Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
J Heart Valve Dis. 2011 Mar;20(2):159-64.

Potential role of Reynolds number in resolving Doppler- and catheter-based transvalvular gradient discrepancies in aortic stenosis.

Author information

  • 1Division of Cardiovascular Diseases, Mayo Clinic, Scottsdale, Arizona 85259, USA.

Abstract

BACKGROUND AND AIM OF THE STUDY:

Discrepancies in mean transvalvular gradient have been observed between Doppler echocardiography and catheter-based techniques in the assessment of aortic stenosis (AS). The Reynolds number (RE) has been shown to influence Doppler-derived gradients, and may be useful in resolving Doppler- and catheter-based gradient discrepancies in AS. The study aim was to assess the influence of the RE on such discrepancies.

METHODS:

A pulsatile in-vitro heart model using a bioprosthetic aortic valve with leaflets sutured together was used to simulate AS. Simultaneous gradients were measured using Doppler echocardiography and high-fidelity catheters while the RE was varied, by testing solutions of different density and viscosity across a range of cardiac outputs.

RESULTS:

The echocardiographic and catheter-derived mean gradient (MG) values were correlated (r = 0.89; p < 0.0001); however, significant differences in the MG were observed across hemodynamic states. A direct linear relationship was identified between RE and the absolute difference in MG measured using the two techniques (r = 0.94, p < 0.0001). Relative to catheter-based measurements, the MG was underestimated by Doppler (range: 13-16 mmHg) at low RE (median 6,999) and overestimated (7-33 mmHg) at high RE (median 34,268). However, agreement between catheter- and Doppler-derived gradients was within 5 mmHg at intermediate RE (median 17,284) (p < 0.0001).

CONCLUSION:

The underestimation of Doppler-derived MGs at low RE relative to catheter-based measurements may be due to an exclusion of viscous friction from the simplified Bernoulli equation, while the overestimation of Doppler-derived MGs at high RE may be due to a pressure recovery effect. However, within an intermediate range of RE, where the effects of viscous and inertial forces are balanced, the agreement between catheter- and Doppler-derived gradients was excellent.

Comment in

PMID:
21560814
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Loading ...
    Write to the Help Desk