• Journal of Chest Surgery
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• 제33권2호
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• pp.146-150
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• 2000

background: The prognosis after an aortic valve replacment can be affected significantly by the transprosthetic pressure gradient which is determined mainly by the size of the patients body and the prosthesis used. We analyzed the hemodynamic feature of two relatively new prosthese the ATS and the evensized Medtronic-Hall(M-H) valves by measuring the transprosthetic pressure gradient in the cases where small sizes (23mm or smaller) were used. Material and method: There were 94 patients who received whom aortic valve replacement with prosthesis smaller than 23 mm from October 1994 to June 1998. In these patients the transprosthetic pressure gradient clalculated from the pressure half time during postoperative Dopper echocardiographic examination was compared between the prostheses of different sizes. The body surface area of each patient was also taken into consideration. result: The mean pressure gradient and body surface area in each group were 21.7$\pm$10.2 mmHg and 1.52$\pm$0.14m2 in ATS 19mm 11.4$\pm$6.5 mmHg and 1,57$\pm$0.20m2 in M-H 20mm 15.2$\pm$6.3 mmHg and 1.54$\pm$0.13m2 in ATS 21mm 9.3$\pm$2.5 mmHg and 1.63 $\pm$0.14m2 in M-H 22 mm and 12.9$\pm$5.3 mmHg and 1.69$\pm$0.13m2 in ATS 23mm. Conclusion: The 19mm ATS prosthesis showed significant trasprosthetic pressure gradient which is similar to the values previously reported with other bileaflet prosthesesm Close follow-up was needed in terms of exercise capacity and change in left ventiricular geometry. In patients with small aortic valve annulus the 20mm M-H valve is recomendable as an alternative to 19mm bileaflet valves because it has less pressure gradient with similar outer diameter.

• 대한기계학회논문집
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• 제19권2호
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• pp.443-450
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• 1995

An analysis of the dynamics of a mechanical monoleaflet heart valve prosthesis in the closing phase is presented. Employing the moment equilibrium principles on the occluder motion and the squeeze film dynamics of the fluid between the occluder and the guiding strut at the instant of impact, the velocity of the occluder tip and the impact force were computed. The dynamics of fluid being squeezed between the occluder and the guiding struts is accounted for by Reynold's equation. The effect of the fluid being squeezed between the occluder and the guiding strut was to reduce the velocity of the occluder tip at the instant of valve closure as well as dampen the fluttering of the occluder before coming to rest in the fully closed position. The squeeze film fluid pressure changed rapidly from a high positive value to a relatively large negative value in less than 1 msec. The results of this study may be extended for the analysis of cavitation inception, mechanical stresses on the formed elements and valve components as well as to estimate the endurance limits of the prosthetic valves.

• Journal of Chest Surgery
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• 제24권1호
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• pp.88-92
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• 1991

Although there have been diverse opinions, permanent anticoagulation is generally recommended in children with mechanical valves. We experienced the thrombotic dysfunction of mitral St. Jude Medical valve in a 4-year-old child who had been under control of anticoagulation with warfarin sodium. Besides the primary problems related to the prosthetic mechanism, various patient factors might have contributed to the valve thrombosis. We would emphasize the necessity of anticoagulation and the close observation for valve dysfunction in pediatric patients with St. Jude Medical valve in mitral position.

• 대한기계학회논문집B
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• 제26권5호
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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 Chest Surgery
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• 제29권5호
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• pp.504-509
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• 1996

대동맥 판 치환술시 봉합법으로써 단순봉합(simple interrupted suture), 8자형 봉합(figure of eight su- ture), 수평 석상봉합법 (horizontal mattress suture method) 등이 이용되고 있다. 그러나 심내막염에 의 해 판륜이 손상되거나 퇴행성 변성으로 판륜이 약화된 환자들에서는 본봉합법으로대동맥판 치환이 어려 울 수 있고,치환후 판막주위 누출등의 합병증이 발생할수 있다. 저자들은 1993년 6월부터 1995년 6월 까지 심내막염에 의한 대동맥판 환자 4례,퇴행성 판막환자 3례,류마티스성 판막병변 환자 1례에서 수직 석상봉합법 (vertical mattress suture method)으로 기계판막(mechanical valve)을 판륜 상연에 위치시 키는 술식을 시행하였다. . 2례에서 농양으로 판륜이 결손되어 자가심막편을 이용하여 결손부위를 봉합하였다. 판막 치환을 위 해 2-0 polyester 봉합사를 이용했고, 봉합사를 지지하는 테프론 조각을 심실쪽에 위치시키고 침사가 심 실쪽에서 발살바동쪽으로 통과하도록 하는 수직 석상봉합법을 이용하였다. 본 수술방법으로 최소한 19mm기계판막의 사용은 완전히 배제할 수 있었다. 술후 평균 13.3개월에 심에코 검사로 추적 관찰한 \ulcorner과, 판막운동의 이상은 발생하지 않았으며, 판막자체에서 발생하는 압력 경사는 3례에서 6mmHg이 하였고 5례에서 20내지 40mmHg였다 이와같은 결과에서 판륜이 손상되거나 약화된 대동맥판 환자에 서 판막치환술시 수직 석상 봉합법을 이용하여 기계판막을 판륜상연에 위치시키므로써 수술이 용이하 고 술후 합병증을 감소시킬 수 있을 것으로 사료된다.

