WAVE-INTENSITY ANALYSIS - A NEW APPROACH TO LEFT-VENTRICULAR FILLING DYNAMICS

In order to explore a new approach to the analysis of diastolic dysfun ction, we adapted wave-intensity analysis (WIA), a time-domain analysi s that provides information regarding both upstream and downstream eve nts, to left ventricular (LV) filling. WIA considers the pressure and flow waves as summations of successive wavelets, characterised by the direction they travel and by the sign of the pressure gradient associa ted with them. Wave intensity is the product, dPdU, calculated from th e incremental differences in LV pressure (dP) and mitral velocity (dU) and, during the diastolic filling interval, yields up to five dPdU pe aks. Peak I is caused by backward-travelling expansion waves that acce lerate the blood while LV pressure falls, and may be related to ''dias tolic suction''. Peak 2 is caused by forward-travelling compression wa ves which occur if acceleration continues after LV pressure begins to increase. Peak 3 is caused by backward compression waves and is associ ated with rising LV pressure and deceleration. Peak 4 is caused by for ward compression waves and is associated with the increasing LV pressu re and acceleration caused by atrial contraction. Peak 5 is caused by backward compression waves and is associated with increasing pressure and deceleration. These preliminary observations suggest that WIA can be useful in describing the mechanics of LV filling and, after much fu rther work has been accomplished, it might prove useful in the detecti on and characterization of diastolic dysfunction.