• Journal of Chest Surgery
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• v.48 no.1
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• pp.25-32
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• 2015

Background: We evaluated operative outcomes after third or more cardiac operations for valvular heart disease, and analyzed whether pericardial coverage with artificial membrane is helpful for subsequent reoperation. Methods: From 2000 to 2012, 149 patients (male : female=70 : 79; mean age at operation, $57.0{\pm}11.3$ years) underwent their third to fifth operations for valvular heart disease. Early results were compared between patients who underwent their third operation (n=114) and those who underwent fourth or fifth operation (n=35). Outcomes were also compared between 71 patients who had their pericardium open during the previous operation and 27 patients who had artificial membrane coverage. Results: Intraoperative adverse events occurred in 22 patients (14.8%). Right atrium (n=6) and innominate vein (n=5) were most frequently injured. In-hospital mortality rate was 9.4%. Total cardiopulmonary bypass time ($225{\pm}77$ minutes vs. $287{\pm}134$ minutes, p=0.012) and the time required to prepare aortic cross clamp ($209{\pm}57$ minutes vs. $259{\pm}68$ minutes, p<0.001) increased as reoperations were repeated. However, intraoperative event rate (13.2% vs. 20.0%), in-hospital mortality (9.6% vs. 8.6%) and postoperative complications were not statistically different according to the number of previous operations. Pericardial closure using artificial membrane at previous operation was not beneficial in reducing intraoperative events (25.9% vs. 18.3%) and shortening operation time preparing aortic cross clamp ($248{\pm}64$ minutes vs. $225{\pm}59$ minutes) as compared to no-closure. Conclusion: Clinical outcomes of the third or more operations for valvular heart disease were acceptable in terms of intraoperative adverse events and in-hospital mortality rates. There were no differences in the incidence of intraoperative adverse events, early mortality and postoperative complications between third cardiac operation and fourth or more.

• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.415-424
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• 1995

Combined models, specified by two or more modeling formalisms, can represent a wide variety of complex systems. This paper describes a methodology for the development of combined models in two model types of discrete event and continuous process. The methodology is based on transformation of continuous state space into discrete one to homomorphically represent dynamics of continuous processes in discrete events. This paper proposes a formal structure which can combine model of the DES and the CS within a framework. The structure employs the DEVS formalism for the DES models and differential or polynomial equations for the CS models. To employ the proposed structure to specify a DEVS/CS combined model, a modeler needs to take the following steps. First, a modeler should identify events in the CS and transform the states of the CS into the DES. Second, a modular employs the formalism to specify the system as the DES. Finally, a moduler developes sub-models for the CS and continguos states of the DES and establishs one-to-one correspondence between the sub-models and such states. The proposed formal structre has been applied to develop a DEVS/CS combined model for the human cardiovascular system. For this, the cardiac cycle is partitioned into a set of phases based on events identified through observation. For each phase, a CS model has been developed and associated with the phase. To validate the DEVS/CS combined model developed, then simulate the model in the DEVSIM + + environment, which is a model simulation results with the results obtained from the CS model simulation using SPICE. The comparison shows that the DEVS/CS combined model adequately represents dynamics of the human heart system at each phase of cardiac cycle.

• The Korean Journal of Emergency Medical Services
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• v.8 no.1
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• pp.149-160
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• 2004

