• Journal of Chest Surgery
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• v.29 no.10
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• pp.1076-1080
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• 1996

The results about the myocardial protection of recta of the nitric oxide precursor L-arginine upon reperrusion injury after ischemia are diverse. These diversities may be model dependent. Experiments were designed and performed to investigate myocardial protection effects according to the concentration of L-arginine. The Isolated rat hearts were subjected in a 30 minutes oi normothermic ischemia and reperfused for 30 minutes with reperfusate containing 0, 1, 2, 3, 4 moil L-arginine. After 30 minutes of reperfusion, group with 1 and 2 mM/L L-arginine showed a trend of better recovery in left ventricular systolic function(left ventricular developed pressure, positive maximum dpfdt), diastolic function(negative maximum dpfdt) and coronary flow compared to control group(reperfusate no L-arginine). Recovery was impaired with a higher concentration, and at 4 moil L-arginine r covery was worse than control(p (0, 05). These results suggest that optimal concentration of L-arginine Is Important or the recovery of myocardial and endothelial function after ischemia and reperfusion.

• Proceedings of the KOSOMBE Conference
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• v.1992 no.11
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• pp.141-145
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• 1992

심부전 환자의 심근회복을 도울 수 있는 장비인 전기유압방식 좌심실보조기를 개발하였다. 좌심실보조기는 혈액펌프, 압력펌프, 제어기로 구성되어 있으며, 혈액펌프에 내장된 혈액주머니는 동물실험을 위하여 50 ml의 크기로 제작하였다. 좌심실보조기의 성능평가를 위하여 최대 박출량을 측정하고 있으나 실험실에서 측정된 간은 동물 실험에서 관찰되는 것보다 일반적으로 증가된 박출량을 보이게 된다. 이는 생체에서는 좌심방의 체적이 박동 주기에 따라 변하여 좌심실보조기가 받아들일 수 있는 유효 혈액량이 변하는 반면, 모의순환장치에서는 좌심방을 단순 저장고로 사용하기 때문에 좌심방의 박동주기에 따른 체적변화를 감안하지 못하여 생기는 것이다. 본 실험에서는 모의순환 장치에 체적변화 가능한 100ml 크기의 좌심방을 연결하여 좌심방으로 들어오는 혈류량이 제한된 동물실험 상황을 모방하였다. 좌심실보조기의 제어방식중 수측기 이완기 비율(SD 비율)변화에 따른 좌심방 음압발생효과를 관찰한 결과 SD 비율을 40 %로 유지하면 행정거리가 클때도 좌심실의 음압발생을 줄일 수 있는 것을 관찰하였다.

• Journal of Chest Surgery
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• v.40 no.1 s.270
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• pp.45-51
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• 2007

Background: Although echocardiography is usually used for quantitative assessment of left ventricular function, the recently developed 16-slice multidetector computed tomography (MDCT) is not only capable of evaluating the coronary arteries but also left ventricular function. Therefore, the objective of our study was to compare the values of left ventricular function quantified by MDCT to those by echocardiography for evaluation of its regards to clinical applications. Material and Method: From 49 patients who underwent MDCT in our hospital from November 1, 2003 to January 31, 2005, we enrolled 20 patients who underwent echocardiography during the same period for this study. Left ventricular end-diastolic volume index (LVEDVI), left ventricular end-systolic volume index (LVESVI), stroke volume index (SVI), left ventricular mass index (LVMI), and ejection fraction (EF) were analyzed. Result: Average LVEDVI ($80.86{\pm}34.69mL$ for MDCT vs $60.23{\pm}29.06mL$ for Echocardiography, p<0.01), average LVESVI ($37.96{\pm}24.52mL$ for MDCT vs $25.68{\pm}16.57mL$ for Echocardiography, p<0.01), average SVI ($42.90{\pm}15.86mL$ for MDCT vs $34.54{\pm}17.94mL$ for Echocardiography, p<0.01), average LVMI ($72.14{\pm}25.35mL$ for MDCT vs $130.35{\pm}53.10mL$ for Echocardiography, p<0.01), and average EF ($55.63{\pm}12.91mL$ for MOCT vs $59.95{\pm}12.75ml$ for Echocardiography, p<0.05) showed significant difference between both groups. Average LVEDVI, average LVESVI, and average SVI were higher in MDCT, and average LVMI and average EF were higher in echocardiogram. Comparing correlation for each parameters between both groups, LVEDVI $(r^2=0.74,\;p<0.0001)$, LVESVI $(r^2=0.69,\;p<0.0001)$ and SVI $(r^2=0.55,\;p<0.0001)$ showed high relevance, LVMI $(r^2=0.84,\;p<0.0001)$ showed very high relevance, and $EF (r^2=0.45,\;p=0.0002)$ showed relatively high relevance. Conclusion: Quantitative assessment of left ventricular volume and function using 16-slice MDCT showed high relevance compared with echocardiography, therefore may be a feasible assessment method. However, because the average of each parameters showed significant difference, the absolute values between both studies may not be appropriate for clinical applications. Furthermore, considering the future development of MDCT, we expect to be able to easily evaluate the assessment of coronary artery stenosis along with left ventricular function in coronary artery disease patients.

