• The Korean Journal of Physiology
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• 제6권2호
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• pp.31-37
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• 1972

The right cervical vagus nerve was electrically stimulated for 30 sec, and 30 minutes recording cardiac rate responses and electrocardiogram. The main purposes of the present experiment are to determine effect of stimulation frequency on the maintenance of cardiac rate responses and to determine recovery time of sinus rhythm after asystole period followed by idioventricular rhythm during prolonged electrical stimulation of the vagus, and the optimal stimulation parameters for vagal stimulation were studied as well. The results obtained are summarized as follows: 1. The maximum negative chrontropic responses were obtained with the following ranges of electrical parameters. Intensity: 3V-7V, Frequency: 20/sec-60/sec, and pulse duration: 5 msec-20 msec. 2. Compared with the responses from sympathetic effectors, cardiac rate responses to electrical stimulation of vagus nerve were well maintained with all stimulation frequencies. 3. At all stimulation frequencies except 20/sec, sinus node started to take over primary pacemaker activity when cardiac rates were restored to about 38-40/min. 4. It was indicated that upper limit of idioventricular rhythm does not exceed 38-40/min. 5. With the stimulation parameter set of 20/sec-5 msec-3 V, sinus rhythm did not appear during 30 minutes of stimulation period. Therefore, this electrical parameter set appears to be optimal for elicitation of prolonged and maximum cardiac rate responses by vagal stimulation.

• Journal of Communications and Networks
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• 제13권2호
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• pp.113-124
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• 2011

Electrocardiography (ECG) is a widely accepted approach for monitoring of cardiac activity and clinical diagnosis of heart diseases. Since cardiologists have been well-trained to accept 12-lead ECG information, a huge number of ECG systems are using such number of electrodes and placement configuration to facilitate fast interpretation. Our goal is to design a wireless ECG system which renders conventional 12-lead ECG information.We propose the three-pad ECG system (W3ECG). W3ECG furthers the pad design idea of the single-pad approach. Signals obtained from these three pads, plus their placement information, make it possible to synthesize conventional 12-lead ECG signals.We provide one example of pad placement and evaluate its performance by examining ECG data of four patients available from online database. Feasibility test of our selected pad placement positions show comparable results with respect to the EASI lead system. Experimental results also exhibit high correlations between synthesized and directly observed 12-lead signals (9 out of 12 cross-correlation coefficients higher than 0.75).

• International Journal of Computer Science & Network Security
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• 제22권5호
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• pp.127-134
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• 2022

Generally developed for medical testing, electrocardiogram (ECG) recordings seizure the cardiac electrical signals from the surface of the body. ECG study can consequently be a vital first step to support analyze, comprehend, and expect cardiac ailments accountable for 31% of deaths globally. Different tools are used to analyze ECG signals based on computational methods, and explicitly machine learning method. In all abovementioned computational simulations are prevailing tools for cataloging and clustering. This review demonstrates the different effective methods for heart disease based on computational methods for ECG analysis. The accuracy in machine learning and three-dimensional computer simulations, among medical inferences and contributions to medical developments. In the first part the classification and the methods developed to get data and cataloging between standard and abnormal cardiac activity. The second part emphases on patient analysis from entire ECG recordings due to different kind of diseases present. The last part represents the application of wearable devices and interpretation of computer simulated results. Conclusively, the discussion part plans the challenges of ECG investigation and offers a serious valuation of the approaches offered. Different approaches described in this review are a sturdy asset for medicinal encounters and their transformation to the medical world can lead to auspicious developments.

• 스마트미디어저널
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• 제7권4호
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• pp.90-98
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• 2018

심전도 신호는 기본적으로 심장의 전기적 활동에 포함되며 이를 통해 심박수 측정, 심장 박동의 리듬 검사, 심장 이상 진단, 정서 인식 및 생체 인식과 같은 다양한 목적으로 분석 및 활용된다. 본 논문의 목적은 다차원 데이터 배열인 텐서 특성을 가진 다선형 판별분석(MLDA: Multilinear Linear Discriminant Analysis) 기법을 이용하여 개인식별을 수행하고자 한다. MLDA는 상위 차원의 텐서를 포함하는 분류 문제에 대해서 차원 문제를 해결 할 수 있으며, 상호 연관된 부분 공간은 서로 다른 클래스를 구별하기 위해 사용될 수 있다. 제시된 방법의 성능을 검증하기 위해 Physionet의 MIT-BIH데이터베이스를 적용하였다. 이 데이터베이스에 대해 실험한 결과, MLDA는 기존 PCA와 LDA와 비교하여 개인식별 성능이 우수함을 확인하였다.

• 전기학회논문지
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• 제63권9호
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• pp.1286-1293
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• 2014

Typically, studies through the simulation system have been progressed, because the evaluation of the driver's arousal state about the service of a actual train has risk of safety for the driver. When configured event same as the real in simulation system, the ability to cope with an accident situation may be the same each other. But the difference in the state of tension or arousal will occur. In this study, requested to cooperate with the railways in order to escape from these constraints, and the target of the experiment was to real engineer service. I was set about experiment when the train was stopped as safe as possible. As a result, the beta wave of EEG signals that representing complex calculations or anxiety is increased rapidly on the basis of a flag station from at the time of departure. The size of the electrodermal activity signal in response to movement of the body gave a noticeable. In terms of HRV, if the train approach a flag station gradually and the R-R interval is narrowed. So that the driver can be estimated as arousal state. In accordance with this study, if the quantitative standard of arousal state be based on the driver's biosignals will provide, it will be able to take advantage of development the system that would prevent train accidents caused by human error.

