MRI assessment of LV relaxation by untwisting rate: A new isovolumic phase measure of τ

Sheng Jing Dong, Paul S. Hees, Cynthia O. Siu, James L. Weiss, Edward P. Shapiro

Research output: Contribution to journalArticle

Abstract

Most noninvasive measures of diastolic function are made during left ventricular (LV) filling and are therefore subject to "pseudonormalization," because variation in left atrial (LA) pressure may confound the estimation of relaxation rate. Counterclockwise twist of the LV develops during ejection, but untwisting occurs rapidly during isovolumic relaxation, before mitral opening. We hypothesized that the rate of untwisting might reflect the process of relaxation independent of LA pressure. Recoil rate (RR), the velocity of LV untwisting, was measured by tagged magnetic resonance imaging and regressed against the relaxation time constant (τ), recorded by catheterization, in 10 dogs at baseline and after dobutamine, saline, esmolol, and methoxamine treatment. RR correlated closely (average r = -0.86) with and was unaffected by elevated LA pressure. Multiple regression showed that τ, but not LA or aortic pressure, was an independent predictor of RR (P < 0.0001, P = 0.99, and P = 0.18, respectively). The rate of recoil of torsion, determined wholly noninvasively, provides an isovolumic phase, preload-independent assessment of LV relaxation. Use of this novel parameter should allow the detailed study of diastolic function in states known to affect filling rates, such as aging, hypertension, and congestive heart failure.

Original languageEnglish (US)
Pages (from-to)H2002-H2009
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume281
Issue number5 50-5
StatePublished - Dec 18 2001

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Keywords

  • Diastole
  • Hemodynamics
  • Imaging
  • Magnetic resonance imaging

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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