Electromechanical analysis of infarct border zone in chronic myocardial infarction

Hiroshi Ashikaga, Steven R. Mickelsen, Daniel B. Ennis, Ignacio Rodriguez, Peter Kellman, Han Wen, Elliot R. McVeigh

Research output: Contribution to journalArticle

Abstract

To test the hypothesis that alterations in electrical activation sequence contribute to depressed systolic function in the infarct border zone, we examined the anatomic correlation of abnormal electromechanics and infarct geometry in the canine post-myocardial infarction (MI) heart, using a high-resolution MR-based cardiac electromechanical mapping technique. Three to eight weeks after an MI was created in six dogs, a 247-electrode epicardial sock was placed over the ventricular epicardium under thoracotomy. MI location and geometry were evaluated with delayed hyperenhancement MRI. Three-dimensional systolic strains in epicardial and endocardial layers were measured in five short-axis slices with motion-tracking MRI (displacement encoding with stimulated echoes). Epicardial electrical activation was determined from sock recordings immediately before and after the MR scans. The electrodes and MR images were spatially registered to create a total of 160 nodes per heart that contained mechanical, transmural infarct extent, and electrical data. The average depth of the infarct was 55% (SD 11), and the infarct covered 28% (SD 6) of the left ventricular mass. Significantly delayed activation (>mean + 2SD) was observed within the infarct zone. The strain map showed abnormal mechanics, including abnormal stretch and loss of the transmural gradient of radial, circumferential, and longitudinal strains, in the region extending far beyond the infarct zone. We conclude that the border zone is characterized by abnormal mechanics directly coupled with normal electrical depolarization. This indicates that impaired function in the border zone is not contributed by electrical factors but results from mechanical interaction between ischemic and normal myocardium.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume289
Issue number3 58-3
DOIs
StatePublished - Sep 2005

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Myocardial Infarction
Mechanics
Electrodes
Pericardium
Thoracotomy
Canidae
Myocardium
Dogs

Keywords

  • Electromechanical mapping
  • Magnetic resonance imaging

ASJC Scopus subject areas

  • Physiology

Cite this

Electromechanical analysis of infarct border zone in chronic myocardial infarction. / Ashikaga, Hiroshi; Mickelsen, Steven R.; Ennis, Daniel B.; Rodriguez, Ignacio; Kellman, Peter; Wen, Han; McVeigh, Elliot R.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 289, No. 3 58-3, 09.2005.

Research output: Contribution to journalArticle

Ashikaga, Hiroshi ; Mickelsen, Steven R. ; Ennis, Daniel B. ; Rodriguez, Ignacio ; Kellman, Peter ; Wen, Han ; McVeigh, Elliot R. / Electromechanical analysis of infarct border zone in chronic myocardial infarction. In: American Journal of Physiology - Heart and Circulatory Physiology. 2005 ; Vol. 289, No. 3 58-3.
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