• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.221-223
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• 2010

Considering the similarity between fluid vortex and arrhythmogenic reentrant waves in heart, we applied the non-dimensionalization method in fluid dynamics to arrhythmia analysis and discovered a new non-dimensional simulation results, there was a threshold value of the number that resulted in the induction of a reentrant wave.

• Proceedings of the KOSOMBE Conference
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• v.1991 no.05
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• pp.94-97
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• 1991

It is well known that multipoint and computerized intraoperative mapping systems improve the results of surgery for Wolff-Parkinson-White syndrome and show tremendous potential for opening an entirely new era of surgical intervention for the more common and lethal types of supraventricular tachyarrhythmias such as atrial flutter and atrial fibrillation. In addition, the ability to map and ablate the sometimes fleeting automatic atrial tachycardia is greatly enhanced by computerized mapping systems. In this study, we have developed 16 channel computerized data analysis system using microcomputer for basic research of electrophysiology and electrical propagation. This system is expected to enable us to study pathophysiology of cardiac arrhythmia and to improve the results of diagnosis and surgical treatment for cardiac arrhythmia.

• Investigative Magnetic Resonance Imaging
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• v.18 no.3
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• pp.244-252
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• 2014

Purpose : We proposed a multi-physiological signals based real-time intelligent triggering system(MITS) for Cardiac MRI. Induced noise of the system was analyzed. Materials and Methods: MITS makes cardiac MR imaging sequence synchronize to the cardiac motion using ECG, respiratory signal and second order derivative of $SPO_2$signal. Abnormal peaks due to arrhythmia or subject's motion are rejected using the average R-R intervals and R-peak values. Induced eddy currents by gradients switching in cardiac MR imaging are analyzed. The induced eddy currents were removed by hardware and software filters. Results: Cardiac MR images that synchronized to the cardiac and respiratory motion are acquired using MITS successfully without artifacts caused by induced eddy currents of gradient switching or subject's motion or arrhythmia. We showed that the second order derivative of the $SPO_2$ signal can be used as a complement to the ECG signals. Conclusion: The proposed system performs cardiac and respiratory gating with multi-physiological signals in real time. During the cardiac gating, induced noise caused by eddy currents is removed. False triggers due to subject's motion or arrhythmia are rejected. The cardiac MR imaging with free breathing is obtained using MITS.

• The Journal of the Korean life insurance medical association
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• v.18
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• pp.103-106
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• 1999

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.1
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• pp.16-22
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• 2010

Electrocardiogram(ECG) analysis and arrhythmia recognition are critical for diagnosis and treatment of ill patients. Cardiac arrhythmia is a condition in which heart beat may be irregular and presents a serious threat to the patient recovering from ventricular tachycardia (VT) and ventricular fibrillation (VF). Other arrhythmias like atrial premature contraction (APC), Premature ventricular contraction (PVC) and superventricular tachycardia (SVT) are important in diagnosing the heart diseases. This paper presented new method to classify various arrhythmias contrary to other techniques which are limited to only two or three arrhythmias. ECG is decomposed into Intrinsic Mode Functions (IMFs) by Empirical Mode Decomposition (EMD). Burg algorithm was performed on IMFs to obtain AR coefficients which can reduce the dimension of feature vector and utilized as Multi-class SVM inputs which is basically extended from binary SVM. We chose optimal parameters for SVM classifier, applied to arrhythmias classification and achieved the accuracies of detecting NSR, APC, PVC, SVT, VT and VP were 96.8% to 99.5%. The results showed that EMD was useful for the preprocessing and feature extraction and multi-class SVM for classification of cardiac arrhythmias, with high usefulness.

• The Journal of Korean Medicine
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• v.42 no.3
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• pp.44-55
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• 2021

Objectives: As the use of herbal medicinal products (HMPs) increases worldwide, systematic verification of the safety of HMPs is required. The induction of cardiotoxicity is one of the major factors in post-approval withdrawal of medicinal products, and drug-induced cardiotoxicity assessment is emerging as an important step in drug development. In the present study, we evaluated human ether-à-go-go-related gene (hERG) potassium channel-related cardiotoxicity to predict the risk of cardiac arrhythmia in thirteen herbal medicines known to have cardiac toxicity. Methods: We measured the inhibition rate of hERG potassium channel activity of 13 medicinal herbal extracts in hERG-expressing HEK 293 cells using an automated patch-clamping system. Quinidine was used as a positive control for inhibition of hERG activity. Results: Extracts of Evodiae Fructus, Strychni Semen, and Corydalis Tuber potently inhibited the activity of hERG, and IC₅₀ values were 3.158, 19.87, and 41.26 ㎍/mL, respectively. Cnidi Fructus, Ephedra Herba, Lithospermi Radix, Polygoni Multiflori Radix, Visci Ramulus et Folium, Asiasari Radix et Rhizoma, and Scolopendra weakly inhibited hERG activity, and the IC₅₀ value for each herbal medicine was more than 400 ㎍/mL. Aconiti Kusnezoffii Tuber and two types of Aconiti Lateralis Radix Preparata (Po and Yeom) had weak inhibitory activity against hERG, and the IC₅₀ values were more than 700 ㎍/mL. The IC₅₀ value of quinidine against hERG was 1.021 𝜇M. Conclusion: Evodiae Fructus, Strychni Semen, and Corydalis Tuber acted as potent inhibitors against hERG. These herbal medicines may cause cardiac arrhythmia through QT prolongation, so care should be taken when taking them.

