• Journal of Biomedical Engineering Research
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• v.25 no.2
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• pp.119-127
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• 2004

In this paper, an automatic external biphasic defibrillator that removes ventricular fibrillation efficiently with a low discharging energy has been developed. The system is composed of software including a fibrillation detection algorithm and a system control algorithm, and hardware including a high voltage charging/discharging part and a signal processing part. The stability of the developed system has been confirmed through continuous charging/discharging test of 160 times and the detection capability of the real-time fibrillation detection algorithm has been estimated by applying a total of 30 various fibrillation signals. In order to verify the clinical efficiency and safety, the system has been applied to five pigs before and after fibrillation inductions. Also, we have investigated the system efficiency in removing fibrillation by applying two different discharging waveforms, which have the same energy but different voltage levels.

• The Korean Journal of Pharmacology
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• v.19 no.1
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• pp.61-69
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• 1983

Hypothermia is an essential preparatory procedure for cardiac surgery, which lows the metabolic rate and myocardial oxygen demand. However, hypothermia itself is a stress enough to change the tonus of sympathoadrenal system, especially the cardiovascular responses to the catecholamines. It is reported that the positive chronotropic and inotropic response of catecholamines is exaggerated during hypothermia because of decreased norepinephrine uptake at the junctional cleft or decreased catecholamine metabolism. On the other hand, there are evidences of diminished catecholamines responses in low temperature ana further, interconversion of adrenergic receptors is also suggested. Present investigation was planned to observe the cardiovascular changes and its responses to catecholamines during surface hypothermia in cat. Healthy mongrel cats, weighing $2{\sim}3\;kg$, anesthetized with secobarbital(30 mg/kg), were permitted to hypothermia by external cooling technic. Esophageal temperature, ECG (lead II), heart rate, left ventricular pressure with dP/dt, carotid artery pressure and left ventricular contractile force were monitored with Polygragh (Model 7, Grass), and the respiration was maintained with artificial respirator (V 5 KG, Narco). Followings are summarized results. 1) Surface cooling caused progressive decrease of body temperature and reached $l8.8{\pm}0.8^{\circ}C$ and $16.9{\pm}0.6^{\circ}C$ in 120 and 150 min respectively, after immersion into ice water, and ventricular fibrillation was developed at $20.4{\pm}0.65^{\circ}C$. 2) Heart rate, blood pressure and myocardial contractility were decreased after initial increase as the body temperature falls. 3) Systolic and diastolicdd P/dt of left ventricular pressure were decreased and that the decrement of diastolic dP/dt was more marked. 4) On ECG, ST depression, Twave inversion and prolongation of PR interval were prominent in hypothermia, and moreover, the prolongation of PR interval was marked just prior to the development of ventricular fibrillation. 5) The cardiovascular responses to catecholamines, especially to isoproterenol, were suppressed under hypothermia.

• Journal of Yeungnam Medical Science
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• v.34 no.2
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• pp.208-215
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• 2017

Background: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a cardiomyopathy characterized by predominant right ventricular fibro-fatty replacement, right ventricular dysfunction and ventricular arrhythmias. It is a rare but important cause of sudden cardiac death in children and young adults. A meta-analysis on risk stratification of major ventricular tachyarrhythmic events indicating the need for implantable cardioverter defibrillator therapy in ARVC was performed. Methods: The pubmed database was searched from its inception to May 2015. Of the 433 citations identified, 12 were included in this meta-analysis. Data regarding major ventricular tachyarrhythmic events were retrieved in 817 subjects from the studies. For the variables, a combined odds ratio (OR) was calculated using a fixed-effects meta-analysis. Results: Extensive right ventricular dysfunction (OR, 2.44), ventricular late potential (OR, 1.66), inducible ventricular tachyarrhythmia during electrophysiology study (OR, 3.67), non-sustained ventricular tachycardia (OR, 3.78), and history of fatal event/sustained VT (OR, 5.66) identified as significant risk factors (p<0.0001). Conclusion: This meta-analysis shows that extensive right ventricular dysfunction, ventricular late potential, inducible ventricular tachyarrhythmia during electrophysiological study, non-sustained ventricular tachycardia, and history of sustained ventricular tachycardia/fibrillation are consistently reported risk factors of major ventricular tachyarrhythmic events indicating implantable cardioverter defibrillator therapy in patients with ARVC.

