Ambulatory ECG Monitoring System Research Articles

실시간 심전도 분석 및 모니터링 시스템 개발

ECG is used on purpose to keep good health or monitor cardiac function of aged person as well as on purpose to diagnose the disease of heart patients. The ambulatory ECG monitoring system under guarantee of safety and accuracy is very efficient to prevent the progress of heart disease and sudden death. These systems can detect the temporary change of ECG that is very significant to diagnose heart disease such as myocardial ischemia, arrhyamia and cardiac infarction. In this paper, we describe the ECG signal analysis algorithm and measurement device for ECG monitoring. The authors designed a small-size portable ECG device that consisted of instrumentation amplifier, micro-controller, filter and RF module. The device measures ECG with four electrodes on the body and detects QRS complex and ST level change in realtime. Also it transmits the measured signals to the personal computer. The developed software for ECG analysis in personal computer has the function to detect the feature points and ST level changes.

Prospective comparison of the diagnostic utility of a standard event monitor versus a “leadless” portable ECG monitor in the evaluation of patients with palpitations

Current ambulatory ECG monitoring systems are limited in their ability to diagnose patients with palpitations. The aim of this prospective study was to compare a new "leadless" ambulatory monitor with a standard event monitor in the evaluation of patients with palpitations. Eighteen consecutive patients (11 female, 56 +/- 16 years) referred for evaluation of palpitations were provided with both a standard event monitor and a "leadless" monitor for 30 days. They were asked to record episodes of palpitations with both monitoring devices. All 18 individuals were compliant with the "leadless" monitor for the 30-day period while only 14 (78%) patients were compliant with the standard event monitor (p = 0.10). During a combined monitoring period of 563 days, 159 symptomatic episodes were recorded with the "leadless" ECG monitor (8.8 +/- 9.7 per patient, range 1-35) and 169 symptomatic episodes were recorded with the event monitor (12 +/- 8.3 per patient, range 1-33) (p = NS). The "leadless" ECG monitor recorded arrhythmias in 13 of 18 patients (72%) and the standard event monitor recorded arrhythmias in 8 of 14 patients (57%) (p = NS). The "leadless" ECG monitor is associated with high patient compliance and results in high quality ECG recordings. The diagnostic yield of this monitoring system is equivalent to a standard event monitor.

Improved detection of transient myocardial ischemia by a new lead combination: Value of bipolar lead Nehb D for Holter monitoring

The investigations of ST-segment changes by Holter monitoring demonstrate asymptomatic and symptomatic episodes of myocardial ischemia, which may occur during daily activities. One factor, which is of great importance for the detection of silent myocardial ischemia during ambulatory monitoring, is the combination of the leads. Former studies showed that the analysis of two channels alone may not adequately detect silent myocardial ischemia. We therefore used a three-channel ambulatory ECG monitoring system with a new lead combination. The Holter monitoring results were correlated with the distribution of coronary stenosis detected by coronary angiography. In 54 patients with single coronary vessel disease and ischemic ST-segment depressions during exercise testing, standard Holter lead combination CM2/CM5 was extended by a bipolar Nehb D-like lead. Lead combination CM2/CM5 identified 23 patients (43%) with ST-segment depressions (total number of ischemic episodes = 372). Additional Nehb D-like lead identified 30 patients (55%) with ST-segment depressions (total number of ischemic episodes = 1048). The combination of leads CM2/CM5 and Nehb D raised the number of patients with documented ST-segment depressions to 33 of 54 (61%). Lead Nehb D showed the highest sensitivity for the detection of inferior wall ischemia (stenosis of the right coronary artery); nevertheless, this lead may not be regarded as specific for ST-segment alterations only caused by inferior wall ischemia. The correlation of ischemic ST-segment depressions during exercise testing (classified as anterior, inferior, or anterior and inferior type of ischemia) and documented ST-segment changes in the different Holter leads underline these results. A control group of 40 healthy volunteers demonstrated the high specifity of this new lead combination. In comparison with the standard lead combination CM2/CM5 for the detection of ST-segment changes, lead combination CM2/CM5 extended by a bipolar Nehb D lead is more sensitive for the detection of ST-segment alterations by Holter monitoring.