• Childhood Kidney Diseases
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• v.27 no.2
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• pp.105-110
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• 2023

Purpose: To analyze electrocardiograms (ECGs) of patients with a salt-losing tubulopathy (SLT) and to determine the frequency and risk factors for long QT and arrhythmia. Methods: A total of 203 patients aged <19 years with SLT, specifically Bartter syndrome and Gitelman syndrome, who had a 12-lead ECG were included in this retrospective study. We analyzed the presence of an arrhythmia or prolonged corrected QT (QTc) on ECGs obtained for these patients. Demographic and laboratory data were compared between patients with abnormal and normal ECG findings. Results: Out of the 203 SLT patients, 38 (18.7%) underwent electrocardiography and 10 (40.0%) of 25 patients with inherited SLT had abnormal ECG findings, including prolonged QTc and arrhythmias. The abnormal ECG group had significantly lower serum potassium levels than the normal group (median [interquartile range]: 2.50 mmol/L [2.20-2.83] vs. 2.90 mmol/L [2.70-3.30], P=0.036), whereas other serum chemistry values did not show significant differences. The cutoff level for a significant difference in QTc interval was serum potassium level <2.50 mmol/L. One cardiac event occurred in a 13-year-old boy, who developed paroxysmal supraventricular tachycardia and underwent cardiac ablation. No sudden cardiac deaths occurred in this cohort. Conclusions: The incidence of ECG abnormalities in patients with inherited SLT was 40.0%, whereas the ECG screening rate was relatively low (18.7%). Therefore, we recommend ECG screening in patients with inherited SLT, especially in those with serum potassium level <2.50 mmol/L.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.945-949
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• 2014

In cardiac magnetic resonance imaging (CMRI), heart and respiratory motions are one of main obstacles in obtaining diagnostic quality of images. To synchronize CMRI to the physiological motions, ECG and respiratory gatings are commonly used. In this paper multi-biological signal (ECG, respiratory, and SPO2) based smart trigger system is proposed. By using multi-biological signal, the proposed system is robust to the induced noise such as eddy current when gradient pulsing is continuously applied during the examination. Digital conversion of the multi-biological signal makes the system flexible in implementing smart and intelligent algorithm to detect cardiac and respiratory motion and to reject arrhythmia of the heart. The digital data is used for real-time trigger, as well as signal display, and data storage which may be used for retrospective signal processing.

• Journal of Biomedical Engineering Research
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• v.16 no.1
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• pp.107-113
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• 1995

It is well known that multipoint and computerized intraoperative mapping systems improve the results of surgery for Wolff-Parkinson-White syndrome and show tremendous potential for opening an entirely new era of surgical intervention for the more common and lethal types of supraventricular tachyarrhythmias such as atrial flutter and atrial fibrillation. In addition, the ability to map and ablate the sometimes fleeting automatic atrial tachycardia is greatly enhanced by computerized mapping systems. In this study, we have developed 64 channel computerized data analysis system using microcomputer (Macintosh ${II}_{x}$) for basic research of electrophysiology and electrical propagation. The bipolar electrogram information is acquired from 64 cardiac sites simultaneously at a sampling rate of 1 ksampls/sec with continuous and total data storage of up to 30 seconds. When the reference electrogram is selected and reference point is picked up, delay time from the reference point is displayed on two dimensional diagram of the heart. System design permits easy expansion to almost 256 simultaneous sites. this system is expected to enable us to study pathophysiology of cardiac arrhythmia and to improve the result of diagnosis and surgical treatment for cardiac arrhythmia.

• Journal of Chest Surgery
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• v.50 no.3
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• pp.171-176
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• 2017

Background: In elderly patients who have atrial fibrillation (AF), surgical ablation of the arrhythmia during cardiac surgery may be challenging. Despite the reported advantages of ablating AF with the Cox maze procedure (CMP), the addition of the CMP may complicate other cardiac operations. We evaluated the effect of the CMP in elderly patients concurrent with other cardiac operations. Methods: From October 2007 to December 2015, we enrolled 27 patients aged >70 years who had AF and who underwent the CMP concurrently with other cardiac operations. The mean preoperative additive European System for Cardiac Operative Risk Evaluation score was $8{\pm}11$ (high risk). Results: Only 1 hospital death occurred (4%). The Kaplan-Meier method showed a high 5-year cumulative survival rate (92%). At mean follow‐up of 51 months, 23 patients (89%) had sinus rhythm conversion. The postoperative left atrial dimensions did not significantly differ between the 8 patients who had reduction plasty for giant left atrium ($53.4{\pm}7.5cm$) and the 19 patients who did not have reduction plasty ($48.7{\pm}5.7cm$). Conclusion: In patients aged >70 years, concurrent CMP may be associated with a high rate of sinus rhythm conversion without increased surgical risk, despite the added complexity of the main cardiac procedure.