• Journal of Chest Surgery
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• v.25 no.6
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• pp.672-677
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• 1992

This is a clinical review of the results from electric cardioversion and pharmacological therapy used in our hospital for reverting cardiac arrythmia in patients with mitral valve surgery between Jan. 1990 and Jun. 1991. Of 62 evaluated patients, 16 patients had regular sinus rhythm and the other 46 had arrhythmias [42; atrial fibrillation 1; atrial flutter 1; premature ventricular contraction] preoperatively. In 2 of patients with sinus rhythm, atrial fibrillation newly developed after surgery and was converted into sinus rhythm soon by intravenous administration of digoxin. Remaining 14 patient resumed sinus rhythm spontaneously. In patients with preoperative arrythmia, 3 patients reverted into sinus rhythm from atrial fibrillation by electric cardioversion at operative field, 1 patient by lidocain and mexiletine, 4 patients by combined use of digoxin and verapamil, 4 patients by 2 times of oral quinidine and 9 patient by long term use of oral amiodarone. Throughout this consecutive trials of anti-arrhythmic drugs and electric cardioversion, Conversion into normal sinus rhythm occurred in 48% of patients with arrhythmia developed after mitral valve surgery.

• Korean Circulation Journal
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• v.48 no.12
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• pp.1148-1156
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• 2018

Background and Objectives: It is controversial that decreased left ventricular function could predict poststroke outcomes. The purpose of this study is to elucidate whether left ventricular ejection fraction (LVEF) can predict cardiovascular events and mortality in acute ischemic stroke (AIS) without atrial fibrillation (AF) and coronary heart disease (CHD). Methods: Transthoracic echocardiography was conducted consecutively in patients with AIS or transient ischemic attack at Soonchunhyang University Hospital between January 2008 and July 2016. The clinical data and echocardiographic LVEF of 1,465 patients were reviewed after excluding AF and CHD. Poststroke disability, major adverse cardiac events (MACE; nonfatal stroke, nonfatal myocardial infarction, and cardiovascular death) and all-cause mortality during 1 year after index stroke were prospectively captured. Cox proportional hazards regressions analysis were applied adjusting traditional risk factors and potential determinants. Results: The mean follow-up time was $259.9{\pm}148.8days$ with a total of 29 non-fatal strokes, 3 myocardial infarctions, 33 cardiovascular deaths, and 53 all-cause mortality. The cumulative incidence of MACE and all-cause mortality were significantly higher in the lowest LVEF (<55) group compared with the others (p=0.022 and 0.009). In prediction models, LVEF (per 10%) had hazards ratios of 0.54 (95% confidence interval [CI], 0.36-0.80, p=0.002) for MACE and 0.61 (95% CI, 0.39-0.97, p=0.037) for all-cause mortality. Conclusions: LVEF could be an independent predictor of cardiovascular events and mortality after AIS in the absence of AF and CHD.

• The Korean Journal of Emergency Medical Services
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• v.9 no.2
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• pp.111-128
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• 2005

