A system for real-time cardiac acoustic mapping

This paper describes the structure of a real-time cardiac acoustic mapping system (RTCAMS) which displays the amplitude of the phonocardiogram (PCG) recorded on the surface of the thorax with an acoustic probe composed of an array of 25 microphones. The basic components of the RTCAMS are the acoustic probe, a PCG module, and a digital signal processing (DSP) board installed in a Pentium computer(PC). The RTCAMS uses the Microsoft(a) Windows 3.1 operating system for its graphical user interface. The essential functions of the software are the data acquisition, the graphic computation, and the display of the PCG envelopes and the acoustic maps. These processes are performed in parallel by the four processors of the DSP board. Parts of the software were written in Assembly language and a real-time micro-kernel was implemented to improve the use of the DSP resources and the overall speed of the system. The preliminary tests show that the system can display the PCG signals and cardiac acoustic maps at a rate of 33 frames per second.