Diastolic intraventricular pressure gradient analysed by digital signal processing

A highly sensitive method of pressure detection is developed by digital signal processing using ASYST software. High-gain, diastolic left ventricular pressures (proximal and distal to the apex, LVPp, LVPd) were measured with a double-sensor micromanometer in the ventricular inflow tract in 10 closed-chest, atrioventricular (AV) blocked dogs paced at a rate of 80 bpm with AV delay of 150 ms. Periods of 5 s were digitally recorded and superimposed in a pressure-time coordinate system. During the initial phase of early diastole, LVPp fell more during a shorter time and to a lower value than LVPd. The rapid filling wave was higher, steeper and shorter at LVPp than at LVPd. After a mid-diastolic equilibrium during atrial contraction the LVPd elevated faster, higher and during a shorter time than LVPp. These differences in pressure and time resulted in a positive and negative intraventricular pressure gradient (IVPG) similar to the transmitral pressure gradient reflecting the dynamics of diastolic intraventricular flow. The analysis of IVPG provides a new method to study diastolic function