• Journal of the Institute of Electronics Engineers of Korea SC
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• v.42 no.5 s.305
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• pp.27-34
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• 2005

Ventricular fibrillation(VF) is generally caused by chaotic behavior of electrical propagation in heart and may result in sudden cardiac death. In this study, we proposed a ventricular fibrillation detection algorithm based on support vector machine classifier, which could offer benefits to reduce the teaming costs as well as good classification performance. Before the extraction of input features, raw ECG signal was applied to preprocessing procedures, as like wavelet transform based bandpass filtering, R peak detection and segment assignment for feature extraction. We selected input features which of some are related to the rhythm information and of others are related to wavelet coefficients that could describe the morphology of ventricular fibrillation well. Parameters for SVM classifier, C and ${\alpha}$, were chosen as 10 and 1 respectively by trial and error experiments. Each average performance for normal sinus rhythm ventricular tachycardia and VF, was 98.39%, 96.92% and 99.88%. And, when the VF detection performance of SVM classifier was compared to that of multi-layer perceptron and fuzzy inference methods, it showed similar or higher values. Consequently, we could find that the proposed input features and SVM classifier would one of the most useful algorithm for VF detection.

• Journal of Chest Surgery
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• v.16 no.1
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• pp.55-64
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• 1983

A hundred and eleven patients of mitral valvular heart disease, who were operated at Seoul National University Hospital, were analysed with echocardiogram before and after operation during the period from November 1979 to February 1982. Twenty-eight patients had mitral stenosis and eighty-three mitral regurgitation. In patients with mitral stenosis, right ventricular end-diastolic volume was in normal range at preoperative and postoperative period. But the left ventricular end-systolic volume was slightly increased preoperatively to 35.4mm and decreased to 33.5mm on immediate postoperative period and 32.5mm after a year later. The left ventricular end-diastolic volume was 50.5mm preoperatively and fell to 46.8mm postoperatively. Ejection fraction was normal preoperatively and postoperatively without changes. Left atrial size fell significantly from 50ram to 37.6mm at the time of late follow-up study. With mitral regurgitation, right ventricular end-diastolic volume was also normal preoperatively and postoperatively. The left ventricular end-systolic volume was increased to 41.9mm and decreased to 31.6mm postoperatively with statistic significance. Left ventricular end-diastolic volume fell from 58.5mm to 45.7mm significantly at the time of late follow-up period. Ejection fraction was also within normal range and had no changes postoperatively. Left atrial size fell from 54.8mm to 45.5mm on a year later [ p value less than 0.01 ]. When atrial fibrillation, the left atrial dimension was increased as 54.9mm compared with 46.8mm of no atrial fibrillation patients.

• Journal of Yeungnam Medical Science
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• v.26 no.2
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• pp.148-155
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• 2009

Brugada syndrome is characterized by an ECG pattern of right bundle branch block and ST segment elevation in the right precordial leads ($V_1-V_3$) without structural heart disease. It is also characterized by sudden cardiac death that's caused by ventricular fibrillation. This is a familial syndrome with an autosomal dominant inheritance pattern and it may be considerably more common in Southeast Asia. Many factors during anesthesia can precipitate malignant dysrrhythmia in these patients, so careful choice of anesthetics is required. We experienced a case of Brugada syndrome in a 59-year-old male patient who was under general anesthesia for trans-sphenoidal surgery to treat a pituitary adenoma, and the patient was diagnosed as having Brugada syndrome without any untoward cardiovascular events.

• Journal of Biomedical Engineering Research
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• v.20 no.6
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• pp.561-571
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• 1999

심실세동은 환자의 생명을 위협하는 가장 치명적인 부정맥으로서, 심실세동의 발견즉시 특별한 조치를 취하지 못할 경우 환자는 급사한다. 심실세동을 정지시키는 유일한 방법은 전기적 제세동이며 이는 환자의 심장 부위에 전기적 에너지를 가해 정상 심장 리듬을 되찾도록 하는 방법이다. 심실세동의 발생은 예측할 수 없고, 이를 진단하기 위한 심전도 교육을 모든 의료인에게 할 수 없으므로 심전도를 자동 분석하여 심실세동을 조기에 검출하는 자동 분석장치의 개발은 심실세동에 의한 급사를 줄이는데 매우 중요하다. 본 연구에서는 교차간섭성분의 제거 능력이 뛰어나며 쉽게 구사할 수 있는 Choi-Williams distriguteion (CWD) 방법을 이용하여 급사를 초래할 수 있는 심실세동을 자동 검출하는 알고리즘을 개발하였다. 그리고 개발된 알고리즘의 성능을 검증하기 위하여 본 논문에서는 두 그룹의 심실세동 데이터를 사용하였다. 검출 알고리즘은 심실세동의 시간 및 주파수 특성을 일곱가지 조건들에 대한 만족 여부를 이용하여 심실세동을 판정하였고, 실험의 민감도와 선택도는 각각 92.1%, 97 .2% 이다.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.873-874
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• 2006