The European ST-T database: standard for evaluating systems for the analysis of ST-T changes in ambulatory electrocardiography.

The project for the development of the European ST-T annotated Database originated from a 'Concerted Action' on Ambulatory Monitoring, set up by the European Community in 1985. The goal was to prototype an ECG database for assessing the quality of ambulatory ECG monitoring (AECG) systems. After the 'concerted action', the development of the full database was coordinated by the Institute of Clinical Physiology of the National Research Council (CNR) in Pisa and the Thoraxcenter of Erasmus University in Rotterdam. Thirteen research groups from eight countries provided AECG tapes and annotated beat by beat the selected 2-channel records, each 2 h in duration. ST segment (ST) and T-wave (T) changes were identified and their onset, offset and peak beats annotated in addition to QRSs, beat types, rhythm and signal quality changes. In 1989, the European Society of Cardiology sponsored the remainder of the project. Recently the 90 records were completed and stored on CD-ROM. The records include 372 ST and 423 T changes. In cooperation with the Biomedical Engineering Centre of MIT (developers of the MIT-BIH arrhythmia database), the annotation scheme was revised to be consistent with both MIT-BIH and American Heart Association formats.

Diurnal change in heart rate variability in healthy and diabetic subjects.

We assessed the hourly coefficient of variance of RR intervals (CVRR) in 29 subjects with non-insulin-dependent diabetes mellitus and 19 age-matched healthy subjects using an ambulatory 24-hour ECG monitoring system. We also evaluated CVRR during 100 beats in both groups in the supine posture at 07:00 and 10:00 in the morning. Hourly CVRR showed an overt diurnal variation in both groups especially in the daytime and at midnight, but was significantly lower (p less than 0.05) in diabetic patients. CVRR during resting 100 beats at 07:00 was significantly higher (p less than 0.05) than that at 10:00 in both groups. These findings indicate that HRV shows an obvious diurnal variation in both groups. As a steep and marked change occurs in the morning, careful consideration is necessary to assess the test performed for a short time span at random times throughout the day, particularly in the morning.

Accuracy of the ambulatory ECG monitoring system CardioData Mk 4 in detecting exercise-induced myocardial ischaemia

Accuracy of the ambulatory ECG monitoring system CardioData Mk 4 in detecting exercise-induced myocardial ischaemia

Frequency response characteristics of ambulatory ECG monitoring systems and their implications for ST segment analysis

Because of the increasing interest in using ambulatory ECG monitoring equipment to study cardiac ischemia, we examined the frequency response characteristics and the reproducibility of a standard ST segment shift for equipment from eight manufacturers. Output/input amplitude versus frequency response curves, derived from input sine waves, were compared with American Heart Association (AHA) standards. Low- and high-frequency cutoffs (−3dB) were examined as well as flat response within the pass band. A new test based on Fourier analysis provided evaluation of phase shift versus frequency response and a more detailed analysis of the amplitude versus frequency response. By using a modified ECG simulator, flat-line ST segment depression from 0 to 10 mm (in 1 mm increments) was input to two or three recording devices for each manufacturer. The outputs from the scanners were evaluated for the amount of ST depression and the quality of the waveform reproduction. No system met all AHA standards for frequency response. Each system also had varying amounts of phase shift which could potentially distort the ECG signal. Although some manufacturers' equipment gave faithful reproductions of the simulated ST segment depression, others did not. We conclude that additional investigation is necessary to determine the clinical implications of our findings and to establish better standards for low- and high-frequency cutoffs, flat response within pass band, and phase shift for ambulatory ECG monitoring equipment.