• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.11
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• pp.1205-1211
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• 2011

In this paper, we developed a pacemaker that can increase the efficacy of a left ventricular assist device (LVAD) and increase the survival rate for patients suffering end-stage heart failure. Because LVAD patients can experience arrhythmia, the pacemaker incorporated into the LVAD has the important role of sustaining sufficient blood circulation during arrhythmia. The electrode of the pacemaker is located at the apex of the left ventricle, where the VAD's inlet cannula is connected. This is efficient placement, in that the electrode can transmit electrical stimulation directly to the Purkinje fibers of the myocardium. The pacemaker can change the stimulation rate from 0 bpm to 191.4 bpm when a button is pressed on the external control module, and the pacemaker normally stimulates the heart at 60 bpm with 0.25 J of energy. We performed animal experiments to evaluate the performance and reliability of the combination of the LVAD and pacemaker. At pacemaker stimulation rates of 86.4 bpm, 100.2 bpm, 126.6 bpm, we recorded the ECGs, aortic pressures, and flow rates to analyze the heart loads.

• Journal of Chest Surgery
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• v.35 no.10
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• pp.745-749
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• 2002

Cardiac rhabdomyoma is a rare type of benign tumor affecting the heart. There are a few previous reports of intracardiac rhabdomyomas causing ventricular arrythmia. We describe a 1-year-old female tuberous sclerosis patient who was presented with a ventricular tachycardia. Diagnostic echocardiography revealed two masses in the left ventricular outflow tract originating from the ventricular septum. The masses were surgically resected through aortotomy using cardiopulmonary bypass and the masses appeared benign. The pathology was that of a cardiac rhabdomyomas. Postoperative course was uneventful and the ventricular tachycardia was controlled.

• Journal of Chest Surgery
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• v.37 no.6
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• pp.543-545
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• 2004

Postinfarction ventricular septal defect often induces cardiogenic shock and requires operative treatment early after myocardial infarction. Although the operative mortality of this disease has decreased during the past 3 decades, it is still relatively high. In this case, to prevent global myocardial ischemia, we used the technique of repair of postinfarction ventricular septal defect on a beating heart. This approach does not requir aortic cross-clamping and provides superior myocardial protection.

• Journal of the Korean Society of Radiology
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• v.85 no.1
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• pp.210-214
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• 2024

Interventricular membranous septal aneurysms are rare. Since these aneurysms can lead to complications such as obstruction of right ventricular outflow and thromboembolism, the detection of this aneurysm has clinical significance. Herein, we report a case of an interventricular membranous septal aneurysm with an internal thrombus thought to be the cause of a cerebral infarction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.8
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• pp.715-720
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• 2014

In order to maximize the effect of left ventricular assist device (LVAD) on ventricular unloading, the therapy should be begun at appropriate level of heart failure severity. We predicted pumping efficacy of LVAD according to the severity of heart failure theoretically. We used 3 dimensional finite element model of ventricle coupled with 6 Wind-kessel compartmental model of vascular system. Using the computational model, we predicted cardiac responses such as contractile ATP consumption of ventricle, left ventricular pressure, cardiac output, ejection fraction, and stroke work according to the severity of ventricular systolic dysfunction under the treatments of continuous LVAD. Contractile ATP consumption, which indicates the ventricular energetic loading condition decreased maximally at the $5^{th}$ level heart-failure under LVAD therapy. We conclude that optimal timing for LVAD treatment is $5^{th}$ level heart-failure when considering LVAD treatment as "bridge to recovery".

• Journal of Chest Surgery
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• v.35 no.12
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• pp.890-893
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• 2002

Ebsteins anomaly is a rare congenital cardiac malformation that is the downward displacement of the septal and posterior leaflets of the tricuspid valve into the ventricular apex, aresulting in the formation of an atrialized portion of the right ventricle. In most patients, symptoms such as cyanosis and progressive heart failure occur during the adolescence or young adulthood. The associated anomalies include ventricular septal defect, transposition of the great arteries, and malformation of the mitral valve. An 8-months-old male with Ebsteins anomaly, ventricular septal defect, and duplication of the mitral valve orifice successfully underwent operation with VSD patch closure. Postoperatively, cardiac size was significantly reduced and tricuspid regurgitation was trivial in echocardiography He has been doing well without any cardiac medication during the 18 months follow up after operation.

• Journal of Chest Surgery
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• v.36 no.9
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• pp.633-637
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• 2003

Sometimes temporary tricuspid valve detachment is applied for closure of ventricular septal defect to facilitate good exposure and avoiding ventriculotomy, but most surgeons hesitate to do it in the fear of tricuspid incompetence. Moreover in recent textbooks the technique of temporary tricuspid detachment is only described for exceptional situations and is not further analysed or commented on. Material and Method: Retrospective study was carried out in all 11 patients operated between 1985 to 1994, with preoperative data and postoperative course and recent echocardiographic and electrocardiographic data. Result: On the basis of the area of the color flow jet, tricuspid valvular regurgitation was graded as none in 9 and trivial in 2, and significant electrocardiographic heart block did not developed in any patients. Conclusion: Takedown and attachment of the tricuspid valve is a safe and effective technique that improves exposure for ventricular septal defect, and does not adversely effect tricuspid valve competence and electrocardiography.

• The Journal of the Korea Contents Association
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• v.9 no.7
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• pp.19-26
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• 2009

This paper presents an approach to classify normal and ventricular tachycardia/fibrillation(VT/VF) from the Creighton University Ventricular Tachyarrhythmia Database(CUDB) using the neural network with weighted fuzzy membership functions(NEWFM) and wavelet transforms. In the first step, wavelet transforms are used to obtain the detail coefficients at levels 3 and 4. In the second step, all of detail coefficients d3 and d4 are classified into four intervals, respectively, and then the standard deviations of the specific intervals are used as eight numbers of input features of NEWFM. NEWFM classifies normal and VT/VF beats using eight numbers of input features, and then the accuracy rate is 90.1%.

• Journal of Chest Surgery
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• v.41 no.6
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• pp.747-750
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• 2008

Although surgical closure is the standard approach for a muscular ventricular septal defect, the procedure may be complicated by poor visualization and the need for incision on the ventricle. Another approach is, catheter-based intervention. However, it also has limitations. A hybrid procedure, the intraoperative combined use of an interventional device may reduce the procedure's invasiveness. We successfully managed two cases of muscular ventricular septal defect with a hybrid procedure. We report here on these 2 cases along with a review of the literature.

• Journal of Chest Surgery
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• v.31 no.7
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• pp.718-721
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• 1998

The surgical closure of VSD in patient with severe pulmonary hypertension has been considered a difficult problem for surgeons, because sudden hemodynamic change after closure of the defect could bring on high perioperative mortality. Recently, it was reported that UVP(unidirectional valve patch), which allows some blood to flow from right to left in case of acute right heart failure, is effective in improving the postoperative hemodynamics after closing septal defects. This 42-year old woman had suffered from VSD for 20 years and recently complained of worsening exertional dyspnea for three months, and was diagnosed of a large VSD(2.0 cm in diameter) with severe pulmonary hypertension(116/38 mm Hg), equal to systemic arterial pressure. We could successfully close VSD with severe pulmonary hypertension using one UVP and the other UVP for the creative ASD to be prepared against possible acute right heart failure. She was discharged on the fourteenth postoperative day and has been well for twelve months with spontanenous closure of UVP patch at the ninth postopeative month.