title: Noninvasive potassium determination using a mathematically processed ECG: proof of concept for a novel "blood-less, blood test".
abstract: OBJECTIVE
  To determine if ECG repolarization measures can be used to detect small changes in serum potassium levels in hemodialysis patients.
  
  
  METHODS
  Signal-averaged ECGs were obtained from standard ECG leads in 12 patients before, during, and after dialysis. Based on physiological considerations, five repolarization-related ECG measures were chosen and automatically extracted for analysis: the slope of the T wave downstroke (T right slope), the amplitude of the T wave (T amplitude), the center of gravity (COG) of the T wave (T COG), the ratio of the amplitude of the T wave to amplitude of the R wave (T/R amplitude), and the center of gravity of the last 25% of the area under the T wave curve (T4 COG) (Fig. 1).
  
  
  RESULTS
  The correlations with potassium were statistically significant for T right slope (P<0.0001), T COG (P=0.007), T amplitude (P=0.0006) and T/R amplitude (P=0.03), but not T4 COG (P=0.13). Potassium changes as small as 0.2mmol/L were detectable.
  
  
  CONCLUSIONS
  Small changes in blood potassium concentrations, within the normal range, resulted in quantifiable changes in the processed, signal-averaged ECG. This indicates that non-invasive, ECG-based potassium measurement is feasible and suggests that continuous or remote monitoring systems could be developed to detect early potassium deviations among high-risk patients, such as those with cardiovascular and renal diseases. The results of this feasibility study will need to be further confirmed in a larger cohort of patients.
authors.affiliation: Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA.
authors.forename: John J
authors.initials: JJ
authors.lastname: Dillon
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA.
authors.forename: Christopher V
authors.initials: CV
authors.lastname: DeSimone
authors.affiliation: Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel.
authors.forename: Yehu
authors.initials: Y
authors.lastname: Sapir
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA.
authors.forename: Virend K
authors.initials: VK
authors.lastname: Somers
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Dugan
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA.
authors.forename: Charles J
authors.initials: CJ
authors.lastname: Bruce
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ackerman
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA.
authors.forename: Samuel J
authors.initials: SJ
authors.lastname: Asirvatham
authors.affiliation: Center for Advanced Imaging, Mayo Clinic, Rochester, MN, USA.
authors.forename: Bryan L
authors.initials: BL
authors.lastname: Striemer
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA.
authors.forename: Jan
authors.initials: J
authors.lastname: Bukartyk
authors.affiliation: Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN, USA.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Scott
authors.affiliation: Division of Engineering, Mayo Clinic, Rochester, MN, USA.
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Bennet
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA.
authors.forename: Susan B
authors.initials: SB
authors.lastname: Mikell
authors.affiliation: Mayo Clinic Ventures, Mayo Clinic, Rochester, MN, USA.
authors.forename: Dorothy J
authors.initials: DJ
authors.lastname: Ladewig
authors.affiliation: Mayo Clinic Ventures, Mayo Clinic, Rochester, MN, USA.
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Gilles
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA.
authors.forename: Amir
authors.initials: A
authors.lastname: Geva
authors.affiliation: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA.
authors.forename: Dan
authors.initials: D
authors.lastname: Sadot
authors.affiliation: Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel. Electronic address: friedman.paul@mayo.edu.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Friedman
mesh_terms: D000465:Algorithms; D015415:Biomarkers / Q000097:blood; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006403:Hematologic Tests / Q000379:methods; D006801:Humans; D006947:Hyperkalemia / Q000097:blood* / Q000175:diagnosis* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011188:Potassium / Q000097:blood*; D006435:Renal Dialysis / Q000009:adverse effects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D011188:Potassium
keywords: Dialysis; ECG; Hyperkalemia; Potassium; Signal processing; T-wave