• Journal of Chest Surgery
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• v.40 no.3 s.272
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• pp.168-179
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• 2007

Background: The recent trend of an increasing number of patients with acute cardiogenic shock or chronic congestive heart failure following myocardial infarction, as well as the considerable number who can not be weaned from cardiopulmonary bypass after open heart surgery, call for immediate efforts to develop affordable ventricular assist devices that are suitable for the Korean physique. Recently, a pneumatic pulsatile ventricular assist device (VAD), named DKUH-75, has been developed by the Department of Biomedical Engineering, in collaboration with the Department of Thoracic and Cardiovascular Surgery of Dankook University College of Medicine. The feasibility of the DKUH-75 VAD was evaluated on the bases of common hemodynamic variables and echocardiographic measurements in pigs, which are subjected to an acute cardiogenic shock state following myocardial infarction, using a novel coronary artery ligation method employing the ischemic preconditioning concept. Material and Method: Acute cardiogenic shock was induced in 10 Yorkshire Landrace Duroc strain pigs by ligating the left anterior descending coronary artery via an ischemic preconditioning process. The hemodynamic variables were monitored, with epicardial echocardiographic measurements performed before and one hour after the ligation. The DKUH-75 VAD was implanted into 5 pigs one hour after the onset of the shock. The hemodynamic variables and echocardiographic measurements were taken one hour after installation of the VAD. Result: The systolic, diastolic and mean systemic arterial pressures were significantly decreased in all the experimental animals one hour after the ligation. The systolic, diastolic and mean pulmonary arterial pressures were increased (Eds note: this completely contradicts the preceding statement? However, if you mean the non-experimental animals this should be stated?). The left ventricular end diastolic pressure (LVEDP) was increased, but the cardiac index decreased, An increase in the left ventricular end systolic dimension and decreases in the fractional shortening and ejection fraction were observed all animals one hour after the coronary artery ligation. In all 5 of the VAD implanted pigs, the systolic and mean systemic arterial pressures were increased, and the pulmonary arterial pressures decreased one hour after the implantation; the LVEDP decreased, but the cardiac index was significantly increased, In the echocardiographic measurements, the left ventricular end systolic dimension decreased after the implantation of the VAD, but the fractional shortening and ejection fraction significantly increased. Conclusion: Significant improvements in the hemodynamic variables and echocardiographic measurements were observed in the 5 VAD implanted animals one hour after installation, which had been subjected to an acute cardiogenic shock state by ligation of the coronary artery, indicating that the DKUH-75 VAD could help in the recovery of the myocardial function. This suggests that the DKUH-75 VAD is feasible in the short term in relation to an acute cardiogenic shock state due to myocardial infarction.

• Proceedings of the KTCVS Conference
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• 1995.10a
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• pp.44-44
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• 1995

• Journal of Chest Surgery
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• v.27 no.5
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• pp.390-393
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• 1994

의료기술의 발달로 오늘날의 개심술은 대부분 성공적으로 시행되고 있지만 극히 일부분은 아직도 개심술후 심한 심실기능의 저하로 사망하는 겨우가 있다. 1960년대 중반 Spencer와 DeBakey에 의해 개심술후 심한 심실기능이 저하된 환자에게 심실보조장치를 이용하여 성공적으로 치험한 이후로 많은 발전을 거듭해 왔다. 저자들은 4개월 (6.5Kg)된 남아에서 개심술후 심한 저심박출증으로 인공심폐기의 제거를 못하여 좌심실 보조장치(Centrifugal Biopump)를 사용하여 성공적으로 치험하였기에 보고하는 바이다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1205-1211
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• 2011

In this paper, we developed a pacemaker that can increase the efficacy of a left ventricular assist device (LVAD) and increase the survival rate for patients suffering end-stage heart failure. Because LVAD patients can experience arrhythmia, the pacemaker incorporated into the LVAD has the important role of sustaining sufficient blood circulation during arrhythmia. The electrode of the pacemaker is located at the apex of the left ventricle, where the VAD's inlet cannula is connected. This is efficient placement, in that the electrode can transmit electrical stimulation directly to the Purkinje fibers of the myocardium. The pacemaker can change the stimulation rate from 0 bpm to 191.4 bpm when a button is pressed on the external control module, and the pacemaker normally stimulates the heart at 60 bpm with 0.25 J of energy. We performed animal experiments to evaluate the performance and reliability of the combination of the LVAD and pacemaker. At pacemaker stimulation rates of 86.4 bpm, 100.2 bpm, 126.6 bpm, we recorded the ECGs, aortic pressures, and flow rates to analyze the heart loads.

