• Proceedings of the PSK Conference
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• 2002.10a
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• pp.247.1-247.1
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• 2002

A number of patients suffering from atrial fibrillation are increasing and many cardiologists are trying to develop the ideal antiarrhythmic drugs for atrial fibrillation. Previously, we found out that CW-2202, a furanocoumarin derivative inhibited the hKvl.5 current expressing predominantly in human atrium without affecting the HERG current expressing mainly in ventricle. (omitted)

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.132-132
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• 2006

Filler loading (fiber or particulate) usually increases the melt viscosity of polymers. In contrast, the addition of these fillers and fibrillation of thermotropic liquid crystalline polymer (LCP) jointly decreased the viscosity of polymer melts to lower than those of pure component polymers, filler-loaded or LCP-blended ones; and even decreased the viscosity with increasing filler loading. Termed as rheological hybrid effect, this phenomenon correlated well with the LCP fibrillation in these ternary systems. Research taking fillers of various shapes and sizes showed that the filler addition promoted the LCP fibrillation, depending upon thermodynamic and dynamic factors involved.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1665-1668
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• 2008

Arrhythmia causes sudden cardiac death. In the past, there were medical limitations in finding the cause of arrhythmia. As an alternative solution for research of arrhythmia, there have been studies to find the causes of arrhythmia by producing a virtual heart model. Medically, arrhythmia has two main causes: abnormal occurrence of action potential and abnormal conduction of action potential. Based on these, the tachycardia, which is one of the arrhythmia, was manifested and the phenomenon of ventricular fibrillation was numerically analyzed in this study. For this purpose, an electrophysiological model of ventricular cells was implemented, which was subsequently applied to the reaction-diffusion partial differential equation to interpret the macroscopic conduction phenomenon in two-dimensional tissues. The ventricular fibrillation refers to a condition where several irregular waves occur in cardiac tissue, whose generation mechanism is pathologically related to the cardiac tissue.

• Journal of Korean Institute of Industrial Engineers
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• v.42 no.4
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• pp.290-295
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• 2016

This paper proposes a new method for the automatic detection of atrial fibrillation (AF), using Markov regime switching GARCH (1, 1) model. The proposed method is based on the observation that variability patterns of heart rate intervals during AF significantly differ from regular patterns. The proposed method captures the different patterns of heart rate intervals between two regimes : normal and AF states. We test the proposed method using Massachusetts Institute of Technology-Beth Israel Hospital (MIT-BIH) atrial fibrillation database, and demonstrate the effectiveness of the proposed method.

• Korean Journal of Veterinary Research
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• v.64 no.3
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• pp.20.1-20.6
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• 2024

We describe the first reported case of grain-free diet-induced dilated cardiomyopathy (DCM) in a dog in Korea. An 11-year-old female dog was referred with abdominal distention, anorexia, and vomiting, having been fed a grain-free diet for more than 5 years. Thoracic radiography revealed cardiomegaly and pulmonary edema. Atrial fibrillation was detected using electrocardiography. The dog was tentatively diagnosed with congestive heart failure (CHF) secondary to grain-free diet-induced DCM, and its diet changed to contain grain. Digoxin and diltiazem were prescribed for the atrial fibrillation, and pimobendan, enalapril, and furosemide for CHF. Significant improvements in echocardiographic indices were confirmed after 3 months.

• Textile Coloration and Finishing
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• v.18 no.4
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• pp.20-27
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• 2006

Lyocell is a not only environmentally-friendly but also very advantageous fiber. When Lyocell is soaked in water, its wet tenacity does not decrease and elongation and moisture regain of it are better than cotton. However, one drawback of lyocell is its fibrillation. The fibrills of lyocell were generated during wet process such as scouring and dyeing deteriorates the dyeing color depth and the appearance of fabric. The purpose of this study was to decrease the fibrillation tendency of lyocell fabric using crosslinking agent, epichlorohydrine(ECH). The effects of NaOH scouring and ECH crosslinking were observed. The different types of ECH addition methods to lyocell and the various concentrations of ECH in crosslinking reaction onto dyeing characteristic and fibriallation were investigated. Weight loss and whiteness index of crosslinked lyocell by ECH were examined. K/S values of ECH treated lyocell fabrics dyed with reactive dye were measured and SEM images of untreated and treated lyocells were observed extensively to define the fibrillation tendency. The results were as follows ; 1) ECH treatment showed the effect of weight loss and scouring because ECH crosslinking reaction was conducted in alkaline condition. 2) The increase in ECH concentration from 5 to 30% does not affected K/S value changes. 3) ECH crosslinking can effectively prevent the fibrillation tendency of lyocell.

