Localization of heart vectors produced by epicardial burns and ectopic stimuli; validation of a dipole ranging method.
Location of the equivalent cardiac dipole has been estimated but not fully verified in several laboratories. To test the accuracy of such a procedure, injury vectors were produced in 14 isolated, perfused rabbit hearts by epicardial searing. Strongly dipolar excitation fronts were produced in 6 additional hearts by left ventricular pacing. Twenty computer-processed signals, derived from surface electrodes on a spherical electrolyte-filled tank containing the test preparation, were optimally fitted with a locatable cardiac dipole that accounted for over 99% of the root-mean-square surface potential. For the 14 burns (mean radius 5.0 mm), the S-T injury dipole was located 3.4 plus or minus 0.7 (SD) mm from the burn center. For the 6 paced hearts, the dipole early in the ectopic beat was located 3.7 mm (range 2.6 to 4.6 mm) from the stimulating electrode. Phase inhomogeneities within the chamber appeared to have a small but predictable effect on dipole site determination. The study demonstrates that equivalent dipole location can be determined with acceptable accuracy from potential measurements of the external cardiac field.
D000818:Animals; D002056:Burns / Q000503:physiopathology; D006321:Heart / Q000502:physiology* / Q000503:physiopathology; D006335:Heart Injuries / Q000503:physiopathology; D008433:Mathematics; D008954:Models, Biological; D011817:Rabbits; D014672:Vectorcardiography / Q000379:methods