Background: Cardiac arrest is one of the most critical diseases which can likely lead to severe cerebral disability or brain death when the cases can not recover their circulation within 10 minutes. Saving out-of-hospital cardiac arrest cases is a recent concern in Korea. Resuscitation has become an important multidisciplinary branch of medicine, demanding a spectrum of skills and attracting a plethora of specialities and organizations. The best survival can be achieved if all the following links have been optimized : rapid access, and early CPR, defibrillation and ACLS, 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, it is not known how effective resuscitation has become to the patients. In other words, there are no guidelines for reviewing, reporting, and conducting research on resuscitation in Korea. This dissertation aims to provide the basic data for a unified reporting guideline of resuscitation in Korea and evaluating the out-of-hospital factors associated with survival discharge of out-of-hospital cardiac arrest. Methods: As for this study, uses the collected data about Out-of-hospital cardiac arrests at 4 area, from January, 2005 to April. 2005. With a retrospective study, 174 cases were analyzed. The data was recorded based on the Out-of-Hospital Utstein Style. Results: Resuscitation was performed on 174 out-of-hospital cardiac arrest cases at the 4 area 14 patients(8.1%) recovered their spontaneous circulation. Overall, the ROSC of the out-of-hospital cardiac arrest patients was 8.1%, which was poorer than that of western countries. Gender distribution was 50 females(28.7%) and 124 males(71.3%), approximately twice as many males as females. ROSC of witnessed arrests was found out to be 97.7%. The ratio of the witnessed arrest groups showed higher results than that of unwitnessed arrest groups in the above-examined cases. Cardiac etiology consisted of cardiac(33.5%), non-cardiac(45.7%), trauma(20.1%), and unknown(6.0%). Cardiac was the best performance. Initial rhythm showed Ventricular Tachycardia/pulseless Ventricular Fibrillation in 8 patients(6.0%), asystole in 100(75.2%) and unknown in 25(18.8%). The results of the Ventricular Tachycardia/pulseless Ventricular Fibrillation showed higher results than the others cases, The proportion of the cardiogenic cause was 33.5%, which was only half of western countries. Ventricular Tachycardia/pulseless Ventricular Fibrillation is relatively rare. These differences were due to the prevalent pattern of Out-of-hospital cardiac arrest as well as prematurity of the EMSS. Bystander CPR was practiced on 13 patients(7.52%). ROSC was shown in 46.2% cases. CPR by EMT was carried out on 167 cases(96.5%). ACLS by EMf was rare. From collapse, 4 cases(2.6%) arrived to ED within 6 minutes. 13 (8.6%) within 10 minutes, and 49(32.5%) over 31 minutes. The sooner the patients arrived, the greater the ratio of ROSC and discharged alive became, and the same with collapse time to ROSC. As the results of the logistic regression analysis, ROSC was found out to be highly influenced by the time of ED arrival from collapse and Ventricular Tachycardia/pulseless Ventricular Fibrillation. Therefore, the ratio of ROSC depends on not any single factor but various intervention factors. Conclusion: This dissertation presents the following suggestions and directions of the study hereafter. First, the first step for a chain of survival should be taken to activate EMSS early with a phone as soon as cardiac arrests are witnessed. Second, it is keenly needed that emergency medical technicians should be increased through emergency education for living. Third, it is necessary to establish the emergency transportation system. Fourth, most of the Koreans have little understanding of EMT and the present operation systems have many problems, which should be fundamentally changed. Fifth, it is required to have an active medical control over Out-of-hospital CPR, And proper psychological supports should be given not only to patients themselves and their family but also individuals who are engaged in emergency situation. Finally, through studies hereafter on nationwide, comprehensive, and standard forms, it is needed to examine into the biological figures of human body, causes and trends of cardiac arrests, and then, to enhance the survival rate of Out-of-hospital cardiac arrests. Korean guidelines for Cardiopulmonary resuscitation need to be made.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.2
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• pp.988-1001
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• 2018

Arrhythmia has recently emerged as one of the major causes of death in Koreans. Premature Ventricular Contraction (PVC) is the most common arrhythmia that can be found in clinical practice, and it may be a precursor to dangerous arrhythmias, such as paroxysmal insomnia, ventricular fibrillation, and coronary artery disease. Therefore, we need for a method that can detect an abnormal heart beat and diagnose arrhythmia early. We extracted the features corresponding to the QRS pattern from the subject's ECG signal and classify the premature ventricular contraction waveform using the features. We modified the weighting and bias values based on the error back-propagation algorithm through learning data. We classify the normal signal and the premature ventricular contraction signal through the modified weights and deflection values. MIT-BIH arrhythmia data sets were used for performance tests. We used RR interval, QS interval, QR amplitude and RS amplitude features. And the hidden layer with two nodes is composed of two layers to form a total three layers (input layer 0, output layer 3).