In this paper, we have developed a ventricular fibrillation detection system based on DSP processor. The developed system was able to detect VF in real time correctly and quickly. We compared the performance of the floating point simulation with that of fixed point simulation. The computational cost of fixed point simulation was remarkably reduced than that of floating point simulation.

• Journal of Yeungnam Medical Science
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• v.24 no.2
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• pp.197-205
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• 2007

Background : The occurrence of atrial fibrillation after ablation of atrial flutter is clinically important. We investigated variables predicting this evolution in ablated patients without a previous atrial fibrillation history. Materials and Methods : Thirty-six patients (Male=28) who were diagnosed as atrial flutter without previous atrial fibrillation history were enrolled in this study. Group 1 (n=11) was defined as those who developed atrial fibrillation after atrial flutter ablation during 1 year follow-up. Group 2 (n=25) was defined as those who has not occurred atrial fibrillation during same follow-up term. Echocardiogram was performed to all patients. We measured left atrial size, left ventricle end diastolic and systolic dimension, ejection fraction and left atrial volume index before and after ablation of atrial flutter. The differences of each variables were compared and analyzed between two groups. Results : The preablation left ventricular ejection fraction (preLVEF) and postablation left ventricular ejection fraction (postLVEF) are $54{\pm}14%$, $56{\pm}13%$ in group 1 and $47{\pm}16%$, $52{\pm}13%$ in group 2. The differences between each two groups are statistically insignificant ($2.2{\pm}1.5$ in group 1 vs $5.4{\pm}9.8$ in group 2, p=0.53). The preablation left atrial size (preLA) and postablation left atrial size (postLA) are $40{\pm}4mm$, $41{\pm}4mm$ in group1 and $44{\pm}8mm$, $41{\pm}4mm$ in group 2. The atrial sizes of both groups were increased but, the differences of left atrial size between two groups before and after flutter ablation were statistically insignificant ($0.6{\pm}0.9mm$ in group 1 vs $-3.8{\pm}7.4mm$ in group 2, p=0.149). The left atrial volume index before flutter ablation was significantly reduced in group 1 than group 2 ($32{\pm}10mm^3/m^2$, $35{\pm}10mm^3/m^2$ in group 1 and $32{\pm}10mm^3/m^2$, $29{\pm}8mm^3/m^2$ in group 2, p<0.05). Conclusion : The difference between left atrial volume index before and after atrial flutter ablation is the robust predictor of occurrence of atrial fibrillation after atrial flutter ablation without previous atrial fibrillation.

• Journal of Chest Surgery
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• v.25 no.12
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• pp.1404-1415
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• 1992

To understand the factors influencing Atrial fibrillation and embolism in mitral valve surgery and prevent their risk, we have reviewed our 324 patients who underwent mitral valve surgery from Fev. 1982 to May 1992. Age, disease duration, lesion type, left ventricular function and left atrial dimension were chosen as preoperative factors influencing the incidence of atrial fibrillation and embolism and their postoperative course, The number and type of replaced valve, site of atriotmy, LA obliteration, ACT and use of Defibrillator were chaser. as operative factors influencing postoperative rhythm change and postop emb-olization. The results of analyses were as follows 1. The incidence of preoperative atrial fibrillation, systemic embolism and LA throbmus was 63. 6%, 10.56% and 19.8% relatively. 2. The preoperative factors of atrial fibrillation onset was old age, prolonged symptom duration, stenotic lesion, lager LAD and lower ejection fraction. In the preoperative systemic embolism preoperative factors were old age, female, stenotic lesion. The left atrial thrombus found more commonly in patients with atrial fibrillation, old age, prolonged symptom duration, stenotic lesion and low ejection fraction. 3. The preoperative atrial fibriation persisted postoperatively in 165[50.9%] and converted to normal sinus rhythm in 50[15.4%]. The preoperative normal sinus rhythm per-eisted in 100[31%] and atrial fibrillation was occured postoperatively in 9[2.7%]. The prolonged symptom duration was the preoperative factor of persist atrial fibrillation. 4. Among 95 long term follow-up patients, atiral fibrillation was continued in 59[60%]. Conversion to normal sinus rhythm was more common significantly in left atriotomy and bileaflet valve replacement. 5. There were 12 patients who had postoperative embolism. Female, persist atrial fibrillation, no LA olbiteration and tilting disc monocusp valve were considered as possible factors influencing postoperative embolism but was impossible to analyse their statistical significance due to small sample size. So we have concluded that the patients with above risk factors need anticoagulant and early surgical intervention. Left atriotomy with minimal atrial injury, left auricular obliteration and bileaflet valve replacement may be needed to reduce postoperative atrial fibrillation persist and embolism.

