• Journal of Korea Multimedia Society
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• v.19 no.3
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• pp.557-566
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• 2016

Heart sounds generated by the beating heart and blood flow reflect the turbulence created when the heart valves snap shut. Cardiac diagnosis is typically started by an auscultation using a stethoscope, from which a medical doctor, depending on his hearing capabilities and training, listens and interprets the acoustic signal. This method of diagnostic is uncertain, mostly due to the fact that human ear loses the acoustic frequency sensitivity through the years. Even though an auscultation has some weaknesses like uncertainty, it is considered as a primary tool due to its simplicity. In this paper, heart murmur detection algorithm is proposed using time and frequency characteristics of heart sound. The propose heart murmur detection method adapted conventional primary heart sound detection method in time domain and modified spectral flatness method in frequency domain for detecting heart murmurs. From experimental results, it is confirmed that the proposed algorithm detect the heart murmurs efficiently.

• Journal of Chest Surgery
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• v.19 no.4
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• pp.584-594
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• 1986

Despite the multivariate improvements in tissue treatment, material, and design of prosthetic heart valves in recent years, numerous complications that may lead to valve dysfunction remain a constant threat after valve replacement. Most common indications for prosthetic valve failure are primary valve failure, infective endocarditis, paravalvular leakage, and thromboembolism. From 1977 to 1986, 15 patients underwent reoperation for prosthetic valve failure in 278 cases of valve surgery. The etiology of prosthetic valve failure were primary valve failure in 12 patients [80 %], infective endocarditis in 2 patients [13.3 %], and a paravalvular leakage [6.7 %]. The average durations of implantation were 45.5 months; 53.9 months in primary valve failure, 16 months in infective endocarditis, and 4 months in paravalvular leakage. The rate of valve failure was high under age of 30 [11/15]. Calcifications and collagen disruption of prosthesis were main cause of primary valve failure in macro- & micropathology. Prosthesis used in reoperation were 5 tissue valves and 10 mechanical valves. Operative mortality were 13.3 % [2/15], due to intractable endocarditis and ventricular arrhythmia.

• Journal of Chest Surgery
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• v.25 no.2
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• pp.158-166
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• 1992

From 1985 to 1990, a total of 160 new valves were implanted for 125 adult patients to whom prosthetic valve replacement had been performed [One patient had consecutive 2 reoperations]. Following data are the results from the follow-up study from January 1985 to February 1991. Mean age of the patients was 37.9$\pm$12.1 years. Mean follow-up period was 25.8$\pm$18.8 months. In bioprosthesis, mean interval between the previous operation and reoperation was 85.6$\pm$36.4 months in aortic valve, and 87.3$\pm$30.0 months in mitral valve. The causes of reoperation were prosthetic valve failure[103 patients, 81.7%], prosthetic valve endocarditis[17 patients, 13.5%], periprosthetic leakage[5 patients, 4.0%], and aneurysm of ascending aorta[1 patient, 0.8%]. Fourteen patients[11.1%] died in hospital; 5 in 22 replacement of aortic valve[22.7%], 6 in 73 rereplacement of mitral valve[8.2%], and 3 in 31 replacement of multiple valves [9.7%] Except for 3 intraoperative deaths, postoperative, major and minor complications occurred in 39 patients[31.0%]. And the actuarial 5-year survival rate of operative survivors was 95.5$\pm$8.6%.

• Journal of Chest Surgery
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• v.13 no.4
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• pp.394-404
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• 1980

During the period of June 1976 October 1980 131 cases of Open heart Surgery was performed at the National Medical Center in Seoul under the extracorpocal circulation. 77 cases were congenital heart disease and 54 were acquired heart disease. The age of the patients ranged between 2$\frac{1}{2}$ and 51 years. For all patients partial hemodilution technique and moderte hypothermia was used during extracorporeal circulation and cardioplegia was done for myocardial protection since April 1978. 41 of congenital cases were non-cyanotic group and 1 case died. 36 of congenital cases were cyanotic group and revealed very high mortiality rate (16 death, 39%). 53 of acquired cases were cases of valvular heart disease, 34 mitral (3 death), 1 aortic, 4 mitral with aortic 12 mitral with tricuspid (3 death), 2 triple valves (2 death), and revealed mortality rate of 15.1% (8 death). 1 of acquired cases were left atrial myxoma. There were 25 cases of operative death and over all motality rate was 19.1%.

• Journal of Chest Surgery
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• v.11 no.3
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• pp.281-295
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• 1978

Last year in this department 100 cases of open heart surgery were done annually. This year 200 cases of open heart surgery were scheduled. During the first 6 months of this year 112 open heart surgery cases were done with 13 deaths [11.6%]. There were 72 cases of cougenital malformation with 9 operative deaths [12.5%], consisting of 23 acyanotic cases with one death [4.5%] and 49 cases of cyanotic cases with 8 deaths [16.3%]. Out of 40 tetralogy of Fallot, 6 cases expired [15%]. For 39 cases of acquired valvular heart disease and one Ebstein anomaly valves were replaced with 4 operative deaths [10%]. Single valve replacement in 33 with 3 operative deaths and double valve replacement in 7 cases with one death were noted. Two patients expired among 28 mitral valve replacement cases [7.1%]. Among 7 double valve replacement patients, consisting of 3 mitral and aortic and 4 mitral and tricuspid valve replacement one case expired. In a case of Ebstein anomaly, tricuspid valve was replaced with plication of atrialized right ventricle successfully. The operative result was excellent.

