• Journal of Chest Surgery
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• v.28 no.6
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• pp.533-541
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• 1995

We recently developed a new model of moving actuator type totally implantable artificial heart[TIAH , based on the reverse position of the aortic and pulmonary conduits. This concept was proposed by one of surgeons in our team[Joon-Ryang Rho, M.D. to facilitate anatomical fitting of TIAHs. The moving actuator type electromechanical TIAH consisted of the left and right blood sacs, and the moving actuator including a motor. The inverted umbrella type polyurethane valves were used in the blood pumps. The aortic conduit was positioned anterior to the pulmonary conduit, which was the opposite relation to the conventional configuration of other total artificial hearts. We also adapted slip-in connectors for the aortic and pulmonary conduits. Two sheep , weighing 60-69 kg, were used for implantation. After small cervical incision and trans-sternal bilateral thoracotomy, cardiopulmonary bypass [CPB was administered using an American Optical 5-head pump and a membrane oxygenator[Univox-IC, Bentley . The anterior and posterior vena cavae were drained separately for venous return. An arterial return cannula was inserted into the right common carotid artery. During CPB, almost all of the ventricular myocardium was excised down to the atrioventricular groove and the artificial heart was implanted. We achieved 3-day survival in the first sheep and 2-day survival in the second. The day after operation the first sheep was successfully extubated and the second sheep was weaned from a respirator with good condition. After extubation, the first sheep walked around in the cage and fed herself. Serial laboratory and hemodynamic examinations were done during the experiments. In both sheep, pulmonary dysfunction was gradually developed, which was accompanied by acute renal failure. The animals were sacrificed and autopsy was done. Unexpected pregnnacy was incidentally found in both sheep. To our knowledge this is the first report of significant survival cases in the orthotopic implantation of electric TIAH using sheep.

• Proceedings of the KTCVS Conference
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• 1993.06a
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• pp.128-128
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• 1993

• Journal of the Korean Society of Visualization
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• v.4 no.1
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• pp.47-55
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• 2006

The left ventricular filling flow is now considered as an indicator which can be used for early diagnosing of cardiovascular diseases. Because the understanding of left ventricular flow physics is critical for this purpose, the downstream flow characteristics of the artificial heart valve are investigated using particle image velocimetry (PIV) method. In this study, we investigated the wake characteristics of flows passing through three different artificial valves (St.Jude medical bileaflet mechanical valve. Bjork-Shiley monostrut mechanical valve and St.Jude medical Biocor bio valve). The downstream flow field has remarkably altered according to the different valves. SJM MHV has the flow field similar to the pulsating circular jet and BS MHV has oblique pulsating jet. SJM BHV shows the similar flow field of clinical data of normal heart.

• Journal of Biomedical Engineering Research
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• v.19 no.3
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• pp.291-296
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• 1998

A new mechanical heart valve prosthesis has been designed appling systematic design methodology. The function of the heart valve was defined, and search for design variation has been carried out according to the functional structure, Optimal model among the various variations was determined in view of the design specificationn. Proto type valve was fabricated and test has been carried out using a mock circulation system. It has been observed that the pressure profile, cardiac output and behavior characteristics are generally satisfactory.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10b
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• pp.858-863
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• 1988

A micro-processor based control system for a brushless DC motor used in the motor-driven electromechanical total artificial heart was developed. Functionally, the control system is composed of two parts. The first part is the velocity and position controller to assure that the motor follows a predetermined optimal velocity profile with minimal energy consumption, and to guarantee the full stroke length. This part also utilize the passive adaptive control method to be robust against the load disturbance, system parameter variation, and uncertainty which is the environment of artificial heart system. The pump output control is the second part, and this part provides the required responses of the artificial heart to the time-varying physiologic demands. The basic requirements of these responses are preload sensitivity, afterload insensitivity, and the balanced ventricular outputs. The performance and reliability of this control system was evaluated through a series of mock circulation tests and animal implantation, and the results are very encouraging.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.748-751
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• 2001

Monoleaflet polymer artificial heart valve was known to show remarkable improvement in antithrombosis and pressure drop compared with other type of artificial valve. In this investigation monoleaflet the vertical and horizontal deflection pattern of polymer heart valve with three types of supporting members straight member, and two curved members was analysed using the large deformation nonlinear finite element method.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.3
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• pp.855-868
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• 1991

본 연구에서는 위에서 언급한바와 같은 제반사항들에 대해 이론적인 해석을 행하고, 그 결과를 이용하여 설계된 모델이 생체내에 이식될 수 있는 가능성의 여부를 판단하며 생체내에 이식 되었을 때의 성능과 생체에 미치는 영향등을 예측하고자 한다.

• Proceedings of the KAIS Fall Conference
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• 2003.06a
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• pp.288-290
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• 2003

Artificial heart is divided by pulsation flow type and continuous flow type according to blood circulation pattern. Axial flow blood pump is a kind of continuous flow type artificial heart. Axial flow blood pump would be different pump performance according to impeller's shape and rotating velocity. Pump performance be able to compare by flow rate according to differential pressure and Impeller's rotating velocity. It confirms Impeller model of better efficiency according to compare Pump performance of axial flow blood pump using CFD with actual experiment result.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.156-163
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• 2005

A monoleaflet polymer artificial heart valve showed the remarkable improvement in pressure drop compared with other types of artificial valve. So, in this study we designed a monoleaflet polymer artificial valve with two supporting members to minimize the deformation and bending stress of the valve with respect to the variation of the gap between two supporting members using nonlinear contact analysis. The marginal valve thickness was also predicted in accordance with the relationship between the thickness and horizontal displacement in order to prevent the dislocation of the valve tip from the frame wall.

• Journal of Chest Surgery
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• v.28 no.6
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• pp.542-548
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• 1995

The goal of this study is to develop an effective control system for cardiac output regulation based upon the preload and afterload conditions without any transducers and compliance chambers in the moving actuator type total artificial heart. Motor current waveforms during the actuator movement are used as an input to the automatic control algorithm. While the current waveform analysis is performed, the stroke length and velocity of the actuator are gradually increased up to the maximum pump output level. If the diastolic filling rate of either right or left pump begins to exceed the venous return, atrial collapse will occur. Since the diastolic suction acts as a load to the motor, this critical condition can be detected by analyzing the motor current waveforms. Every time this detection criterion is met, the control algorithm decreases the stroke velocity and length of the actuator step by step just below the critical detection level. Then, they start to increase. In this way the maximum pump output under given venous return can be achieved. Additionally the control algorithm provides some degree of afterload sensitivity. If the aortic pressure is detected to exceed 120 mmHg, the stroke length and velocity decrease in the same way as the response to the preload. Left-right pump output balance is maintained by proper adjustment of the asymmetry of the stroke angle. In the mock circulatory test, this control system worked well and there was a considerable range of stroke volume difference with adjustment of the asymmetry value. Two ovine experiments were performed. It was confirmed that the required cardiac output regulation according to the venous return could be achieved with adequate detection of diastolic function, at least in the in vivo short-term survival cases[2-3 days . We conclude that this control algorithm is a promising method to regulate cardiac output in the moving actuator type total artificial heart.