A Vectorcardiographic Study of Diastolic Overload of the Left Ventricle in Dogs

In 1952, Cabrera et al1)2) reported that in aortic regurgitation, diastolic overload of the left ventricle would have a different electrocardiographic manifestation than that produced by a systolic overload, as noted in aortic stenosis. They demonstrated that in cases of diastolic overload, increased voltage in the Q loop was manifested by displacement to the right and anterior ; an increase in the voltage of the R loop was manifested by displacement to the left and posterior. It was also noted that in cases of systolic overload, the Q loop became smaller or even disappeared. The R loop voltage increased and became posteriorly displaced and the S loop disappeared or became straightened. The purpose of this study is to observe the vectorcardiographic features in experimentally produced diastolic overloading of the left ventricle, and an attempt was made to search for a correlation between vectorcardiographic changes of diastolic overload and quantitative analysis of hypertrophy.