Quantitative Analysis of Vectorcardiogram in Right Ventricular Overloading

Abstract

Quantitative analysis was made to clarify the ventorcardiographic findings characteristic of mild to moderate right ventricular systolic and diastolic overloadings. Materials and Methods Twenty-two cases of ostium secundum type of atrial septal defect (ASD) proved by cardiac catheterization and/or surgery and clinically typical pure mitral stenosis (MS) were subjected to the present study. The three planar projections of VCG were photographed on 60×60 mm X ray films simultaneously by three channel vectorcardiograph using the Frank system. Three scalar ECG of the Frank system were recorded simultaneously by the paper speed of 100 mm per second using three elements direct-writing electrocardiograph. Parameters of morphological observations and quantitative analysis used in this study are as follows: 1. Directions of inscription of QRS and T loops. 2. Directions of initial and terminal QRS vectors. 3. Length, width and length/width ratio of QRS loop. 4. Maximum QRS vector time, QRS duration and incidence of terminal delay. 5. Magnitudes and directions of maximum QRS and T vectors. 6. QRS-T angle and QRS/T ratio. 7. Magnitudes and directions of instantaneous QRS vectors. 8. Spatial mean linear, angular and areal velocities of QRS loop. 9. Spatial circumference, angle, area and thickness of QRS loop. These were statistically compared with those of normal young men. Results and Discussions 1. Directions of inscription of QRS and T loops. Incidence of clockwise inscription of horizontal QRS loop was higher in ASD than in MS. Bizarre configuration of QRS loop in left sagittal plane was frequently observed in ASD, and was considered as one of the characteristic findings in diastolic overloading of the right ventricle. Direction of inscription of T loop changed earlier than that of QRS loop.