Further studies of the electrocardiographic spatial magnitude curve (in the rabbit)

Abstract

1. 1. Further studies of a new transformation method for studying the cardiac ventricular activation process have been reported. The present experiments have been limited to the rabbit heart. 2. 2. Verification has been found of what appears to be perhaps a basic relation between time of occurrence of local maxima in the spatial magnitude electrocardiographic curve and the time of occurrence of subsequent minima. It has been suggested that the duration of an irregularity, so defined, in the spatial magnitude curve may be related to the amount of depolarization which preceded it. The relation has been verified only as a statistical property. 3. 3. Evidence (further to that previously reported for human patients) suggests that for cardiac muscle death produced experimentally in the rabbit heart, the Form Factor undergoes an irreversible increase in magnitude. This supports the evidence from previous observations upon the course of the Form Factor in cases of myocardial infarction in the human heart. 4. 4. Procedures which induce local reversible alterations in the polarizing properties of cardiac muscle (such as the local application of potassium chloride), have been shown to produce a reversible change in the Form Factor. 5. 5. The single time-dependent parameter which specifies the spatial magnitude electrocardiogram has been shown to possess interesting properties in the study of the ventricular activation process.