• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.11
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• pp.2090-2097
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• 1992

In this paper, fluttering behavior of mechanical monloleaflet heart valve prosthesis was analyzed taking into consideration of the impact between the valve occluder and the stopper. The motion of valve occluder was modeled as a rotating system, and equations were derived by employing the moment equilibrium conditions. Lift force, drag force, gravity and buoyancy were considered as external forces acting on the valve occluder. The 4th order Runge-Kutta method was used to solve the equations. The results demonstrated that the occluder reaches steady eguilibrium position only after damped vibration. The mean damping ratio is in the range of 0.197-0.301. Fluttering frequency does not have any specific value, but varies as a function of time. It is in the range of 11-84Hz. Valve opening appears to be affected by the orientation of the valve relative to gravitational forces.

• Journal of Chest Surgery
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• v.29 no.3
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• pp.326-330
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• 1996

Despite anticoagulation, systemic embolization and anticoagulant-related hemorrhage are the major drawbacks of heart valve replacement with mechanical prostheses. Among many predisposing factors, inadequacy of anticoagulation is the most important one. Surgery can be reserved for patients who do not response to thrombolytic therapy, We have experienced 3 cases of prosthetic valve thrombosis treated by thrombolytic therapy by use of urokinase and heparin. Two patients fully recovered and returned to their employments and active lives but 1 patient,died of intracerebral hemorrhage and infarction. We report prosthetic valve thrombosis thrombolytic therapy with urokinase and heparin which was detected and serially followed by 2-dimensional echocardiography, cinefluoro copy, and monitoring of Swan-Ganz catherterized pressures.

• Journal of Chest Surgery
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• v.28 no.9
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• pp.822-828
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• 1995

This paper reports 15 native valve endocarditis cases had surgical operation in the past 10 years at the department of Cardiovascular and Thoracic Surgery, Chonbuk National University Hospital. In this study, 10 cases out of 15 were in class I or II by the New York Heart Association functional classification. None of the cases had a history of taking addictive drugs. Five cases were congenital heart disease, three cases were rheumatic heart disease and two cases were degenerative heart disease. Thus 10 cases had the underlying disease. All cases had antibiotics treatment for 3 to 6 weeks before operation. In the culture test, only four cases were positive in the blood culture and one case was positive in the excised valve culture. Organisms on blood and valve culture were Streptococcus epidermis, Streptococcus viridans, Staphylococcus aureus and Staphylococcus epidermidis. In the 10 cases without ventricular septal defect, the aortic valve was involved in four, mitral in four, both in two and involved valves in the 5 cases with ventricular septal defect were tricuspid in three, pulmonic in two. Eight cases had operation because they showed moderate congestive heart failure due to valvular insufficiency and vegetation with or without embolism. Seven cases had operation because they showed persistent or progressive congestive heart failure and/or uncontrolled infection. Five cases with ventricular septal defect underwent the closure of ventricular septal defect, vegetectomy and leaflet excision of the affected valves without valve replacement. In the cases without ventricular septal defect, the affected valves were replaced with St. Jude mechanical prosthesis. Postoperative complications were recurrent endocarditis in two, embolism in one, allergic vasculitis in two, spleen rupture in one and postpericardiotomy syndrome in one. At the first postoperative day, one case died of cerebral embolism. At the 11th postoperative month, one case died of recurrent endocarditis and paravalvular leakage in spite of a couple of aortic valve replacement. In the survived cases[13 cases in this study , all cases but one became class I or II by the New York Heart Association functional classification.

• Journal of Chest Surgery
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• v.27 no.8
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• pp.664-668
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• 1994

A total of 217 patients underwent single mitral valve replacement [MVR] with the St. Jude Medical valve between September 1984 and the end of 1992. There were 86 males and 131 females with a mean age of 34.6 $\pm$ 14.4 years[range 5 months-61 years]. A previous valve replacement had been performed in 46 patients [21.2 %]. An early mortality rate was 7.4 % [5.2 % in primary MVR; and 15.2 %in re-replacement MVR]. Early survivors of 201 patients were followed up for a total of 934.5 patient-years[mean 4.7 $\pm$ 2.1years]. A late mortality rate was 2.5 % or 0.54%/patient-year. The linearized rates of thromboembolism, valve thrombosis and anticoagulation-related bleeding were 1.301 %, 0.214 % and 0.428 %/patient-year, respectively. The actuarial survival including operative mortality was 89.9 % $\pm$ 2.1% at postoperative 10 years. The freedom from thromboemolism was 91.3 %$\pm$ 2.5% and the actuarial estimate of incidence free from late deaths and all complications were 80.9 % $\pm$ 3.8 % at 10 years. There were no mechanical failures. In summary, the St. Jude Medical prosthesis performed satisfactorily with an acceptable rate of late complications.

• Journal of Chest Surgery
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• v.24 no.2
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• pp.171-181
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• 1991

Result of St. Jude Medical valve replacement are presented in 106 patients who underwent operation from January 1985 through July 1989. The patient were 52 males and 56 females. Total 136 of St. Jude Medical valves were implanted; 91 in mitral position, 45 in aortic position. The hospital mortality rate was 5.7%o[6 patients] and the late mortality rate was 2.0%[2 patients]. The causes of death were low cardiac output in 5, iatrogenic right ventricular rupture in 1, heart failure in 1, ventricular arrhythmia in l. And, the causes of valve related complication were anticoagulant related hemorrhage in 5 patients[0.03% /patient-year] and thromboembolism[0.01% /patient-year] in 2 patients. In conclusion, the performance of the St. Jude Medical valve compare most favorably with other artificial valves. But it remains still hazards of mechanical prosthesis such as thromboembolism and anticoagulant related hemorrhage.

