No abstract available.
Electrocardiography, Ambulatory*

In a systemvalidation of a ambulatory EKG analysis system we examined the HP 43420A ambulatory EKG analysis system(Fa.Hewlett packard, USA). The complete capture module 43405A with the applied software is able to record 24 hours events without single beat lable. Model 43400B patient analyzer records intermittant the EKG events and represents these in the Ambulatory EKG report. By means of the devices 31 patients were examined. Beat-to-beat analysis of the complete full disclosure is visually carried out. Sensitivity and postitve predictive value were 94(96)% and 100% for ventricular ectopic beat(VEB). The sensitivity amounted to 87% in the detecting of VEB pair(couplet), the positive predictive value 94%. VEB Run/VT(ventriular tachycardia) resulted in a sensitivity of 82% and in positive predictive value of 93%. The automatically edited Ambulatory EKG report with his EKG strips is representative of full disclosure and reliable in comparison with the analyzed results of full disclosure. The HP 43420A Ambulatory EKG Analysis system, a new and developed device with all digital recording system and full disclosure capability is found comparable to the best ones of the presently available Holter monitoring system.
Bioengineering* ; Disclosure ; Electrocardiography ; Electrocardiography, Ambulatory* ; Humans

BACKGROUND AND OBJECTIVES: The aim of the study was to evaluate the difference of temporal lability in myocardial repolarization between acute non-Q (NQMI) and Q-wave myocardial infarction (QMI), and to discern whether the locations of myocardial infarction influence such temporal lability. SUBJECTS AND METHODS: Twelve patients with NQMI and 28 with QMI, including 16 anterior (AMI) and 12 inferior MI (IMI) patients were enrolled. Twenty four-hour ambulatory ECG recordings of each patient were analyzed, and the digitized data was partitioned into 30-min sections. The QT intervals were measured using a template matching strategy. We then calculated the low (LF:0.03 - 0.15 Hz) and high frequency (HF:0.15 - 0.4 Hz) power of the QT interval variability using an algorithm capable of removing the influence of the RR-interval on QT interval variability (Normalized Idioventricular QT variability Index:IV-QT). RESULTS: For patients with QMI, the low frequency IV QT (LF IV-QT) was higher than that of NQMI (1.941+/-0.101 and 1.556+/-0.114 respectively, p<0.05). No difference was seen in the high frequency IV QT (HF IV-QT) of the two groups. For QMI patients, both the LF IV-QT and HF IV-QT were higher in day time (6AM-6PM) than in night time (6PM-6AM). Comparing the differences of these indices by the location of QMI, both the LF IV-QT and HF IV-QT of AMI were higher than those of IMI patients (2.231+/-0.135 vs 1.355+/-0.131 and 2.341+/-0.161 vs 1.346+/-0.145 respectively, p<0.0005). Both indices of each group also demonstrated a circadian change. CONCLUSION: In cases of QMI, the temporal lability in myocardial repolarization is larger than that seen in NQMI. Moreover, it was worse in AMI than IMI. Finally, such temporal repolarization lability tends to have a circadian pattern in QMI.
Electrocardiography ; Electrocardiography, Ambulatory ; Humans ; Myocardial Infarction*

Aiming at the ECG performance indicators in the YY 0885-2013 "Medical electrical equipment Part 2: Particular requirements for the safety including essential performance of ambulatory electrocardiographic systems", the traditional detection methods are time-consuming and the test results are greatly affected by human factors. In this paper, an automated detection method is proposed. A set of automatic detection software for ECG performance is designed and developed based on a single-channel ECG recorder, and an automated detection system is set up in combination with standard testing equipment. And then, the MSA tool is used to analyze the repeatability and stability of the detection system, and the results show that the detection system is acceptable, and it can improve detection efficiency.
Electricity ; Electrocardiography ; Electrocardiography, Ambulatory ; Humans ; Software