• Journal of Chest Surgery
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• v.33 no.11
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• pp.906-909
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• 2000

심폐바이패스를 사용하지 않고 심장박동 상태에서 시행하는 관상동맥 우회수술은 심 비대와 좌심실 기능저하가 동반된 협증심 환자에서는 심장 뒤쪽에 위치한 관상동맥에 대한 접근이 어렵고 수술 중 혈역학적으로 불안정하여 시행하기에 어려운 경우가 많다. 우심실 보조장치 하의 심장박동 상태에서 시행하는 관상동맥 우회수술은 대동맥의 삽관을 피하고, 심폐바이패스의 합병증을 줄일 수 있으며, 심장 뒤쪽에 위치한 혈관의 문합시에도 안정된 혈역학적 상태를 유지 할 수 있어 고위험군 환자에게 도움을 줄 수 있다. 좌심실 기능저하와 심 비대가 동반된 환자에서 우심실 보조장치 하의 심장박동 상태에서 시행한 관상동맥 우회수술을 2례 시행하여 좋은 결과를 얻어 보고하고자 한다.

• Journal of Chest Surgery
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• v.32 no.5
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• pp.428-432
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• 1999

Background: It has been shown that low-grade electrical stimulus can transform fatigue resistant muscles which then can be used to protect the heart. The bulky and cumbersome power sources of the artificial heart or implantable ventricular assist devices are still in need of solution; however, on the other hand, the implantable ventricular assist devices using the resistant muscles as the power source have the advantages of using its own muscle contractions. The purpose of this study was to determine the possibility of a clinical application of the skeletal muscle ventricle. Material and Method: Latissimus dorsi muscles (LDM) of 8 canines were used for skeletal muscle ventricle. A latex chamber was wrapped one and a half times with LDM. The chamber was attached to a pressure transducer via Tygon tube. An electrode stimulator was placed around the thoracodorsal nerve and LDM was stimulated in cyclic bursts of 0.31 sec on time and 6.0 sec off time using 3.0 volt Itrel stimulator. The preload volume was added to the system in 25cc increments. Ejection volumes, pressures, and peak power outputs were measured. Result: Ejection volume was 76.3cc with 0cc of preload. Ejection volumes were less than 70ml with increments of preload over 75cc Pressures were more than 107 mmHg when the preloads were less than 75cc and less than 100 mmHg when the preloads were more than 100cc. Peak power output of 16.6 W/kg was observed at 50cc preload. Conclusion: Depending on the changes of preload, the volumes ejected from skeletal muscle ventricle and pressures from the skeletal muscle contraction surpassed those of the normal heart. These data suggest that there are clinical applications for skeletal muscle ventricular assist system.

• Journal of Chest Surgery
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• v.36 no.3
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• pp.123-130
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• 2003

Background: In order to develop the acute heart failure model for the animal experiment of the pneumatic ventricular assist device, we decided to use young pig whose coronary artery distribution is almost the same as humans and also very cheap in price. The purpose of this study is to develop stable, reproducible acute ischemic heart failure model in swine using coronary artery ligation method. Material and Method: Five young pigs whose weights are the same as adult humans are under experiment. Each pig was under endotracheal intubation and connected to a mechanical ventilator. Through left lateral thoracotomy, we exposed the heart and induced ischemic heart failure by coronary artery ligation. The ligation began at the distal part of the left anterior descending coronary artery. After 5 minutes of initial ligation we reperfused the artery and then re-ligated. Before and after each ligation-reperfusion procedure we assessed the left ventricular end-diastolic pressure, arterial pressure, and cardiac index. We also measured left ventricular end-diastolic dimension, end-systolic dimension, fractional shortening, ejection fraction using intraoperative epicardial echocardiography. After appropriate heart failure was established with sequential (from distal part of LAD to proximal location) ligation-reperfusion-ligation procedure, we inserted the ventricular assist device and operated. Result: We established stable acute ischemic heart failure in 3 of 5 young pigs with this sequential ligation-reperfusion-ligation procedure, and could maintained 50% less ejection fraction before the procedure according to intraoperative epicardial echocardiography. We also observed no ventricular arrhythmia usually associated with simple coronary artery ligation in large animals and no cardiac arrest associated with ventricular arrhythmia or myocardial stunning. In pathologic specimen, we observed scattered ischemic myocardium in all around the ischemic field induced by coronary artery ligation. Conclusion: Under the concept of ischemic preconditioning, we developed safe and reproducible acute ischemic heart failure model in swine using sequential coronary artery ligation-reperfusion-ligation method.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.78-81
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• 1995

