Abstract
We have designed a new body surface isopotential mapping system under 8-bit microprocessor control. In this system, ECG data of 96 lead points on the human body surface are simultaneously held with 96 S/H circuits, amplified 60 dB with 96 AC amplifiers, scanned by multiplexers at a rate of 10, μsec/channel, digitized through an A-D converter into 10 bits, and stored in the data area (48 kilobytes' RAM). This process is repeated 250 times at an appropriate time interval of either 1, 2 or 4 msec, and all the ECG data are stored in the data area. After compensation of DC potential superimposed on the stored ECG data, isopotential maps are constructed from 87 out of 96 ECGs by use of a linear interpolation method. Both 12 lead ECGs and Frank lead VCGs of the same cardiac cycle as is used for construction of the maps, are also obtained from some of the 87 ECGs and the remaining 8 ECGs. Generation of maps, scalar ECGs and vector loops as well as their digital formats, can be displayed on a CRT within 20 minutes after the beginning of electrode placement on the body surface. If necessary, all the stored ECG data can be recorded on a cassette magnetic tape for permanent data storage. In addition, four kinds of data acquisition mode (Regular, Irregular, Next, and Precede) are designed for the selection of any required cardiac cycle of various arrhythmias. In conclusion, besides being downsized and cost-efficient because of the microcomputer incorporated, this system also has several advantage for clinical use, namely, data acquisition, map generation, and reduced time for data output.
