Resistivity of body tissues at low frequencies.

• A theoretical model capable of explaining the relationship between the EMP generated by the heart and the electrocardiographic lead voltages must be based on quantitative knowledge of the resistivities of the tissues of the thorax. At the time this study was undertaken, the most recent investigations of tissue resistivity in living animals were those whose results are summarized in the first three columns of table I.' 3 More recently, the results summarized in column 4 were published. Differences in results range from 40% for lung to 400% for heart muscle, and no two groups of investigators are in substantial agreement on all measurements.