Relevant to mobile health, the design of a portable electrocardiograph (ECG) device using AD823X ... more Relevant to mobile health, the design of a portable electrocardiograph (ECG) device using AD823X microchips as the analog front-end is presented. Starting with the evaluation board of the chip, open-source hardware and software components were integrated into a breadboard prototype. This required modifying the microchip with the breadboard-friendly Arduino Nano board in addition to a data logger and a Bluetooth breakout board. The digitized ECG signal can be transmitted by serial cable, via Bluetooth to a PC, or to an Android smartphone system for visualization. The data logging shield provides gigabytes of storage, as the signal is recorded to a microSD card adapter. A menu incorporates the device’s several operating modes. Simulation and testing assessed the system stability and performance parameters in terms of not losing any sample data throughout the length of the recording and finding the maximum sampling frequency; and validation determined and resolved problems that arose i...
This paper makes an analysis of the ECG leads obtained with the triads of electrodes proposed in ... more This paper makes an analysis of the ECG leads obtained with the triads of electrodes proposed in [I]. Also makes an analysis and gives recommendations about the sampling frequency of the XBee used. En este articulo se hace un analisis de las derivaciones ECG que se obtienen con las triad as de electrodos propuestos en [I]. Tambien se analiza y se hacen recomendaciones sobre la frecuencia de muestreo de los XBee que se utilizan. To obtain bipolar ECG leads (i.e. I, ll, Ill) traditionally, surface electrodes are placed at three specific points on the skin, defmed by the triangle of Einthoven: RA, LA Y LL. Each electrode picks up a biopotential which is carried by conductive wires to an electrocardiograph where the ECG leads are built. In a previous published work [1], we proposed to remove wires between the electrodes and electrocardiograph, by using triads of electrodes at each point of the Einthoven triangle (Fig. 1), which are attached to instrumentation amplifiers inputs. Now in this article: (A) we make an analysis of the ECG leads obtained with the triads of electrodes, and (B) we make recommendations about how to improve the sampling frequency about the XBee that was also previously proposed in [1]. A. ECG Leads Analysis. We hypothesized that the biopotentials collected by the electrode triads could represent the potential at each point of the triangle of Einthoven; therefore, standard bipolar leads could be constructed using the potentials recorded by the triads. It is well known that the difference between LA-RA = DI, LL-RA = Dll and LL-LA = DIll. Therefore, standard leads can be written in terms of biopotentials taken by the triad as: DI = (b'-a')-(b-a), Dll = (b"-a")-(b-a) y Dll = (b"-a")-(b'-a'). So, the three leads computed with the sets of electrode triads and other leads taken with a standard commercial electrocardiograph (the CARDIAX PC-ECG) were compared visa -vis, obtaining correlation coefficients of 0.75, 0.80 and 0.70, respectively. B. XBee Sample Frequency Analysis. The biopotentials at the output of each instrumentation amplifier are inputted to three XBee SI trasmitters, respectively [1]. Each XBee SI transmits the biopotentials toward XBee SI receivers [1]. The XBee SI receivers input the biopotentials to a computer where the three bipolar ECG leads are built [1]. Unfortunately XBee SI is restricted in sampling frequency (i.e. maximum = 333 s/s). When the sampling frequency is a critical factor as in the case in the ECG recording, errors that alter the diagnoses may occur [2]; for example: in the detection of the J-point, or in the shape detection of the P-wave, or in the detection of micropotentials within the QRS complex. There for, a sample frequency at least of 500 s/s is recommended. To achieve an adequate sampling frequency we have replaced the XBee SI by XBee PRO S3B. The PRO S3B reaches maximum stable sampling frequencies up to 1000 s/s. Conclusions. Although correlation coefficients between conventional and electrode triads leads have been good, more and other types of tests should be done to see if the correlation improves. For example improving the placement orientation of the electrode triads or probing other configurations in the triads like the Wilson's central terminal. Frequency analysis of the signals sampled by the XBee PRO S3B should be performed to ensure that important frequencies are contained and have not been distorted in the built leads.
El Electrocardiograma (ECG) convencional y el ECG de alta resolución representan unas de las técn... more El Electrocardiograma (ECG) convencional y el ECG de alta resolución representan unas de las técnicas de pre-diagnóstico no invasivo de mayor recurrencia en estudios de prevención de Infarto al Miocardio (IAM). La información obtenida en un ECG es posteriormente procesada y guardada ya sea en una base de datos o mostrada al especialista para su análisis. Una de las técnicas de análisis de ECG mediante métodos computacionales consiste en el modelado y la reconstrucción de las ondas características. El problema es que los modelos de ECG empleados en la actualidad son complejos y tienen un tiempo de procesamiento computacional muy alto, además de que la cantidad de espacio real de los archivos que se generan en la reconstrucción del mismo es grande. Tal es el caso de la transmisión de datos de ECG de manera inalámbrica, en la cual el modelo de reconstrucción de ECG pierde información relevante como la aparición de la onda Q. En el siguiente trabajo se presenta una evaluación del algoritmo de reconstrucción de ECGs utilizando Modelos- Gaussianos y una base de datos de ECG real del estado de Baja California (B.C.). Los resultados muestran que al utilizar modelos Gaussianos se puede obtener un Coeficiente de Determinación (R2) de entre 0.70 y 0.90, lo cual muestra una aproximación inicial de los trazos ECG reales.
