• Journal of Biomedical Engineering Research
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• 제23권4호
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• pp.309-315
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• 2002

Since the discovery, in the 1980s, of erosion-pit-induced fractures in implanted mechanical heart valves. cavitation on the surface of mechanical heart valves has been widely studied as a possible cause of pitting. Several factors, including peak dp/dt of the ventricular pressure. maximum closing velocity of the leaflet, and squeeze flow. have been studied as indices of the cavitation threshold. In the present study. cavitation erosion on the surface of a mechanical valve was examined by focusing on squeeze flow and the water hammer phenomenon during the closing period of the valve. In this study, we measures pressure wave forms near a valve and closing velocities of a disk, which were placed in a holder with and without compliance. In case of all holders, pressure drop of below vapor pressure expect at near the surface disk. It was also found that the closing velocity of the disk increased and that cavitation erosion was enhanced too. These results suggest that disk closing velocity during the closing phase has signifiant effects on pitting erosion.

• Journal of Chest Surgery
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• 제34권7호
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• pp.561-565
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• 2001

Patients who have complex endocarditis with involvement of both the aortic and mitral valves and intervalvular fibrous skeleton are among the most difficult to treat and still have the highest surgical mortality and morbidity rates. We report one case of aortic and mitral valve replacement with reconstruction of the fibrous skeleton performed in a 55-year-old female patient who had an aortic annular abscess and both the aortic and mitral prosthetic valve endocarditis with destruction of the fibrous skeleton. Previously, she had undergone redo double valve replacement\`, Transesophageal echocardiogram showed the paravalvular defect at the noncoronary aortic sinus and abnormal sinus tract along the fibrous skeleton. Emergent operation was performed due to positive blood cultures of staphylococcus epidermidis and persistent sepsis despite appropriate antibiotic therapy. After aortotomy extended to the roof of left atrium, both prosthetic valves and destroyed fibrous skeleton were completely resected and the aortic annular abscess was debrided and closed with a bovine pericardial patch. Reconstructions of both aortic and mitral annuli and the fibrous skeleton were done by using two separate bovine pericardial patches in triangular shape and mechanical valves were implanted. Postoperatively, adequate antibiotic therapies were continued and the patient was discharged at the postoperative 72 days without evidence of recurrence of endocarditis. Transthoracic echocardiogram of the postoperative 8 months shows no paravalvular leakage or recurrence of endocarditis and the patient has been followed up with no symptom.

• Journal of Chest Surgery
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• 제16권1호
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• pp.10-17
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• 1983

Valve replacement in children, aging up to 15 years [Mean 11.g years], has been done at Seoul National University Hospital over the past 14 years since 1968. Fifty-one patients have received 59 artificial valves: 55 bioprosthetic and 4 prosthetic valves. Thirty-one patients [60.8%] had rheumatic heart disease and the remainder [39.2%] had congenital heart disease. Forty-two patients [82.4%] survived operation: 9 patients [17.7%] died within one monfi3 postoperatively and 4 patients [7.8%]during the follow-up period with the overall mortality rate of Thromboembolic complication occurred in 3 patients with 2 deaths: 5.9% embolic rate or 4.68% emboli per patient-year. One patient who had been on coumadin anticoagulation died from cerebral hemorrhage. One mitral Ionescu-Shiley valve failed 19 months after first replacement and this was successfully re-replaced with the same kind of valve. Actuarial survival rate was 59.9% at 4 years after surgery. Thromboembolism-free and valve failure-free survivals were 80.0% and 93.1% respectively. These clinical results in the pediatric age group suggested that valve replacement in children was a serious undertaking with a higher mortality rate than in adults. However, the main superiority on the low thrombogenecity of the xenograft valve over the mechanical one warrants its continuing use until the question of its durability would otherwise be answered by a further study of clinical follow-up.

