• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.241-242
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• 1998

For the aritificial heart valve, two types of valves-polymer and mechanical valve- are generally used. The polymer valve is used as a new low-cost artificial valve. Among the several properties of the artificial valve, the low-regurgitation property is important because it can provide better cardiac output characteristic. So in this study we analyzed and compared the regurgitation property of the mechanical valve which is generally used nowdays and the polymer valve which was made in our group. As results, the polymer valve showed the better regurgitation property compared to the mechanical valve approximately by 3 times, and increased the cardiac output by 10%.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.05
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• pp.146-151
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• 1993

A new hydrodynamic mock circulation system was developed, which can test prosthetic heart valves of various sizes in order to obtain valve parameters, such as pressure drop, regurgitation and valve performance index with a high reproducibility. High reproducibility can be obtained only under equal testing conditions, i.e., the compliance, resistance and inertance of the mock circulation system must be constant parameter estimation using actual pressure and flow data was applied to calculate these systemic variables in order to adjust them to create the necessary equal testing conditions.

• Journal of Chest Surgery
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• v.49 no.1
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• pp.42-45
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• 2016

Thrombosis at the left ventricular outflow tract occurs without any detectable heart disease or predisposing factors only extremely rarely. A 48-year-old male visited Konkuk University Medical Center with loss of consciousness one month prior to presentation. Before he visited our hospital, he had been diagnosed with a cardiac tumor, which was located between the left atrium and posterior aortic root, and which was adjacent to both the aortic and mitral valves. Cardiac transplantation was recommended at the other hospital because of the high risk of cardiac dysfunction induced by both aortic and mitral valvular dysfunction after surgical resection. Based on preoperative transthoracic echocardiography, cardiac computed tomography, cardiac magnetic resonance imaging, and intraoperative transesophageal echocardiography, we considered it to be a benign tumor. Complete resection was achieved and the pathology confirmed organizing thrombus. We report a case of organizing thrombus mimicking a cardiac tumor, which was located at the mitral-aortic intervalvular fibrosa of the left ventricular outflow tract without any heart disease.

• Journal of Chest Surgery
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• v.14 no.1
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• pp.49-59
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• 1981

This is one case report of surgically treated partial atrioventricular canal. The 22 year-old male patient had no definitive history of frequent respiratory infection and cyanosis in his early childhood. Since his age of 7 years, dyspnea was manifested on exertion. First appearance of congestive heart failure was at his age of 16 years old. The physical examination revealed that the neck veins were distended and heaving of precordium. A thrill was palpable on the left 3rd-4th intercostal space extending from the sternal border toward the apex and Grade IV/VI systolic ejection murmur was audible on it. Neither cyanosis nor clubbing was noted. Liver was palpable about 5 finger breadths. Chest X-ray revealed increased pulmonary vascularity and severe cardiomegaly (C-T ratio = 74%). EKG revealed LAD, clockwise rotation, LVH and trifascicular block. Echocardiogram showed paradoxical ventricular septal movement, narrowed left ventricular outflow tract and abnormal diastolic movement of the anterior leaflet of mitral valve. Right heart catheterization resulted in large left to right shunt (Qp : Qs = 5.7: 1), ASD and moderate pulfllonary hypertension. Finally, left ventriculogram revealed typical goose neck appearance of left ventrlcalar outflow tract. On Oct. 10, 1980, open heart surgery was performed. Operative findings were: 1. Large primum defect ($6{\times}5$ Cm in diameter) 2. Cleft on the anterior leaflet of mitral valve. 3. The upper portion of ventricular septum was descent but no interventricular communication. 4. Downward attachment of the atrioventricular valves on the ventricular muscular septum. 5. Medium sized secumdum defect ($2{\times}1$ Cm in diameter). The cleft was repaired with 4 interrupted sutures. The primum defect was closed with Teflon patch and the secundum defect was closed with direct suture closure. Postoperatively atrial flutter-fibrillation in EKG and Grade U/VI apical systolic murmur were found. The postoperative course was uneventful and discharged on 29th postoperative day in good general conditions.

• Journal of Yeungnam Medical Science
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• v.37 no.4
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• pp.345-348
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• 2020

Papillary fibroelastomas are the second most common primary cardiac tumor in adults. Over 80% of fibroelastomas occur on the cardiac valves, usually on the left side of the heart, while the remaining lesions are typically scattered throughout the atria and ventricles. Although the optimal timing for surgery is controversial and depends on tumor size and location, prompt surgical resection is warranted in patients at high risk of embolism. A tumor on the cardiac valve can be removed using the slicing excision technique without leaflet injury. Here we present two cases of papillary fibroelastomas occurring on the ventricular surface of the aortic valve and in the right ventricle.

• Journal of Mechanical Science and Technology
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• v.17 no.7
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• pp.1073-1082
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• 2003

Many researchers have investigated the blood flow characteristics through bileaflet mechanical heart valves using computational fluid dynamics (CFD) models. Their numerical approach methods can be classified into three types; steady flow analysis, pulsatile flow analysis with fixed leaflets, and pulsatile flow analysis with moving leaflets. The first and second methods have been generally employed for two-dimensional and three-dimensional calculations. The pulsatile flow analysis interacted with moving leaflets has been recently introduced and tried only in two-dimensional analysis because this approach method has difficulty in considering simultaneously two physics of blood flow and leaflet behavior interacted with blood flow. In this publication, numerical calculation for pulsatile flow with moving leaflets using a fluid-structure interaction method has been performed in a three-dimensional geometry. Also, pulsatile flow with fixed leaflets has been analyzed for comparison with the case with moving leaflets. The calculated results using the fluid-structure interaction model have shown good agreements with results visualized by previous experiments. In peak systole. calculations with the two approach methods have predicted similar flow fields. However, the model with fixed leaflets has not been able to predict the flow fields during opening and closing phases. Therefore, the model with moving leaflets is rigorously required for advanced analysis of flow fields.

