Clinical application of electron beam CT in the diagnosis of ventricular septal defect classification of double-outlet right ventricle

Objective: To explore the clinical application of electron beam CT (EBCT) in the diagnosis of ventricular septal defect (VSD) classification of double-outlet right ventricle. Methods: Retrospective analysis of EBCT findings in 14 patients with double-outlet right ventricle confirmed by operation or angiocardiography was done. The double-outlet right ventricle patients complicated with complete endocardial cushion defect were not included in authors' research. The 10 male and 4 female patients ranged in age from 1 to 29 years (median age was 9.7 years). Serial 3 mm contrast single slice mode scan without slice interval was obtained. The authors laid stress on observation and measurement as follows: (1) The location relationship and distances among upper borders of VSD and tricuspid annulus, lower borders of aortic and pulmonary valves. (2) Location of muscular outlet. (3) Overriding of great arteries. All the distances were calculated by means of the difference of examination table perch. Results: (1) In the 7 patients with subaortic VSD, the mean distance between VSD and aortic valve was 5.6 mm while that between VSD and pulmonary valve was 15 mm. The difference had extreme statistic significance (t = 4.69, P < 0.005). The level of aortic valve was lower than that of pulmonary valve and closer to VSD in all the patients. Aortic valve overrode VSD in 3 patients. (2) In the 4 patients with sub-pulmonary VSD, the mean distance between VSD and pulmonary valve was 3 mm while that between VSD and aortic valve was 9 mm. There was significant difference (t = 4.91, P < 0.05). The level of pulmonary valve was lower than that of aortic valve and closer to VSD in all the patients. Pulmonary valve overrode VSD in 2 patients. (3) 2 patients with doubly committed VSD, the VSD situated directly under the aortic and pulmonary valve. The distance between VSD and aortic or pulmonary valve was 0-1.5 mm. In the above-mentioned three types VSD, the upper border of VSD was higher than that of tricuspid annulus in all patients but 1 patient being on the same level. (4) 1 patient with non-committed VSD, the distance between VSD and aortic valve was 30 mm while that between VSD and pulmonary valve was 45 mm. The upper border of VSD was 30 mm lower than that of tricuspid annulus'. Conclusion: EBCT was valuable in accurately outlining the location of VSD in double-outlet right ventricle. VSD classification of double-outlet right ventricle may be easily determined by means of the situation relationship among aortic valve pulmonary valve and tricuspid valve in EBCT