Comparison of diastolic filling models and their fit to transmitral Doppler contours

Nudelman, Scott P.; McGuire, Abigail Manson; Hall, A.F.; Kovács, Sándor J.

doi:10.1016/0301-5629(95)00040-x

Cited by 25 publications

(13 citation statements)

References 10 publications

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“…Although several nonlinear and one linear model of diastolic filling have been proposed (15,21), no previous work addresses the efficiency of filling (diastole) by itself, in either mechanical or thermodynamic terms. Because the kinematic model and other nonlinear models (21) of filling accurately predict E wave contours, the modeling paradigm itself provides a method by which filling efficiency can be characterized.…”

Section: Discussionmentioning

confidence: 99%

Frequency-based analysis of the early rapid filling pressure-flow relation elucidates diastolic efficiency mechanisms

Kovács

2006

American Journal of Physiology-Heart and Circulatory Physiology

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Stiffness- and relaxation-based diastolic function (DF) assessment can characterize the presence, severity, and mechanism of dysfunction. Although frequency-based characterization of arterial function is routine (input impedance, characteristic impedance, arterial wave reflection), DF assessment via frequency-based methods incorporating optimization/efficiency criteria is lacking. By definition, optimal filling maximizes (E wave) volume and minimizes "loss" at constant stored elastic strain energy (which initiates mechanical, recoil-driven filling). In thermodynamic terms, optimal filling delivers all oscillatory power (rate of work) at the lowest harmonic. To assess early rapid filling optimization, simultaneous micromanometric left ventricular pressure and echocardiographic transmitral flow (Doppler E wave) were Fourier analyzed in 31 subjects. A validated kinematic filling model provided closed-form expressions for E wave contours and model parameters. Relaxation-based DF impairment is indicated by prolonged E wave deceleration time (DT). Optimization was assessed via regression between the dimensionless ratio of 2nd (Q2) and 3rd flow harmonics (Q3) to the lowest harmonic (Q1), i.e., (Q2/Q1) or (Q3/Q1) vs. DT or c, the filling model's viscosity/damping (energy loss) parameter. Results show that DT prolongation or increased c generated increased oscillatory power at higher harmonics (Q2/Q1 = 0.00091DT + 0.09837, r = 0.70; Q3/Q1 = 0.00053DT + 0.02747, r = 0.60; Q2/Q1 = 0.00614c + 0.15527, r = 0.91; Q3/Q1 = 0.00396c + 0.05373, r = 0.87). Because ideal filling is achieved when all oscillatory power is delivered at the lowest harmonic, the observed increase in power at higher harmonics is a measure of filling inefficiency. We conclude that frequency-based analysis facilitates assessment of filling efficiency and elucidates the mechanism by which diastolic dysfunction associated with prolonged DT impairs optimal filling.

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Section: Discussionmentioning

confidence: 99%

Frequency-based analysis of the early rapid filling pressure-flow relation elucidates diastolic efficiency mechanisms

Kovács

2006

American Journal of Physiology-Heart and Circulatory Physiology

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“…Their derivation used Newton's law (only valid in linear dynamic system) to predict that the deceleration portion of all E-waves have the shape of a cosine function. A more accurate kinematic model, previously proposed by Kovács et al (1987;Hall and Kovács, 1994), uses a linear model for suction-initiated filling (a linear harmonic oscillator) that predicts and fits transmitral E-wave contours as well as nonlinear models (Hall and Kovács, 1994;Kovács et al, 1987Kovács et al, , 2000a and has the advantage of being able to solve the "inverse-problem" and thereby determine model parameters uniquely (Hall and Kovács, 1994;Nudelman et al, 1995). In Fig.…”

Section: Validation Of the Methodsmentioning

confidence: 99%

Frequency-Based Analysis of Diastolic Function: The Early Rapid Filling Phase Generates Negative Intraventricular Wave Reflections