• Journal of Biomedical Engineering Research
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• v.19 no.1
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• pp.39-46
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• 1998

In this paper, we present a neural network identification and a control of highly complicated nonlinear left ventricular assist device(LVAD) system with a pneumatically driven mock circulation system. Generally, the LVAD system needs to compensate for nonlinearities. It is necessary to apply high performance control techniques. Fortunately, the neural network can be applied to control of a nonlinear dynamic system by learning capability. In this study, we identify the LVAD system with neural network identification(NNI). Once the NNI has learned the dynamic model of the LVAD system, the other network, called neural network controller(NNC), is designed for a control of the LVAD system. The ability and effectiveness of identifying and controlling the LVAD system using the proposed algorithm will be demonstrated by computer simulation.

• Journal of Chest Surgery
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• v.36 no.4
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• pp.273-276
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• 2003

We report a surgical case of 39-year-old male with a pseudoaneurysm of the left ventricle. Four years ago, the patient underwent aortic and mitral valve replacements with mechanical valves and abscess removal for infective endocarditis with annular abscess. Recent echocardiography demonstrated a communication between left ventricle and abscess pocket, and the size of pocket increased further at the follow-up echocardiography. The patient underwent patch closure of the defect between left ventricle and pseudoaneurysm located at the aortomitral fibrous continuity, under the cardiopulmonary bypass and cardioplegia. The postoperative course was uneventful and the patient was discharged on the 9th postoperative day.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1995.10b
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• pp.387-392
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• 1995

전기 유압식 좌심실 보조장치에서 모터 전류 파형을 정보로 하여 작동기의 이완기 속도를 조절함으로써 좌심방으로부터 유입되는 혈류량을 조절하는 알고리즘을 개발하였다. 좌심실 보조장치(Left Ventricular Assist Device, LVAD)는 허혈성 심장질환 등으로 좌심실 의 혈액 박출 기능이 저하된 환자에게 시술하여 정상 상태의 심박출량을 유지할 수 있도록 하는 보조 혈액 박출 기능이이다. 전기 유압식 좌심실 보조장치에서는 혈액의 유입이 능동 적으로 이루어지므로, 좌심방 함몰로 인한 심근 손상 및 외부 공기 유입으로 인한 색전증을 방지하기 위해 유입혈류량을 현재 좌심방내의 상태에 따라 적절히 조절해 주어야 한다. 좌 심방 내의 혈액량 정도는 혈액을 유입해 내는 작동기의 이완기 동작 시에 소모되는 에너지 크기에 반영되고, 작동기를 구동하는 모터에 들어가는 전류의 크기는 작동기에 공급되는 에 너지에 비례하므로, 이전류 파형의 정보들을 통해 좌심방내의 상태를 추정해 볼 수 있다. 본 논문에서는 퍼지로직을 적용하여 모터 전류 파형의 정보들을 통해 좌심방 내의 상태를 추정 해 볼 수 있다. 본 논문에서는 퍼지로직을 적용하여 모터 전류 파형의 이상 유무를 판단한 뒤 에에 따라 작동기의 이완기 속도를 조절하는 알고리즘을 개발하여 모의순환장치 실험을 통해 그 실효성을 검증한 결과를 정리하였다.

• Journal of Chest Surgery
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• v.38 no.10 s.255
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• pp.685-692
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• 2005

Background: Wall motion abnormalities may be a significant predictor for long-term survival after coronary bypass surgery (CABG). The aim of this study is to see whether post-infarction wall motion abnormality of left ventricle affect on the long-term survival after CABG. Material and Method: One-hundred and thirty-three patients (male/female, 92/41) undergoing CABG more than 9 years ago were included in this study. Fifty-six patients (M/F, 42/14; mean age, $59.2\pm9.2$ years) with LV wall motion abnormalities were compared to 77 patients (M/F, 50/27; mean age, $58.0\pm7.6$ years) without the wall motion abnormalities. Most patients (112/133, $84.2\%$) had undergone on-pump CABG with the in-situ left internal thoracic artery and free grafts of saphenous vein, in which the proximal and distal anastomoses were done for the single aortic cross-clamping period. Result: Ejection fraction of left ventricle was lower in the group with LV wall motion abnormalities (mean ejection fraction, $48.7\pm13.2\%$) compared to the group without wall motion abnormalities (mean ejection fraction, $57.1\pm10.1\%$)(p=0.0001). Risk­unadjusted survivals after CABG in the group without wall motion abnormalities were $85.7\pm4.0\%,\;76.2\pm4.9\%,\;and\;57.2\pm10.3\%$ at 5, 10, and 13 years, respectively, and in the group with wall motion abnormalities were $80.4\pm5.3\%,\;58.7\pm7.3\%,\;and\;51.9\pm7.9\%$ at 5, 10, and 13 years, respectively (p=0.1). In univariate analysis, predictable factors of long-term survival in the patients with LV wall motion abnormalities were LV ejection fraction and post operative outpatient treatment. In multivariate analysis, predictable factor of long-term survival in the patients with the wall motion abnormalities was postoperative outpatient treatment, and that in those without the wall motion abnormalities was female. Conclusion: Although there was no significant survival difference after CABG between the group with LV wall motion abnormalities and that without wall motion abnormalities, the survival in the group with wall motion abnormalities seems to be more decreased. For the patients with LV wall motion abnormalities after myocardial infarction, the post-CABG outpatient treatment is suggested to be an important factor for the long-term survival.

