title: Real-time assessment of myocardial contractility using shear wave imaging.
abstract: OBJECTIVE
  The goal of this study was to assess whether myocardial stiffness could be measured by shear wave imaging (SWI) and whether myocardial stiffness accurately quantified myocardial function.
  
  
  BACKGROUND
  SWI is a novel ultrasound-based technique for quantitative, local, and noninvasive mapping of soft tissue elastic properties.
  
  
  METHODS
  SWI was performed in Langendorff perfused isolated rat hearts (n = 6). Shear wave was generated and imaged in the left ventricular myocardium using a conventional ultrasonic probe connected to an ultrafast scanner (12,000 frames/s). The local myocardial stiffness was derived from shear wave velocity every 7.5 ms during 1 single cardiac cycle.
  
  
  RESULTS
  The average myocardial stiffness was 8.6 ± 0.7 kPa in systole and 1.7 ± 0.8 kPa in diastole. Myocardial stiffness was compared with isovolumic systolic pressure at rest and during administration of isoproterenol (10(-9), 10(-8), and 10(-7) mol/l, 5 min each). Systolic myocardial stiffness increased strongly up to 23.4 ± 3.4 kPa. Myocardial stiffness correlated strongly with isovolumic systolic pressure (r(2) = [0.94; 0.98], p < 0.0001).
  
  
  CONCLUSIONS
  Myocardial stiffness can be measured in real time over the cardiac cycle using SWI, which allows quantification of stiffness variation between systole and diastole. Systolic myocardial stiffness provides a noninvasive index of myocardial contractility.
authors.affiliation: Institut Langevin, École Supérieure de Physique et de Chimie Industrielles, ParisTech, 10 rue Vauquelin, Paris, France. mathieu.pernot@espci.fr
authors.forename: Mathieu
authors.initials: M
authors.lastname: Pernot
authors.forename: Mathieu
authors.initials: M
authors.lastname: Couade
authors.forename: Philippe
authors.initials: P
authors.lastname: Mateo
authors.forename: Bertrand
authors.initials: B
authors.lastname: Crozatier
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Fischmeister
authors.forename: Mickaël
authors.initials: M
authors.lastname: Tanter
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D004452:Echocardiography / Q000379:methods; D004548:Elasticity; D054459:Elasticity Imaging Techniques; D006321:Heart / Q000502:physiology; D006352:Heart Ventricles / Q000473:pathology; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D009200:Myocardial Contraction; D009206:Myocardium / Q000378:metabolism; D011312:Pressure; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D012044:Regression Analysis; D013314:Stress, Mechanical; D013599:Systole; D013997:Time Factors
chemical_list: D011943:Receptors, Adrenergic, beta; D007545:Isoproterenol; D002118:Calcium