• 대한의용생체공학회:의공학회지
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• 제38권6호
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• pp.285-290
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• 2017

Radiofrequency catheter ablation is the interventional therapy that be employed to eliminate cardiac tissue caused by arrhythmias. During radiofrequency catheter ablation, The thrombus can occur at electrode tip if the temperature of tissue and electrode is excess $100^{\circ}C$. To prevent this phenomenon, we investigated numerical model of electrode for radiofrequency catheter ablation considering saline irrigation and temperature-controlled radiofrequency system. The numerical model is based on coupled electric-thermal-flow problem and solved by COMSOL Multiphysics software. The results of the models show that the dimensions of the thermal lesion are increased if the flow rate of the saline irrigation and the set temperature are increased. The surface width characterized to determine the thermal lesion isn't need to measure in temperature-controlled radiofrequency system due to convective heat transfer by saline irrigation at tissue-electrode interface.

• Journal of Chest Surgery
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• 제14권2호
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• pp.168-174
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• 1981

Since cardiac pacemaker was first totally implanted by Chardack, Gage and Greatbatch [1966], the electrical circuity of the cardiac pacemaker has been improved, modified, and refined. The problem of transvenous electrodes, however, is still remained; this may be due to electrode displacement, exit and/or entrance block, lead fracture and insulation defects. In permanent cardiac pacing, Irreversible loss of function of the transvenous electrode catheter eventually requires insertion of new lead. Authors now report one case that disclosed easy displacement of electrode tip in early phase of implantation and then two years and five months later, malfunctioning electrode could not be withdrawn from the cardiovascular system because it has become firmly enclosed by fibrous tissue along its course from the vein tract to the right ventricle. Under such circumstances, the electrode catheter tip was left in tricuspid annulus after being sutured at its entrance and burying the loop of lead in generator pocket. New other one electrode was then reimplantation through left external jugular vein.

• The Korean Journal of Physiology and Pharmacology
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• 제20권5호
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• pp.507-514
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• 2016

Although 3D-complex fractionated atrial electrogram (CFAE) mapping is useful in radiofrequency catheter ablation for persistent atrial fibrillation (AF), the directions and configuration of the bipolar electrodes may affect the electrogram. This study aimed to compare the spatial reproducibility of CFAE by changing the catheter orientations and electrode distance in an in -silico left atrium (LA). We conducted this study by importing the heart CT image of a patient with AF into a 3D-homogeneous human LA model. Electrogram morphology, CFAE-cycle lengths (CLs) were compared for 16 different orientations of a virtual bipolar conventional catheter (conv-cath: size 3.5 mm, inter-electrode distance 4.75 mm). Additionally, the spatial correlations of CFAE-CLs and the percentage of consistent sites with CFAE-CL<120 ms were analyzed. The results from the conv-cath were compared with that obtained using a mini catheter (mini-cath: size 1 mm, inter-electrode distance 2.5 mm). Depending on the catheter orientation, the electrogram morphology and CFAE-CLs varied (conv-cath: $11.5{\pm}0.7%$ variation, mini-cath: $7.1{\pm}1.2%$ variation), however the mini-cath produced less variation of CFAE-CL than conv-cath (p<0.001). There were moderate spatial correlations among CFAE-CL measured at 16 orientations (conv-cath: $r=0.3055{\pm}0.2194$ vs. mini-cath: $0.6074{\pm}0.0733$, p<0.001). Additionally, the ratio of consistent CFAE sites was higher for mini catheter than conventional one ($38.3{\pm}4.6%$ vs. $22.3{\pm}1.4%$, p<0.05). Electrograms and CFAE distribution are affected by catheter orientation and electrode configuration in the in-silico LA model. However, there was moderate spatial consistency of CFAE areas, and narrowly spaced bipolar catheters were less influenced by catheter direction than conventional catheters.

