THE RELATION OF THE T WAVE TO THE ASYNCHRONISM BETWEEN THE ENDS OF RIGHT AND LEFT VENTRICULAR EJECTION

Abstract

The time relation of the T wave to ejection in the left and right ventricle was determined from measurements of simultaneous optically registered aortic and pulmonary arterial pressure curves and a standard lead II (or III) of the electrocardiogram. No parallelism existed between the asynchronism of the end of ejection in the 2 ventricles and the character of the T wave. The changes in asynchronism which accompanied alteration in the experimental conditions were not consistently related to the variations of the T wave, even when the latter became inverted. The time relation between the T wave and the end of ejection in the 2 ventricles was also very variable, both when the different animals were compared and when conditions were altered in the same animal. In extrasystoles, however, a parallelism was found between the changes in asynchronism and the T wave. The results, when correlated with the recent tendencies in the interpretation of electrical variations, indicate that the electrocardiogram is to be considered a first differential quotient expressing the changes in the algebraic sum of electrical stresses in the heart from moment to moment oriented in the line of the lead. The T wave is evidence of the condition of unstable electrical stress at the end of activity due to the non-simultaneous cessation of activity in all fractions of the heart. This non-simultaneous cessation is in part due to asynchronous onset of activity and in part to differences in duration of activity in different fractions. The lack of relationship between the T wave and end of ejection in the 2 ventricles is to be explained by the fact that the end of ejection marks only the time when the ventricle as a unit has ceased to contract and begun to relax, and that activity continues in certain fractions even after this time.