A vectorcardiographic study of right ventricular systolic overloading with the Frank system.

In clinical research and practice, vectorcardiography is now being used as an additional procedure to electrocardiography. It is expected that any additional diagnostic procedure in certain situations would give additional informations. The VCG and ECG present a different display of the same information; it is quite possible that some characteristics may be revealed in one type of display and may be hidden in another, which is, of course, the justification for clinical vectorcardiography. In 1952 Cabrera and Monroy1 presented the new concept on the cardiac performance from the hemodynamic view points. The work performed by any machine is equal to a certain mass times the energy gain of that mass. This means that the work performed by the heart as a pump would be equivalent to the mass of blood ejected times the mean pressure of the corresponding arterial vessel. Consequently, any increase in heart work, i.e., any ventricular overloading, could be due to an increase in the volume of blood per beat (volume overloading or diastolic overloading) or to an increase in the mean arterial pressure (pressure overloading or systolic overloading). Mitral stenosis and pulmonary stenosis2,3 are expected to cause the right ventricular systolic (pressure) overloading, while atrial septal defect4,5 is considered to cause the right ventricular diastolic (volume) overloading.6 The concept of volume and pressure overloading of the cardiac chambers has been quite useful in the interpretation of vectorcardiogram of patients with right ventricular overloading. The vectorcardiographic manifestations associated with right ventricular overloading correlate very well with