High resolution 2 channel Electrocardiography


ECG recording on breath-hold divers already dates Prototypeback to the 1970s where Prof. Data used a magnetic tape recorder. Additionally depth and water temperature were stored. ECG recorders for underwater use have to be waterproof and pressure resistant to more than 20bar (breath-hold divers have already passed the 200m mark) and for good acceptance have to be small, lightweight and easy to use. Moreover the should have a minimum overall recording capacity of several hours. Recent experiments with a novel underwater Doppler-Echography system also demonstrate cardiovascular changes during breath hold dives at 3 and 10m [Marabotti et al. Echocardiographic changes during breath-hold diving. Proceedings of Blue 2005. Pisa. Italy]. These cardiovascular changes might also affect the timing of the ECG. To investigate possible depth dependent variances of the PQ or the PR interval, high resolution recorders with a sampling frequency like 1kHz are needed.

To fulfil all requirements, an ECG recorder was ECG electrodesdeveloped with 1200 Hz sampling frequency, 16 bit resolution and data storage on SD card. The electronics can be powered by a small and lightweight rechargeable Lithium battery. An overall power consumption of 30mA allows a continuous operation on one battery set for a minimum of 40h. The recorded data are stored on the SD card in .txt files in FAT16 or FAT32 file format, thus can be processed easily with standard analysis software or more sophisticated tools under Labview or Matlab. While in the first prototypes an analog pressure sensor was used that allowed depth measurements to 60m, the actual version includes a digital pressure sensor with 16 bit resolution (1,2 mbar) and for temperature measurement and compensation and integrated digital temperature sensor. This pressure sensor can be used to pressures up to 30 bar, even if in the specifications as maximum pressure 14 bar is stated.


This project was done by our team in collaboration with the Scuola Superiore Sant Anna, Pisa, Italy, Profactor, Steyr-Gleink, Austia and CNR - Institute of Clinical Physiology, Pisa, Italy.



A. Sieber, R. Bedini, X. Yong, A. Navari, M. Dalle Luche, A. L’Abbate Antonio, P. Dario, High resolution ECG monitoring device for research on variances in the P – QRS interval during breath hold diving, EUBS 2007, Sharm el Sheikh, Egypt, 2007






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