• Journal of Chest Surgery
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• v.31 no.11
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• pp.1031-1036
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• 1998

Background: Medtronic-Hall mechanical valve is a world widely using prosthesis. But, in Korea, the clinical result from Medtronic-Hall valve replacement is not frequenthy available. Materials and methods: From March 1986 to May 1990, 50 patients underwent valve replacement surgery with Medtronic-Hall valve at Pusan National University Hospital. Seventeen were male and thirty three were female and ra nging in age from 16 to 70 years of age(mean=35 years). Results: The causes of valvular lesion were rheumatic in 43 patients, bicuspid aortic valve in 3 patients, degenerative lesion in three patients and bacterial endocarditis in one patient. The operative procedures were mitral valve replacement(MVR) in 38, aortic valve replacement(AVR) in 5 and double valve replacement(DVR) in 7. The most commonly used valve size was 21mm in AVR, 29mm in MVR. Concomitant surgical procedures were performed in 15 patients; left atrial thrombectomy in 9, left atrial auricle obliteration in 6 and tricuspid annuloplasty in 5(Kay: 2, DeVega: 3). New York Heart Association functional class was mostly Class Ⅲ or Ⅳ(91.5%) preoperatively and ClassⅠor Ⅱ(87.2%) after operation. The findings of postoperative echocardiogram of LAD, LVESD, LVEDD were reduced compared with preoperative period and ejection fraction was increased compared with preoperative period. Postoperative complications were massive bleeding in three, low cardiac output syndrome in two, thromboembolism in one and fulminant hepatitis in one patient. There were three hospital deaths and their causes were low cardiac output syndrome in two and rupture of left ventricle in one patient. The 5 year survival rate was 93.65±0.71% and 10 year actuarial survival rate was 88.27±6.42%. Conclusions: Medtronic-Hall mechanical valve has low valve related complication rate. It's durability and hemodynamic performance is comparable to other mechanical valves.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.247-248
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• 1998

The effect of unattached valve leaflet on flow field downstream of a floating and flapping polyurethane heart valve prosthesis was investigated. With a triggering system and a time-delay circuit the instantaneous velocity field downstream of the valve was measured by particle image velocimetry (PIV) in conjunction with the opening posture of a flexible valve leaflet during a cardiac cycle. Reynolds shear stress distribution was calculated from the velocity fields and wall shear stress was directly measured by hot-film anemometry (HFA). The floating motion of the valve leaflet resulted in the reduction of pressure drop and recirculating flow region downstream of the valve.

• Journal of Chest Surgery
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• v.29 no.5
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• pp.504-509
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• 1996

When a valve prosthesis is to be implanted in the aortic position, simple interrupted suture, figure-of- eight suture, or horizontal mattress suture technique is used as a suture method. However, the suture techniques may be unacceptable for aortic valve replacement in patients with friable annulus caused by some lesions, such as endocarditis and degenerative change. We used an alternative technique for the aortic vlave replacement in 4 patients with valve endocarditis, ) patients with degenerative valvular lesion, and 1 with rheumatic valvular disease. Mattress sutures through the annulus were placed with pledgets on the ventricular side of the annulus, whi h resulted in implantation of the prosthesis at a supra-annular level. Mechanical valves of 21 mm or larger were implanted in the supra-annular position in all patients and there was no impeded motion of leaflets during the follow-up period of mean 13.3 mouths. The transvalvular pressure gradient was less than 6 mm Hg in 3 patients and 20 to 40 mm Hg in 5 patients. The supra-annular implantation of mechanical aortic valve using a vertical mattress suture technique may be a useful alternative method of aortic valve replacement for the selected patients with friable or destroyed aortic annulus.

• Journal of Yeungnam Medical Science
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• v.31 no.2
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• pp.144-147
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• 2014

Despite the necessity of surgical aortic valve replacement, many patients with symptomatic severe aortic stenosis (AS) cannot undergo surgery because of their severe comorbidities. In these high-risk patients, percutaneous transcatheter aortic valve implantation (TAVI) can be safely accomplished. However, no study has shown that TAVI can be performed for patients with severe AS accompanied by acute decompensated heart failure. In this case report, 1 patient presented a case of severe pulmonary hypertension with decompensated heart failure after diagnosis with severe AS, and was successfully treated via emergency TAVI. Without any invasive treatment, acute decompensated heart failure with severe pulmonary hypertension is common in patients with severe AS, and it can increase mortality rates. In conclusion, TAVI can be considered one of the treatment options for severe as presented as acute decompensated heart failure patients with pulmonary hypertension.

• Journal of Chest Surgery
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• v.27 no.2
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• pp.114-121
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• 1994

St. Jude Medical cardiac valve replacement was performed in 135 consecutive patients from Aug.1986 to Dec. 1991.72 had mitral, 28 had aortic, 1 had tricuspid and 34 had double valve replacement. The hospital mortality rate was 4.4% & the late mortality rate was 3.7 %. Follow-up was done on 115 surviving patients:mean follow-up period was 29.78 $\pm$ 18.32 months. Paravalvular leakage was observed in two patients, possible prosthetic valvular endocarditis wasobserved in one patient and other specific valve-related complications were none. The overall actuarial survival rate at 6 years were 91.6% in total, 96.4% in aortic, 95.5 % in mitral and 81.9 % in double valve replacement.We concluded, therefore that good clinical results and a low complication rate could be achieved with St. Jude Medical valve in short-term follow-up & long-term follow-up was also necessary.