The Frank Vectorcardiogram in Mitral Stenosis and Its Postoperative Changes

Preoperative and one-month postoperative Frank vectorcardiograms were recorded on 44 patients with mitral stenosis, which were divided into four groups according to their preoperative mean pulmonary pressures. In the group with absent pulmonary hypertension, the leftward components of the 0.04-second and the maximum QRS vectors were significantly increased postoperatively. In the group with minimal pulmonary hypertension, the leftward components of the 0.03-, 0.04-second and maximum QRS vectors and the maximum leftward component were significantly increased post-operatively. In these two groups, however, the postoperative QRS loops in the horizontal plane were about the same in configuration as the preoperative ones. Therefore, it was noted that the quantitative analyses of instantaneous vectors rather than mere morphologic comparisons of QRS loops were necessary to demonstrate the relatively small postoperative changes that occurred in the two groups. In the group with moderate pulmonary hypertension, the preoperative horizontal loops showing evidence of RVH made marked changes to the direction of normality postoperatively. The maximum posterior component was significantly decreased postoperatively. The leftward components of the 0.02-, 0.03-, 0.04-second and maximum QRS vectors and the maximum leftward component were significantly increased postoperatively. In the group with severe pulmonary hypertension, the postoperative loops in the horizontal plane still showed evidence of RVH, though the degree of RVH was much less severe in comparison with that of the preoperative ones. The postoperative increase in the maximum leftward component, the postoperative decrease both in the maximum right-ward component and the maximum posterior component were all significant. The leftward components of the 0.03-, 0.04-second and maximum QRS vectors were markedly increased postoperatively.