• Toxicological Research
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• 제12권2호
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• pp.195-201
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• 1996

Endotoxic shock causes death in humans and animals via extreme hypoperfusion of peripheral organs. A massive production of nitric oxide (NO) both from the endothelical cells and smooth muscle cells has been proposed as a possible mechanism in this process. Since NO attenuated the contractility to vasoconstricting agents such as norepinephrine (NE) by directly acting on the smooth muscle cells, this mechanism was considered mainly as a postsynaptic mechanism. In this research it was investigated whether NO, thus released, also participates in the presynaptic events for the regulation of vascular tone in endotoxic shock. The role of NO was studied by adding NO donors or NO synthase inhibitor $N^\omega $methyl-L-arginine (NMA) in stimulated sympathetic nerves of the mesenteric vascular bed and the Langendorff heart of rats. Sodium nitroprusside (SNP), an NO donor, reduced the pressor responses of isolated mesenteric artery either to electrical stimulation or exogenously administered phenylephrine (PE). In this mesentery, although neither agent influenced NE release, in the presence of the adrenergic $\alpha_2$-receptor antagonist yohimbine, elecrical stimulation-evoked NE release was augumented by SNP. In the heart SNP facilitated the NE release induced by electrical stimulation, while NMA had no effect. From these results it is proposed that there exists a local reflex phenomenon in the junction between the sympathetic nerve terminals and the smooth muscle of resistance blood vessels; by which sympathetic responses are reduced by NO at the postjunctional level while NO facilitates NE release contributing to augumentation of sympathetic tone. All these facts suggest that NO produced during endotoxic shock has dual effects: whereas NO blunts the vasoconstrictive activity of NE at the postsynaptic level, NO presynaptically facilitates the release of NE from sympathetic nerve terminals.

• Clinical and Experimental Pediatrics
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• 제46권10호
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• pp.996-1002
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• 2003

목 적 : Rett 증후군 환자에서는 일반인에서 보다 돌연사의 확률이 높은 것으로 알려져 있으며, 그 원인으로 자율신경계 기능 부전에 의한 치명적인 부정맥 같은 심장의 전기 생리적 불안정성이 가장 의심되고 있다. 본 연구는 Rett 증후군 환자에서 심박수 변이도와 교정 QT 간격을 측정하여 실제로 자율신경 활성도에 문제가 있는지의 여부를 확인하기 위하여 실시하였다. 방 법 : 분자유전학적 염색체검사나 임상적 진단기준에 의하여 진단된 Rett 증후군 환자 12례를 대상군으로, 나이가 비슷한 정상아 30례를 대조군으로 하여 이들에서의 자율신경 활성도인 심박수 변이도와 교정 QT 간격을 측정하여 비교하였다. 심박수 변이도는 24시간 보행 심전도를 기록한 후 디지털화 된 심전도를 자동적으로 분석하여 power spectrum을 만들고 그 중 주파수영역(고주파 성분, 저주파 성분, 극소저주파 성분, LF/HF 비율)과 시간 영역(평균 RR 간격, SDNN, rMSSD, pNN50), 교정 QT 간격을 측정하여 비교하였다. 비교는 세 그룹으로 나누어서 전체 Rett 증후군과 정상 대조군 사이, 전형적인 Rett 증후군과 정상 대조군 사이, 비전형적 Rett 증후군과 정상 대조군 사이에서 실시하였다. 결 과 : 1) Rett 증후군 환자에서는 대조군에서 보다 시간영역의 rMSSD이 통계적으로 의미있게 낮았고(P<0.005), LF/HF 비율이 의미있게 높았으며(P<0.005), 교정 QT 간격도 의미있게 연장되어(P<0.005) 있었다. 2) 전형적인 Rett 증후군 환자에서도 대조군에서 보다 rMSSD이 통계적으로 의미있게 낮았고(P<0.005), LF/HF 비율도 의미있게 높았으며(P<0.05), 교정 QT 간격도 의미있게 연장되어 있었다(P<0.001). 3) 비전형적 Rett 증후군에서도 마찬가지로 rMSSD이 통계적으로 의미있게 낮았고(P<0.05), LF/HF 비율도 의미있게 높았으며(P<0.001), 교정 QT간격도 의미있게 연장되어 있었다(P<0.05). 4) 이상의 결과에서 Rett 증후군에서는 전형적인 환자나 비전형적인 환자 모두 미주신경긴장의 변화와 호흡에 의해 민감한 영향을 받는 rMSSD의 저하가 있었고, 교감-부교감신경 균형성을 나타내는 LF/HF 비율의 증가가 있었으며, 자율신경계에 영향을 받는 교정 QT 간격이 연장되었던 것으로 보아, 교감-부교감신경의 균형성에 이상이 있는 것으로 사료된다. 결 론 : Rett 증후군 환자에서 자율신경 활성도의 지표인 심박수 변이도의 의미있는 저하와 교정 QT 간격의 의미있는 연장이 나타나는 것으로 미루어 보아, 이 질환에서 자주 동반되는 돌연사가 일어나는 원인 중의 하나로 이러한 교감-부교감신경의 불균형을 의심할 수 있겠다.

