Determination of left ventricular chamber stiffness from the time for deceleration of early left ventricular filling
Little, W.C.; Ohno, M.; Kitzman, D.W.; Thomas, J.D.; Cheng, C.P.
Circulation 92(7): 1933-1939
1995
ISSN/ISBN: 0009-7322 PMID: 7671378 Document Number: 441670
Background: A noninvasive measure of left ventricular (LV) chamber stiffness (K-LV) would be clinically useful. Our theoretical analysis predicts that K-LV can be calculated from the time for deceleration of LV early filling (t-dec) by K-LV = p cntdot L/A cntdot (pi/2 cntdot 1 cntdot t-dec)-q where p=density of blood, L=effective mitral length, and A=mitral area. 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 p=1.0 and that L/A=3.4. Thus, we predicted that K-LV = (0.08/t-dec)-2. The LV filling pattern was deter-mined from the derivative of LV volume (dV/dt). t-dec, was measured from peak early filling to the end of early filling. Predicted K-Lv and actual K-LV were closely correlated (r=.94, SEE=0.06 mm Hg/mL, P lt .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-dec and K-LV t-dec determined from the mitral valve flow velocity measured with Doppler echocardiography correlated well with that measured by dV/dt (r=.89, P lt .01) but was 0.02 seconds longer. K-LV-calculated t-dec from the corrected Doppler t,c, provided a good estimate of measured K-LV (r=.75, SEE=0.5 mm Hg/mL, P lt .01). Conclusions: LV chamber stiffness can be determined from the time for deceleration of LV early filling, which can be measured noninvasively.