A Study on Developing Cardiac Signals Recording Framework (CARDIF) Using a Reconfigurable Real-Time Embedded Processor

A Study on Developing Cardiac Signals Recording Framework (CARDIF) Using a Reconfigurable Real-Time Embedded Processor

Uma Arun (MSRIT, Bengaluru, India) and Natarajan Sriraam (MSRIT, Bengaluru, India)
Copyright: © 2019 |Pages: 14
DOI: 10.4018/IJBCE.2019070102

Abstract

Due to recent developments in technology, there is a significant growth in healthcare monitoring systems. The most widely monitored human physiological parameters is electrocardiogram (ECG) which is useful for inferring the physiological state of humans. Most of the existing multi-channel ECG acquisition systems were not accessible in resource-constrained settings. This research study proposes a cardiac signal recording framework (CARDIF) using a reconfigurable input-output real-time embedded processor by employing a virtual instrumentation platform. The signal acquisition was configured using Lab VIEW virtual instrumentation block sets. A graphical user interface (GUI) was developed for real-time data acquisition and visualization. The time domain heart rate variability (HRV) statistics were calculated using CARDIF, and the same were compared with a clinical grade 12-channel ECG system. The quality of the acquired signals obtained from the proposed and standard systems was measured and compared by calculating signal-to-noise ratio (SNR). The proposed CARDIF was evaluated qualitatively by visual inspection by a clinician and quantitatively by fidelity measures and vital parameters estimation. The results are quite promising and can be extended for clinical validations.
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Proposed Cardif (Cardiac Signals Recording Framework)

The electric action of a heart is described by ECG bio-signal. This signal comprises three components of P-wave, T-wave and QRS-complex. These signals originate from various parts of a heart. The stress of the heart at the time of measurement decides their shape and duration. The measurement location and distance between electrodes decide the wave amplitude.

ECG measurement in hospitals use nine electrodes placed on a patient’s body. The electrodes convert ionic flow into electric current. Disposable Ag-AgCl electrodes are commonly used for ECG-measurements. Electrolytic gel is used to improve the contact between skin and electrode in disposable electrodes. These electrodes can be kept at a specific location that depends on the type of configuration and they can be kept in the chest or limb.

As per Einthoven's triangle limb, electrodes were placed in this proposed work. In electrocardiography, two shoulders and a pubis form an imaginary triangle of three limb leads. This represents an inverted equilateral triangle that results in a voltage sum of zero which considers the heart at the centre. In Lead II configuration the potential is measured between right arm(-ve) and left leg(+ve). In Lead III Configuration it is measured between left leg(+ve) and left arm(-ve). In this proposed work, Lead I configuration was used as shown in the Figure 1 and the electrodes were connected between the right arm and left arm. The right leg serves only as the reference and hence there is no electrode connected from right leg.

Figure 1.

Einthoven's triangle

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In this CARDIF system as shown in Figure 2, a real-time ECG recording and monitoring method was implemented using an in-built amplifier and a reconfigurable input-output real-time embedded processor (Uma Arun, Sriraam N, Srinivas Avvaru (2016). An appropriate ADC unit converts the recordings into Lab VIEW platform, where the ECG recordings were assessed quantitatively and qualitatively. The proposed CARDIF was a single channel system with three disposable Ag/AgCl electrodes connected through wire to the limb (right arm, left arm and right wrist). A laptop, display the result in the front panel of the block diagram.

Figure 2.

Proposed CARDIF system

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