• Journal of Chest Surgery
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• 제28권4호
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• pp.346-354
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• 1995

Records of 71 consecutive patients who had received multiple valve replacement were reviewed[34male,37female,mean age 40.5$\pm$11.2 <14-63> . The early death rate was 2.8%[2/71 . A completed follow-up rate of 95.7% was accomplished in these 69 patients who left hospital[mean 42.5 $\pm$29.5 patients-years . Five of these patients died. The late death rate was 7.2%. Four patients experienced anticoagulant-related hemorrhage[all were minor . One patient had a thromboembolic episode[permanent ,and 2 had late prosthetic valve endocarditis. There was no clinical evidence of hemolysis and structural failure of valves used. Of those patients who survived,NYHA functional class improved significantly[from 87.2% class III & IV before to 95.8% class I & II after . Linearized rates for thromboembolism and anticoagulant-related hemorrhage,and for prosthetic valve endocarditis were 0.67%/100 patient-years,2.95%/100 patient-years,1.34%/100 patient-years, respectively. The actuarial estimates of incidence free of all complications and valve-related deaths were 92.2%/patient-years.Despites the advanced heart disease involving two or more native valves, the patients who had multiple valve replacement had very good results, over a 9-year period.

• Journal of Chest Surgery
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• 제42권5호
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• pp.566-575
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• 2009

Background: The function of a bioprosthetic heart valve is determined largely by the material properties of the valve cusps. The uniaxial tensile test has been studied extensively. This type of testing, however, does not replicate the natural biaxial loading condition. The objective of the present study was to investigate the regional variability of the biaxial strain versus pressure relationship based on the types of fixation liquid models. Material and Method: Porcine aortic valves and pulmonary valves were assigned to three groups: the untreated fresh group, the fixed with glutaraldehyde (GA) group, and the glutaraldehyde with solvent (e.g., ethanol) group. For each group we measured the radial and circumferential stretch characteristics of the valve as a function of pressure change. Result: Radial direction elasticity of porcine aortic and pulmonary valves were better than circumferential direction elasticity in fresh, GA fixed and GA+solvent fixed groups (p=0.00). Radial and circumferential direction elasticity of pulmonary valves were better than aortic valves in GA fixed, and GA+solvent fixed groups (p=0.00). Radial and circumferential direction elasticity of aortic valves were decreased after GA and GA+solvent fixation(p=0.00), except for circumferential elasticity of GA+solvent fixed valves (p=0.785). The radial (p=0.137) and circumferential (p=0.785) direction of elasticity of aortic valves were not significantly different between GA fixed. and GA+solvent fixed groups. Radial (p=0.910) and circumferential (p=0.718) direction of elasticity of pulmonary valve also showed no significant difference between GA fixed and GA+solvent fixed groups. Conclusion: When fixing porcine valves with GA, adding a solvent does not cause a loss of mechanical properties, but, does not improve elasticity either. Radial direction elasticity of porcine aortic and pulmonary valves was better than circumferential direction elasticity.

• Journal of Chest Surgery
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• 제36권5호
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• pp.316-320
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• 2003

Background: The detection of circulating microemboli by transcranial Doppler ultrasonography (TCD) has the potential to select the patients with high risk for future symptomatic brain embolism. We prospectively evaluated the positive rate and the frequency of microembolic signals (MES) before and after the heart valve surgery (HVS). Material and Method: Fifty in-patients with heart valve disease were enrolled in this study. Patients with history of previous stroke or heart valve surgery were excluded. Two unilateral TCD monitoring sessions were peformed from middle cerebral artery for 1-hour, before and after HVS. Result: Mechanical Heart valves were implanted in 28 patients, tissue valves were implanted in 10 patients, and remaining 12 patients received mitral valve repair. Positive rate of MES was significantly increased after HVS (50%), compared to that of before HVS (8%, p=0.00). There was no relation between MES after HVS and intensity of anticoagulation, cardiac rhythm, patients' age, and history of hypertension. The positive rate of MES after implantation of mechanical heart valve (71.4%) was significantly higher than those after implantation of tissue valve or mitral valve plasty (p=0.002). Conclusion: Positive rate of MES was increased significantly after the implantation of HVS. The changes of MES in those with mechanical prosthesis may be related to the increased risk or embolism after Hvs.

