Quantitative assessment of left ventricular diastolic function via Longitudinal and Transverse flow impedances

Erina Ghosh, Sandor J. Kovacs

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

1 Scopus citations

Abstract

Flow impedance has been used to characterize the physical properties of the vascular system by assessing its phasic flow response to pulsatile pressure input in terms of resistance as a function of frequency. Impedance has also been used to characterize global diastolic left ventricular (LV) chamber properties. In early diastole the LV is a mechanical suction pump and accommodates filling by simultaneously expanding in two principal spatial directions: longitudinal (base-to-apex, long-axis) and transverse (radial, short-axis). Total (characteristic) impedance ZC is the product of longitudinal (Z L) and transverse (ZT) impedance as ZC 2=ZLZT where the two impedances reflect the relative spatial propensity for volume accommodation. In this work we compute ZL and ZT for the LV in early diastole. We analyze simultaneously recorded dual pressure-transducer and transthoracic echocardiographic flow data obtained during cardiac catheterization in 11 subjects. We found that ZL was 2 orders of magnitude smaller than ZT in all subjects, providing the first hemodynamic evidence, in concordance with cine-MRI imaging data that longitudinal volume accommodation is indeed, nature's preferred spatial filling mechanism. We also investigated the effect of impaired diastolic function on directional impedances and found that ZL increased (becomes worse) while ZT decreased (becomes better) indicating that as diastolic function becomes impaired radial filling compensates for decreased longitudinal volume accommodation to preserve stroke volume. These results provide mechanistic insight and show that normal diastolic function defines a properly impedance matched state and that diastolic dysfunction is equivalent to a state of impedance mismatch.

Original languageEnglish
Title of host publication2012 Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBC 2012
Pages5595-5598
Number of pages4
DOIs
StatePublished - Dec 14 2012
Externally publishedYes
Event34th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS 2012 - San Diego, CA, United States
Duration: Aug 28 2012Sep 1 2012

Publication series

NameProceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS
ISSN (Print)1557-170X

Conference

Conference34th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS 2012
CountryUnited States
CitySan Diego, CA
Period08/28/1209/1/12

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