title: The assessment of neural injury following open heart surgery by physiological tremor analysis.
abstract: BACKGROUND
  The appearance of post-operative cognitive dysfunction as a result of open heart surgery has been proven by several studies. Focal and/or sporadic neuron damage emerging in the central nervous system may not only appear as cognitive dysfunction, but might strongly influence features of physiological tremor.
  
  
  METHODS
  We investigated 110 patients (age: 34-73 years; 76 male, 34 female; 51 coronary artery bypass grafting (CABG), 25 valve replacement, 25 combined open heart surgery, 9 off-pump CABG) before surgery and after open-heart surgery on the 3(rd) to 5(th) post-operative day. The assessment of the physiological tremor analysis was performed with our newly developed equipment based on the Analog Devices ADXL 320 JPC integrated accelerometer chip. Recordings were stored on a PC and spectral analysis was performed by fast Fourier transformation (FFT). We compared power integrals in the 1-4 Hz, 4-8 Hz and 8-12 Hz frequency ranges and these were statistically assessed by the Wilcoxon rank correlation test.
  
  
  RESULTS
  We found significant changes in the power spectrum of physiological tremor. The spectrum in the 8-12 Hz range (neuronal oscillation) decreased and a shift was recognised to the lower spectrum (p < 0.01). The magnitude of the shift was not significantly higher for females than for males (p < 0.157). We found no significant difference between the shift and the cross-clamp or perfusion time (p < 0.6450).
  
  
  CONCLUSIONS
  The assessment of physiological tremor by means of our novel, feasible method may provide a deeper insight into the mechanism of central nervous system damage associated with open heart surgery.
authors.affiliation: Heart Institute, Medical Faculty, University of Pécs, Hungary.
authors.forename: Adám
authors.initials: A
authors.lastname: Németh
authors.forename: László
authors.initials: L
authors.lastname: Hejjel
authors.forename: Zénó
authors.initials: Z
authors.lastname: Ajtay
authors.forename: Lóránd
authors.initials: L
authors.lastname: Kellényi
authors.forename: Andor
authors.initials: A
authors.lastname: Solymos
authors.forename: Imre
authors.initials: I
authors.lastname: Bártfai
authors.forename: Norbert
authors.initials: N
authors.lastname: Kovács
authors.forename: Zsófia
authors.initials: Z
authors.lastname: Lenkey
authors.forename: Attila
authors.initials: A
authors.lastname: Cziráki
authors.forename: Sándor
authors.initials: S
authors.lastname: Szabados
keywords: cognitive dysfunction; open heart surgery; physiological tremor