• Journal of Chest Surgery
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• v.37 no.9
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• pp.755-761
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• 2004

We evaluated the efficacy of Dor procedure in patients with ischemic left ventricular dysfunction. Material and Method: Between April 1998 and December 2002, 45 patients underwent the Dor procedure con-comitant with coronary artery bypass grafting (CABG). Left ventricular ejection fraction (LVEF) and left ventricular end-diastolic/end-systolic volumes (LVEDV/LVESV) were measured by echocardiography, myocardial SPECT, and cardiac catheterization and angiography performed at the sequence of preoperative, early postoperative, and one year postoperative stage. Result: Cardiopulmonary bypass and aortic clamp times were mean 141$\pm$64, 69$\pm$24 minutes, respectively. Intraaortic balloon pump (IABP) therapy was required in 19 patients (42%; 7 preoperatively, 9 intraoperatively, 3 postoperatively). Operative mortality rate was 2.2% (1/45). Postoperative morbidities were low cardiac output syndrome (12), atrial fibrillation (5), acute renal failure (4), and postoperative bleeding (4). Functional class (NYHA) was improved from classes 2.8 to 1.1 (p < 0,01). When we compared between the preoperative and early postoperative values, LVEF was improved from 32$\pm$9% to 52$\pm$11% (p<0.01). The asynergy portion decreased from 57$\pm$12% to 22$\pm$9%, and LVEDV/LVESV indexes improved from 125$\pm$39 mL/$m^2$, 85$\pm$30 mL/$m^2$ to 66$\pm$23 mL/$m^2$, 32$\pm$16 mL/$m^2$ (p<0.01). Although these changes in volumes were relatively preserved at postoperative one year, the left ventricular volumes showed a tendency to increase. Conclusion: After the Dor procedure for ischemic left ventricular dysfunction, LVEF improvement and left ventricular volume reduction were maintained till postoperative one year. The tendency for left ventricular volume to increase at postoperative one year suggested the requirement of strict medical management.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.739-741
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• 2002

좌심실의 파라미터는 심장의 기능을 분석하기 위해 측정되는 정량적인 표현으로, 특히 지역적 파라미터인 두께와 두께의 변화는 심판 기능을 분석하기에 적합한 파라미터이다. 본 연구에서는 이러한 좌심실의 지역적 파라미터를 측정하고, 이를 위해 사용되는 삼자원적 방법을 개선하여 구현함으로써 기존의 폭정 방법의 제약을 극복하고자 하였다. 또한, 측정 결과를 가시화하여 직관적인 분석이 가능하도록 하고, 이를 시스템에 구축하여 임상에서 직접적으로 활용할 수 있도록 하였다.

• Journal of the korean veterinary medical association
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• v.41 no.12
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• pp.1142-1147
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• 2005

생명체 안에는 정맥혈과 동맥혈이라는 두 가지 종류의 혈액이 흐른다. 여기에는 신체 내 세 가지 기관이 관여하는데, 간은 영양과 성장의 임무를 심장은 생명의 원동력을 뇌는 인지와 이성을 담당한다. 영양과 성장은 간에서 형성되는 '정맥혈'을 통해 형성되고 생명의 원동력은 심장에서 형성되는 '동맥혈'을 통해 전신으로 퍼진다. 이 혈액들은 심장으로 다시 돌아오지 않고 온 몸에 퍼져 소비된다. 혈액은 심장이 이완될 때 심장 안으로 빨아들여진다. 심장은 혈액을 펌프질하는 기능이 없으며 동맥이 그 스스로가 '박동성'을 가지고 혈액을 밀어낸다. 좌심실에서 정맥혈과 프네우마(Pneuma)가 섞이게 되는데 심장 오른쪽 심실과 심방의 정맥혈은 좌심실과 우심실 사이 중격(심실중격, interventricularseptum)의 작은 구멍을 통해 좌심실로 이동한다.