본 연구에서는 슬라이딩 모드를 전기유압식 심실보조기의 직류모터제어기의 속도와 위치제어에 적용하였다. 슬라이딩 모드 컨트롤은 가변구조시스템(varaiable sturucture system)의 일종으로 적절한 내부스위칭 논리를 갖는 연속적인 부시스템(subsystem)의 모임으로 구성된다는 접에서 고정된 제어구조를 갖는 일반적인 제어시스템과 다르다. 이 시스템은 불연속적인 동적시스템이나 시변적인 요소를 갖는 시스템등에서 사용되고 있다. 이 논문에서는 슬라이딩 모드 제어를 적용하여 좌심실보조기를 제어하는 경우에 넓은 작동범위에서도 시스템이 안정적이며 혈류역학적인 외란에 대해서도 기준입력에 대한 속도의 추종이 잘 이루어지는지의 여부를 실제의 구현에 앞서 컴퓨터모델을 통해 검증하고 문제점들을 조사하였다.

• Journal of Chest Surgery
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• v.32 no.1
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• pp.62-65
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• 1999

Infantile lobar emphysema is an uncommon disease affecting newborns and infants with varying degree of respiratory distress, lobar overaeration, mediastinal shift and herniation. Although the etiology of the condition is most commonly idiopathic, there is a clear association with congenital heart disease, particularly in the presence of pulmonary hypertension due to left to right shunt. Sites of predilection are the left main bronchus, the left upper and right middle bronchi. This report describes a two-week-old boy who had right middle lobe emphysema with large ventricular septal defect. At first, patch closure of perimembranous ventricular septal defect was performed. Postoperatively, the patient required continuing assisted ventilation and the lobar emphysema was not improve. One week following the initial operation, right middle lobectomy was successfully performed and the patient was weaned from artificial ventilator on the 5th postoperative day. The patient was discharged with good general condition on the 45th postoperative day.

• Journal of Chest Surgery
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• v.43 no.1
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• pp.20-24
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• 2010

Background: Fulminant myocarditis is a rare, but life threatening condition. Its prognosis is related with proper management in the acute phase. A cardiopulmonary support device can be very useful in this phase. We report on our experiences with managing acute fulminant myocarditis with a cardiopulmonary support (CPS) device. Material and Method: We reviewed retrospectively 9 patients who had a CPS device used for their fulminant myocarditis between September, 2006 and October, 2008. A Capiox emergency bypass system (Terumo Inc, Tokyo, Japan) was percutaneously inserted in all the patients. Upon implantation, all the patients were in cardiogenic shock because of ventricular arrhythmia or severe left ventricular dysfunction. The mean left ventricular ejection fraction (EF) was $20{\pm}6%$ according to transthoracic echocardiography. Result: 3 patients died despite CPS. The CPS was bridged to a transplanted heart in one patient. The rest were successfully explanted after a mean time of $107{\pm}70$ hours of running. The mean EF after discharge was $56{\pm}7%$ without dilated cardiomyopathy. Conclusion: Fulminant myocarditis can be fatal, but its prognosis is excellent if these patients receive proper, timely treatment. A cardiopulmonary support device can be very useful in this acute period. However, the implantation and management protocol of cardiopulmonary support are not yet settled. Further study is necessary to lower the complications of cardiopulmonary support for patients with fulminant myocarditis.