Bioelectromagnetism--relative merits of electric and magnetic measurements in cardiac studies.

This lecture gives a general overview to the relationship of bioelectric and biomagnetic phenomena: The most important issue in bioelectromagnetism is: Are the biomagnetic measurements independent on bioelectric ones and do they bring new information from the source or are they only a different modality of the same phenomenon? This issue is discussed with application on cardiac studies. The three orthogonal dipolar magnetic leads (vector magnetocardiography) are equal in the sense of diagnostic performance to the three dipolar electric leads (vector electrocardiography). Therefore the VMCG has quite the same diagnostic performance as the VECG. We have shown with a patient material of 313 subjects that when combining these methods to vector electromagnetocardiography, VEMCG, the number of incorrectly diagnosed patients may be decreased to one half. This is a statistically significant improvement in the diagnostic performance. We have also proven that our explanation for the Helmholtz's theorem is correct: What are fully independent are the lead fields of electric and magnetic measurements, not the signals. The dipolar electric and magnetic signals are similarly independent from each other as the three orthogonal dipolar electric signals are.