• 한국가시화정보학회지
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• 제4권1호
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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 Chest Surgery
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• 제27권12호
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• pp.995-1001
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• 1994

The CarboMedics valve prosthesis is a relatively new. low profile bileaflet prosthesis. During a 6 year period from Aug. 1988 to July 1994. 158 patients had CarboMedics prostheses implanted in the mitral [n=94], aortic [n=25], or aortic and mitral [n=39] in National Medical Center. Hospital mortality was 9.4% and the main cause of death was low output syndrome. Follow up was 96% complete, with 365.4 patient-years and a mean follow up of 30 months [ range 1 to 72 months ] . The overall actuarial 6 year survival rate was 91.61 3.47% and actuarial 6year freedom from all valve related complications was 73.9 7.67%. The linearized incidence of vavle related complications was as follows: thromboembolism 1.37%/patient-year ; valve thrombosis 0.82%/ patient-year ; anticoagulant related hemorrhage 0.85%/patient-year ; perivalvular leakage 0.55%/paitent-year: prosthetic valve endocarditis 0.82%/patient-year ; reoperation 1.37%/patient-year. There were no instances of structural failure. We conclude that the Carbomedics valve has a low rate of complications that further improves the quality of life in patients with heart valve prostheses.

• Journal of Chest Surgery
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• 제28권1호
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• pp.23-30
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• 1995

From January 1985 to December 1992, of 1257 patients who underwent a heart valve replacement 210 [16.8% underwent reoperation on prosthetic heart valves, and 6 of them had a second valve reoperation. The indications for reoperation were structural deterioration [176 cases, 81.5% , prosthetic valve endocarditis [25 cases, 11.6% , paravalvular leak [12 cases, 5.6% , valve thrombosis [2 cases, 0.9% and ascending aortic aneurysm [1 case, 0.4% . Prosthetic valve failure developed most frequently in mitral position [57.9% and prosthetic valve endocarditis and paravalvular leak developed significantly in the aortic valve [40%, 75% [P<0.02 . Mean intervals between the primary valve operation and reoperation were 105.3$\pm$28.4 months in the case of prosthetic valve failure, 61.5$\pm$38.5 months in prosthetic valve endocarditis, 26.8$\pm$31.2 months in paravalvualr leak, and 25.0$\pm$7.0 months in valve thrombosis. In bioprostheses, the intervals were in 102.0$\pm$23.9 months in the aortic valve, and 103.6$\pm$30.8 months in the mitral valve. The overall hospital mortality rate was 7.9% [17/26 : 15% in aortic valve reoperation [6/40 , 6.5% in reoperation on the mitral prostheses [9/135 and 5.7% in multiple valve replacement [2.35 . Low cardiac output syndrome was the most common cause of death [70.6% . Advanced New York Heart Association class [P=0.00298 , explant period [P=0.0031 , aortic cross-clamp time [P=0.0070 , prosthetic valve endocarditis [P=0.0101 , paravalvularr leak [P=0.0096 , and second reoperation [P=0.00036 were the independent risk factors, but age, sex, valve position and multiple valve replacement did not have any influence on operative mortality. Mean follow up period was 38.6$\pm$24.5 months and total patient follow up period was 633.3 patient year. Actuarial survival at 8 year was 97.3$\pm$3.0% and 5 year event-free survival was 80.0$\pm$13.7%. The surgical risk of reoperation on heart valve prostheses in the advanced NYHA class patients is higher, so reoperation before severe hemodynamic impairment occurs is recommended.

• 대한기계학회논문집
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• 제16권11호
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• pp.2090-2097
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• 1992

본 연구에서는 밸브판의 거동을 2차의 회전계로 간주하고, 양력 및 항력(drag force)을 구하는데 있어 Reif등이 구한것과 동일한 방법을 이용하되 정지핀에 의해 그 최대 열림각이 제한을 받는 물리적 사실을 고려하고, 밸브를 통과하는 유량도 단위 입 력이 아닌 정현파(sine wave)로 간주하여 밸브판의 동적거동을 해석하였다. 해석대 상의 밸브 모델로는 Bjork-Shiley 27mm 1엽 밸브를 선정하였다.

• 대한의용생체공학회:의공학회지
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• 제13권3호
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• pp.235-244
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• 1992

In this paper, fluttering behavior of mechanical monoleaflet tilting disc heart valve prostheses during the opening phase was analyzed taking into consideration the impact between the occluder and the guiding strut at the fully open position. The motion of the valve occluder was modeled as a rotating system, and equations were derived by employing the moment equilibrium principle. Forces due to lift, drag, gravity and buoyancy were considered as external forces acting on the occluder. The 4th order Runge-Kutta method was used to solve the governing equations. The results iimonstrated that the occludes reaches steady equilibrium position only after damped vibration. Fluttering frequency varies as a function of time after opening and is in the range of 8-84 Hz. Valve opening appears to be affected by the orientation of the valve relative to gravitational force. The opening velocities are in the range of 0.65-1.42m/sec and the dynamic loads by impact of the occludes and the strut are in the range of 90-190 N.

• Journal of Chest Surgery
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• 제22권4호
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• pp.589-593
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• 1989

The frequency spectrum of the metallic closing sound and its loudness were measured by non invasive techniques in 66 patients. They had examined a total of 7 Carbomedics valve, 10 Duromedics valve, 11 St. Jude heart valve in mitral position and 8 Carbomedics, 10 Duromedics, 20 St. Jude heart valve prostheses functioning normally in aortic position. Statistical comparison of the loudness from sound produced by the three valves in each position, the following; The Carbomedics valve has the lowest average loudness, followed by the St. Jude medical valve, and finally the Edward Duromedics valve. And we analysis the changing factor of the loudness of valve sound, only the velocity of the flow through the valve influenced to the valve sound.