• Journal of Chest Surgery
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• 제13권3호
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• pp.219-228
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• 1980

The heart block and bradyarrhythmia with or without Stokes-Adams attacks are serious, usually terminal events and the immediate mortality is very high. Stimulation with an artificial pacemaker is now an accepted form of treatment in cases of Stokes-Adams syndrome in which medication in unable to produce any lasting improvement. Permanent pacemaker therapy is indicated in these circumstances. The purpose of this report is to describe the successful use of pacemaker in 3 cases of Stokes-Adams syndromes and a case of sinoatrial block with bradyarrhythmia at the Department of Thoracic and Cardiovascular Surgery, Kyungpook National University School of Medicine. Electrode catheter was passed through the right external jugular vein and attached to the endocardial surface of the right ventricle. In case 1, fixed type generator was used at first and for the case 2, 3, 4, and case 1 at second, demand type generators were used. The bipolar electrode catheters were used for the three cases and unipolar electrode catheter for case 4. The results of immediate and late period were satisfactory.

• 마이크로전자및패키징학회지
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• 제24권2호
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• pp.29-35
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• 2017

본 논문에서는 서브 밀리미터 직경의 카테터 표면 위에 금속 마이크로 와이어를 접착하는 공정을 연구하였다. 최근 유연 전자 디바이스 분야는 유연한 평면 폴리머 기판과 그 기판 위의 마이크로 전극 공정이 계속해서 연구되고 있다. 하지만, 의료 분야에서는 카테터와 같이 곡면을 가진 기판이 중요하다. 특히 카테터 중에서도 여러 한계점을 가진 뇌혈관 수술을 개선하기 위한 서브 밀리미터의 직경을 가진 조향 가능한 카테터의 중요성이 대두되고 있다. 이러한 카테터를 구현하기 위해 조향을 위한 엑추에이터들은 연구가 되고 있지만 이를 구동하기 위한 배선 연구는 진행된 바가 없다. 그러므로 본 연구에서는 이러한 서브 밀리미터 카테터 위에 마이크로 금속 와이어를 접착하는 공정을 개발하였다. 적합한 지그를 설계함으로써 마이크로 와이어를 서브 밀리미터 직경의 카테터에 정렬한다. 그리고 자외선 경화 시스템과 상용품을 이용하여 공정 시간 및 공정 비용을 감소시켰다. 상용품으로 골드 마이크로 와이어, 자외선 경화 에폭시, 자외선 램프 그리고 서브 밀리미터 카테터를 이용하였다. 공정 후 카테터는 광학 현미경, 저항 측정기, 만능 시험기를 통해 분석하였다.

• The Korean Journal of Pain
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• 제29권1호
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• pp.23-28
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• 2016

Background: Sacral nerve stimulation is a therapeutic option with demonstrated efficacy for conditions presenting with perineal pain caused by different etiologies. We aimed to assess whether a sacral electrode ($Interstim^{(R)}$, Medtronic, Minneapolis, MN, USA) inserted through the caudal pathway is able to offer an acceptable level of sacral stimulation and rate of catheter migration. Methods: We present 12 patients with pelvic pain who received sacral neuromodulation via the sacral hiatus with the InterStim electrode. We evaluated patient satisfaction as well as migration and removal of the electrode, if necessary. Results: Our experience included 12 patients, 10 women and two men, with a mean age of 60 years. In eight of the 12 patients, the initial therapy was effective, and the final system implantation was performed. During subsequent follow-up, patient satisfaction was good. To date, there have been no cases of electrode displacement or migration. Conclusions: The caudal insertion of the InterStim electrode, with its own fixation system, and initially designed for transsacral insertion, appears in our experience to be a satisfactory option which can minimize electrode displacements, achieving similar results in therapeutic efficacy and causing no difficulties in removal.

