• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.349-352
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• 2009

최근 유비쿼터스 헬스케어가 부각됨에 따라 심장의 활동상태를 보다 편리하게 측정하기 위하여 이동성 및 휴대성을 강조한 심전도 계측 시스템 및 스트레스 상태를 분석하기 위한 연구들이 수행되고 있다. 하지만 기존 심전도 계측은 전극의 부착 및 계측시스템과의 연결을 위한 리드선의 사용으로 인해 활동의 불편함을 유발한다. 본 연구에서는 기 연구 수행된 가정 또는 사무실에서 무구속적인(unconstrained) 방법으로 지속적인 심장의 활동상태의 모니터링이 가능한 무구속 의자형 심탄도 계측 시스템을 구현하였다. 무구속적인 방법으로 심탄도 신호를 계측하고 심탄도신호로부터 심박동변이율을 추출함으로써 일상생활 중 스트레스를 모니터링 하고자 하였다. 구현된 시스템을 통한 스트레스 모니터링의 가능성을 평가하기위하여 안정상태의 심박동변이율과 인위적인 신체적 스트레스인 Valsalva 조작를 유도한 후 심박동 변이율을 비교평가 하였다. 건강한 대학생 10명을 대상으로 비교분석을 수행한 결과 안정 상태와 육체적 스트레스 인가 후 심박동 변이율의 변화 양상을 관찰할 수 있었으며, 무구속적인 방법에 의해 스트레스의 모니터링이 가능함을 확인 할 수 있었다.

• Korean Journal of Biological Psychiatry
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• v.16 no.2
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• pp.69-75
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• 2009

Objectives : The detrended fluctuation analysis is one of the nonlinear methods for the investigation of biological time series. It quantifies the fractal scaling properties and is known to be useful in the evaluation of long-range correlations in time series. The heart rate variability(HRV) of obstructive sleep apnea syndrome (OSAS) patients during nighttime was analyzed by detrended fluctuation analysis to assess its relationship with the severity of the symptoms. Methods : Fifty nine untreated male OSAS patients with moderate to severe symptoms(mean age=45.4${\pm}$11.7 years, apnea-hypopnea index, AHI${\geq}$15) underwent nocturnal polysomnography. Moderate(AHI=15-30, N=22) and severe(AHI>30, N=37) OSAS patients were compared for the indices derived from detrended fluctuation analysis and frequency domain analysis of HRV. Results : In the detrended fluctuation analysis, the alpha values were 0.75${\pm}$0.11 and 0.82${\pm}$0.07 for the severe and the moderate OSAS groups respectively. The difference was significant(p<.01). The alpha value had negative correlation with AHI(r=-.425, p=.001). Negative correlation coefficients were also found in the relationships between the alpha values and very low frequency(VLF)(r=-.425, p=.001), low frequency(LF)(r=-.633, p= <.001) and the LF/HF ratio(r=-.305, p=.019) respectively. LF/HF ratio(p=.005) was higher in the severe OSAS group compared to that of the moderate OSAS group. Conclusion : In this study, the detrended fluctuation analysis showed the significant difference between the two OSAS groups classified according to their severity of symptoms. The scaling exponent showed the negative correlation with AHI and indicies of frequency domain analysis. This result suggests that detrended fluctuation analysis can be helpful to estimate the severity of OSAS.

• Journal of Korea Association of Health Promotion
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• v.4 no.1
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• pp.28-38
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• 2006

Background : Phentermine classified by "sympathomimmetic amie", is a stimulant of sympatheic tone But there has been no concrete study which presents the influence of phentermine on autonomic nervous system. Analysis of Heart rate variability is reliable, non-invasive and very useful for evaluating function of autonomic nervous system. We tried to elucidate the influence of phentermine on autonomic nervovs system by heart rate variability. MethodsAmong the 70 candidates who participated in the double-blind case control study whichwas designed in purpose of approving whether- Adipekⓓ is effective for treatment of obesity, 45persons were folled up. From April, 2005 to May 2005, HRV of the candidates who takes phentermine or placebo for 1month, was recorded using BFM-5000ⓓ(medi-core) for 5 minutes in resting state. HRV measures were assessed by time-domain and by frequency- domain analysis. Time domain parameters contain SDNN(Standard Deviation of NN intervals) and RMSSD(Root-Mean-Square of Successive Differences), etc and frequency domain Parameters contain Total Power(TP), Low frequency(LF'0.04-0.15Hz) power. High Frequency(HF:0.15-0.4Hz) power and LF/HF ratio etc. Results: Intakes of phentermine reduce HRV significant1y. SDNN & RMSSD, the main tine domain parameters of HRV, were decreased significantly(P=0.007. 0.016). PSI(Physical Stress Index of Pressure Index) was increase significantly(P=0.002)The main frequency domain parameters(TP, LF & VLF), also decreased significantly. (P=0.024,0.033, 0.015)Conclusion: The result showed that intakes of phentermine reduce heart rate variability and influence on most parameters of HRV. So phentermine not only accelerates sympathetic tone, but also inhibit the balance and function of autonomic nervous system.

• Journal of Chest Surgery
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• v.34 no.12
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• pp.901-908
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• 2001

Background : Coronary artery bypass graft(CABG) in patients with advanced left ventricular dysfunction has often been regarded as having high mortality rate, despite the great improvement in operative result of CABG. With recent advances in surgical technique and myocardial protection, surgical revascularization improved the symptom and long-term survival of these high risk patients more than the medical conservative treatment. Material and Methold : Clinical data of 31(4.1％) patients with preoperative ejection fraction less than 30% among 864 CABGs performed between January 1995 and March 1999 were retrospectively analyzed and pre- and postoperative changes of the ejection fraction on echocardiography were analyzed. There were 26 men and 5 women. The mean age was 60.7 years(range 41 to 72 years). History of myocardial infarction(30 cases, 98％) was the most common preoperative risk factor. There were seven irreversible myocardial infarction on thallium scan. Most patients had triple vessel diseases(26 cases, 84％) and first degree of Rentrop classification(16 cases, 52％) on coronary angiography. The mean number of distal anastomosis during CABG was per patient was 4.9${\pm}$0.8 sites in each patient. In addition to long saphenous veins, the internal mammary artery was used in 20 patients. Total bypass time was 244.7${\pm}$3.7 minutes(range, 117 to 567 minutes), and mean aortic cross-clamp time was 77.9 ${\pm}$ 1.6 minutes(range, 30 to 178 minutes). There were five other reparative procedures such as two left ventricular aneurysrmectomy, two mitral repair, and one aortic valve replacement. There were twelve postoperative complications such as three cardiac arrhythmia, two bleeding(re-operation), one delayed sternal closure, eleven usage of intra-aortic balloon counterpulsation for low cardiac output. Two patients died, postoperative mortality was 6.5% . Twenty-nine patients were relieved of chest pain and left ventricular ejection fraction after operation was significantly higher(38.5${\pm}$11.6%, p 0.001) as compared with preoperative left ventricular ejection fraction(25.3${\pm}$2.3%). The follow up period of out patient was 25. 3 months. Conclusion: In patients with coronary artery disease and advanced left ventricular dysfunction, coronary artery bypass grafting can be performed relatively safely with improvement in left ventricular function, but it will be necessary to study long term results.