A BASIS FOR THE ANALYSIS OF VARIATIONS IN THE FORM OF ELECTROCARDIOGRAPHIC CURVES RESULTING FROM EXPERIMENTAL PREMATURE CONTRACTIONS

Abstract

Analysis of electrocardiographic curves obtained by systematic application of stimuli to the epicardial surface of the cat''s ventricles revealed the existence of lines of transition for leads I and III. These lines of transition appeared to divide the ventricles into 2 equal, but in each case different, muscle masses, without strict regard to any anatomic boundaries. Rotation of the heart on its long axis did not materially affect the location of these lines of transition with respect to the body. Their position on the heart was changed in proportion to the degree and direction of rotation. These results provide further evidence that the duration and contour of the initial deflection of ventricular ectopic beats depend upon the location of the impulse initiation with reference to the hypothetical line of transition for a specific lead and so upon the general direction of the impulse spread in relation to the recording line of that lead.