• 대한의용생체공학회:의공학회지
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• 제38권6호
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• pp.277-284
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• 2017

This paper presents an implantable pH measurement electrode for wireless gastroesophageal reflux measurement. Usually, gastroesophageal reflux is diagnosed by a catheter-type wire connection between the esophagus and the diagnostic device which brings many side effects such as restriction of daily living, pain, and discomfort in the nasal cavity and pharynx of patients. In order to solve these issues, researchers have been studied a wireless measurement method and a micro-sized pH electrode for human body insertion is necessary. Commercial glass packaged pH meter is formed by a sensing and a reference electrodes in a KCl solution. However, if the glass meter is inserted into the human body, there are risks of leakage of the solution, breakage of the glass package, injury of the body elements. Therefore, the solution should be solidified on the micro-sized noble metal wire which has a characteristic of biocompatible. After solidified wire fabrication, the designed meter was tested for feasibility of measurement and the result was well agreed with pH values of commercial pH meter. Potentials in pH 1 to 12 solution was measured to obtain the sensitivity of the sensor with linearity. And we have designed a simulation of gastroesophageal reflux with symptom frequency, interval, and duration time in pH 2 solution. The proposed sensor has capable to get the same potential for 24 measurements in 3 days, and it has sensed same pH values of 2 for one hour with every 10 minutes. Furthermore, the sensor was survived for 48 hours with reasonable potentials in the acid solution.

• Clinical Pain
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• 제18권2호
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• pp.142-146
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• 2019

This is a case report of the provocative discographic findings before and after focal selective coagulation of the major annular fissure using intradiscal navigable catheter. A 46-year-old woman had a 30-month history of axial low back pain and magnetic resonance imaging findings suspicious for painful L4/5 disc. The provocative discography confirmed painful disc before coagulation. The final electrode tip position in the coagulation procedure was at the largest fissure within the outer annular margin identified through the discography. Six months after the successful coagulation therapy, inadvertently performed discography resulted in decreased pressure rise over time. Neither evoked pain nor change in the integrity of outer annulus as compared with the previous results was reported. Such an interventional method has not been reported previously, and the analytic results suggest that it may be possible to relocate the pressure of the entire nucleus pulposus only by focal selective coagulation of the fissure.

• 한국임상수의학회지
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• 제26권6호
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• pp.539-546
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• 2009

잡종견 15마리를 이용하여 ketamine, propofol 및 isoflurane 마취견에서 실험적 출혈이 뇌 파에 미치는 영향을 평가하였다. 실험견은 마취제의 종류에 따라 군당 5마리씩, 3개 실험군으로 분류하였다 (1군: ketamine 5 mg/kg, IV, 2 군: propofol $156\;{\mu}g$/kg/min, IV, 3군: 2.0% end-tidal concentration of isoflurane). 모든 군에 전마취제로 Medetomidine ($40\;{\mu}g$/kg, IM)을 투여하였다. 뇌파기록전극은 Cz 위치에서 피하에 장착하였다. 뇌파, 심박수, 수축기/이완기 동맥혈압, $pO_2$, $pCO_2$ 및 혈액 pH를 마취 전, 마취 후, 매 출혈 후에 각각 측정하였다. 대퇴동맥에 삽관한 카테타를 통해 총 혈액량의 10%인 7 ml/kg을 10분동안 출혈시켰으며, 총 3회 실시하였다. 출혈기동안 수축기 및 이완기 동맥혈압은 모든 군에서 지속적으로 감소하였다. $pCO_2$ 농도와 심박수는 모든 군에서 증가하였다. $pO_2$ 농도는 다른 군과 비교하여 1군에서 가장 유의적으로 증가하였다. 혈액 pH의 유의적인 변화는 없었다. 뇌파 분석결과 1군과 3군에서는 유의적인 변화는 없었다. 2군의 band 3, 4 및 7은 2번째 및 3번째 출혈 후에 유의성있게 변화하였다. 이와 같은 변화는 propofol 점적 유지마취에서 총 혈액량의 20% 이상 출혈과 관계되는 것으로 사료된다. 따라서, Propofol 마취견이 총 혈액량의 20% 이상 출혈할 경우 propofol 점적 투여율의 조절이 고려되어야 한다.