Bowman

Kov

2005

Cardiovasc Eng

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To assess global diastolic function (DF), both invasive and noninvasive methods have been utilized. Except for the end-diastolic pressure-volume relationship, currently all proposed parameters for diastolic function are derived purely from pressure or flow. To characterize the physiology of diastole in the context of atrioventricular pressure gradient generated transmitral flow, and in analogy to frequency-based characterization of ventricular-vascular coupling, we subjected the simultaneously recorded transmitral flow (E-wave) and micromanometric intraventricular pressure (LVP) waveforms to Fourier analysis in 20 subjects. This permitted computation of input impedance, characteristic impedance, the phase angle φ relating pressure to flow, and the complex reflection coefficient R * during the E-wave. We found that the magnitudes of input impedance were 32 ± 12, 13.9 ± 4.4, 37 ± 13, and 53 ± 23 mmHg s/m for DC, 1st, 2nd, and 3rd harmonics, respectively. The characteristic impedance was 30 ± 15 mmHg s/m. The magnitude and phase angle of complex reflection coefficient R * were 0.43 ± 0.11 and 3.58 ± 0.52 rad, respectively. The magnitude of the input impedance carrying most oscillatory power (1st harmonic) is lower than the characteristic impedance, verifying our finding that the real portion of R * was negative. We also found that E waves with prolonged deceleration time (DT > 180 ms-"delayed relaxation" pattern) manifest increased phase differences between pressure and flow, voiding an optimal pressure-flow relationship. These findings elucidate the frequency-based (amplitude/phase) mechanisms by which early diastolic mechanical ventricular suction (dP/dV< 0) achieves left ventricular filling.

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“…3). It is important to note that, unlike the PDF model, other more mathematically sophisticated nonlinear and multiparameter models of diastolic physiology do not allow for unique parameter extraction from clinically observed E-waves (85). Just as with the stiffness and relaxation model of IVR above, the stiffness and relaxation model of the E-wave predicts different regimes of filling dynamics, depending on the relative values of model parameters.…”

Section: Early Rapid Fillingmentioning

confidence: 99%

What global diastolic function is, what it is not, and how to measure it

Chung

Shmuylovich

Kovács

2015

American Journal of Physiology-Heart and Circulatory Physiology

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Leonardo da Vinci's observation (circa 1511) that "the atria or filling chambers contract together while the pumping chambers or ventricles are relaxing and vice versa," the dynamics of four-chamber heart function, and of diastolic function (DF) in particular, are not generally appreciated. We view DF from a global perspective, while characterizing it in terms of causality and clinical relevance. Our models derive from the insight that global DF is ultimately a result of forces generated by elastic recoil, modulated by cross-bridge relaxation, and load. The interaction between recoil and relaxation results in physical wall motion that generates pressure gradients that drive fluid flow, while epicardial wall motion is constrained by the pericardial sac. Traditional DF indexes (, E/E=, etc.) are not derived from causal mechanisms and are interpreted as approximating either stiffness or relaxation, but not both, thereby limiting the accuracy of DF quantification. Our derived kinematic models of isovolumic relaxation and suction-initiated filling are extensively validated, quantify the balance between stiffness and relaxation, and provide novel mechanistic physiological insight. For example, causality-based modeling provides load-independent indexes of DF and reveals that both stiffness and relaxation modify traditional DF indexes. The method has revealed that the in vivo left ventricular equilibrium volume occurs at diastasis, predicted novel relationships between filling and wall motion, and quantified causal relationships between ventricular and atrial function. In summary, by using governing physiological principles as a guide, we define what global DF is, what it is not, and how to measure it. diastolic function; echocardiography; hemodynamics; mathematical modeling; suction pump LEFT VENTRICULAR (LV) DIASTOLIC dysfunction is typically reported and indexed as either an increase in myocardial stiffness or a slowing of relaxation (i.e., cross-bridge dissociation). In actuality, diastolic function (DF) is the result of the continuous interaction between the restoring force of elastic recoil and the opposing force generated by cross bridges that have yet to uncouple from the previous systole. The restoring forces seek to lengthen the muscle, while the cross-bridge forces previously acted to shorten the muscle. The simultaneous action of these two opposing forces during both isovolumic relaxation (IVR) and filling result in wall motion, constrained by pericardial sac volume, and simultaneous generation of pressure gradients. This review discusses the governing physical laws and the constraints of DF, as well as which indexes of DF are consistent with diastolic physiology. Deriving and evaluating indexes of DF using this conceptual framework both clarifies and advances our understanding of DF and diastolic dysfunction in health and disease. Physiology of DiastoleCardiovascular physiology is taught using the Wiggers diagram, which segments the cardiac cycle into systole and diastole ( Fig. 1) (49, 124). Systole begins...

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Comparison of diastolic filling models and their fit to transmitral Doppler contours

Cited by 25 publications

References 10 publications

Frequency-based analysis of the early rapid filling pressure-flow relation elucidates diastolic efficiency mechanisms

Frequency-based analysis of the early rapid filling pressure-flow relation elucidates diastolic efficiency mechanisms

Frequency-Based Analysis of Diastolic Function: The Early Rapid Filling Phase Generates Negative Intraventricular Wave Reflections

What global diastolic function is, what it is not, and how to measure it

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