The Preoperative and Postoperative Vectorcardiogrom in Tetralogy of Fallot

Vectorcardiographic diagnosis of right ventricular hypertrophy in the presence of right bundle branch block in young subjects

Two groups of young patients, one with right bundle branch block complicated by right ventricular hypertrophy due to congenital heart disease, the other with right bundle branch block and no right ventricular hypertrophy, could be separated on the basis of a few quantitative vectorcardiographic and electrocardiographic criteria. Vectorcardiographic criteria proved better than electrocardiographic criteria in detecting right ventricular hypertropy in individual patients with complete right bundle branch block. Criteria based on the configuration of the QRS loop were also specific but much less sensitive for the diagnosis of this association. In a similar population, that is, young patients with postoperative right bundle branch block, the existence of a residual right ventricular overload would be strongly suggested by the presence of any one of the following criteria: (1) a clockwise rotation of the QRS loop in the horizontal plane, (2) a ratio of the magnitude of the R wave to that of the S wave (R/S ratio) in lead X at less than 2.0, (3) a mean QRS vector in lead X more negative than--10 mv.msec, or (4) a maximal QRS vector located between 90 degrees and 270 degrees in the horizontal plane. In contrast, an R/S ratio in lead X that was equal or superior to 2.0 or an azimuth angle of the mean spatial QRS vector that was not between 90 degrees and 180 degrees would indicate that the right ventricular conduction defect is probably uncomplicated.

Vectocardiography in tetralogy of Fallot before and after operation (palliative and corrective surgery)

Vectorcardiograms from 55 patients with diagnosed tetralogy of Fallot were studied and divided into the following three groups: A, 35 nonoperated cases; B, 23 with systemic-pulmonary shunt (nine studied preoperatively and also in A); and C, ten after total correction. In group A, two different types of QRS loop occurred in the horizontal plane (HP); 23 clinically and hemodynamically severe cases had right anterior position with clockwise (C) rotation, and 12 less severe cases had right posterior position with counterclockwise (CC) rotation or figure-8 morphology. In the frontal plane the QRS loop was located inferiorly and to the right, with C rotation (80 percent); two cases had the left anterior hemiblock (LAHB) pattern, and another two severe cases had CC rotation and right superior position. Group B had an evident increase of left ventricular forces in the HP, compared with group A; group-B rotation was preferentially CC or figure-8 morphology. Group C had a pattern of right bundle-branch block in nine cases (classic in one and uncharacteristic in eight); four cases also had LAHB.