• International Journal of Control, Automation, and Systems
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• v.3 no.1
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• pp.100-108
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• 2005

This work presents a novel control index to regulate the pump speed of an axial flow blood pump for the left ventricular assist device (LVAD). The control index is based on the characterization of pump operating conditions such as normal or suction status. The pump operating characteristics reveal that a certain pulsatility relationship between the pump pressure difference and the pump flow is a unique index to identify the pump operating status under the diverse pump operating environments.

• Journal of Biomedical Engineering Research
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• v.16 no.1
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• pp.61-66
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• 1995

We have developed a monoleaflet polymer valve as an inexpensive and viable alternative, especially for short-term use in the ventricular assist device or total artificial heart. The frame and leaflet of the polymer valve were made from polyurethane. To evaluate the hemodynamic performance of the polymer valve a comparative study of flow dynamics past a polymer valve and a St. Jude Medicals prosthetic valve under physiological pulsatile flow conditions in vitro was made. Comparisons between the valves were made on the transvalvular pressure drop, regurgitation volume and maximum valve opening area. The polymer valve showed smaller regurgitation volllme and transvalvular pressure drop compared to the mechanical valve at higher heart rate. The results showed that the functional characteristics of the polymer valve compared favorably with those of the mechanical valve at higher heart rate.

• Journal of Power System Engineering
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• v.10 no.4
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• pp.153-158
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• 2006

최근 임상용 LVAD의 계속된 발전으로 인해 환자들의 삶이 연장되었다. 그러나 LVAD가 환자의 삶을 연장하였지만, 우심실 심부전증을 야기 시켰고, 결론적으로 환자들은 RVAD가 필요하게 되었다. 이러한 이유로 장시간 사용할 수 있는 BVAD의 도입이 요구 되어졌다. 최근 BVAD에 관련된 연구들을 보면 장시간 사용을 위한 원심 BVAD의 디자인과 BVAD에서의 누수 정도를 파악하는데 목적을 두고 있다. 따라서 본 논문에서는 BVAD의 누수를 파악하기 위한 속도 데이터와 용적당 흐름 비율의 계산을 CFD를 사용하여 해석적으로 조사하고자 하였다. CFD의 해석 결과 틈새부위의 회전수가 증가 할수록 혈액의 흐름을 방해하는 역류가 증가하고 유량도 줄어들어, 틈새부위의 누수량이 회전속도의 변화에 의존된다는 것을 확인 할 수 있었다.

• The Korean journal of internal medicine
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• v.34 no.1
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• pp.11-43
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• 2019

Heart failure (HF) is an important cardiovascular disease because of its increasing prevalence, significant morbidity, high mortality, and rapidly expanding health care cost. The number of HF patients is increasing worldwide, and Korea is no exception. There have been marked advances in definition, diagnostic modalities, and treatment of HF over the past four decades. There is continuing effort to improve risk stratification of HF using biomarkers, imaging and genetic testing. Newly developed medications and devices for HF have been widely adopted in clinical practice. Furthermore, definitive treatment for end-stage heart failure including left ventricular assist device and heart transplantation are rapidly evolving as well. This review summarizes the current state-of-the-art management for HF and the emerging diagnostic and therapeutic modalities to improve the outcome of HF patients.

• Journal of Yeungnam Medical Science
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• v.38 no.2
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• pp.95-106
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• 2021

Infections involving the heart are becoming increasingly common, and a timely diagnosis of utmost importance, despite its challenges. F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is a recently introduced diagnostic tool in cardiology. This review focuses on the current evidence for the use of FDG PET/CT in the diagnosis of infective endocarditis, cardiac implantable device infection, left ventricular assist device infection, and secondary complications. The author discusses considerations when using FDG PET/CT in routine clinical practice, patient preparation for reducing physiologic myocardial uptake, acquisition of images, and interpretation of PET/CT findings. This review also functions to highlight the need for a standardized acquisition protocol.

• Journal of Biomedical Engineering Research
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• v.22 no.5
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• pp.449-458
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• 2001

This is a test report of system efficiency for the moving-actuator type Bi-ventricular assist device (AnyHear $t^{MT}$ ) Seoul National University). $AnyHeart^{TM}$), as an energy converter. utilities a brushless DC motor(S/M 566-26A. Sierracin/ Magnedyne, Carlsbad, CA. U.S.A.) generating their pendulous motion in the epicyclic gear train. It is necessary to know about the overall efficiency of the system. The system is subdivided into three parts: motor part, actuator part and blood sac part (including valves, etc.) according to system mechanism. The motor was operated with a variable range of torque. angular speed and width of voltage Pulse In this report. $AnyHeart^{TM}$ is focused on the efficiency of the motor and actuator parts. 4 $\ell/min$ pump output. which is normal condition of $AnyHeart^{TM}$ system, the total system efficiency is 8%, which is composed of 50%, 85% and 17% efficiency (motor Part, actuator Part and blood sac Part) respectively. In the analyzed result. applied input voltage on normal condition of $AnyHeart^{TM}$ is determined. Also speed Profile with considering filling state of blood sac is Provided. In the test of the in vitro mock circulation. some experimental results are Provided to demonstrate the effectiveness of the Presented approach.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.84-87
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• 1996

