Mitral inertance in humans: Critical factor in Doppler estimation of transvalvular pressure gradients

Satoshi Nakatani, Michael S. Firstenberg, Neil L. Greenberg, Pieter M. Vandervoort, Nicholas G. Smedira, Patrick M. McCarthy, James D. Thomas*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

The pressure-velocity relationship across the normal mitral valve is approximated by the Bernoulli equation ΔP = 1/2 ρΔν2 + M · dv/dt, where ΔP is the atrioventricular pressure difference, ρ is blood density, ν is transmitral flow velocity, and M is mitral inertance. Although M is indispensable in assessing transvalvular pressure differences from transmitral flow, this term is poorly understood. We measured intraoperative high-fidelity left atrial and ventricular pressures and simultaneous transmitral flow velocities by using transesophageal echocardiography in 100 beats (8 patients). We computed mean mitral inertance (M̄) by M̄ = ∫(ΔP - 1/2 ·ρν2) dt/∫(dv/dt)dt and we assessed the effect of the inertial term on the transmitral pressure-flow relation. M̄ ranged from 1.03 to 5.96 g/cm2 (mean = 3.82 ± 1.22 g/cm2). ΔP calculated from the simplified Bernoulli equation (ΔP = 1/2·ρν2) lagged behind (44 ± 11 ms) and underestimated the actual peak pressures (2.3 ± 1.1 mmHg). M̄ correlated with left ventricular systolic pressure (r = -0.68, P < 0.0001) and transmitral pressure gradients (r = 0.65, P < 0.0001). Because mitral inertance causes the velocity to lag significantly behind the actual pressure gradient, it needs to be considered when assessing diastolic filling and the pressure difference across normal mitral valves.

Original languageEnglish (US)
Pages (from-to)H1340-H1345
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume280
Issue number3 49-3
DOIs
StatePublished - 2001

Keywords

  • Doppler echocardiography
  • Mitral valve

ASJC Scopus subject areas

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

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