The Electrocardiogram of the Ageing Male Rat

Abstract

The heart rate of the male rat showed a small decrease with age from young adult life until senility. The voltage of the R wave in lead II decreased with age, because the axis of the QRS vector rotated to the left. The magnitude of the QRS vector did not change significantly with age. The voltages of the P and T waves in lead n increased with age, due to corresponding increases in the magnitude of the P and T vectors. The direction of the P and T vectors did not change significantly with age. The P-QRS and the QRS-T angles widened with age. A small increase occurred in the weight of the heart ventricles with age.