• 대한의생명과학회지
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• 제24권1호
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• pp.43-49
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• 2018

Electrocardiogram (ECG) is a widely used method to diagnose electrical activity of heart. Although it is a reliable and easy method, ECG could be interfered by electrical signals. One of the interfering signals is electromyogram (EMG) that is caused by muscle contraction in any parts of the body except heart. To avoid the EMG noise, an examinee is advised to be relaxed on supine position while measuring ECG. Sometimes, patients who can't put their arms and legs down on bed due to some reasons such as cast on arms or legs necessarily have the EMG noise. But detailed information about how much of the noise could be induced by positional change of arms and legs has not been reported. Here we examined the noise by analyzing ECG data from 14 candidates, 7 males and 7 females. The ECG data was obtained using the standard 12 lead ECG. EMG noise was induced by raising arms and legs at $90^{\circ}$, $60^{\circ}$ or $30^{\circ}$. Because arms are located close to the heart, noise by the raised arms was analyzed toward left or right arm separately. All of the examinees showed similar pattern of the EMG noise. EMG noise by positional change of left or right arm was clearly monitored in different limb leads. Change of leg positions induced the noise that was monitored in aVF of augmented leads and II and III of limb leads. There was a difference in degree of the noise between male and female examinees. In addition to the EMG noise, decrease of PR interval was monitored in particular positional changes, which was prominent in male examinees. These results will enlarge fundamental understanding about EMG noise in ECG.

• The Korean Journal of Physiology and Pharmacology
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• 제7권6호
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• pp.333-339
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• 2003

It has been demonstrated that an unidentified cytosolic factor(s) reduces $K_{ACh}$ channel function. Therefore, this study attempted to elucidate the cytosolic factor. Fresh cytosol isolated from normal heart (FC) depressed the $K_{ACh}$ channel activity, but cytosol isolated from the ischemic hearts (IC) did not modulate the channel function. Electrophorectic analysis revealed that a protein of ${\sim}80 kDa was markedly reduced or even lost in IC. By using peptide sequencing analysis and Western blot, this 80 kDa protein was identified as transferrin (receptor-mediated $Fe^{3+}$ transporter, 76 kDa). Direct application of transferrin (100 nM) to the cytoplasmic side of inside-out patches decreased the open probability ($P_o$, 12.7${\pm}6.4%, n=4) without change in mean open time (${\tau}_o$, $98.5{\pm}1.3$%, n=4). However, the equimolar apotransferrin, which is free of $Fe^{3+}$, had no effect on the channel activity (N*$P_o$, $129.1{\pm}13.5$%, n=3). Directly applied $Fe^{3+}$ (100 nM) showed results similar to those of transferrin (N*$P_o$: $21.1{\pm}3.9$%, n=5). However $Fe^{2+}$ failed to reduce the channel function (N*$P_o$, $106.3{\pm}26.8$%, n=5). Interestingly, trivalent cation La3+ inhibited N*$P_o$ of the channel ($6.1{\pm}3.0$%, n=3). Taken together, these results suggest that $Fe^{3+}$ bound to transferrin can modulate the $K_{ACh}$ channel function by its electrical property as a polyvalent cation.

• 대한수의학회지
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• 제27권1호
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• pp.27-34
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• 1987

To verify the direct effects of the thyroid hormone ($T_3$) on the rabbit heart, $T_3$-Tyrode solution in vitro was perfused on the normal atrial muscles and enzymatically isolated ventricular myocytes of the rabbit. All the experimental procedures were conducted at $35^{\circ}C$ and the same procedures were repeated after Ca. 120 minutes from the beginning of $T_3$-Tyrode perfusion. Compared to the state between the normal Tyrode solution and $T_3$-Tyrode solution, results were observed on the same cells by electrophysiological methods (conventional intracellular recording and whole cell patch clamping) as soon as possible. The results obtained were as follows : 1. Action potential duration (APD) on the left atrial muscle was reduced under the perfusion of $T_3$-Tyrode. 2. Absolute refractory Period was shortened by $T_3$-Tryrode perfusion. (117 msec./114 msec., 90 msec./78 msec.) 3. Maximal Ca currents ($i_{Ca}$) were decreased in single: ventricular myocytes under the $T_3$-Tyrode (2.98 nA) than under the normal Tyrode (6.65 nA) 4. On I-V relation, reversal potential was shifted to lower membrane potential and membrane potential showing maximal $i_{Ca}$was lowered from +10mV to -20mV by $T_3$ effect. 5. Above results were likely to explain that tachycardia in the hyperthyroid state was caused in part by the reduced repolarization phase and the reduced refractory period due to the decrease of the Ca current.