Processing Electrocardiographic Signals using a Custom Designed Sigma-Delta Modulator

This paper introduces the experimental results obtained after processing an electrocardiographic signal by a full-custom, low-complexity, Sigma-Delta Modulator integrated circuit, designed and fabricated using the C5N CMOS technology available through MOSIS. By exploiting a large oversampling ratio, it was possible to obtain an effective number of bits equal to 11 at the proposed single-bit modulator’s output. The resulting bitstream was captured with a logic-state analyzer and processed offline. After decimation and digital filtering, the electrocardiographic signal was reconstructed and plotted in the time domain. Commonly referred quality metrics over the retrieved signal were calculated. A total signal-to-noise and distortion ratio, superior to 66[Formula: see text]dB, was achieved by analyzing the entire system. The proposed approach shows the feasibility of processing electrocardiographic signals using low-cost and straightforward CMOS technology circuits. Since the proposed converter uses a single voltage supply of 1.5[Formula: see text]V, exhibits a power consumption of 38[Formula: see text][Formula: see text]W, and uses a silicon area of 0.052[Formula: see text]mm2, it is suitable for single battery-operated systems on a chip.

A novel algorithm based on ensemble empirical mode decomposition for non-invasive fetal ECG extraction

Non-invasive fetal electrocardiography appears to be one of the most promising fetal monitoring techniques during pregnancy and delivery nowadays. This method is based on recording electrical potentials produced by the fetal heart from the surface of the maternal abdomen. Unfortunately, in addition to the useful fetal electrocardiographic signal, there are other interference signals in the abdominal recording that need to be filtered. The biggest challenge in designing filtration methods is the suppression of the maternal electrocardiographic signal. This study focuses on the extraction of fetal electrocardiographic signal from abdominal recordings using a combination of independent component analysis, recursive least squares, and ensemble empirical mode decomposition. The method was tested on two databases, the Fetal Electrocardiograms, Direct and Abdominal with Reference Heartbeats Annotations and the PhysioNet Challenge 2013 database. The evaluation was performed by the assessment of the accuracy of fetal QRS complexes detection and the quality of fetal heart rate determination. The effectiveness of the method was measured by means of the statistical parameters as accuracy, sensitivity, positive predictive value, and F1-score. Using the proposed method, when testing on the Fetal Electrocardiograms, Direct and Abdominal with Reference Heartbeats Annotations database, accuracy higher than 80% was achieved for 11 out of 12 recordings with an average value of accuracy 92.75% [95% confidence interval: 91.19–93.88%], sensitivity 95.09% [95% confidence interval: 93.68–96.03%], positive predictive value 96.36% [95% confidence interval: 95.05–97.17%] and F1-score 95.69% [95% confidence interval: 94.83–96.35%]. When testing on the Physionet Challenge 2013 database, accuracy higher than 80% was achieved for 17 out of 25 recordings with an average value of accuracy 78.24% [95% confidence interval: 73.44–81.85%], sensitivity 81.79% [95% confidence interval: 76.59–85.43%], positive predictive value 87.16% [95% confidence interval: 81.95–90.35%] and F1-score 84.08% [95% confidence interval: 80.75–86.64%]. Moreover, the non-invasive ST segment analysis was carried out on the records from the Fetal Electrocardiograms, Direct and Abdominal with Reference Heartbeats Annotations database and achieved high accuracy in 7 from in total of 12 records (mean values μ < 0.1 and values of ±1.96σ < 0.1).

Sensitivity and Adjustment Model of Electrocardiographic Signal Distortion Based on the Electrodes’ Location and Motion Artifacts Reduction for Wearable Monitoring Applications

Wearable vital signs monitoring and specially the electrocardiogram have taken important role due to the information that provide about high-risk diseases, it has been evidenced by the needed to increase the health service coverage in home care as has been encouraged by World Health Organization. Some wearables devices have been developed to monitor the Electrocardiographic in which the location of the measurement electrodes is modified respect to the Einthoven model. However, mislocation of the electrodes on the torso can lead to the modification of acquired signals, diagnostic mistakes and misinterpretation of the information in the signal. This work presents a volume conductor evaluation and an Electrocardiographic signal waveform comparison when the location of electrodes is changed, to find a electrodes’ location that reduces distortion of interest signals. In addition, effects of motion artifacts and electrodes’ location on the signal acquisition are evaluated. A group of volunteers was recorded to obtain Electrocardiographic signals, the result was compared with a computational model of the heart behavior through the Ensemble Average Electrocardiographic, Dynamic Time Warping and Signal-to-Noise Ratio methods to quantitatively determine the signal distortion. It was found that while the Einthoven method is followed, it is possible to acquire the Electrocardiographic signal from the patient’s torso or back without a significant difference, and the electrodes position can be moved 6 cm at most from the suggested location by the Einthoven triangle in Mason–Likar’s method.

RECORDINGDATE AS AN ALTERNATIVE TO EXISTING METHODS OF DIAGNOSIS OF ATRIAL FIBRILLATION

По статистике, более 30% людей, имеющих заболевания сердца, страдают аритмией. Самой распространенной формой является мерцательная аритмия (около 2% всего населения России) [1]. Мерцательная аритмия, как нарушение сердечной деятельности, зачастую становится основной причиной тромбообразования и тромбоэмболий, вызывающих ишемию сосудов сердца и головного мозга. Как правило, данное заболевание развивается незаметно и через несколько приступов преобразуется в хроническую или персистирующую форму. В данной статье рассматриваются проблемы диагностики мерцательной аритмии, усугубляющиеся помехами электрокардиографического сигнала, а также представлена необходимость использования реокардиографического сигнала в качестве дополнительного средства диагностики, обеспечивающего повышение достоверности выявления заболевания According to statistics, more than 30% of people with heart disease suffer from arrhythmia. The most common form is atrial fibrillation (about 2% of the total population of Russia) [1]. Atrial fibrillation, as a violation of heart activity, often becomes the main cause of thrombosis and thromboembolism, causing ischemia of the heart and brain vessels. As a rule, this disease develops imperceptibly and after a few attacks turns into a chronic or persistent form. This article discusses the problems of diagnosis of atrial fibrillation, aggravated by interference with the electrocardiographic signal, and also presents the need to use the reocardiographic signal as an additional diagnostic tool that provides increased confidence in the detection of the disease