• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.329-332
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• 1997

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 supplementary valves. The autologous pericardium was attached to deficient portion of the porcine valve which was dissected completely and partially. The instantaneous motion of the leaflet was pictured by the 35mm camera and the pressure drop through the valve and cardiac output were measured in mock circulatory system. The durability of the valves were tested in severe hemodynamic conditions.

• Proceedings of the Korean Society of Life Science Conference
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• 2003.10a
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• pp.28-37
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• 2003

Tissue engineering and stem cells show potentials to restore lost or malfunctioning human tissues or organs. Another cell source for tissue engineering of cardiovascular tissues is stem cell. This study reports the development of cardiovascular tissues using tissue engineering and mesenchymal stem cells. The blood vessels and heart valves were fabricated by culturing mesenchymal stem cells on biodegradable synthetic or natural matrices. Bone marrow was isolated from dogs or rats and mesenchymal stem cells were cultured. The cells were seeded onto biodegradable synthetic or natural matrices and implanted in dogs. Histological and immunohistochemical analyses were performed to examine the regenerated cardiovascular tissues. Histological and immunohistochemical analyses showed the complete regeneration of blood vessels and heart valves. Fluorescent labeling of cells prior to implantation and fluorescence examination of the regenerated tissues revealed that the implanted cells reconstituted the cardiovascular tissues. This study demonstrates the potential of tissue engineering and mesenchymal stem cells for the regeneration of functional cardiovascular tissues or organs.

• Journal of Chest Surgery
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• v.11 no.4
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• pp.535-540
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• 1978

Between January 1974 and November 1978, 23 cases of double valve replacement were done in the Department of Thoracic Surgery, Seoul National university Hospital. All had symptoms of rheumatic valvular heart disease and belonged to functional class III or IV according to NYHA classification. Among 23 cases, mitral and aortic valves were replaced in 14, and mitral and tricuspid valves in 9 cases. Six operative deaths [26%] and 4 late deaths [23%] were found. In the former group 5 and in latter one operative death were noted. Main cause of operative death was low cardiac output syndrome due to myocardial failure. Among 4 late deaths, 2 were caused by thromboembolism, one by bacterial endocarditis, and one by arrhythmia.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.1045-1048
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• 2000

This paper presents the application of the wavelet transform analysis and the neural network method to the phonocardiogram (PCG) signal. Heart sound is a acoustic signal generated by cardiac valves, myocardium and blood flow and is a very complex and nonstationary signal composed of many source. Heart sound can be discriminated normal heart sound and heart murmur. Murmurs have broader frequency bandwidth than the normal ones and can occur at random position of cardiac cycle. In this paper, we classified the group of heart sound as normal heart sound(NO), pre-systolic murmur(PS), early systolic murmur(ES), late systolic murmur(LS), early diastolic murmur(ED). And we used the wavelet transform to shorten artifacts and strengthen the low level signal. The ANN system was trained and tested with the back- propagation algorithm from a large data set of examples-normal and abnormal signals classified by expert. The best ANN configuration occurred with 15 hidden layer neurons. We can get the accuracy of 85.6% by using the proposed algorithm.

• Journal of Biomedical Engineering Research
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• v.19 no.1
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• pp.47-52
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• 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 Biomedical Engineering Research
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• v.14 no.2
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• pp.163-167
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• 1993

We developed a ventricular assist device(VAD) to be used as a bridge to heart transplantation or a circulatory assist device for patients with end-stage heart disease or poor myocardial function after cardiac surgery. It is a pneumatic and diaphragm-type VAD and its stroke volume is 90 cc. The upper housing and diaphragm is made of a segmented polyurethane and the lower back plate is made of a polycarbonate. Two Carbomedics$^R$ mechanical valves are used as inlet and outlet valves. It was tested in vitro and the cardiac output of the VAD was 7 L/min at a heart rate of 70 bpm. The line pressure from a pressure transducer inserted in the pneumatic line was recorded and compared with the ideal pressure tracing.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.05
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• pp.105-108
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• 1994

A comparative study was made of the valvular sounds produced by normal prosthetic valves with thrombosed prosthetic valves. Comparisons of the closing sound were made for the power frequency spectra associated with individual valves. We used periodogram approach to obtain the spectral characteristics of the valve. Spectral analysis system was tested in mock circulatory system by comparing normal valves with those produced by the same valves but having simulated thrombosis at the hinge of the valve. The heart sounds was recorded from two patients having normal mechanical valve and thrombosed mechanical valve. The estimated spectrum of the thrombosed mechanical valve displayed lower apparent peak frequency than that of the normal valve. The results showed that frequency spectra gave information pertinent to the valve malfunction. Sound spectral analysis is simple and alternative diagnostic tool for early detection of prosthetic valve mal function.

• Journal of Chest Surgery
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• v.17 no.2
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• pp.305-314
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• 1984

From May 1977 to April 1984, 204 cases of open heart surgery were performed under cardiopulmonary bypass. There were 99 male and 105 female patients ranging in age from 19 months to 58 years. 136 cases [66.7%] were congenital heart disease, and 68 cases [33.3%] were acquired heart disease, which were 66 valvular disease [97.1%], 1 IVC obstruction, and 1 myxoma. There were 136 congenital heart anomaly with 16 operative deaths [11.8%], consisting of 94 acyanotic cases with 7 death [7.4%] and 42 cases of cyanotic cases with 9 deaths [21.4%]. In 66 patients of acquired valvular disease, 52 valves were implanted; 47 mitral valve replacement with 4 death [8.5%] and 5 double valve replacement [MVR+AVR] with 1 death [20%]. Postoperative, warfarin sodium was medicated with checking prothrombin time. Finally, the operative mortality was 11.8% in congenital anomaly, and 11.8% in acquired heart disease, overall mortality rate was 8.5%.

• Journal of Chest Surgery
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• v.18 no.3
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• pp.383-390
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• 1985

108 cases of open heart surgery were done at our department in 1984. There were 58 male and 50 female patients ranging in age from 20 months to 52 years. 75 cases were congenital heart disease, and 33 cases were acquired heart disease. There were 75 congenital heart anomalies with 5 operative deaths [6.7%], consisting of 62 acyanotic cases with 2 deaths [3.2%] and 13 cases of cyanotic cases with 3 deaths [23.1]. In 33 patients of acquired valvular disease, 29 valves were implanted; 20 mitral valve replacement with 2 death [10%], 2 aortic valve replacement with 1 death [50%], 2 double valve replacement [MVR+AVR] and 2 open mitral commissurotomy plus aortic valve replacement with no death. Postoperative, Warfarin sodium was medicated with checking prothrombin time. Finally, the operative mortality was 9.2% in congenital anomaly, and 9.1% in acquired heart disease, overall mortality rate was 9.3%.

• Journal of Chest Surgery
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• v.20 no.1
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• pp.148-155
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• 1987

From May 1977 to June 1986, 500 cases of open heart surgery were performed under the cardiopulmonary bypass. There were 278 male and 222 female patients ranging from 6 months to 69 years. 363 cases[73.6%] were congenital heart diseases, and 137 cases[27.4%] were acquired heart diseases, which were 33 valvular diseases, 3 myxomas and 1 IVC obstruction. There were 363 congenital heart anomaly with 35 operative deaths[9.6%], consisting of 279 acyanotic cases with 12 deaths [4.3%] and 85 cases of cyanotic cases with 23 deaths[28.4%]. In 133 patients of acquired valvular disease, 124 valves were implanted and operative death of valvular disease was 12%. Finally the operative mortality was 9.6% in congenital anomaly, and 12.4% in acquired heart disease, overall mortality rate was 10.4%.