title: Regional myocardial three-dimensional principal strains during postinfarction remodeling.
abstract: BACKGROUND
  The purpose of this study was to quantify myocardial three-dimensional (3D) principal strains as the left ventricle (LV) remodels after myocardial infarction (MI). Serial quantification of myocardial strains is important for understanding the mechanical response of the LV to MI. Principal strains convert the 3D LV wall-based strain matrix with three normal and three shear elements, to a matrix with three nonzero normal elements, thereby eliminating the shear elements, which are difficult to physically interpret.
  
  
  METHODS
  The study was designed to measure principal strains of the remote, border zone, and infarct regions in a porcine model of post-MI LV remodeling. Magnetic resonance imaging was used to measure function and strain at baseline, 1 week, and 4 weeks after infarct. Principal strain was measured using 3D acquisition and the optical flow method for displacement tracking.
  
  
  RESULTS
  Principal strains were altered as the LV remodeled. Maximum principal strain magnitude decreased in all regions, including the noninfarcted remote, while maximum principal strain angles rotated away from the radial direction in the border zone and infarct. Minimum principal strain magnitude followed a similar pattern; however, strain angles were altered in all regions. Evolution of principal strains correlated with adverse LV remodeling.
  
  
  CONCLUSIONS
  Using a state-of-the-art imaging and optical flow method technique, 3D principal strains can be measured serially after MI in pigs. Results are consistent with progressive infarct stretching as well as with decreased contractile function in the border zone and remote myocardial regions.
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: James J
authors.initials: JJ
authors.lastname: Pilla
authors.affiliation: Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Koomalsingh
authors.affiliation: Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Jeremy R
authors.initials: JR
authors.lastname: McGarvey
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Walter R T
authors.initials: WR
authors.lastname: Witschey
authors.affiliation: Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Larry
authors.initials: L
authors.lastname: Dougherty
authors.affiliation: Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Gorman
authors.affiliation: Gorman Cardiovascular Research Group, Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania. Electronic address: robert.gorman@uphs.upenn.edu.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Gorman
mesh_terms: D000818:Animals; D057791:Cardiac Imaging Techniques; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging; D009203:Myocardial Infarction / Q000473:pathology*; D013552:Swine; D020257:Ventricular Remodeling