Electrocardiomultigraphimeter using a home computer

The drop in hardware costs has fostered the widespread use of home-computer systems. Because of this situation, the home computer can be profitably employed in some highly specialized fields. We believe electrocardiographic instrumentation to be one such field. We have built an electrocardiomultigraphimeter (ECXGM), which can be considered as a development of the traditional electrocardiograph that performs some additional functions. Our prototype features vectorcardiography, polar coordinate tracing, automatic measurements between fiducial points selected by the user with a joystick and screen cursor and trace filing by patient on labelled floppy disks. The standard hardware consists of a Commodore 64 console, a monitor, two floppy disk drives and an Epson HI-80 plotter, all of which are readily available. The special hardware consists of an A/D converter, which receives the electrocardiographic signal downstream of the amplifying stage, which is a standard feature of any electrocardiograph. Prototype development mostly involved the software. Difficulties were posed by the limited resources available on home computers, an important point in view of the problem to be tackled. The solutions adopted are based on the use of assembler language and overloading techniques and minimizing the interconnections among the software modules defined in a compactly built program. The result is an instrument with significantly advanced clinico-scientific capabilities as compared to current electrocardiographic instruments. This fact, and the class of the hardware used and special software built, confer originality to this work. The new instrument ought to be especially suitable for the offices of cardiologists who have an interest in such capabilities, and for schools of electrocardiography.