Objective: We studied the efficacy of the power spectral and nonspectral analysis and its diurnal variations for the early detection of the diabetic autonomic neuropathy. METHOD: The spectral and nonspectral analysis of 24hour-Holter monitoring were done for both diabetic neuropathy patients and controls. We also made a comparative analysis of the diurnal variations between the patient and control groups by means of hourly power spectral analysis. RESULT: 1) The power spectral density of the diabetic neuropathy patients was below than that of the normal controls (P<0.05) (Table 2, Fig. 1). 2) The nonspectral analysis of the diabetic neuropathy patients was below than that of the normal controls except for the mean RR intervals (P<0.05) (Table 3). 3) Every hour-power spectral analysis showed a diurnal variation of day time (06:00 to 16:00) decrease in high frequency area of the normal controls. On the contrary, there was a disappearance of the diurnal variation in patient group. CONCLUSION: The power spectral and nonspectral analyses after 24hour-Holter monitoring and its diurnal variation in the diabetic patients are considered as good means of the early detection of autonomic neuropathy, but further study of its diagnostic value will be needed.
Diabetic Neuropathies* ; Electrocardiography, Ambulatory* ; Humans

A new handheld fast ECG detector based on low gain amplifier, the high resolution analog to digital converter, the real-time digital filter, fast P-QRS-T wave detection and abstraction algorithm was designed. The results showed that the ECG detector can meet the requirements of fast detecting heart rate and ECG P-QRS-T waveforms.
Electrocardiography, Ambulatory ; instrumentation ; Equipment Design

A kind of real-time remote monitoring embedded terminal which is combined with mobile communication technology and GPS localization technology, has been developed. The results of preliminary experiments show that the terminal can transmit ECG signals and localization information in real time and continuously, supply a real-time monitoring of out-of-hospital cardiac patients and trace the patients.
Electrocardiography, Ambulatory ; instrumentation ; Telemedicine ; instrumentation ; Telemetry ; instrumentation

OBJECTIVES: Signal-averaged electrocardiography (SAECG) has been found to be a useful noninvasive technique for identifying patients at risk for life-threatening ventricular tachycardia. Delayed and fragmented activation of abnormal myocardial tissues causes the occurrence of high frequency low amplitude (HFLA) electocardiographic signals or late potentials. Generally, there are two methods in analyzing signal-averaged electrocardiography. Late potentials in the time domain analysis do not provide sufficient diagnostic power with regard to life-threatening Ventricular tachycardia. Buckingham et al. (1989) reported a time-domain sensitivity of 62%, a specificity of 75%. Spectral turbulence analysis (STA) of the signal-averaged ECG is the most recent frequency domain technique to improve the time domain sensitivity and specificity. So, We designed the study to compare the efficacy of Time Domain Analysis and Spectral Turbulence Analysis among five groups (Normal control, QRS widening, Postmyocardial infarction, Frequent VPC's with group beats, Nonsustained ventricular tachycardia). METHODS: 88 patients were selected from the patients who had been admitted between January 1994 and October l994, at National Medical Center. Patients were divided into five groups, which were respectively, Group A: Normal control group (n=33), Group B: QRS widening group (n=14), Group C: Postmyocardial infarction group (n=10), Group D: Frequent VPC's with group beats (n=22), Group E: Nonsustained VT group (n=9). We compared Spectral Turbulence Analysis and Time Domain Analysis of Signal-Averaged Electrocardiogram by 24 hours-Holter monitoring. RESULTS: 1) In normal control group(Group A), 9.1%(3 patients) were positive by Time Domain Analysis, but, all were negative by Spectral Turbulence Analysis. 2) In QRS widening group (Group B), 71.4%(10 patients) were positive by Time Domain Analysis, but, all were negative by Spectral Turbulence Analysis. 3) In postmyocardial infarction group (Group C), 309o were positive by Time Domain Analysis, and 10% were positive by Spectral Turbulence Analysis. 4) In frequent VPC's group (Group D), 22.7% (5 patients) were positive by Time Domain Analysis, and, 4.5%(1 patient) was positive by Spectral Tur-bulence Analysis. 5) In Nonsustained VT group (Group E), 33.3% (3 patients) were positive by Time Domain Analysis, and 11.1% (1 patient) was positive by Spectral Turbulence Analysis. CONCLUSIONS: In Time Domain Analysis, abnormal results were presented at Group R (QRS widening group) by 71.4%, which was markedly higher than other groups. But, in Spectral Turbulence Analysis, abnormal results were not presented at Group A and Group B. In Group A and Group B, Spectral Turbulence Analysis shows less false positive results than Time Domain Analysis.
Electrocardiography* ; Electrocardiography, Ambulatory* ; Humans ; Infarction ; Sensitivity and Specificity ; Tachycardia, Ventricular

