Isovolumic pressure-to-early rapid filling decay rate relation: Model-based derivation and validation via simultaneous catheterization echocardiography

Charles S. Chung, David M. Ajo, Sándor J. Kovács

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Transmitral Doppler echocardiography is the preferred method of noninvasive diastolic function assessment. Correlations between catheterization-based measures of isovolumic relaxation (IVR) and transmitral, early rapid filling (Doppler E-wave)-derived parameters have been observed, but no model-based, causal explanation has been offered. IVR has also been characterized in terms of its duration as IVR time (IVRT) and by τ, the time-constant of IVR, by approximating the terminal left ventricular IVR pressure contour as P(t) = P∞ + Poe-t/τ, where P(t) is the continuity of pressure, P∞ and Po are constants, t is time, and τ is the time constant of IVR. To characterize the relation between IVR and early rapid filling more fully, simultaneous (micromanometric) left ventricular pressure and transmitral Doppler E-wave data from 25 subjects undergoing elective cardiac catheterization and having normal physiology were analyzed. The time constant τ was determined from the dP/dt vs. P (phase) plane and, simultaneous Doppler E-waves provided global indexes of chamber viscosity/relaxation (c), chamber stiffness (k), and load (xo). We hypothesize that temporal continuity of pressure decay at mitral valve opening and physiological constraints permit the algebraic derivation of linear relations relating 1/τ to both peak atrioventricular pressure gradient (kxo) and E-wave-derived viscosity/relaxation (c) but does not support a similar, causal (linear) relation between deceleration time and τ or IVRT. Both predicted linear relations were observed: kxo to 1/τ (r = 0.71) and viscosity/relaxation to 1/τ (r = 0.71). Similarly, as anticipated, only a weak linear correlation between deceleration time and IVRT or τ was observed (r = 0.41). The observed in vivo relationship provides insight into the isovolumic mechanism of relaxation and the changing-volume mechanism of early rapid filling via a link of the respective relaxation properties.

Original languageEnglish
Pages (from-to)528-534
Number of pages7
JournalJournal of Applied Physiology
Volume100
Issue number2
DOIs
StatePublished - Feb 2006

Keywords

  • Deceleration time
  • Diastole
  • Isovolumic relaxation
  • Kinematic modeling

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