title: Changes in myocardial electrical impedance in human heart graft rejection.
abstract: BACKGROUND
  Monitoring of post-transplant heart rejection is currently based on endomyocardial biopsy analysis. This study aimed to assess the effects of heart graft rejection on myocardial electrical impedance.
  
  
  RESULTS
  Twenty-nine cardiac transplant patients and 9 controls underwent measurement of myocardial electrical impedance using a specifically designed amplifying system. The module and phase angle of myocardial impedance were measured. Histopathological rejection grading was performed according to ISHLT classification. Fifty impedance tests were performed in transplanted patients. Myocardial impedance (Z) was higher in controls than in transplanted patients (p<0.001) and followed a progressive decline at increasing current frequencies (p<0.001). Likewise, the phase angle of impedance in controls ranged from positive values at low frequencies to negative values at higher frequencies (from 2.5+/-0.9 degrees at 10 kHz to -3.8+/-2.1 degrees at 300 kHz, p<0.001). Rejection was associated with a significant decrease in myocardial impedance (Z) (15+/-6.6 Omega in grade 0, 13+/-6.0 Omega in grade 1A, and 3.3+/-0.9 Omega in grade 3A at 10 kHz, p<0.003).
  
  
  CONCLUSIONS
  Mild degrees of cardiac graft rejection are associated with significant changes in myocardial electrical impedance in transplant patients. Further clinical investigation is warranted to assess the potential of cardiac impedance to detect heart graft rejection.
authors.affiliation: Department of Cardiology, Hospital de la Santa Creu i Sant Pau, Autonomous University of Barcelona, Barcelona, Spain. jcinca@santpau.es <jcinca@santpau.es>
authors.forename: Juan
authors.initials: J
authors.lastname: Cinca
authors.forename: Juan
authors.initials: J
authors.lastname: Ramos
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Garcia
authors.forename: Ramon
authors.initials: R
authors.lastname: Bragos
authors.forename: Antoni
authors.initials: A
authors.lastname: Bayés-Genís
authors.forename: Yolocuauhtli
authors.initials: Y
authors.lastname: Salazar
authors.forename: Ramon
authors.initials: R
authors.lastname: Bordes
authors.forename: Sonia
authors.initials: S
authors.lastname: Mirabet
authors.forename: Josep M
authors.initials: JM
authors.lastname: Padró
authors.forename: Joan Garcia
authors.initials: JG
authors.lastname: Picart
authors.forename: Xavier
authors.initials: X
authors.lastname: Viñolas
authors.forename: Javier
authors.initials: J
authors.lastname: Rosell-Ferrer
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D017097:Electric Impedance; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods*; D005260:Female; D006084:Graft Rejection / Q000175:diagnosis*; D016027:Heart Transplantation; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011237:Predictive Value of Tests; D012720:Severity of Illness Index; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors