LEFT-VENTRICULAR CHAMBER STIFFNESS FROM MODEL-BASED IMAGE-PROCESSING OF TRANSMITRAL DOPPLER E-WAVES

Background Model-based image processing (MBIP) of Doppler E-waves elim inates the need for digitizing waveforms by hand or determining the co ntour 'by eye'. Little et al. (Circulation 1995, 92:1933-1939) used pr essure-volume measurements for dogs to verify the physiologic-model-de rived prediction that the left ventricular chamber stiffness, K-LV, ca n be determined from the deceleration time t(dec), when that portion o f the E-wave contour is fit by a cosine function. MBIP of clinical Dop pler E-wave images to determine chamber stiffness K-LV has not been pe rformed. Objective We sought to determine K-LV by MBIP of clinical Dop pler E-wave images and elucidate the physiologic meaning of the harmon ic oscillator filling model's parameter k. Methods and results The uni que mathematical relationship between the kinematic, harmonic oscillat or model of filling and K-LV predicts that the oscillator's spring con stant k be linearly proportional to the chamber stiffness K-LV. To ver ify this, digitally acquired, clinical Doppler transmitral flow veloci ty images from 21 subjects were analyzed. The parameter k and the stif fness K-LV were computed independently for each subject and compared. In accordance with prediction, a linear relationship between k and the stiffness K-LV, namely k = 1.16 [A/(rho L)]K-LV + 41, r = 0.96, was o bserved. Conclusions The oscillator parameter k is linearly proportion al to the left ventricular chamber stiffness K-LV. The MBIP approach a llows automated computation of k and K-LV, provides a robust, automate d, observer-independent method of Doppler transmitral flow velocity an alysis, and eliminates the need for visual determination of the contou r or measurement of its attributes by eye. It provides a stimulus for further validation of the relationships among k, K-LV, and catheteriza tion-based diastolic chamber properties in humans and their correlatio ns with selected diastolic function-altering syndromes. (C) Rapid Scie nce Publishers.