Background : To save out-of-hospital cardiac arrest cases is a major concern for Korea. Cardiac arrest is a very common problem, with > 18,000 cases dying each year in Korea. Overall, survival to hospital discharge remains poor. Resuscitation has become an important multidisciplinary branch of medicine, demanding a spectrum of skills and attracting a plethora of specialities and organizations. Since the "Utstein Style" was advocated in 1991, many reports about out-of-hospital cardiac arrest have been published based on this guideline. These differences prevent valid inter-hospital and international comparisons. However, we do not know the true effectiveness of resuscitation. There are no guideline for reviewing, reporting, conducting research on resuscitation in Korea. This study evaluated the out-of-hospital factor associated with survival discharge of out-of-hospital cardiac arrest, was especially to provide basic data for the unified reporting guideline of resuscitation in Korea. Methods : From January 1990 to July 2004, we collected data about out-of-hospital cardiac arrest at Wonju Christian Hospital(WCH-CAD), Ewha Women University Mokdong Hospital(Ewha-CAD), I used same record form based on the "Utstein Style". The "Utstein Style" is internationally recommended guidelines for reporting outcome data from resuscitation events. Results : Resuscitation was performed in 1443 out-of-hospital cardiac arrest patients at 2 hospitals. Five hundred eighty(40.25%) patients recovered the spontaneous circulation at least once and One hundred sixty eight(11.66%) patients discharged alive. Initial EKG showed Ventricular Tachycardia/Ventricular Fibrillation in One hundred thirty five(9.33%) patients, asystole in one thousand nine(69.73%) patients and other rhythms in one hundred thirty nine(20.94%) patients. Among one hundred two cardiogenic cardiac arrest patients, two(2.0%) patients was discharged alive. Conclusion : Overall survival rate of out-of-hospital cardiac arrest patients was 11.66% which was poorer than that of the western country. The proportion of the cardiogenic cause was 33.38% which was only half of the western country. VT/VF is relatively not common ac a initial EKG rhythm. These differences might be to due difference in the prevalence pattern of out-of-hospital cardiac arrest as well as prematurity of the EMSS. It is needed that the best survival can be achieved if all following links have been optimized : rapid access, early CPR, early defibrillation, early ACLS.

• Journal of Chest Surgery
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• v.49 no.5
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• pp.356-360
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• 2016

Background: The standard approach in treating cardiac myxoma is the median full sternotomy. With the evolution of surgical techniques, the right minithoracotomy approach has emerged as an alternative method. Since few studies have been published assessing the right minithoracotomy approach, we performed a retrospective study to compare the clinical outcomes of the right minithoracotomy approach with those of the sternotomy approach. Methods: From January 2005 to December 2014, 203 patients underwent resection of a cardiac myxoma. Patients with preexisting cardiac problems were excluded from this study. 146 patients were enrolled in this study; 83 patients were treated using a median sternotomy and 63 patients were treated using a right minithoracotomy. Results: No early mortalities were recorded in either group. Although the cardiopulmonary bypass time and aorta cross-clamp time were significantly shorter in the sternotomy group (p<0.001 and p=0.005), postoperative blood transfusions and arrhythmia events were significantly less common in the thoracotomy group (p=0.004 and p=0.025, respectively). No significant differences were found in the duration of the hospital stay, postoperative intubation time, the duration of the intensive care unit stay, and recurrence. Conclusion: The minimally invasive right minithoracotomy approach is a good alternative method for treating cardiac myxoma because it was found to be associated with a lower incidence of postoperative complications and a shorter postoperative recovery period.

• Korean Circulation Journal
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• v.53 no.11
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• pp.727-743
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• 2023

Although cardiac rehabilitation (CR) has been shown to improve exercise tolerance and prognosis in patients with cardiovascular diseases, there remains low participation in outpatient CR. This may be attributed to the patients' busy schedules and difficulty in visiting the hospital due to distance, cost, avoidance of exercise, and severity of coronary disease. To overcome these challenges, many countries are exploring the possibility of remote CR. Specifically, there is increasing attention on the development of remote CR devices, which allow transmission of vital information to the hospital via a remote CR application linked to a wearable device for telemonitoring by dedicated hospital staff. In addition, remote CR programs can support return to work after hospitalization. Previous studies have demonstrated the effects of remote CR on exercise tolerance. However, the preventive effects of remote CR on cardiac events and mortality remain controversial. Thus, safe and effective remote CR requires exercise risk stratification for each patient, telenursing by skilled staff, and multidisciplinary interventions. Therefore, quality assurance of telenursing and multi-disciplinary interventions will be essential for remote CR. Remote CR may become an important part of cardiac management in the future. However, issues such as cost-effectiveness and insurance coverage still persist.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.1
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• pp.1-7
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• 2002