We have been developed electrohydraulic left ventricular assist device and done various in vivo evaluation on the device. Through the in vivo experiment conducted from Jan. 23, 1996 to Feb. 8, we could have experience of long-term evaluation fur the first time. The sheep used in this experiment had survived for 16 days. We used new actuator with reduced size and linear motion guide replacing oil box and ball bearings. Also, we used improved blood chamber with reduced size, reduced weight facilitating fixing the chamber to animal's body, and polymer sac having improved folding pattern. Against suction problem, we used absolute pressure limiter only. Motor current for driving this new actuator was not much higher than older one. Effective stroke volume was about 48 cc. Thrombosis was found around top area and peripheral boundary of the sac and valves. There was no sign of damage from suction problem in the atrium observed at autopsy. Main cause of death was presumed to be progressive formation of thrombosis in the cannulae. In this paper, the results of this experiment are documented.

• Journal of Chest Surgery
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• v.10 no.1
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• pp.133-139
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• 1977

Two cases of congenital aneurysm of sinus of Valsalva, ruptured into the right ventricle, and associated with ventricular septal defects, were undergone intracardiac repair with the aid of extracorporeal circulation using Bentley bubble oxygenator and moderate hypothermia. Case 1. A 20 year old male, with the chief complaints of palpitation and dyspnea, was admitted to Kyungpook National University Hospital on Dec. 16, 1976. Continuous machinery murmur was heard best at left 3rd. intercostal space along the sternal border. Retrograde aortography disclosed aneurysm of the right coronary cusp, which ruptured into the right ventricle. Utilizing cardiac bypass and moderate hypothermia, the right ventricle was opened and aneurysm was closed by direct sutures. Associated ventricuar septal defect was directly ,closed and suture line was reinforced by Dacron patch. Total bypass time was 112 minutes and total aortic cross clamping time was 37 minutes. Assist ventilation was carried out for 28 hours postoperatively. His postoperative course was smooth except removal o1 substernal hematoma and he was .discharged on 24th postoperative day. Case 2. A 28 year old man was admitted to our Hospital on June 9, 1976. two weeks prior to this admission, suddenly he had collapsed while he was walking on the street. Following `this episode, palpitation, dyspnea on exertion and frequent respiratory infection developed. Grade IV systolic murmur was heard best at 3rd intercostal space along the sternal border. Retrograde aortography confirmed the diagnosis of rupture of aneurysm of the sinus Valsalva ruptured into the right ventricle. Under the cardiopulmonary bypass the right ventricle was opened and ruptured aneurysm and infracristal ventricular septal defect were directly closed and reinforced with Dacron patch. Postoperative course was uneventful and he was discharged on 14th postoperative day. The pathogenesis of aneurysm of the sinus Valsalva and mode of diagnosis were discussed. Principle of surgical repair was presented.

• Journal of Sensor Science and Technology
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• v.9 no.1
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• pp.51-60
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• 2000

This paper outlines the development of a non-pulsatile axial flow type blood pump control system. By utilizing blood pressure and heart rate, this system can assist the left ventricle in controlling blood pressure and blood volume. The system is comprised of a blood pump, signal sensor, signal interface, and signal-processing component. A control algorithm is also proposed which can control non-pulsatile, continuous blood flow in the human circulatory system. To facilitate the control required for non-pulsatile blood pump in a physiological system, an experimental control rule was developed utilizing ECG and blood pressure data, both of which are easily detectable variables in the body. The system was then tested using a mock-up circulation system and we found that it is possible that this systems could be temporarily used in clinic.

• Journal of Biomedical Engineering Research
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• v.13 no.3
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• pp.225-234
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• 1992

In order to use a low cost polymer valve in our total artificial heart and ventricular assist device, we have developed a slit-type bileaflet polymer valve[BPV 1. The aim of this study is to determine the hydrodynamic effectiveness of the newly-designed BPV and its feasibility for temporary use in the blood pumps. For hydrodynamic comparison, we investigated in-vitro the pressure drop across the valve, the leakage volume, the flow rate and the flow pattern of the BPV, two mechanical valves and a trileaflet polymer valve. We employed the ventriculo-pulmonary bypassing method for in-vivo tests of the BPV's together vilh our electrohydraulic left venIn ricular assist device in mongrel dogs. The BPV showed adquate gydrodynamic performances and in the preliminary animal bests, there was no xvi dence of thrombus formation on the valve leaflets and around the struts. Detailed results obtained from the animal tests will be separately reported. This report involves the design criteria, fabrication and hydrodynamic charateristics of she BPV, and the basic merits and demerits of the valve are dis- cussed from the hydrodynamic point of view.