Evaluation of intracoronary pressure and blood flow velocity for the assessment of coronary stenoses severity

For the assessment of coronary stenoses severity, intracoronary pressure and blood flow velocity were measured simultaneously during catheterization procedures. In 10 patients pressure measurements were performed distal and proximal of the stenoses. Simultaneously, the coronary blood flow velocity was recorded using Doppler ultrasound catheters. Data was recorded at resting conditions and at hyperemia. All signals were digitized at 200 Hz. Mean pressure gradients were plotted versus flow velocity, and linear regression was applied to the data. The slopes of the resulting lines were used as an indicator for stenosis severity. In addition, a new parameter for the degree of obstruction was derived by frequency analysis of proximal and distal pressure waveforms. For verification, the described methods were compared to clinically established methods.