An Integrated System for Intraoperative Cardiac Activation Mapping

This paper describes an electrophysiological data acquisition and processing system which is programmed to rapidly generate cardiac activation maps for experimental studies and antiarrhythmia surgery. The basic system consists of a PDP-11/23+ minicomputer (DEC) with 1.5 Mbit memory and a 10 Mbit hard disk, a 64-channel data acquisition unit controlled by a specially designed interface card, and a modified video terminal. The data acquisition unit includes 64 instrumentation amplifiers with programmable gain and bandwidth. Signals are sampled and digitized at a maximum rate of 1000 samples/s/channel (10 bits) and transferred to the interface card by an optically isolated data bus. The operator controls the system by pointing to function boxes and signals appearing on the graphic terminal with a light pen. The software is based on a general-purpose data acquisition program with a command language interpreter. This program includes a setup section to define the system's parameters (gains, bandwidths, sampling rate) and an acquisition section to initiate data recording into a ring buffer, display the signals simultaneously on the screen, select heartbeats, and store or retrieve data on disk. The data processing procedures (in this case, mapping) can be easily interchanged to accommodate future signal processing needs. Current mapping procedures include an automatic detection section and an editor to manually define the local activation times on any electrogram. Another section displays the activation sequence as a map of isochronal lines. Typical processing time from the selection of a heartbeat to the visualization of the corresponding isochrone map is 2 min.