• 순환기질환의공학회:학술대회논문집
• /
• 2001.11a
• /
• pp.39-40
• /
• 2001

• Journal of Chest Surgery
• /
• v.34 no.6
• /
• pp.490-493
• /
• 2001

A 17 year-old high school girl was admitted for anterior chest pain. Pulmonary edema and circulatory collapse progressed in spite of the medical treatment and intra-aortic balloon pump. Left ventricular assist device(LVAD, Bio-Pump, Medtronic Bio-Med, USA) was instituted under the impression of acute fulminant myocarditis. The inlet cannula was inserted in the left atrium(LA) via left submammary anterior thoracotomy. Biopsy was taken from left atrial appendage. The outlet cannula inserted to the left femoral artery using PTFE cuff. After 158 hours of extracorporeal circulation, LVAD was able to be weaned successfully with nearly normalized LV motion on echocardiogram, Coxsakievirus was identified with immunochemistry and serum neutralization test. She was discharged without any heart failure symptoms after 23 days of hopitalization.

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

• The Transactions of the Korean Institute of Power Electronics
• /
• v.5 no.3
• /
• pp.209-214
• /
• 2000

In this paper, we propose a FB ZVT(full bridge zero voltage transition) PWM OC~OC converter which uses a a saturable reactor, instead of two additional switches, to achieve zero voltage switching. The conventional h high frequency phase shifted FB ZVT PWM OC-OC converter has a disadvantage that a circulating current f flows through high frequency transformer and switching devices during the free-wheeling interval. Due to this c circulating current, conduction loss increases. In order to reduce such the loss as this, we propose circuit of r reducing conduction loss at the secondary side of transformer. The operation principles are explained in detail a and the several interesting simulations and experimental results verify the validity of the proposed circuit.

• Journal of Chest Surgery
• /
• v.29 no.11
• /
• pp.1218-1222
• /
• 1996

The reported incidence of postcardiotomy cardiogenic shock not responding to conventional therapy is still 0.1 to 0.8%. For this group of patients, more aggressive form of circulatory support must be employed. Centrifugal pumps are a ventricular assist device most commonly used on this purpose, due to low cost and easy availability. Currently, however, clinical experience of centrifugal pumps as a ventricular assist device is rarely reported in Korea. From January 1992 to January 1996, 2986 patients underwent cardiac operations on cardiopulmonary bypass at Seoul National University Hospital. Refractory postcardiotomy cardiac failure requring ventricular support with a Biomedicus centrifugal pump developed in ten of these patients. There were eight men and two women, ranged in age from nine years to 77 years with a mean of 50$\pm$20 years. The primary surgical procedures consisted of isolated coronary revascularization in four patients, combined coronary revascularization and aortic valve replacement in two, aortic dissection repair in two, pulmonary embolectomy in one, and heart transplantation in one. Of the ten patients, five had left ventricular assistance, one had right ventricular assistance, and four had biventricular assistance. Duration of ventricular assistance ranged from 24 to 175 hours, with a mean of 76$\pm$51 hours. Seven patients were weaned from ventricular assistance, and four of them discharged. The causes of death for nonsurvivors were progressive cardiac failure in two patients and multiorgan failure, intractable ventricular fibrillation, irreversible brain injury, and mechanical problem, respectively, in the other four. Survival was not predicted by time on cardiopulmonary bypass, aortic cross-clamp time, or duration of ventricular support. Major complications included bleeding(7), renal failure(6), infection(3) and neurologic complication(2). These results indicate that a centrifugal pump can provide reasonably satisfactory short-term circulatory support.

• Journal of Chest Surgery
• /
• v.42 no.2
• /
• pp.259-262
• /
• 2009

Surgery on the distal trachea or the carina presents special problems for maintaining the airway and systemic oxygenation. Cardiopulmonary bypass is an alternative method for respiratory support for the patients with these conditions. Percutaneous cardiopulmonary support (PCPS) applied under local anesthesia has recently been used for respiratory support in tracheal surgery and the outcome is satisfactory. We encountered a patient who had severe distal tracheal stenosis after prolonged intubation. We had a gratifying result with performing tracheal resection and repair under the support of PCPS.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.11
• /
• pp.1191-1198
• /
• 2011

The use of a ventricular assist device (VAD) can raise the one-year survival rate without cardiac transplantation from 25% to 52%. However, malfunction of the VAD system causes 6% of VAD patients' deaths, which could possibly be avoided through the development of new VADs in which VAD malfunctions do not affect the patient's heart movement or hemodynamic state. A conventional VAD has an impeller or vane for propelling blood that can allow blood to regurgitate when the propelling force is weaker than the aortic pressure. In this paper, we developed a new pulsatile conduit-shaped VAD that has two valves. This device removes the possibility of blood regurgitation and has a small stationary area even when the pumping force is extremely weak. We estimated the characteristics of the device by measuring the outflow and the pressure of the pump in in-vitro and in-vivo experiments.

• Journal of Chest Surgery
• /
• v.43 no.6
• /
• pp.804-807
• /
• 2010

Blunt bronchial injuries rarely occur in children. This can be a life threatening condition and respiratory management is important for successful treatment. We present here a pediatric patient who had traumatic bronchial transection with difficult airway management. Surgical treatment was carried out under ventilatory support using extracorporeal membrane oxygenation (ECMO) in the emergency room. During the application of ECMO, systemic heparization was unnecessary and. there were no thrormbotic complications. In conclusion， ventilatory SUpport using ECMO is useful for treating selected patients with blunt trauma regardless of using heparin.

• Journal of Biomedical Engineering Research
• /
• v.19 no.1
• /
• pp.47-52
• /
• 1998

To develop the supplementary heart valve which could reduce the complications of prosthetic heart valve, in vitro experiments were performed to analyze the movement of the supplement valves from the view point of the flow dynamics and leaflet dynamics. The autologous pericardium was attached to deficient portion of the porcine valve which was dissected completely and partially. The pericardium was treated by buffered glutaraldehyde solution in the preshaped mould to preserve the shape of the leaflet. The function of the valves were evaluated in the mock circulatory system and three sets of experiment were performed. The instantaneous motion of the leaflet was pictured by the 35mm camera and the pressure drop through the valve and cardiac output were measured. The supplementary valve which was replaced completely performed better thatn the valve replaced partially. In vitro experiments showed that the supplementary valve which was replaced completely performed better than the valve replaced partially. In vitro experiments showed that the supplementary valve could undertake the prosthetic heart valve in clinic.

• Journal of Chest Surgery
• /
• v.39 no.11 s.268
• /
• pp.854-857
• /
• 2006

The patient was an eight-year-old female. She was diagnosed as dilated cardiomyopathy. She was supported with bi-ventricular assist because of heart failure for 15 days. After 7 days, she was suffered from prerenal type ARF and support with continuous veno-veno hemodyalisis(CVVHD). And then heart transplantation was performed, heart donor's blood type was A. Immune suppressants were used after due consideration for renal toxicity. ARF was resolved on post operative $14^{th}$ day. She was discharged on post operative $52^{nd}$ day without any specific post operative complication. She has been followed up without any immune rejection reaction upto 14 months.