• Journal of Chest Surgery
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• v.34 no.5
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• pp.403-406
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• 2001

본 증례는 66세(51.8kg)된 남자에서 수술전 심한 좌심실 기능 부전과 승모판 및 삼첨판 폐쇄부전이 있어 개심술 시행후 심한 저심박출증 발생으로 인공심폐기 이탈에서 실패하고 양심실 보조장치(Centrifugal Biopump)를 사용한 후 이로부터 성공적인 이탈과 퇴원이 보고하는 바이다.

• Journal of Biomedical Engineering Research
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• v.22 no.5
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• pp.439-448
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• 2001

This paper considers the acoustical characteristics of the closing click sounds of the mechanical valves employed in an implantable biventricular assist device (BYAD) and their re1evance to the Physical states of the valved. Bj rk Shiley Convexo Concave tilting disk valve was chosen for the study and acoustic measurement was made for the BYAD operated in a mock circulatory system as well as implanted in an animal (sheep). In the BYAD operated in the mock circulatory system. three different states of the valve were examined, ie. normal. mechanically damaged. pseudo-thrombus attached. Microphone measurement for the BVAD implanted in the animal was carried out for five days at a regular time interval from one day after implantation. Characteristic spectrum of the sound from the valve was estimated using Multiple Signal Classification (MUSIC) in which the optimal order was determined according to Bayesian Information Criterion (BIC) . It was observed that the mechanical damage of the valve resulted in changes of the structure of the acoustic spectrum. In contrast. the thrombus formed on the valve did not change much the basic structure of the spectrum but brought about altering the spectral Peak frequencies and energies. Maximum spectral Peak (MSP) with the greatest energy was seen at 2 kHz for the normal valve and it was shifted to 3 kHz for the calve attaching the Pseudo-thrombus. Unlike the normal valve, strong spectral Peak appeared around 7 kHz in the sound from the valve mechanically damaged. In the case of the BYAD implanted in the animal. as the thrombus grew, acoustic energy was reduced relatively more in the low frequency components (〈 2 kHz) and the frequencies of the 1st, 2nd and 3rd MSP were increased little. The thrombus formation would result in reduction in both the variability of the 1st, 2nd and 3rd MSP and the value of the BIC optimal order.

• Journal of Chest Surgery
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• v.35 no.7
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• pp.548-552
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• 2002

Korean artificial heart(AnyHeart) is a single-pieced and implantable hi-ventricular pulsaile pump adapting a moving actuator mechanism. The authors report a case of clinical application of AnyHeart as a life-saving device for the patients with end-stage heart disease combined with biventricular failure.

• Journal of Chest Surgery
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• v.34 no.4
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• pp.296-304
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• 2001

배경: 이번 연구의 목적은 체내이식형 양심실 보조장치의 개발을 위한 안전하고 간편한 동물실험 모델을 확립하는 것이며 이동작동형 완전 인공심장의 양심실 보조장치로의 사용 가능성을 알아보는 것이다. 대상 및 방법: 7마리의 Corridale 양을 대상으로 실험하였다. 5번째 늑간극을 통하여 좌측 개흉술을 시행하고 좌측 유출로 캐뉼라는 하행 대동맥에 Dacron graft을 사용하여 연결하였고 유입로 캐뉼라는 좌심방에 삽입하였다. 우측 유출로 캐뉼라는 하행 대동맥과 같은 방법으로 주폐동맥에 연결하였으며 유입로 캐뉼라는 혜동맥을 하방으로 젖혀 우심방이를 노출시킨 다음 우심방이에 삽입하였다. 4마리에 있어서는 양심실 보조장치를 전복막강(preperitoneal space)에 위치시켰으며 2마리에 촤측흉강 내에, 1마리에서는 외부에 위치시켰다. aPTT는 수술전 aPTT의 2∼2.5배로 맞추어 주었다 결과: 수술중 또는 수술직후 사망한 경우는 없었으며 7마리 모두 인공호흡기 이탈이 가능하였고 스스로 기립하고 음식물 섭취도 가능하였다. 1마리는 술후 2일째 혈전 색전증 및 인공호흡기 작동 잘못으로 사망하였으며 2마리의 겨우는 술후 2일째 각각 양심실 보조장치의 작동 잘못 및 호흡부전으로 사망하였고, 3마리의 경우는 술후 4일째 혈전색전증으로 인한 급성신부전 및 호흡부전 등으로 사망하였다. 1마리에 있어서는 28일간 생존하였으며 양심실 보조장치의 구동 장치에 연결된 라인의 마로로 인해 양심실 보조장치의 작동이 정지되었으나 바로 양심실 보조장치를 제거하고 살릴 수 있었다. 모든 경우에 있는 캐뉼라를 삽입하고 양심실 보조장치를 작동시키는데 큰 어려움이 없었다. 7마리 중 4마리에서 혈전이 발견되었으며 특히 판막을 연결한 부위에 혈전생성이 많았다. 그러나 캐뉼라에는 혈전생성이 없었다. 결론: 양에 있어서 좌측 개흉술 및 전복막강 공간에 양심실 보조장치를 위치시키는 이번 동물실험 모델은 체내 이식형 양심실 보조장치 개발을 위한 좋은 동물실험 모델이라고 생각된다. 또한 디동 작동기형 완전 인공심장의 혈전생성을 억제할수 있는 방법들의 연구개발이 지속된다면 장기간의 체내 이식형 양심실 보조장치로 사용할 수 있을 것으로 생각된다.

