The Frank vectorcardiograms were taken in 86 cases of congenital heart diseases. (37 ventricular septal defect, 17 tetralogy of Fallot, 12 patent ductus arteriosus, 11 atrial septal defect of secundum type, 3 endocardial cushion defect and 6 dextrocardia-D. Vectorcardiographic findings of each congenital heart diseases were analysed and the relationship between hemodynamics and vectorcardiographic parameters were studied.
The results were as follows:
1. The vectorcardiographic findings of V.S.D. were very various depending the size of the defect and the degree of right ventricular pressure and the relationship between hemodynamics and vectorcardiographic parameters was significant. Right ventricular systolic pressure was related to the amplitude of M.R.S.V. and the angle between the azimuth of M.L.S.V. and the azimuth of M.R.S.V. Flow ratio was related to the amplitude of M.L.S.V. There were also serial changes of horizontal loop inscription with increase of right ventricular pressure.
2. The vectorcardiographic findings of T:O.F, were severe right ventricular hypertrophy. In some cases, whose main vector directed to right posterior quadrant in horizontal plane, the E.K.G. did not show the right ventricular hypertrophy easily. A certain qualitative changes of horizontal loop inscription suggest the mild T.O.F.
3. The vectorcardiographic findings of P.D.A. were very similiar to that of V.S.D. The amplitude of M.R.S.V. was closely related to right ventricular pressure.
4. In A.S.D., initial and typical changes were terminal appendage of horizontal plane. With increase of right ventricular pressure, the main loop of horizontal- plane displaced to right and anterior side. The vectorcardiogram showed -the.-right ventricular hypertrophy more frequently than E.K.G. especially in mild atrial septal defect and adult patients. The relationship between M.R.S.V. and right ventricular pressure was significant.
5. In endocardial cushion defect, typical vectorcardiographic findings were confirmed. The mechanism of counterclockwise superior frontal plane loop and the other congenital heart disease which show similar loop were discussed.
6. In dextrocardia, vectorcardiogram gave some help in determining the atrial situs and bulboventricular loop.
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