Some improvements in the acquisition of pulsed signals of TTFM type for USB compatible display in cardiovascular ultrasonic flow-metering

The blood flow in coronary vessels is measured, in a non-invasive way, by using a method known as Transit Time Flow Measurement (TTFM), which is considered as the most accurate at present. It is an indispensable complement in the checking of coronary implants (artery bypass grafts) during surgery process. This paper shows an improvement in TTFM blood flow-metering systems designed for narrowband and broadband regimes, in the CSIC and the ICIMAF centres, into the frame of a consortium CYTED R&D project. An efficient signal acquisition and a useful USB compatible display are provided. These TTFM systems are composed by a detection analogic module, an acquisition & pre-processing stage and a portable PC. Our own-design acquisition system has been upgraded by integrating a PIC18F4550 microcontroller, which lets that to be cheaper and smaller. And practical new software is presented offering to surgeons good operation facilities and a more economic and robust flow-metering tool.