Acquisition of raw intracoronary Doppler signal for better characterization of flows

Intracoronary investigations using Doppler-tipped guidewires are now performed routinely to assess the severity of stenosis. Maximal peak velocity and average peak velocity computed on-line are used to this end, but when the quality of the Doppler signal is poor, the contour recognition fails to follow maximal velocity. We describe a system allowing the acquisition of intracoronary raw Doppler signals (I and Q components) with pressures, ECG and other signals for recording and postprocessing. The technique of multiple beats averaging allowed improvement of signal to noise ratio to be obtained. In-vitro experiments on steady and pulsatile flows in small tubes were performed. Influencing factors such as depth of measurements, rotations, and quality of the signal have been investigated. Our system may help collect high quality Doppler signals along with pressures which is useful for coronary blood flow assessment.