title: Noninvasive detection of repolarization changes in the heart.
abstract: OBJECTIVE
  Previously reported inverse method based on dipolar representation of differences in QRST integral maps with and without manifestation of local repolarization changes has shown the ability to identify small areas in the myocardium responsible for these changes in a group of patients with coronary artery diseases underwent revascularization. The aim of this study was to verify this approach on a group of 4 healthy persons and a group of 7 patients suffering from effort angina pectoris.
  
  
  METHODS
  Changes in QRST integral maps after nitroglycerine sublingual application were examined and single dipole best representing the difference QRST integral map was inversely computed.
  
  
  RESULTS
  After attempted compensation of heart rate variations, changes in QRST integral maps greater than expected intra - individual variability (over 15%) were detected in 4 persons. Obtained difference integral maps could be sufficiently approximated by maps generated by single current dipole only in 2 persons with relative root mean square (rms) error less than 35%; in the rest of subjects relative rms error of the dipolar map approximation was greater than 50%.
  
  
  CONCLUSIONS
  Results suggest that small repolarization changes might be detectable after nitroglycerine test, however this test did not induce detectable changes in some patients with effort angina pectoris.
authors.affiliation: Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia. umerhebl@savba.sk
authors.forename: Eva
authors.initials: E
authors.lastname: Heblakova
authors.forename: Milan
authors.initials: M
authors.lastname: Tysler
authors.forename: Marie
authors.initials: M
authors.lastname: Turzova
authors.forename: Jana
authors.initials: J
authors.lastname: Svehlikova
authors.forename: Krisztina
authors.initials: K
authors.lastname: Szakolczai
authors.forename: Kristof
authors.initials: K
authors.lastname: Haraszti
authors.forename: Slavomira
authors.initials: S
authors.lastname: Filipova
mesh_terms: D000286:Administration, Sublingual; D000787:Angina Pectoris / Q000188:drug therapy; D001145:Arrhythmias, Cardiac / Q000175:diagnosis* / Q000503:physiopathology; D018780:Body Surface Potential Mapping; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D005996:Nitroglycerin / Q000008:administration & dosage / Q000627:therapeutic use; D011237:Predictive Value of Tests; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000627:therapeutic use
chemical_list: D014665:Vasodilator Agents; D005996:Nitroglycerin