title: Detection of myocardial ischaemia by epicardial accelerometers in the pig.
abstract: BACKGROUND
  We describe a novel technique for continuous real-time assessment of myocardial ischaemia using a three-axis accelerometer.
  
  
  METHODS
  In 14 anaesthetized open-chest pigs, two accelerometers were sutured on the left ventricle (LV) surface in the perfusion areas of the left anterior descending (LAD) and circumflex (CX) arteries. Acceleration was measured in the longitudinal, circumferential, and radial directions, and the corresponding epicardial velocities were calculated. Regional LV dysfunction was induced by LAD occlusion for 60 s. Global LV function was altered by nitroprusside, epinephrine, esmolol, and fluid loading. Epicardial velocities were compared with strain by echocardiography during LAD occlusion and with aortic flow and LV dP/dt(max) during interventions on global LV function.
  
  
  RESULTS
  LAD occlusion induced ischaemia, shown by lengthening in systolic strain in the LV apical anterior region (P<0.01) and concurrent changes in LAD accelerometer circumferential velocities during systole (P<0.01) and during the isovolumic relaxation phase (P<0.01). The changes in accelerometer circumferential velocities during LAD occlusion were greater compared with the changes during the interventions on global function (P<0.01). For the LAD accelerometer circumferential velocities, sensitivity was 94-100% and specificity was 92-94% in detecting ischaemia.
  
  
  CONCLUSIONS
  Myocardial ischaemia can be detected with epicardial three-axis accelerometers. The accelerometer had the ability to distinguish ischaemia from interventions altering global myocardial function. This novel technique may be used for continuous real-time monitoring of myocardial ischaemia during and after cardiac surgery.
authors.affiliation: The Interventional Centre, Rikshospitalet University Hospital, N-0027 Oslo, Norway. per.steinar.halvorsen@rikshospitalet.no
authors.forename: P S
authors.initials: PS
authors.lastname: Halvorsen
authors.forename: L A
authors.initials: LA
authors.lastname: Fleischer
authors.forename: A
authors.initials: A
authors.lastname: Espinoza
authors.forename: O J
authors.initials: OJ
authors.lastname: Elle
authors.forename: L
authors.initials: L
authors.lastname: Hoff
authors.forename: H
authors.initials: H
authors.lastname: Skulstad
authors.forename: T
authors.initials: T
authors.lastname: Edvardsen
authors.forename: E
authors.initials: E
authors.lastname: Fosse
mesh_terms: D000054:Acceleration; D000818:Animals; D001783:Blood Flow Velocity; D005260:Female; D006439:Hemodynamics; D008297:Male; D017202:Myocardial Ischemia / Q000175:diagnosis* / Q000000981:diagnostic imaging; D015588:Observer Variation; D010496:Pericardium / Q000503:physiopathology*; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D034421:Sus scrofa; D014463:Ultrasonography; D016277:Ventricular Function, Left