抄録
It is the purpose of this communication to present the Frank lead VCG's recorded on nine patients with proved atrial septal defect of the secundum type and post-operative modifications of the VCG's.
The ages of the patients ranged from 8 to 23. The three orthogonal leads (scalar records of X, Y, Z) were recorded simultaneously with a high gain (20mm=1mV) at a paper speed of 10cm per second. Then, photographs of three plane loop display were taken with various gain levels.
From the loop display the maximum QRS and T vectors were determined as well as the rightward maximum QRS vector which is characteristic of A. S. D. The scalar records were subjected to manual measurement of amplitudes for the analysis of instantaneous QRS vectors at every 10 msec. from the beginning of QRS to its end. The X, Y, Z amplitudes were translated into the spatial magnitude and orientation (azimuth and elevation) of the maximum and instantaneous vectors with the aid of a digital computer (NEAC 2203), Spatial speeds (angular, linear, and area) of the QRS loop per 10msec. were also calculated.
The means and standard deviations of the spatial and scalar items were determined and post-operative changes of the items were evaluated by the t-test. Results:
The ratio between the rightward maximum QRS vector (approximately 60msec, instan taneous vector) and the (leftward) maximum QRS vector (approximately 40 msec, vector) decreased from 0.79 (mean) of the preoperative value to 0.40 (mean) of the 6-8 months post-operative value.
The 50msec, and later instantaneous QRS vectors, which are oriented anteriorly to the right in contrast to the nomal, showed a marked regression post-operatively. The 50msec. vector, which was located in the right anterior quadrant pre-operatively, changed its location to the right posterior quadrant at 6-8 months post-operatively.
The maximum T vector in A. S. D. pointed posteriorly to the left, in contrast to the normal in which it pointed anteriorly to the left. At one month after surgery, however, it turned further posteriorly, indicating an increased degree of abnormality. At 6-8 months, it turned anteriorly, but still remained at the left posterior quadrant.
The angle between the maximum QRS and T vectors was 41.2° (mean) pre-operatively. It increased to 55.8° at one month, and decreased to 22.5° at 6-8 months post-operatively.
The total QRS duration in A. S. D., which is longer than in normal, decreased post-operatively. The change after 6-8 months was statistically significant.
In conclusion, surgical repair of atrial septal defect caused shortening of the total QRS duration; and marked changes in VCG to the direction of normality. The changes, however, did not gain the full normality at 6-8 months post-operatively.
