Left ventricular chamber stiffness from model-based image processing of transmitral Doppler E-waves.
BACKGROUND
Model-based image processing (MBIP) of Doppler E-waves eliminates the need for digitizing waveforms by hand or determining the contour 'by eye'. Little et al. (Circulation 1995, 92:1933-1939) used pressure-volume measurements for dogs to verify the physiologic-model-derived prediction that the left ventricular chamber stiffness, KLV1 can be determined from the deceleration time tdec, when that portion of the E-wave contour is fit by a cosine function. MBIP of clinical Doppler E-wave images to determine chamber stiffness KLV has not been performed.


OBJECTIVE
We sought to determine KLV by MBIP of clinical Doppler E-wave images and elucidate the physiologic meaning of the harmonic oscillator filling model's parameter k.


RESULTS
The unique mathematical relationship between the kinematic, harmonic oscillator model of filling and KLV predicts that the oscillator's spring constant k be linearly proportional to the chamber stiffness KLV. To verify this, digitally acquired, clinical Doppler transmitral flow velocity images from 21 subjects were analyzed. The parameter k and the stiffness KLV were computed independently for each subject and compared. In accordance with prediction, a linear relationship between k and the stiffness KLV, namely k = 1.16 [A/(rho L)]KLV+41, r = 0.96, was observed.


CONCLUSIONS
The oscillator parameter k is linearly proportional to the left ventricular chamber stiffness KLV. The MBIP approach allows automated computation of k and KLV, provides a robust, automated, observer independent method of Doppler transmitral flow velocity analysis, and eliminates the need for visual determination of the contour or measurement of its attributes by eye. It provides a stimulus for further validation of the relationships among K, KLV, and catheterization-based diastolic chamber properties in humans and their correlations with selected diastolic function-altering syndromes.
Kovács
S J
SJ
Cardiovascular Biophysics Laboratory, Barnes-Jewish Hospital at Washington University Medical Center, St Louis, MO 63110, USA.
Setser
R
R
Hall
A F
AF
D001783:Blood Flow Velocity; D003971:Diastole / Q000502:physiology; D015150:Echocardiography, Doppler / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008943:Mitral Valve / Q000000981:diagnostic imaging* / Q000502:physiology; D008962:Models, Theoretical; D011237:Predictive Value of Tests; D016277:Ventricular Function, Left / Q000502:physiology*