• Journal of Chest Surgery
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• v.27 no.4
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• pp.266-271
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• 1994

Between 1985 and 1993, 29 children from 1 to 15 years of age have undergone cardiac valve replacements at Buchon Sejong Hospital. The patients were composed of 20 males and 9 females and 17 patient had congenital heart disease and 12 patients had acquired heart disease. Two of these patients have had second valve replacements due to paravalvular leakage and valve thrombosis. Single valve replacements were 29 and double valve replacements were 2. All the patients had received prosthetic valves except one. Among the 25 patients who had definite post-operative records, the overall mortality was 12%[4% was early mortality and 8% was late mortality].25 patients were followed up with coumadin anticoagulation for total 633 patient-months[minimum 2 months to maximum 93 months, mean 25.3 months] and actuarial survival rate was 88.5 $\pm$ 6.3% at 7 years and event free rate was 70.3 $\pm$ 11.7% at 7 years. These results suggest that pediatric valve replacements can now be performed at a low operative risk although various problems are still remained and the choice of valve is prosthetic valve mainly due to its durability at the present time.

• Journal of Chest Surgery
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• v.41 no.4
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• pp.516-519
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• 2008

Aorto-cutaneous fistula is a rare complication after performing open heart surgery, but if this develops, it is a fatal condition. So, prompt diagnosis and aggressive surgical treatment is needed. We report here on a patient who had two mechanical double valves placed during heart surgery and she was treated for repeated sternal wound infections for about 5 years. She visited the ER due to abrupt bleeding at the sternal wound. She was diagnosed as having an aorto-cutaneous fistula by performing an aortogram and we then performed cardio-pulmonary bypass surgery. The patient is currently doing well and is under follow up 24 months after the repair.

• Journal of Biomedical Engineering Research
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• v.15 no.4
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• pp.489-497
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• 1994

The most serious problems related to the cardiovascular prothesis are thrombosis and hemolysis. It is known that the flow pattern of cardiovascular prostheses is highly correlated with thrombosis and hemolysis. Laser Doppler Anemometry (LDA) is a usual method to get flow pattern, which is difficult to operate and has narrow measure region. Particle Image Velocimetry (PIV) can solve these problems. Because the flow speed of valve is too high to catch particles by CCD camera, high-speed camera (Hyspeed : Holland-Photonics) was used. The estimated maximum flow speed was 5m/sec and maximum trackable length is 0.5 cm, so the shutter speed was determined as 1000 frames per sec. Several image processing techniques (blurring, segmentation, morphology, etc) were used for the preprocessing. Particle tracking algorithm and 2-D interpolation technique which were necessary in making gridrized velocity pronto, were applied to this PIV program. By using Single-Pulse Multi-Frame particle tracking algorithm, some problems of PIV can be solved. To eliminate particles which penetrate the sheeted plane and to determine the direction of particle paths are these solving methods. 1-D relaxation fomula is modified to interpolate 2-D field. Parachute artificial heart valve which was developed by Seoul National University and Bjork-Shiely valve was testified. For each valve, different flow pattern, velocity profile, wall shear stress and mean velocity were obtained.

• Korean Journal of Clinical Pharmacy
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• v.23 no.3
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• pp.232-238
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• 2013

Background: Although thromboembolism is common and one of the major causes of mortality in cancer patients, maintaining therapeutic anticoagulation effect with warfarin is challenging. This study aimed to determine the prevalence and the causes of non-therapeutic INR (International Normalized Ratio) in cancer patients. Methods: Medical and pharmacy records for cancer patients managed by the pharmacist-run anticoagulation service (ACS) between May, 2010 and April, 2011 at Seoul National University Hospital were retrospectively reviewed. The causes of non-therapeutic INR were identified and compared with the results from a former study with mechanical heart valve patients. Results: A total of 335 cancer patients and 6,737 patient-visits were analyzed producing 68% (n=4,590) of non-therapeutic INR readings. Eighty-five percent of the non-therapeutic INR readings were categorized as sub-therapeutic. Frequent causes linked to non-therapeutic INR included inadequate dosage adjustment (21.8%), changes in health status (11.8%), dietary changes (8.1%), and drug interactions (4.2%). More than half of the non-therapeutic INR values had no known etiology. As causes for non-therapeutic INR, changes in health status (p<0.0001), adverse reactions (p<0.0001), and dietary changes (p=0.017) were statistically more frequent in cancer patients than in patients with mechanical heart valves. Furthermore, exposure to sub-therapeutic INR were more prevalent in cancer patients than in patients with mechanical heart valve (p<0.0001). Conclusions: This study shows that there is a tendency to keep the level of INR low and that health status change, dietary change, and drug interactions are found to be frequent causes for non-therapeutic INR in cancer patients.