Minimum Measurement Time Affecting the Reliability of the Heart Rate Variability Analysis

BACKGROUND: Heart rate variability (HRV) test is in widely used for measurement of autonomic nerve system. Although the standard measurement time for short-term HRV analysis is regarded as 5 minutes, it could be varied depending on the clinical situation. Thus, we examined that the valid minimum measurement time for HRV through comparison of HRV among 10 segments per 30 seconds from 30 seconds to 300 seconds. METHODS: The study included 1,457 adult participants who visited the health promotion center in Seoul, Korea from the March 2009 to December 2012. The variables of the time domain and frequency domain analysis of HRV among 10 segments from 30 seconds to 300 seconds were compared using one-way ANOVA test with post-hoc analysis. RESULTS: Compared with 5-minute (300 seconds) HRV, the components of HRV measurement were statistically equal in condition with 180 seconds for standard deviation of all normal-to-normal interval (SDNN), 270 seconds for NN50, 180 seconds for total power, 180 seconds for low frequency power in normalized units (LFn), and 180 seconds for high frequency power in normalized units (HFn), respectively. CONCLUSIONS: Our results suggest that the minimum duration of HRV measurement might be more or than 180 seconds.

Electro-Mechanical Safety Testing of Portable ECG Devices for Home Healthcare Usage / 대한의료정보학회지

OBJECTIVES: This paper suggests the experimental guidelines to evaluate the electro-mechanical safety of belt type equipment. The electro-mechanical safety was determined by using the International Electrotechnical Commission guidelines, which are widely used as important factors for assessing the electro-mechanical safety of belt type equipment. However, the local guidelines on wearable healthcare sensors are currently not well-established. Therefore, safety guidelines suited for the actual circumstances in Korea are required, and this paper attempts to try a new experimental safety test procedure of the wearable healthcare sensor. METHODS: This belt type device measures the electrocardiogram (ECG) and heart rates by attaching to the chest. Examination lists were selected by analyzing the common standards ofelectro-mechanical safety (IEC 60601-1) and environment tests (IEC 60068-1, IEC 60068-2) of home-healthcare equipment. RESULTS: The essential electrical safety, which was required for the RS300G3 as a medical device, was evaluated, and most of the examination lists were selected by considering the circumstances of the users. The device passed all the selected examinable lists that are applicable to the Korean environment. CONCLUSIONS: This study has limitations to estimate and to conduct electro-mechanical safety experiments because our study focused on the belt type of heart-rates equipment. We are not taking into account the overall electro-mechanical home-healthcare measurements. According to industrial and technological development, there are infinite possibilities for the advancement of home-healthcare equipment, so more examination lists for safety are being added in addition to what we have done.

Effects of Aerobic Exercise on Heart Rate Variability(HRV)

BACKGROUND: This study was conducted to find out the difference of heart rate variability between practicing Tai Chi and walking at 6 km/hr. METHODS: Twelve healthy volunteers aged 25 to 35 were recruited through advertisement. All the subjects gave their informed consent, and the study was approved by the Institutional Review Board of the Catholic Medical Center Research Foundation. The subjects either practised Tai Chi or walked at 6 km/ hr on a treadmill machine, maintaining 5-minute rest, 20-minute exercise, and 30-minute rest. After 1 week, they switched and performed the other form of exercise. During the exercise, beat-to-beat HRV data was recorded by Polar S-810. We calculated HRV indices using Matlab software program and analyzed the mean value of HRV indices. RESULTS: The differences of the mean value of HRV indices of pre-exercise resting period were not significant. However, repeated ANOVA revealed that there were significant differences of change in the mean of SDNN (-14.27+/-13.03 ms, -33.67+/-20.23 ms; P=0.023), RMSSD (-10.17+/-9.59 ms, -21.90+/-12.60 ms; P=0.087), and STIDX (171.60+/-196.84, 1003.49+/-812.56; P=0.003) between practising Tai Chi and walking. The differences of change in mean heat rate, LF/HF ratio, LF, HF and TP were not significant. The differences of the mean value of HRV indices of the post-exercise resting period were not significant compared to the pre- exercise period. CONCLUSION: The result of this study suggest that exertional intensity of practising Tai Chi is similar to that of walking. Moreover, practising Tai Chi may be more profitable than walking in the aspect of HRV.

Analysis of P Wave Signal-Averaged Electrocardiogram in Patients with Paroxysmal Atrial Fibrillation

BACKGROUND AND OBJECTIVES: The diagnosis of paroxysmal atrial fibrillation (PAF) and the prediction of its recurrence are sometimes difficult. There have been several recent studies attempting to detect patients at risk for PAF while in sinus rhythm by using the P wave signal-averaged ECG. We undertook to define an appropriate technique of P wave signal-averaged ECG and to estimate the reproducibility of the test. Additionally, we estimated the usefulness of P wave signal-averaged ECG in patients at risk for PAF. SUBJECTS AND METHODS: Forty-five patients with PAF were included in the study undertaken between March 1997 and June 1998. Twelve-lead surface ECG and P wave signal-averaged ECG were performed in the patients. The total P wave duration was measured by the P wave signal-averaged ECG using P wave template and least-square fit filter. The same process was followed in forty sex- and age-matched controls. RESULTS: The measurement of P wave duration with P wave signal-averaged ECG was highly reproducible. The measured P wave duration showed significant prolongation in the patient group at cutoff frequencies of 20 Hz and 30 Hz (123.6+/-15.3 vs. 114.8+/-14.5 msec, p=0.009 at 20 Hz, 120.1+/-17.8 vs. 107.5+/-18.8 msec, p=0.002 at 30 Hz). An abnormal P wave duration defined as over 120 msec in duration by P wave signal-averaged ECG was able to detect PAF with a sensitivity of 60%, specificity of 73%, positive predictive value of 71%, and a negative predictive value of 62%. CONCLUSION: A prolonged P wave duration as measured by P wave signal-averaging technique may be a simple noninvasive marker of risk for the development of atrial fibrillation.

Design and Evaluation of a Prototype Algorithm for 12 Channel Computer ECG Analysis / 대한의료정보학회지

The outline of the Prototype Algorithm, software package for computerized electrocardiography, is described. The developed module-based ECG analysis program consists of system interface, beat detection, feature extraction, rhythm analysis and diagnostic module. The overall evaluation of the proposed algorithm was done using the CSE library. The CSE diagnostic library and evaluation methods, which developed for evaluation of ECG analysis program are introduced. The prototype' s beat marker position is satisfied with recommended range of CSE median results. The performance of proposed algorithm compared with clinical truth and commercial programs. Now is the time to start to modify and revise the program in order to achieve the reliable performance, responding to the complaints of clinicians and making use of the EGG database, which is developing continuously.