• Journal of Chest Surgery
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• 제43권2호
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• pp.176-179
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• 2010

Cardiac papillary fibroelastomas are the second most common primary tumor of the heart and they most commonly affect the left cardiac valves. However, occurrence of this tumor on the right side of the heart has been rarely reported, with only a few cases having been documented on the pulmonary valve. We present here a rare case of a papillary fibroelastoma that occurred on the pulmonary valve and this was successfully managed by replacing the pulmonary valve in a patient with congestive heart failure.

• Proceedings of the KOSOMBE Conference
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• 대한의용생체공학회 1993년도 추계학술대회
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• pp.81-84
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• 1993

Artificial Heart Valve is the one of the most important artificial organ which has been implanted to many patients. The most important problems related to the artificial heart valve prosthesis are thrombosis and hemolysis. Usual method to test against this problem in vivo experiment, which is complex and hard work. Nowadays the request for In vitro Artificial Heart Valve testing system is increasing. Several papers has announced us flow pattern of Artificial Heart Valve is highly correlated with thrombosis and hemolysis. They usually gel flow pattern by LDA, it is also hard work and has narrow measuring region. In this reason we have determined to develop PTV(Particle Tracking Velocimetry). By using High-speed camera and image processing technique, flow pattern could be relatively easily obtained. Parachute and Bileaflet Artificial Heart Valve designed by SNU were testified.

• Journal of Chest Surgery
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• 제53권5호
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• pp.285-290
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• 2020

Background: This study was conducted to evaluate the hemodynamic performance and the incidence of prosthesis-patient mismatch (PPM) after aortic valve replacement (AVR) using bovine pericardial valves (Carpentier-Edwards Perimount Magana and Magna Ease). Methods: In total, 216 patients (mean age, 70.0±10.5 years) who underwent AVR using stented bovine pericardial valves and had follow-up echocardiography between 3 months and 2 years (mean, 12.0±6.6 months) after surgery were enrolled. The implanted valve sizes were 19, 21, 23, and 25 mm in 32, 56, 99, and 29 patients, respectively. Results: On follow-up echocardiography, the mean transvalvular pressure gradients for the 19-mm, 21-mm, 23-mm, and 25-mm valves were 13.3±4.4, 12.6±4.2, 10.5±3.9, and 10.2±3.7 mm Hg, respectively. The effective orifice area (EOA) was 1.25±0.26, 1.54±0.31, 1.81±0.41, and 1.87±0.33 ㎠, respectively. These values were smaller than those suggested by the manufacturer for the corresponding sizes. No patients had PPM, when based on the reference EOA. However, moderate (EOA index ≤0.85 ㎠/㎡) and severe (EOA index ≤0.65 ㎠/㎡) PPM was present in 56 patients (11.8%) and 9 patients (1.9%), respectively, when using the measured values. Conclusion: Carpentier-Edwards Perimount Magna and Magna Ease bovine pericardial valves showed satisfactory hemodynamic performance with low rates of PPM, although the reference EOA could overestimate the true EOA for individual patients.

• Journal of Chest Surgery
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• 제13권4호
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• pp.375-384
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• 1980

Since 1958 up to the end of October 31, 1980, 2032 cases of cardiovascular lesions were operated, including 1225 open heart surgery and 354 valve replacement patients. There were 1271 Congenital anomaly cases and 761 acquired lesions including 149 vascular lesions. Among 1~271 congenital malformations 819 cases belong to acyanotic and 452 to cyanotic group. Over all mortality was 11.1 %, consisting of 12.4% for congenital and 8.9% for acquired lesions. Mortality for 1225 open heart surgery cases was 15% and 13.8% for various 354 valve replacement cases. In most of the open heart surgery cases Shiley oxygenator was utilized and Ionescu-Shiley bovine pericardial xenograft bioprosthesis**** valves were used mainly for valve replacement.