title: Continuous monitoring of cardiac function by 3-dimensional accelerometers in a closed-chest pig model.
abstract: OBJECTIVE
  Cardiac wall motions reflect systolic and diastolic function. We have previously demonstrated the ability of a miniaturized three-axis (3D) accelerometer to monitor left ventricular function in experimental models and in patients. The main aim of this study was to investigate the clinical utility of the method for monitoring the left and right ventricular function during changes in global and regional cardiac function in a postoperative closed-chest situation.
  
  
  METHODS
  In 13 closed-chest pigs, miniaturized 3D accelerometers were placed on the left ventricle in the apical and basal regions and in the basal region of the right ventricle. An epicardial 3D motion vector was calculated from the acceleration signals in each heart region. Peak systolic velocity along this 3D vector (3D V(sys)) was compared with the positive time derivative of the left and right ventricular pressure and with cardiac index during changes in global LV function (unloading, fluid loading, esmolol, dobutamine) and with ultrasound during regional left ventricular dysfunction (3-min occlusion of the left anterior descending coronary artery).
  
  
  RESULTS
  Significant and typical changes in accelerometer 3D V(sys) were seen in all heart regions during changes in global cardiac function. 3D V(sys) reflected the left and right ventricular contractility via significant correlations with the positive time derivative of the left and right ventricular pressure, r = 0.86 and r = 0.72, and with cardiac index r = 0.82 and r = 0.73 (all P < 0.001), respectively. The miniaturized accelerometers also detected regional dysfunction, but showed reduced ability to localize ischaemia as the 3D V(sys) in all heart regions showed similar reductions during coronary artery occlusion.
  
  
  CONCLUSIONS
  Miniaturized 3D accelerometers placed on the heart can assess global and regional function in a closed-chest model. The technique may be used for continuous postoperative monitoring after cardiac surgery.
authors.affiliation: The Intervention Centre, Oslo University Hospital, Oslo, Norway Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway olegry@ous-hf.no.
authors.forename: Ole-Johannes H N
authors.initials: OJ
authors.lastname: Grymyr
authors.affiliation: Department of Micro and Nano Systems Technology, Buskerud and Vestfold University College, Kongsberg, Norway.
authors.forename: Anh-Tuan T
authors.initials: AT
authors.lastname: Nguyen
authors.affiliation: Department of Micro and Nano Systems Technology, Buskerud and Vestfold University College, Kongsberg, Norway.
authors.forename: Fjodors
authors.initials: F
authors.lastname: Tjulkins
authors.affiliation: The Intervention Centre, Oslo University Hospital, Oslo, Norway Department of Anaesthesiology, Oslo University Hospital, Oslo, Norway.
authors.forename: Andreas
authors.initials: A
authors.lastname: Espinoza
authors.affiliation: The Intervention Centre, Oslo University Hospital, Oslo, Norway K.G. Jebsen Cardiac Research Centre, University of Oslo, Oslo, Norway.
authors.forename: Espen W
authors.initials: EW
authors.lastname: Remme
authors.affiliation: Department of Cardiology, Oslo University Hospital, Oslo, Norway.
authors.forename: Helge
authors.initials: H
authors.lastname: Skulstad
authors.affiliation: The Intervention Centre, Oslo University Hospital, Oslo, Norway Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway.
authors.forename: Erik
authors.initials: E
authors.lastname: Fosse
authors.affiliation: Department of Micro and Nano Systems Technology, Buskerud and Vestfold University College, Kongsberg, Norway.
authors.forename: Kristin
authors.initials: K
authors.lastname: Imenes
authors.affiliation: The Intervention Centre, Oslo University Hospital, Oslo, Norway Department of Anaesthesiology, Oslo University Hospital, Oslo, Norway.
authors.forename: Per S
authors.initials: PS
authors.lastname: Halvorsen
mesh_terms: D061725:Accelerometry / Q000295:instrumentation*; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008991:Monitoring, Physiologic / Q000379:methods*; D013552:Swine; D013599:Systole; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis / Q000503:physiopathology*; D018497:Ventricular Dysfunction, Right / Q000175:diagnosis / Q000503:physiopathology*; D016277:Ventricular Function, Left / Q000502:physiology*; D016278:Ventricular Function, Right / Q000502:physiology*
keywords: Cardiac monitoring; Left ventricular function; Motion sensor; Right ventricular function