Congenital Long QT syndrome (LQTs) is a relatively rare pathologic disorder but results frequently in sudden cardiac death. Of the six LQTs that have been clinically described, five have been worked out for their genetic and biophysical profile. Most are generated by mutations which cause a loss of function in two delayed $K^+$ currents, $i_{Ks}\;and\;i_{Kr}.$ One syndrome is generated by mutations in the $Na^+$ channel which causes essentially a gain of function in the channel. Clinically the syndromes are characterized by slowed repolarization of the cardiac ventricular action potential and the occurrence of typical arrhythmias with undulating peaks in the electrocardiogram, called Torsade de Pointes. Arrhythmias are initiated by early or delayed afterdepolarizations and continue as reentry. Triggers for cardiac events are exercise (swimming; LQT1), emotion (arousal; LQT2) and rest/sleep (LQT3). ${\beta}-blockers$ have a high efficacy in the treatment of LQT1 and LQT2. In LQT3 their use is questionable. The study of congenital LQTsyndromes is a remarkable example of how basic and clinical science converge and take profit of each other's contribution.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.275-278
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• 1997

Standard methods estimating the power spectral density(PSD) from an irregularly sampled cardiac event series require deriving a new evenly-spaced signal applicable to those methods. To avoid that requirement, in this study, the power spectrum of heart rate variability was estimated by Lomb-Scargle's algorithm, which is a means of obtaining PSD estimates directly from irregularly sampled timeseries observed in astronomy. To assess the performance of Lomb-Scargle algorithm in the power spectral analysis of heart rate variability, it was applied to various cardiac event series derived through integral pulse frequency modulation model(IPFM) simulation and from real ECG signals, and the resultant power spectra was compared with those obtained by a conventional method based on the FFT. In result, it is concluded that Lomb-Scargle's periodogram is very effective in the power spectral analysis of heart rate variability, especially in the presence of arrhythmia and/or dropouts of cardiac events.

• Journal of Veterinary Clinics
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• v.41 no.2
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• pp.106-111
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• 2024

A 4-year-old neutered female domestic shorthair cat weighing 5.1 kg was referred to Jeju National University Hospital with acute onset respiratory distress, weakness, and anorexia. The patient had a history of stressful antecedent events that involved bullying by a newly introduced cat. Thoracic radiography and echocardiography revealed a stage C hypertrophic cardiomyopathy phenotype based on the American College of Veterinary Internal Medicine classification system with pulmonary edema, pleural effusion, and pericardial effusion at the same time. The patient was treated with furosemide, pimobendan, and rivaroxaban. Pericardiocentesis was performed because pericardial effusion was identified. Reevaluation after 30 days revealed a normal respiratory rate on physical examination, normal cardiac shape on thoracic radiographs, and normal cardiac measurements on echocardiography. The patient was tentatively diagnosed with transient myocardial thickening (TMT) and all medications were discontinued. Six months after the initial hospitalization, the cat continued to do well without any clinical signs or left ventricular wall thickening. This case is the first report describing feline TMT in Korea. Moreover, it involves a rare case in which pulmonary edema, pleural effusion, and pericardial effusion, which induce cardiac tamponade, occurred simultaneously due to TMT-related congestive heart failure.

• Journal of Chest Surgery
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• v.45 no.3
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• pp.183-185
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• 2012

Abdominal aortic occlusion (AAO) caused by detachment of cardiac myxoma (CM) is a very rare complication in patients with CM. Although the nature of CMs has been well established, detachment of CM may cause unexpected serious complications such as vicious embolic events. Actually, in several cases of AAO caused by detachment of CM, it has been reported that CM fragments easily migrated to the brain, heart, and lungs, and caused lifelong neurological complications despite appropriate surgical therapy. Herein, we report a case of a patient with AAO caused by detachment of CM who underwent CM excision and abdominal aortic thromboembolectomy. Additionally, we have presented the preoperative and postoperative images using 64-multidetector computed tomography.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.542-546
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• 2008

In this study, we developed a whole cardiovascular system model combined with a Laplace heart based on the numerical cardiac cell model and a detailed arterial network structure. The present model incorporates the Laplace heart model and pulmonary model using the lumped parameter model with the distributed arterial system model. The Laplace heart plays a role of the pump consisted of the atrium and ventricle. We applied a cellular contraction model modulated by calcium concentration and action potential in the single cell. The numerical arterial model is based upon a numerical solution of the one-dimensional momentum equations and continuity equation of flow and vessel wall motion in a geometrically accurate branching network of the arterial system including energy losses at bifurcations. For validation of the present method, the computed pressure waves are compared with the existing experimental observations. Using the cell-system-arterial network combined model, the pathophysiological events from cells to arterial network are delineated.