Impact of the Heart Rate on Normal STT Integral Body Surface Potential Maps

We suggested a method for localization of ischemic lesions from difference integral body surface potential maps (IBSPMs) computed by subtraction of IBSPM without manifestation of ischemia from the IBSPM during ischemia that can be obtained at rest and during the stress test. In this work the possible changes in IBSPMs of healthy subjects with increasing HR were studied. BSPMs were measured during the stress test in 12 subjects (age 30-53). During the test, the HR of each subject increased from the rest value up to the value higher than 85% of the value (220-age) at the top of the load. The IBSPMs were computed for 5 HR values up to the highest one. Correlation and power of IBSPMs at subsequent values of the HR were evaluated. The correlation coefficient between the IBSPM at rest and IBSPM at the top HR was higher than 70%. The root-mean-square value of the IBSPM at the top HR varied from 43% to 128% of the root-mean-square value of the IBSPM at rest. The existence of remarkable differences in STT IBSPMs at rest and at stress in healthy subjects should be considered when the IBSPMs during the stress test are evaluated for ischemic patients.