A dynamic three-dimensional display of ventricular excitation and the generation of the vector and electrocardiogram.

Computer models, such as those produced by Solomon and Selvester, have helped increase our understanding of the heart's electrical activity. In the present report, we describe a dynamic three-dimensional computerized display of the myocardial excitation sequence that is based on this fundamental research. The display is based on the vectors of the potential differences generated in the various parts of the myocardium during its excitation. The sums of these individual vectors form composite vectors that are related to the ECG signals recorded from the body's surface. The display simultaneously portrays the temporal changes of the composite vectors in 3 dimensions and in each plane (the transverse, frontal and left sagittal). It also shows the corresponding changes in the QRS complexes in each of the 12 scalar ECG leads. The display shows the patterns of activation of the normal heart and an example of posterolateral myocardial infarction. The technique facilitates the understanding of myocardial activation and how it is modified by specific pathological conditions. It is believed that this method of presentation and visualization of the generation of the ECG will be of value in the teaching of this process.