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Mechanisms of diastolic intraventricular regional pressure differences and flow in the inflow and outflow tracts

Kjetil Steine, MD, PhD^*,*, Marie Stugaard, MD, PhD and Otto A. Smiseth, MD, PhD, FACC

^* Medical Department, Aker University Hospital, Oslo, Norway
Institute for Surgical Research, Rikshospitalet, University of Oslo, Oslo, Norway

View larger version (18K): [in a new window]   Figure 1 Schematic presentation of the locations of the pressure sensors. placement of the color m-mode doppler cursor lines in the left ventricular (lv) inflow and outflow tracts is indicated by the dotted lines.

View larger version (66K): [in a new window]   Figure 2 Color M-mode Doppler image of early diastolic flow velocities (encoded red) in the left ventricular inflow tract in one representative dog at baseline.

View larger version (54K): [in a new window]   Figure 3 Color M-mode Doppler image of diastolic apex to subaortic valve flow velocities (encoded blue) in the left ventricular outflow tract in one representative dog at baseline. Note that the outflow tract flow component starts before cessation of early inflow and is not finished until late diastole.

View larger version (32K): [in a new window]   Figure 4 (A) Representative pressure recordings and timing of pressure differences in the left ventricular (LV) inflow and outflow tracts. The data are presented as the mean value ± SD at baseline for 12 dogs. a, Duration of pressure gradient between the mitral tip and subaortic regions. b, Interval from the start of the pressure gradient (onset of flow) in the LV inflow tract to its peak. c, Interval from the start of the LV outflow tract pressure gradient to its peak. (B) The same pressure recordings as in part A, with the timing of flow velocities in LV inflow and outflow tracts. Again, the data are presented as the mean value ± SD at baseline for the same 12 dogs as in part A. LAP and LVP = pressure in left atrium and left ventricle, respectively.

View larger version (22K): [in a new window]   Figure 5 Representative experiment showing left ventricular (LV) pressure and volume during isoprenaline infusion. Note that the pressure in the left ventricle at the apex (LVPapex) declined at a faster rate than LVPmitral and LVPaorta during isovolumic pressure decay (upper panel). However, minimal first derivative of LV pressure (dP/dtmin) of the LVPapex (middle vertical broken line) was delayed, as compared with the dP/dtmin of the LVPaorta and LVPmitral (left vertical broken line). The right vertical broken line indicates the first crossover between all three LV and left atrial pressures.

View larger version (18K): [in a new window]   Figure 6 One representative dog showing intraventricular diastolic pressure gradients between the left ventricular (LV) mitral and apical regions at baseline (upper panel), after induction of acute LV failure by microembolization (middle panel), and during isoprenaline (lower panel). The LV inflow tract pressure gradient is indicated by the vertical lines, and its peak at baseline, during LV failure, and isoprenaline is 2.6, 1.4, and 5.3 mm Hg, respectively. LVP = pressure in the left ventricle.