 6$\ell/min$ 박출량의 경우, 전체 효율은 5.5 %정도였다. 분석된 결과를 바탕으로 효율을 개선하기 위해 박출량에 따른 필요 구동 전압을 결정하고. 혈액주머니의 충만 상태에 따른 속도 파형을 연구. 제안하였다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 추계학술대회
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• pp.273-276
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• 1996

In the Total Artificial Heart (TAH) and Ventricular Assist Device (VAD), the size implanting the internal controller into human body is very serious problem. Hence, we need the size reduction of that controller for safe implantation. Using PSD302 chip for microcontroller-based applications, we could decrease the number of components in the digital control board and miniaturize the digital control board. We could replace a ROM, RAM, and a latch with that single chip, so the size of the newly developed board could be half the previous board.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1999년도 학술발표대회 논문집 제18권 2호
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• pp.131-134
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• 1999

This paper considers the acoustical characteristics of the mechanical valve employed in the Korean type Artificial Heart. $Bj\"{o}rk-Shiley$ tilting disc valve was chosen for the study and acoustic measurements were performed for the artificial heart operated in a mock circulation system as well as implanted to an animal as a Bi Ventricular Assist Device (BVAD). In the mock system, three different conditions of the valve were examined which were normal, damaged (torn off), pseudothrombus attached. Microphone measurements for the BVAD were carried out at a regular time interval for 5 days after the implantation operation. Of the recorded acoustic emissions from the artificial heart, click sounds mainly originated from the valves were further analyzed using Multiple Signal Classification (MUSIC) for estimating their spectral properties. It was shown that the spectral peaks below 4 kHz and the optimal order number for MUSIC, equivalent to the number of the spectral component, might be the key parameters which were highly correlated to the physiological states of the valve like the mechanical damage of the valve or the formation of thrombus on the valves.

• 대한의용생체공학회:의공학회지
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• 제18권2호
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• pp.147-156
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• 1997

Various prosthetic heart valves have been developed and used clinically, but they have problems, such as thrombogenecity, hemoltsis, high cost and low durability. New types of trileaflet polymer heart valves have been developed in order to use them as inlet and outlet valves in a ventricular assist device. The aim of this study is to determine the hydrodynamic effectiveness of the newly designed trileaflet polymer valves and their feasibility for temporary use in the blood pumps. Trileaflet polymer valves are made of polyurethane, because of its good blood compatibility, high tonsil strength and good resistance to fatigue. An in vitro experimental investigation was perf'ormed in order to ev91ua1e hydrodynamic performance of the trileaflet polymer valves having different design and fabrication tech- niques. The St. Jude Medical valve (SJMV) and floating-type monoleaflet polymer valve (MLPV) were also tested The pressure drop across the valve, leakage volume, and the flow patterns mere investigated for valves. The result of comparative tests showed that the trileaflet polymer valves had a better hydrodynamic performance than the others. TPV which has two stable membrane shape showed the lowest back flow. The pressure hops of TPVs were lower than that of MLPV, but slightly higher than SJMV. The hydrodynamic performance of valves under the pulastile flow showed the similar results as steady flow. The velocity profiles and turbulent intensities were measured at the distal sites of valves using a hot-film anemometer. Central flow was maintained in trileaflet polymer valves, and the maximum turbulent intensities were lower in TPVs comparing to MLPV.

• Clinical and Experimental Pediatrics
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• 제50권11호
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• pp.1041-1048
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• 2007

Not a few patients in children and adolescents are suffering from right ventricular (RV) dysfunction resulting from various conditions such as chronic lung disease, left ventricular dysfunction, pulmonary hypertension, or congenital heart defect. The RV is different from the left ventricle in terms of ventricular morphology, myocardial contractile pattern and special vulnerability to the pressure overload. Right ventricular failure (RVF) can be evaluated in terms of decreased RV contractility, RV volume overload, and/or RV pressure overload. The management for RVF starts from clear understanding of the pathophysiology of RVF. In addition to correction of the underlying disease, management of RVF per se is very important. Meticulous control of volume status, inotropic agents, vasopressors, and pulmonary selective vasodilators are the main tools in the management of RVF. The relative importance of each tool depends on the individual clinical status. Medical assist device and surgery can be considered selectively in case of refractory RVF to optimal medical treatment.

• 대한의용생체공학회:의공학회지
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• 제3권1호
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• pp.43-48
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• 1982

Ventricular assist device(VAD) has been clinically applied as a temporary circulatory sup- porting system in the patients with severe heart failure, but small sized VAD for infant is not available. The purpose of this paper is to introduce small sized VAD and presents the result of in vitro test. Sejong VAD is diaphragmatic type of pneumatic pump and stroke volume is 11cc. Cardiac outputs of the Sejong VAD were measured by overflow tank under variable conditions of driving parameters. The cardiac output was 1.3 1/min at the heart rate of 120 per minute, left atrial pressure of 15cmH2O, percent systole of 43%, driving pressure of 240 mmHg, vacuum pressure of -40 mmHg, and mean aortic pressure of 70 mmHg. No mechanical problem was developed during the continuous in vitro test for 3 months.

• 한국지능시스템학회논문지
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• 제22권4호
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• pp.500-506
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• 2012

좌심실보조장치의 모델과 안전한 장치 구동을 위한 흡입현상 검출을 위한 방법을 제안한다. 좌심실보조장치인 축류혈액펌프는 심장에 문제가 있는 환자를 보조하기 위하여 사용되어 왔다. 축류혈액펌프는 비맥동성 펌프이며, 맥동성 펌프에 비하여 작은 크기와 효율성과 같은 장점이 있으나, 안전한 펌프 운전 조건을 결정하는 데 어려움이 있다. 축류혈액펌프는 정상상태와 흡입상태와 같은 상이한 펌프 동작 상태를 가지며, 이는 좌심실에서 흡입현상 발생여부에 좌우된다. 퍼지 subtractive 클러스터링 기법을 이용하여, 이와 같은 동작 특성을 가지는 축류혈액펌프 모델을 개발하며, 개발한 펌프 모델을 이용하여 흡입현상 발생 전후의 펌프 혈류량을 추정한다. 또한 퍼지 subtractive 클러스터링 기법을 이용하여 좌심실에서 흡입현상 발생여부를 감지할 수 있는 흡입현상 검출 모델을 개발한다.