• Journal of The Korean Society of Clinical Toxicology
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• v.5 no.1
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• pp.67-70
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• 2007

Aconitum is an extremely dangerous plant that contains various toxic diterpenoid alkaloids, primarily concentrated in the roots. We report a case of acute intoxication of a 60-year-old man admitted to our emergency department after ingestion of a large amount of homemade aconitine decoction. At presentation about one hour after intake, the patient was unconscious and electrocardiographic analysis showed a ventricular tachycardia/fibrillation. Several times defibrillation was applied and antiarrhythmic agents were administered, but the patient still exhibited a refractory ventricular fibrillation and failed to return to spontaneous circulation. Sustained cardiopulmonary resuscitation finally produced a pulsatile cardiac rhythm at two hours after intake. The patient was discharged from our hospital on day 8. The authors stress that clinicians must be aware of the possible occurrence of life-threatening ventricular arrhythmia in cases of aconitine intoxication and be prepared to persist with prolonged CPR as necessary.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.4
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• pp.181-188
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• 2006

The purpose of this study is to predict the defibrillation success of a ventricular Fibrillation ECG signal using time-frequency analysis. During CPR, coronary perfusion pressure and electrocardiogram were measured. Parameters extracted from time-frequency domain were served as predictor of resuscitation success. Time frequency distribution(TFD) of ECG signals was estimated from the smoothed pseudo Wigner-Ville distribution(SPWVD). Median frequency, peak frequency, 1/f slope, frequency band ratios$(2{\sim}4Hz,\;4{\sim}6Hz,\;6{\sim}8Hz,\;8{\sim}10Hz,\;10{\sim}12Hz,\;12{\sim}15Hz)$ were extracted from each TFD as function of time. Paired t-test was used to determine the differences in ROSC and non-ROSC groups. In the statistical results, we selected four significant parameters - median frequency, 1/f slope, $2{\sim}4Hz$ band ratio, $8{\sim}10Hz$ band ratio. We made an attempt to predict defibrillation success by combining features extracted from time frequency distribution. Independent t-test was used to determine the differences ROSC and non-ROSC groups. Consequently, we selected four significant parameters-median frequency, 1/f slope, $2{\sim}4Hz$ band ratio, $8{\sim}10Hz$ band ratio. The relationship between coronary perfusion pressure and ECG parameters was analyzed with linear regression analysis. R-square value was 55%. 1/f slope and $8{\sim}10Hz$ band ratio had the significant relationship with coronary perfusion pressure.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.1
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• pp.47-52
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• 1999

Blood flow restoration to ischemic zone of the heart is essential to salvage of ischemic tissue. However, there is a large body of evidence documenting that the reperfusion can induce reperfusion injury like reperfusion-induced malignant arrhythmias. In the present study, employing a cat model of regional cardiac ischemia, we examined if reperfusion rendered in a gradual fashion could lower the incidence of reperfusion-induced ventricular fibrillation (VF), which usually precipitated within a few to several tens of seconds after abrupt reperfusion. The experiments were conducted with male mongrel cats (n=46, 2.5-5 kg). The animals in the control and 30 MIN groups were subjected to an episode of 20- and 30-min left anterior descending coronary artery occlusion, respectively, followed by abrupt reperfusion. The animals in 5 G and 10 G groups received gradual reperfusion over a 5- and 10-min period, respectively, following a 20-min occlusion. The proportion of animals that exhibited VF during the reperfusion phase was 11/15 in the control, 7/10 in the 30 MIN, 5/10 in the 5 G and 2/11 in the 10 G groups. The incidence of VF in the 10 G group was significantly lower than that in the control or 30 MIN group subjected to abrupt reperfusion. These results suggest that the gradual reperfusion is a useful procedure against reperfusion-induced VF.