Measurement of the human magnetic heart vector.
A unipositional lead system has been developed to record the human magnetic heart vector and to permit comparison with the electric heart vector recorded with a conventional Frank lead system. Recordings made in five normal subjects showed a remarkably consistent relation between the electric and magnetic heart vectors. However, the angle between electric heart vector R and T waves was markedly different from the magnetic heart vector R-T angle. In addition, recordings made in two patients with bundle branch block showed a different relation between the electric and magnetic heart vectors compared to normal subjects. These data support the hypothesis that magnetic measurements have a different sensitivity to some components of cardiac activation compared with body surface potential measurements.
D004562:Electrocardiography; D006321:Heart / Q000502:physiology* / Q000503:physiopathology; D006327:Heart Block / Q000503:physiopathology*; D006801:Humans; D008280:Magnetics