• Journal of Chest Surgery
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• v.26 no.4
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• pp.249-254
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• 1993

Atrial fibrillation is commonly associated with organic mitral valve disease including rheumatic valvular heart diasease or mitral valve prolapse and so forth. Although spontaneous sinus reversion may occur in some patients after mitral valve operation, recurrence of atrial fibrillation is the rule in most of these patients. We have tried to maintain sinus rhythm after mital valve operation with oral quinidine therapy, and we will show the efficacy of this therapy in this report. From January 1986 to August 1992, 60 patients of mitral valvular heart disease, who had had atrial fibrillation preoperatively and gained sinus rhythm postoperatively, were selected for this study. These patients were divided into 2 groups: Control group [n=30] and Quinidine trial group [n=30]. The age,sex, duration of symptoms,left atrial size and other risk factors of the reversion to atrial fibrillation were adjusted to be similar between the two groups. The maintenance rate of sinus rhythm was calculated by Kaplan-Meier method, and the rate was significantly higher in quinidine trial group than in control group [ p=0.0001 ]. Univariate analysis was performed on the risk factors of reversion to atrial fibrillation, and the difference of maintenance rate between the two groups were corrected with this result: the difference was still statistically significant [ p=0.0205 ]. The quinidine levels were measured in postoperative days, and there were no difference of serum quinidine level between the quinidine success group and quinidine failure group. In conslusion, oral quinidine therapy was effective for the maintenance of sinus rhythm after mitral valve operation compared to control group, and there was no correlation between the serum quinidine level and clinical efficacy of quinidine therpy.

• Journal of Chest Surgery
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• v.44 no.1
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• pp.18-24
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• 2011

Background: We evaluated the efficacy of Cox-maze IV procedure using bipolar irrigated radiofrequency ablation and cryothermy in chronic atrial fibrillation associated with valvular heart disease. Material and Methods: From November 2005 to June 2009, ninety four patients have undergone valvular heart surgery with Cox-maze IV procedure. Preoperative duration of atrial fibrillation was $7.6{\pm}6.5$ years and follow-up duration was $22.7{\pm}12.3$ months. Results: There were two (2.1%) postoperative deaths not related to maze procedure. Two cerebrovascular accidents, five low cardiac output syndromes and two permanent pacemaker implantations have occurred after surgery. Preoperative ejection fraction on echocardiography was $55.3{\pm}8.1%$ and ejection fraction of postoperative six month was $54.7{\pm}6.5%$. Left atrial size of preoperative and postoperative were $61.5{\pm}11.6\;mm$ and $53.1{\pm}8.4\;mm$ at each. Freedom from atrial fibrillation rate at postoperative six-month was 80.7% and the cases of recurrence of atrial fibrillation after six months were three (3.3%). Risk factors for failure or recurrence of maze procedure were old age (p=.010) and preoperative moderate or severe tricuspid regurgitation (p=.033). Conclusion: The Cox-maze IV procedure using RFBP2 and cryothermy is quite safe and freedom from atrial fibrillation at postoperative 6 month was 82.5%. Risk factors for failure or recurrence of atrial fibrillation after Cox-maze IV were old age and preoperative over moderate tricuspid regurgitation.

• 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.

• Journal of Chest Surgery
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• v.30 no.3
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• pp.287-292
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• 1997

.Itrial fibrillation is one of the most common cardiac arrhythmias requiring treatment. About 60% of patients with mitral valvular disease have atrial fibrillation and one third of patients with atrial fibrillation may have the past history of thromboembolic events. Between April 1994 and June 1995, 20 patients with organic heart diseases combined with atrial fibrillation underwent open heart surgery including Cox-maze 111 procedure. There were 6 men and 14 women with an average age of 48 years (range, 31 to 66 years). Nineteen patients had valvular heart diseases and 1 ventricular septal defEct (VSD). Mean duration of atrial fibrillation was 36 months (:42 months) (range, 1 to 132 months). T e past medical history of thromboembolic events was positive in 7 patients (35%) and left atrial thrombus was detected in 9 patients (45%). The concomitant procedures were mitral valve replacement (MVR) and aortic valve replacement (AVR) in 5 patients, MVR in 4, MVd and tricuspid annuloplasty(TAP) in 4, mitral valvuloplasty(Mln) in 3, Mln and Tln in 1, MIW and coronary artery bypass surgery in 1, AVR in 1, and patch closure of VSD in 1. Mean aortic cross-clamping time was 175 minutes (range, 116 to 270 minutes). Atrial fibrillation recurred in 16 patients (80%) during the early postoperative period, but, recurrent atrial fibrillation was converted to regular rhythm at postoperative forty-first day in average. There was no early or late death in this series of 20 patients and postoperative complications were inappropriate tachycardia in 5 patients (25%), low cardiac output syndrome in 3 (15%), aggravated hemiplegic in 1, and acute renal failure in 1. Mean follow-up interval of patient was 16.5 months (range, 10.5 to 24 months) and all patients are currently in regular rhythm. Seventeen patients (85%) are in sinus rhythm and 3 (15%) in junctional rhythm. Right atrial contraction was detected in 95% of patients and left atrial contraction in 63% on postoperative transthoracic echocardiogram. The surgical treatment of atrial fibrillation concomitant with open heart surgery is warranted in the recent clinical setting of improved myocardial protection technique, considering the untoward side-effects of atrial fibrillation.