The vectorcardiogram in mitral valve disease.

The Frank system vectorcardiogram has been studied in 61 patients with severe mitral valve disease to determine the value of the vectorcardiogram in the recognition of the relative degree of left and right ventricular hypertrophy in this situation. The appearance of the usual evidence of right ventricular hypertrophy is delayed in mitral valve disease by the vertical electrical position of the heart which may be due to alterations in the intrathoracic electrical field produced by left atrial enlargement. Voltage criteria for the recognition of isolated left or right ventricular hypertrophy in the vectorcardiogram are not applicable to combined ventricular hypertrophy in mitral valve disease. The present analysis is based on the spatial pattern of the QRS loop. The vectorcardiograms show a continuous gradation from posterior to anterior direction, the extremes indicating dominant left and right ventricular hypertrophy, respectively. Five groups are recognized from the appearance in the horizontal plane. Long posterior loops (Fig. 1) are associated with severe left ventricular hypertrophy, open posterior loops (Fig. 2) with left ventricular dominance, and wide posterior loops (Fig. 3) with moderate hypertrophy of both ventricles. Wide crossed loops (Fig. 4) indicate right ventricular dominance, and anterior clockwise loops (Fig. 5) are found with severe right ventricular hypertrophy. The vectorcardiogram rarely showed large QRS voltages in left ventricular hypertrophy, though these changes were often evident in the conventional electrocardiogram. The vectorcardiogram appeared to be more successful than the electrocardiogram in the recognition of severe right ventricular hypertrophy. An unusual rightwards displacement of the QRS loop was found in patients with tricuspid valve disease. It is concluded that the vectorcardiogram gives useful additional information for the recognition of ventricular hypertrophy that is not evident in the conventional electrocardiogram in mitral valve disease.