[The normal electrocardiogram of miniature swine]

Mean normal values for heart rate of 111 (64-190) actions/min, for duration of the PR-interval of 88 (63-120) ms, for the QRS-complex of 36 (26-46) ms and the QT-interval of 252 (183-353) ms were determined from the ECG in 204 male and female Göttinger mini-pigs (mean body weight 12.4 kg). The mean total amplitudes (voltages) of QRSI-III amount to 0.8, 0.9 and 1.1 mV. Considering leads I, II and III positive P-waves are most frequently found in II with 91% and negative ones in III with 23%. Positive T-waves appear in III with 86% and negative ones in I with 88% most frequently. The main polarity of QRS is most frequently positive in I with 56% and negative in III with 48%. The incidence of Q is highest in lead I with 71%, that one of S in II with 55%. The T-waves are mostly discordant with QRS, especially in I with 54%, more seldom concordant yet frequently in II with 30%. A significant negative correlation (r = -0.77) is evident between heart rate and QT-duration, slight negative correlations also exist between heart rate and PR- as well as QRS-duration. The mean angle a QRS from I, II, III and aVR, aVL, aVF in the frontal plane (direction of the cardiac vector; n = 35) amounts to -47 degrees (-150 degrees to +165 degrees). The position of the heart axis is more sagittal with a characteristic deviation of the electrical from the anatomical axis of the heart. Concerning the observed parameters there is also a less intraindividual variability in investigations in series besides the considerable interindividual one. Examples for physiological specialities or variations from the norm of rhythm and configuration of the ECG typical for the miniature pig are presented and discussed.