Determination of left ventricular chamber stiffness from the time for deceleration of early left ventricular filling

Background: A noninvasive measure of left ventricular (LV) chamber stiffness (K(LV)) would be clinically useful. Methods and Results: We tested this hypothesis in eight conscious dogs instrumented for measurement of LV pressure (P) with use of a micromanometer and volume (v) with use of sonomicrometers. K(LV) was determined as the slope of the late diastolic portion of the LV P-V loop. K(LV) was varied from 0.99 ± 0.35 to 2.58 ± 0.92 mm Hg/mL with use of three graded doses of phenylephrine. We assumed that ρ=1.0 and that L/A=3.4. Thus, we predicted that K(LV) = (0.08/t(dcc))². The LV filling pattern was determined from the derivative of LV volume (dV/dt). t(dcc) was measured from peak early filling to the end of early filling. Predicted K(LV) and actual K(LV) v were closely correlated (r=.94, SEE=0.06 mm Hg/mL, P<.05). The regression line was close to the line of identity (slope=0.95, intercept=0.13 mm Hg/mL). Dobutamine did not alter the relation between t(dcc) and K(LV). t(dcc) determined from the mitral valve flow velocity measured with Doppler echocardiography correlated well with that measured by dV/dt (r=.89, P<.01) but was 0.02 seconds longer. KN v- calculated t(dcc) from the corrected Doppler t(dcc) provided a good estimate of measured K(LV) (r=.75, SEE=0.5 mm Hg/mL, P<.01). Conclusions LV chamber stiffness can be determined from the time for deceleration of LV early filling, which can be measured noninvasively.