• Journal of Chest Surgery
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• 제22권3호
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• pp.393-401
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• 1989

Between Dec. 1984, and May, 1988,96 prostheses were implanted in 80 patients at Dept. of Thoracic k Cardiovascular Surgery of National Medical Center. 43 patients had mitral valve replacement, 21 underwent aortic valve replacement, and 15 had double valve replacement [Mitral k Aortic], and 1 had tricuspid valve replacement. Seventy-one cases [88.8 %] were in NYHA Class III or IV. The mean duration of follow up was 22.1 months and follow-up information was available for 74 [92.5 %] of the patients. The overall actuarial survival rate at 45 months was 93.05 % and overall hospital mortality was 10 %, late Mortality was 5 %. The linearlized incidence of thromboembolism [2.4%/pt-yr], thrombotic valve obstruction [1.6 %/pt-yr], anticoagulant related bleeding [0.8 %/pt-yr]. There were no fatal valve related complications. The blood was studied in 40 patients 1 year after valve operation. Hgb and reticulocyte count were within normal values and Serum LDH value was slightly elevated but it was not of clinical significance. In conclusion, Monostrut Bjork-Shiley valve prosthesis to be a reliable valve substitute with an acceptable incidence of complications.

• Journal of Chest Surgery
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• 제30권7호
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• pp.663-669
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• 1997

ATS 인공판막을 이용하여 심장판막 치환수술을 시행받은 100명의 연속적인 환자를 대상으로 조기 성적 과 외래 추적 결과를 분석하였다. 또한 수술 후 시행한 도플러 심에코 검사 결과를 통하여 이 판막의 혈역학 적 특성을 살펴보았다. 환자들의 평균 연령은 48.6세였으며 총 124개의 판막이 치환되었다. (승모판막 71, 대 동맥판막 46, 삼첨판막 7) 가장 많이 사용된 크기는 승모판막에서는 27 mm(40.8%), 29 mm(35.2%)였고 대동 맥판막에서는 23 mm(30.4%), 21 mm(28.3%)였다. 수술후 조기 사망은 1례도 없었고 총 950 patientmonths의 외래추적이 이루어졌다(추적율=99%). 만기 사망도 없었으며 혈전-색전증이나 판막의 구조적 결합에 의한 합병증은 발생하지 않았다. 2명의 환자가 각각 Valsava동의 파열과 심내막염에 의한 대동맥 인공판막 dehi nce로 재수술을 받았고 고혈압을 가지고 있던 환자 1명에서 두개내 출혈이 발생하였다. 도플러 에코검사 결과 판막 전후의 최대 및 평균 압력차는 승모판막의 경우 각각 평균 6.9 mmHg, 2.6 mmHg였고 대동맥판막의 경우 26.4 mmHg, 14.2mmHg였으며 승모판막의 평균 개구부 면적은 2.7 cm2였다. 27-mm이상 크기\ulcorner 승모판막에서는 판막크기에 따른 압력차나 개구부 면적의 차이가 없었으나 대동맥판막에 서는 판막크기의 감소와 압력차의 증가간에 유의한 상관관계가 있었다. 19-mm와 21-mm 대동맥판막의 경우 는 최대 및 평균 압력차가 각각 52.2 mmHg, 26.9 mmHg 및 27.1 mmHg, 13.3 mmHg였다. 상기 연구결과로써 ATS 인공판막의 조기 임상 성적은 만족스러운 것으로 결론지을 수 있으며 혈역학적 특성은 기존의 동일 유형 판막들과 비교하여 더 우수하다고 할 수는 없으나 차이가 없는 것으로 판단된다.

• Journal of Chest Surgery
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• 제16권3호
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• pp.265-271
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• 1983

• Journal of Chest Surgery
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• 제54권1호
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• pp.25-30
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• 2021

Background: Life-long anticoagulant therapy is mandatory for patients who undergo heart valve replacement with implantation of a mechanical prosthesis. The aim of this study was to investigate the effects of a nurse-led patient educational program concerning oral anticoagulant therapy intake after heart valve replacement surgery on patients' knowledge of important parameters of anticoagulant administration. Methods: In this single-center study, 200 patients who underwent surgical implantation of a mechanical prosthesis were divided into 2 groups. The control group received the basic education concerning oral anticoagulants, while the intervention group received a personalized educational program. Results: Personalized education was correlated with a better regulation of therapeutic international normalized ratio (INR) levels and adequate knowledge among patients. Therapeutic levels of INR were achieved in 45% of the patients during the first month, 71% in the third month, and 89% in the sixth month after discharge in the intervention group, compared to 25%, 47%, and 76% in the control group, respectively. Patients' satisfaction with the information was higher in the intervention group than in the control group. The percentage of satisfaction reached 80% for the intervention group versus 37% for the patients of the control group. Conclusion: The implementation of the nurse-led educational programs was associated with improved clinical results and increased adherence to oral anticoagulant treatment.

• Journal of Chest Surgery
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• 제27권10호
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• pp.858-861
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• 1994

Prosthetic valve thrombosis is rare but it is one of fatal complication after heart valve surgery. Improvements of the valve design and the material have decreased the frequency of thrombosis but have not eliminated completely. And some cases of prosthetic valve thrombosis during pregnancy were reported inspite of adequate anticoagulation therapy.Urgent surgical intervention is indicated for prosthetic valve thrombosis but it is associated with high operative risk, therefore medical thrombolytic therapy such as urokinase or streptokinase therapy is regarded as an alternative therapy. This is a case report of the successful thrombolytic therapy for valve thrombosis in a pregnant patient after mechanical mitral valve replacement.