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 (KLV) would be clinically useful. Our theoretical analysis predicts that KLV can be calculated from the time for deceleration of LV early filling (tdec) by [formula: see text] where p = density of blood, L = effective mitral length, and A = mitral area.


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. KLV was determined as the slope of the late diastolic portion of the LV P-V loop. KLV 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 KLV = (0.08/tdec)2. The LV filling pattern was determined from the derivative of LV volume (dV/dt). tdec was measured from peak early filling to the end of early filling. Predicted KLV and actual KLV 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 tdec and KLV.tdec 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. KLV-calculated tdec from the corrected Doppler tdec provided a good estimate of measured KLV (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.
Little
W C
WC
Cardiology Section, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC 27157-1045, USA.
Ohno
M
M
Kitzman
D W
DW
Thomas
J D
JD
Cheng
C P
CP
D000818:Animals; D016279:Atrial Function, Left / Q000502:physiology; D002316:Cardiotonic Agents / Q000494:pharmacology; D003971:Diastole / Q000502:physiology; D004280:Dobutamine / Q000494:pharmacology; D004285:Dogs; D015150:Echocardiography, Doppler; D006439:Hemodynamics / Q000187:drug effects; D008365:Manometry / Q000295:instrumentation; D010656:Phenylephrine / Q000494:pharmacology; D014160:Transducers, Pressure; D016277:Ventricular Function, Left / Q000502:physiology*; D017725:Ventricular Pressure / Q000502:physiology
D002316:Cardiotonic Agents; D010656:Phenylephrine; D004280:Dobutamine