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.393-395
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• 2009

심장의 활성 근육의 움직임에 의하여 발생되는 전기적 변화량을 나타내는 심전도는 부정맥 또는 허혈성 심장질환을 진단하는데 널리 활용되고 있다. 특히 심실빈맥(Ventricular Tachycardia) 또는 심실세동(Ventricular Fibrillation)과 같이 치명적인 심장리듬이 발생하기 이전에, 심실조기수축(Ventricular Premature Contraction)을 검출하여 생명을 위협할 수 있는 부정맥을 조기에 진단할 수 있는 연구들이 일부 진행되고 있다. 이에 따라서 본 연구에서는 심전도 신호의 R-R 간격 정보와 R-peak 정보의 진위성을 판단하여 PVC 부정맥 패턴뿐만 아니라 PVC 파형이 연속적으로 진행되는 PVC-RUNs을 효율적으로 검출할 수 있는 부정맥 진단 알고리즘을 제안하고자 하였다.

• Journal of Chest Surgery
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• v.20 no.2
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• pp.241-250
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• 1987

We scrutinized the preoperative electrocardiographic and hemodynamic findings in adult atrial septal defects older than 15 years, and then followed up the postoperative electrocardiographic changes sequentially. In preoperative electrocardiographs, the mean PR interval [0.17 sec] was prolonged than normal adults [M;0.13,F;0.15], and the mean QRS axis [93.1*] was deviated to rightward than normal [M;63.7*,F;64.4*], and 122 cases of all 159 patients [77.8%] were in RAD quadrant. The QRS morphology was classified into three groups; a] crista supraventricularis hypertrophy, 25 cases, b] right ventricular outflow tract hypertrophy, 89 cases, c] right ventricular hypertrophy, 44 cases, and normal rs pattern, 1 case. Comparing the QP/QS, Pp/Ps, Rp/Rs in these three groups, Qp/Qs increased a] 2.65 to b] 2.97 and decreased b] 2.97 to c] 2.55, Pp/Ps increased a] 0.27 to b] 0.35 to c] 0.44, and Rp/Rs increased a] 0.1 to b] 0.14 to c] 0.2. In comparing the atrial fibrillation with sinus rhythm, the patient`s mean age was increased [26.4 to 45.7], the mean Qp/Qs was decreased [2.97 to 2.7], the mean Pp/Ps was increased [0.35 to 0.46], the mean Rp/Rs increased [0.14 to 0.2], and the QRS morphology was RVOT hypertrophy;7 cases, RVH;2 cases in all 11 cases. Therefore, the atrial fibrillation was appeared in progressed status. Increasing the mean pulmonary arterial pressure, size of the R` wave in Vl lead increased, and the QRS morphology tended to become severe patterns. Postoperatively, the PR interval shortened and QRS axis tended to normal axis quadrant, and size of R` wave decreased sequentially, atrial fibrillation disappeared in 4 cases. Conclusively, by use of the conventional surface electrocardiography, we could anticipate the hemodynamic changes and the prognosis at outpatient department.

• Journal of IKEEE
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• v.25 no.1
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• pp.212-217
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• 2021

Premature contraction arrhythmia is the most common disease among arrhythmia and it may cause serious situations such as ventricular fibrillation and ventricular tachycardia. Most of arrhythmia clasification methods have been developed with the primary objective of the high detection performance without taking into account the computational complexity. Also, personalized difference of ECG signal exist, performance degradation occurs because of carrying out diagnosis by general classification rule. Therefore it is necessary to design efficient method that classifies arrhythmia by analyzing the persons's physical condition and decreases computational cost by accurately detecting minimal feature point based on only QRS features. We propose method for personalized specific classification of premature contraction arrhythmia based on QRS features in smart healthcare environments. For this purpose, we detected R wave through the preprocessing method and SOM and selected abnormal signal sets.. Also, we developed algorithm to classify premature contraction arrhythmia using QRS pattern, RR interval, threshold for amplitude of R wave. The performance of R wave detection, Premature ventricular contraction classification is evaluated by using of MIT-BIH arrhythmia database that included over 30 PVC(Premature Ventricular Contraction) and PAC(Premature Atrial Contraction). The achieved scores indicate the average of 98.24% in R wave detection and the rate of 97.31% in Premature ventricular contraction classification.