The thermodynamics of diastole: Kinematic modeling-based derivation of the P-V loop to transmitral flow energy relation with in vivo validation

Sina Mossahebi, Leonid Shmuylovich, Sándor J. Kovács

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Pressure-volume (P-V) loop-based analysis facilitates thermodynamic assessment of left ventricular function in terms of work and energy. Typically these quantities are calculated for a cardiac cycle using the entire P-V loop, although thermodynamic analysis may be applied to a selected phase of the cardiac cycle, specifically, diastole. Diastolic function is routinely quantified by analysis of transmitral Doppler E-wave contours. The first law of thermodynamics requires that energy (ε) computed from the Doppler E-wave (εE-wave) and the same portion of the P-V loop (ε P-V E-wave) be equivalent. These energies have not been previously derived nor have their predicted equivalence been experimentally validated. To test the hypothesis that εP-V E-wave and εE-wave are equivalent, we used a validated kinematic model of filling to derive εE-wave in terms of chamber stiffness, relaxation/ viscoelasticity, and load. For validation, simultaneous (conductance catheter) P-V and echocadiographic data from 12 subjects (205 total cardiac cycles) having a range of diastolic function were analyzed. For each E-wave, εE-wave was compared with εP-V E-wave calculated from simultaneous P-V data. Linear regression yielded the following: εP-V E-wave = αεE-wave + b (R2 = 0.67), where α = 0.95 and b = 6e-5. We conclude that E-wave-derived energy for suction-initiated early rapid filling εE-wave, quantitated via kinematic modeling, is equivalent to invasive P-V-defined filling energy. Hence, the thermodynamics of diastole via εE-wave generate a novel mechanism-based index of diastolic function suitable for in vivo phenotypic characterization.

Original languageEnglish
Pages (from-to)H514-H521
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume300
Issue number2
DOIs
StatePublished - Feb 1 2011
Externally publishedYes

Keywords

  • Diastolic function
  • Echocardiography
  • Pressure-volume loop

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