BACKGROUND: We addressed the problem of the circadian changes in neural control of the circulation in ambulant hypertensive subjects. With spectral analysis of heart rate variability the tonic sympathetic and vagal activities and their changes are respectively assessed by the power of 0.050 - 0.015Hz(low frequency, LF) and 0.150 - 0.350Hz(respiratory linked, high frequency, HF) components of the spectrum of the beat by beat variability of RR interval. METHODS: Heart rate variability(HRV) and its circadian rhythm were evaluated in 15 patients with hypertension. By using 24-h Holter monitoring, HRV and its spectral components were measured. Finding were compared with 15 age-matched normal controls. RESULTS: The 24-hour plot of the SDs revealed that heart rate variability was significantly lower in the hypertensive patients, and the differences reached statistical significance during hours 2, 3, 9, 13, 16, 18, 19, and 23(p<0.05). Spectral analysis showed that power in the high-frequency range(0.150 to 0.350Hz) was lower among the hypertensive patients than among the normal controls during 22 of 24 hours but that the difference was statistically significant only during 2 hours(p<0.05). Power in the low frequency range(0.050 to 0.150Hz) was low at night, increased in the morning, and high during the day among controls ; this circadian rhythm was absent among hypertensive patients. CONCLUSIONS: Among hypertensive patients, HRV is decreased with a partial withdrawal of parasympathetic tone, and the circadian rhythm of sympathetic/parasympathetic tone is altered.
Circadian Rhythm ; Electrocardiography, Ambulatory ; Heart Rate ; Humans ; Hypertension

BACKGROUND: It is known that QT dispersion represents asynchronous repolarization of ventricle which is related to ventricular fibrillation. The incidence of ventricular arrhythmia is increased after acute myocardial infarction. So this study compared QT dispersion and other repolarization indexes for detection of asynchronous repolarization in acute myocardial infarction. We also investigated which portion of repolarization is the key portion of the asynchrony. METHODS: In 37 acute myocardial infarction patients and 38 angina patients dispersion of QT, JT, JTpeak and QTpeak were measured. We also measured maximum adjacent dispersion of same parameters in precordial leads. In 20 survived patients and 17 dead patients after acute myocardial infarction were also compared. We also investigated correlation of PVC's on Holter monitoring with these repolarization parameters. RESULTS: 1) All ventricular repolarization indexes(QT, QTc, JT, JTpeak, QT peak and TpeakTend dispersion) were significantly increased in acute myocardial infarction group than compared with those of angina group(p<0.05). 2) Maximal precordial dispersion(QT, QTc, JT, JTpeak and QTpeak) were also significantly increased in acute myocardial infarction group than angina group(p<0.05). 3) Dead patient group after myocardial infarction showed significantly increased QTc and TpeskTend dispersion compared with those of survived patient group(p<0.05). 4) Multivariate linear correlation showed that TpeakTend dispersion and JT dispersion was correlated with QT dispersion. CONCLUSIONS: There were asynchronous myocardial repolarization changes in acute myocardial infarction. Our study demonstrated that T wave change was major determinant of dispersion of myocardial repolarization.
Arrhythmias, Cardiac ; Electrocardiography, Ambulatory ; Humans ; Incidence ; Myocardial Infarction* ; Ventricular Fibrillation