• Journal of Biomedical Engineering Research
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• v.17 no.1
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• pp.49-60
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• 1996

An experimental investigation was performed under steady flow condition to assess hydrodynamic performance of floating-type monoleaflet polymer valves (MLPV) withdifferent leaflet thickness. The St. Jude Medical valve (SJMV) was also used for comparison test. Pressure drops of MLPVS are larger than those for other types of polymer valves and mechanical valves. Furthermore, the thicker is the leaflet thickness of the polymer valve, the larger are the corresponding pressure drop. The velocity profiles for MLPs reveal a large reversed flow region downward to the valve position. The maximum wall shear stresses of MLPVS at a flow rate of $30{\ell}$/min are in the range 50-130 dyn/$cm^2$, and the corresponding maximum Reynolds shear stresses are in the range of 100-500 dyn/$cm^2$, respectively, which are beyond the allowable limit clinically. In contrast, floating-type monoleaflet polymer valves show better hydrodynamic performance in leakage volume. From the designing point of view, it may be concluded that the optimum thickness of leaflet for better hydrodynamic performance is one of the Important parameters.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.241-246
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• 1995

An experimental investigation was performed under steady flow condition to assess hydrodynamic performance of floating-type monoleaflet polymer valves (MLPV) with different leaflet thickness. The St. Jude Medical valve (SJMV) was also used for comparison tests. Pressure drops of MLPVs are larger than those for other types of polymer valves and mechanical valves. Furthermore, the thicker is the leaflet thickness of a polymer valve, the larger arc the corresponding press drop. The velocity profiles for MLPV reveal a large reversed flow region downward to the valve position. The maximum wall shear stresses of MLPVs at a flow rate of 30 l/min are in the range $54-130\;dyn/cm^2$, and the corresponding maximum. Reynolds shear stresses are in the range of $100-500\;dyn/cm^2$, respectively. Both arc beyond the allowable limit clinically. In contrast, floating-type monoleaflet polymer valves show better hydrodynamic performance in leakage volume. From the designing point of view, it can be concluded that the optimum thickness of leaflet for better hydrodynamic performance is one of the important parameters.

• Journal of Chest Surgery
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• v.21 no.2
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• pp.276-282
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• 1988

Surgery is now the usual mode of therapy in patients with severe valvular heart disease. Until recently, clinicians and pathologists attributed nearly all acquired valvular heart diseases to a rheumatic origin, except some obviously resulting from acute infection and syphilis. Although many clinicians and pathologists describe that the origin of aortic valvular disease is a nonrheumatic origin, we recognize the major origin of aortic valvular disease in Korea as a rheumatic origin. We excised 47 cardiac valves from valvular heart diseased patients and performed anatomical and pathological analysis for its origin and underlying pathology. The purpose of this article is to provide an update for the clinicians of evolving issues related to the pathology of valvular heart disease. But myxomatous origin and infective endocarditis valvulitis will not be covered in detail.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.5
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• pp.629-639
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• 2002

In-vitro flow characteristics downstream of a polyurethane artificial heart valve and a Bjork-Shiley Monostrut mechanical valve have been comparatively investigated in pulsatile flow using particle image velocimetry (PIV). With a triggering system and a time-delayed circuit the velocity distributions on the two perpendicular measurement planes downstream of the valves are evaluated at any given instant in conjunction with the opening behaviors of valve leaflets during a cardiac cycle. The regions of stasis and high shear stress can be found simultaneously by examining the entire view of the instantaneous velocity and Reynolds shear stress fields. It is known that high shear stress regions exist at the interface between strong axial jet flows along the wall and vortical flows in the central area distal to the valves. In addition. there are large stagnation or recirculation regions in the vicinity of the valve leaflet, where thrombus formation can be induced by accumulation of blood elements damaged in the high shear stress zones. A correlation between the unsteady flow patterns downstream of the valve and the corresponding opening postures of the polyurethane valve membrane gives useful data necessary for improved design of the frame structure and leaflet geometry of the polyurethane valve.

• Journal of Biomedical Engineering Research
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• v.19 no.3
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• pp.297-303
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• 1998

The sinus distal to the prosthetic heart valve influences the valve closure behavior and velocity field near the valve, therefore affects the hydrodynamic performance of the prosthetic heart valve. In order to study the effects of valve distal geometry on the hydrodynamic performance of the prosthetic valves, mechanical bileaflet valve(SJMV), monoleaflet polymer valve(MLPV) and trileaflet polymer valve(FTPV) are inserted in the test sections which have the straight and the sinus shape distal to the valve. Leakage volumes and systolic mean pressure drops are measured in the pulsatile mock circulation flow loop. Leakage volumes are slightly less and systolic mean pressure drops are higher in the sinus test section comparing to those in the straight test section, but the differences are statistically insignificant. Flow waveforms are analyzed in order to predict the valve closure behavior. The distal sinus does not affect the closure of the MLPV, but early valve closure of SJMV is observed in the sinus test section. This effect is more significant in FTPV, and the reverse flow peak of FTPV is reduced in the sinus test section. Therefore the sinus distal to the valve can reduce the reverse flow jet caused by sudden valve closure.