[A contribution to the subject of the parameters PQ, QRS and QT being functions of heart rate in the ECG of the beagle dog (author's transl)].

We examined the degree of dependency of the ECG parameters PO, QRS and QT on the heart rate. In 252 beagles of standardised breeding and accommodation (strain: Chbi : BEAGLE), a total of 1456 ECG recordings was made from the three Einthoven extremity leads, and the heart rate and PQ-, QRS-, and QT-times were measured. The animals used were dogs from eleven subacute toxicity studies. 683 of the registrations were obtained from control animals and 773 from drug-treated animals whose ECG curves had remained unchanged and in which no histopathological changes were found in the heart at the end of the toxicity studies. The data obtained were biometrically evaluated by regression and correlation analyses. The range of the heart rate was 34-238 actions/min, median value 108. The range of the PQ interval was 0.07-0.18 sec, the QRS interval 0.03-0.09 sec and the QT interval 0.14-0.26 sec. The median values were 0.11, 0.05 and 0.19 sec, respectively. Positive skew distributions were found. The data were transformed to obtain values with normal distribution. The various correlation coefficients were then heart rate/PQ time: -0.408 (p less than 0.001), heart rate/QRS time: -0.057 (p less than 0.05), heart rate/QT time: - 0.611 (p less than 0.001). This means that the PQ and QT intervals clearly decrease as the heart rate increases, whereas the QRS interval is only minimally affected. Correlation ellipses were also calculated and presented graphically. These show areas within which 50, 75, 90 and 95% of our values are to be expected.