Layer-specific strain analysis by speckle tracking echocardiography reveals differences in left ventricular function between rats and humans

Noa Bachner-Hinenzon, Offir Ertracht, Marina Leitman, Zvi Vered, Sara Shimoni, Ronen Beeri, Ofer Binah, Dan Adam*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

The rat heart is commonly used as an experimental model of the human heart in both health and disease states, assuming that heart function of rats and humans is alike. When studying a rat model, echocardiography is usually performed on sedated rats, whereas standard echocardiography on adult humans does not require any sedation. Since echocardiography results of sedated rats are usually inferred to alert humans, in the present study, we tested the hypothesis that differences in left ventricular (LV) function may be present between rats sedated by a low dose of ketamine-xylazine and alert humans. Echocardiography was applied to 110 healthy sedated rats and 120 healthy alert humans. Strain parameters were calculated from the scans using a layer-specific speckle tracking echocardiography program. The results showed that layer longitudinal strain is equal in rats and humans, whereas segmental strain is heterogeneous (P < 0.05) in a different way in rats and humans (P < 0.05). Furthermore, layer circumferential strain is larger in humans (P < 0.001), and the segmental results showed different segmental heterogeneity in rats and humans (P < 0.05). Radial strain was found to be homogeneous at the apex and papillary muscle levels in humans and heterogeneous in rats (P < 0.001). Additionally, whereas LV twist was equal in rats and humans, in rats the rotation was larger at the apex (P < 0.01) and smaller at the base (P < 0.001). The torsion-to-shortening ratio parameter, which indicates the transmural distribution of contractile myofibers, was found to be equal in rats and humans. Thus, when evaluating LV function of sedated rats under ketamine-xylazine, it is recommended to measure the global longitudinal strain, LV twist, and torsion-to-shortening ratio, since no scaling is required when converting these parameters and inferring them to humans.

Original languageAmerican English
Pages (from-to)H664-H672
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume299
Issue number3
DOIs
StatePublished - Sep 2010
Externally publishedYes

Keywords

  • Contractility
  • Speckle training
  • Strain imaging

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