What is the clinical evidence from this study?

Population: Left ventricular pressure-volume loops (n=13). Intervention: Regression algorithms for isochrone shape analysis. Primary outcome: Shape of the isochrones.

What does this research mean for the field?

The linear time-varying elastance theory fails to robustly model pressure-volume changes in the mouse ventricle, as isochrones exhibit marked curvilinearity and linear regression with a fixed intercept shows poor correlation. Novelty: ClaimNovelty.CONTRADICTORY. Consensus alignment: ConsensusAlignment.CHALLENGES_CONSENSUS.

What question did this study set out to answer?

To evaluate the validity of the linear time-varying elastance model by assessing whether left ventricular pressure-volume isochrones remain linear with a stable volume intercept across the cardiac cycle in mice.

November 12, 2005AJP Heart and Circulatory PhysiologyOpen Access

Nonlinear isochrones in murine left ventricular pressure-volume loops: how well does the time-varying elastance concept hold?

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Key result

Linear time-varying elastance failed to robustly model pressure-volume changes in the mouse ventricle, as linear regression with a fixed intercept showed poor correlation (R2 < 0.75).

Key Points

To evaluate the validity of the linear time-varying elastance model by assessing whether left ventricular pressure-volume isochrones remain linear with a stable volume intercept across the cardiac cycle in mice.
Acquired left ventricular pressure-volume loops in 13 open-chest anesthetized mice using a combined pressure-conductance catheter.
Assessed isochrone morphology across the cardiac cycle using six regression algorithms (two linear, two quadratic, and two logarithmic, incorporating either fixed or time-varying volume intercepts).
Isochrones showed marked curvilinearity and were described equally well by quadratic or logarithmic regression, whereas the volume intercept varied considerably over time.
Linear regression with a fixed intercept yielded poor correlation (R² < 0.75) during isovolumic relaxation and early ventricular filling.
Logarithmic regression demonstrated superior accuracy in estimating the fixed volume intercept of the end-systolic pressure-volume relationship.

Structured PICO

Population

13 open-chest anesthetized mice

Intervention

Pressure-volume measurements using a combined pressure-conductance catheter analyzed with six regression algorithms (two linear, two quadratic, and two logarithmic)

Outcome

Shape of the isochrones and validity of the linear time-varying elastance conceptsurrogate

The linear time-varying elastance concept is inadequate for modeling pressure-volume changes in the mouse ventricle, highlighting the need for a new nonlinear framework.

Discussion

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Implication

Questions linear elastance assumptions in mice; challenges consensus and leaves open nonlinear modeling needs.

Cite This Study

Claessens et al. (2005) studied Left ventricular pressure-volume loops (n=13). Regression algorithms for isochrone shape analysis was evaluated on Shape of the isochrones. Linear time-varying elastance failed to robustly model pressure-volume changes in the mouse ventricle, as linear regression with a fixed intercept showed poor correlation (R2 < 0.75).

synapsesocial.com/papers/6a1744c21891c104f68d76eb https://doi.org/10.1152/ajpheart.00663.2005

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Nonlinear isochrones in murine left ventricular pressure-volume loops: how well does the time-varying elastance concept hold?

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Nonlinear isochrones in murine left ventricular pressure-volume loops: how well does the time-varying elastance concept hold?

Key Points

Structured PICO

Discussion

Implication

Cite This Study

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