Relevant to mobile health, the design of a portable electrocardiograph (ECG) device using AD823X ... more Relevant to mobile health, the design of a portable electrocardiograph (ECG) device using AD823X microchips as the analog front-end is presented. Starting with the evaluation board of the chip, open-source hardware and software components were integrated into a breadboard prototype. This required modifying the microchip with the breadboard-friendly Arduino Nano board in addition to a data logger and a Bluetooth breakout board. The digitized ECG signal can be transmitted by serial cable, via Bluetooth to a PC, or to an Android smartphone system for visualization. The data logging shield provides gigabytes of storage, as the signal is recorded to a microSD card adapter. A menu incorporates the device’s several operating modes. Simulation and testing assessed the system stability and performance parameters in terms of not losing any sample data throughout the length of the recording and finding the maximum sampling frequency; and validation determined and resolved problems that arose i...
This paper makes an analysis of the ECG leads obtained with the triads of electrodes proposed in ... more This paper makes an analysis of the ECG leads obtained with the triads of electrodes proposed in [I]. Also makes an analysis and gives recommendations about the sampling frequency of the XBee used. En este articulo se hace un analisis de las derivaciones ECG que se obtienen con las triad as de electrodos propuestos en [I]. Tambien se analiza y se hacen recomendaciones sobre la frecuencia de muestreo de los XBee que se utilizan. To obtain bipolar ECG leads (i.e. I, ll, Ill) traditionally, surface electrodes are placed at three specific points on the skin, defmed by the triangle of Einthoven: RA, LA Y LL. Each electrode picks up a biopotential which is carried by conductive wires to an electrocardiograph where the ECG leads are built. In a previous published work [1], we proposed to remove wires between the electrodes and electrocardiograph, by using triads of electrodes at each point of the Einthoven triangle (Fig. 1), which are attached to instrumentation amplifiers inputs. Now in this article: (A) we make an analysis of the ECG leads obtained with the triads of electrodes, and (B) we make recommendations about how to improve the sampling frequency about the XBee that was also previously proposed in [1]. A. ECG Leads Analysis. We hypothesized that the biopotentials collected by the electrode triads could represent the potential at each point of the triangle of Einthoven; therefore, standard bipolar leads could be constructed using the potentials recorded by the triads. It is well known that the difference between LA-RA = DI, LL-RA = Dll and LL-LA = DIll. Therefore, standard leads can be written in terms of biopotentials taken by the triad as: DI = (b'-a')-(b-a), Dll = (b"-a")-(b-a) y Dll = (b"-a")-(b'-a'). So, the three leads computed with the sets of electrode triads and other leads taken with a standard commercial electrocardiograph (the CARDIAX PC-ECG) were compared visa -vis, obtaining correlation coefficients of 0.75, 0.80 and 0.70, respectively. B. XBee Sample Frequency Analysis. The biopotentials at the output of each instrumentation amplifier are inputted to three XBee SI trasmitters, respectively [1]. Each XBee SI transmits the biopotentials toward XBee SI receivers [1]. The XBee SI receivers input the biopotentials to a computer where the three bipolar ECG leads are built [1]. Unfortunately XBee SI is restricted in sampling frequency (i.e. maximum = 333 s/s). When the sampling frequency is a critical factor as in the case in the ECG recording, errors that alter the diagnoses may occur [2]; for example: in the detection of the J-point, or in the shape detection of the P-wave, or in the detection of micropotentials within the QRS complex. There for, a sample frequency at least of 500 s/s is recommended. To achieve an adequate sampling frequency we have replaced the XBee SI by XBee PRO S3B. The PRO S3B reaches maximum stable sampling frequencies up to 1000 s/s. Conclusions. Although correlation coefficients between conventional and electrode triads leads have been good, more and other types of tests should be done to see if the correlation improves. For example improving the placement orientation of the electrode triads or probing other configurations in the triads like the Wilson's central terminal. Frequency analysis of the signals sampled by the XBee PRO S3B should be performed to ensure that important frequencies are contained and have not been distorted in the built leads.
El Electrocardiograma (ECG) convencional y el ECG de alta resolución representan unas de las técn... more El Electrocardiograma (ECG) convencional y el ECG de alta resolución representan unas de las técnicas de pre-diagnóstico no invasivo de mayor recurrencia en estudios de prevención de Infarto al Miocardio (IAM). La información obtenida en un ECG es posteriormente procesada y guardada ya sea en una base de datos o mostrada al especialista para su análisis. Una de las técnicas de análisis de ECG mediante métodos computacionales consiste en el modelado y la reconstrucción de las ondas características. El problema es que los modelos de ECG empleados en la actualidad son complejos y tienen un tiempo de procesamiento computacional muy alto, además de que la cantidad de espacio real de los archivos que se generan en la reconstrucción del mismo es grande. Tal es el caso de la transmisión de datos de ECG de manera inalámbrica, en la cual el modelo de reconstrucción de ECG pierde información relevante como la aparición de la onda Q. En el siguiente trabajo se presenta una evaluación del algoritmo de reconstrucción de ECGs utilizando Modelos- Gaussianos y una base de datos de ECG real del estado de Baja California (B.C.). Los resultados muestran que al utilizar modelos Gaussianos se puede obtener un Coeficiente de Determinación (R2) de entre 0.70 y 0.90, lo cual muestra una aproximación inicial de los trazos ECG reales.
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Papers by Marco A. Reyna