Left ventricular myocardial contractility is depressed in the borderzone after posterolateral myocardial infarction

Rafael Shimkunas, Zhihong Zhang, Jonathan F. Wenk, Mehrdad Soleimani, Michael Khazalpour, Gabriel Acevedo-Bolton, Guanying Wang, David Saloner, Rakesh Mishra, Arthur W. Wallace, Liang Ge, Anthony J. Baker, Julius M. Guccione, Mark B. Ratcliffe

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Background: Contractility in the borderzone (BZ) after anteroapical myocardial infarction (MI) is depressed. We tested the hypothesis that BZ contractility is also decreased after posterolateral MI. Methods: Five sheep underwent posterolateral MI. Magnetic resonance imaging (MRI) was performed 2 weeks before and 16 weeks after MI, and left ventricular (LV) volume and regional strain were measured. Finite element (FE) models were constructed, and the systolic material parameter, Tmax, was calculated in the BZ and remote myocardium by minimizing the difference between experimentally measured and calculated LV strain and volume. Sheep were sacrificed 17 weeks after MI, and myocardial muscle fibers were taken from the BZ and remote myocardium. Fibers were chemically demembranated, and isometric developed force, F max, was measured at supramaximal [Ca2+]. Routine light microscopy was also performed. Results: There was no difference in T max in the remote myocardium before and 16 weeks after MI. However, there was a large decrease (63.3%, p = 0.005) in Tmax in the BZ when compared with the remote myocardium 16 weeks after MI. In addition, there was a significant reduction of BZ Fmax for all samples (18.9%, p = 0.0067). Myocyte cross-sectional area increased by 61% (p = 0.021) in the BZ, but there was no increase in fibrosis. Conclusions: Contractility in the BZ is significantly depressed relative to the remote myocardium after posterolateral MI. The reduction in contractility is due at least in part to a decrease in contractile protein function.

Original languageEnglish
Pages (from-to)1619-1625
Number of pages7
JournalAnnals of Thoracic Surgery
Volume95
Issue number5
DOIs
StatePublished - May 2013

Bibliographical note

Funding Information:
This study was supported by NIH grants R01-HL-84431 (Dr Ratcliffe), R01-HL-63348 (Dr Ratcliffe), R01-HL-77921 (Dr Guccione), and R01-HL-86400 (Dr Guccione) Dr. Baker's support, a VA Merit Award, and a Grant in Aid from the American Heart Association , Western States (Dr. Baker). This support is gratefully acknowledged.

ASJC Scopus subject areas

  • Surgery
  • Pulmonary and Respiratory Medicine
  • Cardiology and Cardiovascular Medicine

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