The development of a microprocessor system for simultaneously monitoring heart rate from multiple subjects

Two computer systems developed in our laboratory to monitor the heart rate of freely moving rats are described below. The first system uses the Commodore CBM microcomputer and monitors a single rat. The second system uses the IBM CS9000, monitors up to four rats simultaneously, and provides real-time graphics. Both systems rely on a Schmitt-trigger circuit which digitizes the electrical signal generation by the heart during every cardiac cycle. Both systems also employ the same algorithm to handle the appreciable levels of noise generated by subject movement. The algorithm developed for filtering this noise and its effectiveness are presented. This paper illustrates a software-intensive approach to handling signal timing, and the advantages provided by 16/32-bit versus an 8-bit microcomputer.