• Journal of Chest Surgery
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• 제33권1호
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• pp.45-50
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• 2000

Background: The CarboMedics prosthetic heart valve was produced in an attempt to improve the existing valve designs and was especially concerned with easily the implantation and further reduction of turbulence. Precise positioning of the valve in situ was achieved by the abilityof the valve to rotate relative to the sewing ring. Improved monitoring is possible due to increased radiopacity and the dacron sewing ring is coated with carbon to reduce pannus overgrowth. The leaflets have an opening angle of 78 degrees that apparently allows a rapid synchronous closure The aim of this study was to analyze the clinical performance of the CarboMedics valve prostheses(45 mitral 13 aortic and 7 double aortic-mitral valve replacement) were implanted in 65 patients(mean age 48.75$\pm$9.74 years) Result: The operative mortality was 3.1%(2/65) causes of death were low cardiac output syndrome. Total follow up was 1831 patient-months and mean follow up was 29.06$\pm$10.97 months/patient. No structural failure hemorrhage valve thrombosis and late death have been observed. Embolism occurred at a rate of 0.65%/Patient-year. Actuarial survival and thrombo-mbolism free rate at 36 months were 96.9% and 98.4% respectively. Consclusions: The CarboMedics valve stands for low valve related complicatons.

• Journal of Chest Surgery
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• 제29권3호
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• pp.326-330
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• 1996

유로키나제와 헤파린을 사용하여 혈전용해요법에 의해 치료된 기계판막 혈전의 3례를 경험하였다. 두 명의 환자는 완전히 회복하여서 자신의 직업과 활동적인 삶으로 되돌아갔으나, 다른 한 명은 뇌출혈과 뇌경색으로 사망하였다.

• 대한의용생체공학회:의공학회지
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• 제15권4호
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• pp.489-497
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• 1994

The most serious problems related to the cardiovascular prothesis are thrombosis and hemolysis. It is known that the flow pattern of cardiovascular prostheses is highly correlated with thrombosis and hemolysis. Laser Doppler Anemometry (LDA) is a usual method to get flow pattern, which is difficult to operate and has narrow measure region. Particle Image Velocimetry (PIV) can solve these problems. Because the flow speed of valve is too high to catch particles by CCD camera, high-speed camera (Hyspeed : Holland-Photonics) was used. The estimated maximum flow speed was 5m/sec and maximum trackable length is 0.5 cm, so the shutter speed was determined as 1000 frames per sec. Several image processing techniques (blurring, segmentation, morphology, etc) were used for the preprocessing. Particle tracking algorithm and 2-D interpolation technique which were necessary in making gridrized velocity pronto, were applied to this PIV program. By using Single-Pulse Multi-Frame particle tracking algorithm, some problems of PIV can be solved. To eliminate particles which penetrate the sheeted plane and to determine the direction of particle paths are these solving methods. 1-D relaxation fomula is modified to interpolate 2-D field. Parachute artificial heart valve which was developed by Seoul National University and Bjork-Shiely valve was testified. For each valve, different flow pattern, velocity profile, wall shear stress and mean velocity were obtained.

• Journal of Chest Surgery
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• 제31권12호
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• pp.1165-1171
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• 1998

배경 : 인공판막치환술을 받은 환자에서 인공판막의 기능부전이나 합병증으로 재치환술의 빈도가 증가하고있는 추세이다. 본 논문은 인공심장판막에 대한 재치환술시 위험인자를 분석하여 향후 수술성적을 향상시키는데 도움을 얻고자 하였다. 대상 및 방법: 1985년 1월부터 1996년 7월까지 계명대학교 흉부외과학교실에서 인공심장판막질환에 대한 재치환술을 받은 124예에 대하여 술전 임상적 소견 및 수술성적을 중심으로 분석하였다. 이중 3예는 2차로 재치환술은 받은 경우였다. 심장판막재치환술의 원인으로 조직판막자체의 구조적 실패가 96례(77.4%)로 가장 많았고 판막혈전증 16례(12.9%), 심내막염 7례(5.6%), 판막주위누출 5례(4.1%)가 있었다. 결과: 심장판막재치환술의 병원사망률은 8.9%였고, 술후 사망원인으로는 저심박출증이 가장 많았다(70.6%). 생존군과 사망군의 비교에서는 NYHA functional class, 혈중 크레아티닌 수치, LVSD, 체외순환시간이 사망군에서 유의하게 높았다(p < 0.05). 재치환술후 병원사망의 술전 위험인자들로는 LVSD, NYHA functional class IV, 혈중 크레아티닌 수치 등이었으며( p < 0.05), 연령이나 성별, 흉부 엑스선상 심흉곽의 비 등은 위험인자가 되지 못하였다. 결론: 술전의 임상적 소견중 LVSD, NYHA functional class, 혈중 크레아티닌 수치 등이 재치환술후의 예후를 추측할 수 있는 술전 인자라는 것을 알 수 있었다. 그리하여 심장판막재치환술은 심장 및 신기능이 악화되기 이전에 가능한한 조기에 시행하는 것이 바람직하리라 생각된다.