• Journal of Biomedical Engineering Research
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• v.28 no.4
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• pp.569-576
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• 2007

Ventricular Assist Device(VAD) has switched its goal from a short-tenn use for bridge-to-transplantation to a long-tenn use for destination therapy, With this goal, the importance of long-tenn reliability gets more interests and importances, H-VAD is an portable extracorporeal biventricular assist device, and adopts an electro-pneumatic driving mechanism. The pneumatic pressure to pump out blood is generated with compression of bellows, and is transmitted in a closed pneumatic circuit through a pneumatic line. The existing pneumatic VAD adopts a air compressor which can generate stable pressures but has defects such as a noise and a size problem. Thus, it is not suitable for being used as a portable device, These problems are covered with adopting a closed pneumatic circuit mechanism with a bellows which has a small size and small noise generation, but it has defects that improper pneumatic setting causes a failure of adequate flow generation. In this study, the pneumatic pressure regulation system is developed to cover these defects of a bellows-type pneumatic VAD. The optimal pneumatic pressure conditions according to various afterload conditions for an optimal flow rate were investigated and the afterload estimation algorithm was developed, The final pneumatic regulation system estimates a current afterload and regulate the pneumatic pressure to the optimal point at a given afterload condition. The afterload estimation algorithm showed a sufficient performance that the standard deviation of error is 8.8 mmHg, The pneumatic pressure regulation system showed a sufficient performance that the flow rate was stably governed to various afterload conditions. In a further study, if a additional sensor such as ultrasonic sensor is developed to monitor the direct movement of diaphragm in a blood pump part, the reliability would be greatly increased. Moreover, if the afterload estimation algorithm gets more accuracy, it would be also helpful to monitor the hemodynamic condition of patients.

• Journal of Chest Surgery
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• v.29 no.11
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• pp.1218-1222
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• 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
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• v.35 no.5
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• pp.329-335
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• 2002

Background: The surgical technique for biventricular assist device(BVAD) implantation has mainly consisted of cannulation procedures. A median sternotomy has been the technique of choice as it gives a surgeon an excellent exposure of the heart. However, considering that most patients require a future sternotomy or already have a previous sternotomy, sternotomy-related complication remains a major concern in BVAD implantation. Based on this consideration as well as the clinical experiences of conventional heart surgery, the authors have hypothesized that the cardiac chambers for BVAD cannulation can be approached from the right side of the heart. The purpose of this studs to develop a novel surgical technique of right thoracotomy for BVAD implantation in an animals study. Material and Method: For last two years, 16 (11 calves, 3 canines, and 2 sheep) out of 30 experimental animals with AnyHeart implantation underwent a right thoracotomy. The device was used as an implantable BVAD in 14 animals, a wearable BVAD in 1, and an implantable LVAD in 1. The chest cavity was entered through the 4th intercostal space or the 5th periosteal bed. As for the BVAD use, a right inflow cannula was inserted into the right atrial free wall and a right outflow cannula was grafted onto the main pulmonary artery. A left inflow cannula was inserted into the interatrial groove and a left outflow cannula was grafted on the innominate artery of the ascending aorta. The connecting tubes were brought out through the thoracotomy wound and connected to the pump located in the subcutaneous pocket at the right flank. Result: Except for the 5 animals for a lilting test or during the early learning curve, all recovered smoothly from the procedures. The inflow drainage allowed the pump output 6.5 L/min at the maximum with 3-3.5 L/min in an average. Of the survivors, there noted no procedure-related mortality or morbidity. Necropsy findings demonstrated the well-positioned cannula tips in the each cardiac chamber