New approach to assessing coronary stenosis hemodynamics

In 16 patients studied before coronary angioplasty, simultaneous measurements of trans-stenotic pressure gradient and mean blood flow velocity were obtained with miniaturized sensor-tip pressure and Doppler guidewires. A flow/gradient index was calculated from the integration of the pressure gradient and now velocity measurements obtained in baseline conditions and at the peak effect of an intracoronary infusion of papaverine. This index, inversely related to stenosis resistance, showed a better correlation with minimal luminal cross-sectional area (r = .68, P < .005) than any independent flow or pressure gradient measurement. The instantaneous pressure gradient/flow velocity relationship was also assessed using a beat-to-beat analysis of simultaneously acquired high-fidelity flow velocity and pressure signals. The equation with best fit for the diastolic measurements of Flow velocity and trans-stenotic pressure gradient was calculated in six patients using four consecutive beats post-papaverine, and the slope of this equation was correlated with the angiographic measurements. Our results indicate that direct and simultaneous measurement of the parameters defining coronary stenosis hemodynamics can be obtained. Also, indices of stenosis resistance or conductance can be derived from the integration of the mean or instantaneous flow/gradient measurements.