In vivo validation of longitudinal-circumferential area change ratio to estimate myofiber shortening in the heart

Hiroshi Ashikaga, Jeffrey H. Omens

Research output: Contribution to journalArticle

Abstract

The aim of this paper was to validate area change ratio (%AC) against myofiber shortening (%λ f) in the heart in vivo. AC is emerging as a mechanical index that may approximate λ f by incorporating both circumferential and longitudinal shortening. However, the physiological significance of %AC remains unclear. We studied the time course of %AC in the anterior midleft ventricular wall of normal canine heart in vivo (n 14) during atrial pacing over the entire cardiac cycle using transmurally implanted markers and biplane cineradiography (8 ms/frame). %AC was calculated as the myocardial area change relative to the elemental material area on the circumferential-longitudinal plane at the reference configuration (end diastole). %AC was compared with %λ f that was determined from the transmural fiber orientation directly measured in the heart tissue. The time course of both %AC and %λ f was determined in the subepicardial, midwall, and subendocardial layers. The time course of %AC and %λ f was significantly different, and the difference was more pronounced towards the endocardium. %AC consistently overestimated %λ f. The timing of the peak %AC was significantly delayed compared to that of the peak %λ f. We conclude that %AC is significantly different from %λ f both in magnitude and timing in vivo. %AC overestimates %λ f , and the overestimation is worse toward the endocardial layers. This may be a potentially important limitation when applying %AC to optimization and responder identification for cardiac resynchronization therapy.

Original languageEnglish (US)
Article number6153052
Pages (from-to)1391-1397
Number of pages7
JournalIEEE Transactions on Biomedical Engineering
Volume59
Issue number5
DOIs
StatePublished - May 1 2012

Keywords

  • Biomechanics
  • biomedical imaging
  • strain

ASJC Scopus subject areas

  • Biomedical Engineering

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