Sizing of the ventricular septal defect in children with tetralogy of Fallot: Echocardiographic, angiocardiographic and surgical correlation

Background: Ventricular septal defect (VSD) in patients with tetralogy of Fallot (TOF) is a malalignment defect which makes the size more difficult to measure than that of an isolated VSD. This study was designed to evaluate the accuracy of two-dimensional echocardiography and angiocardiography in measuring this kind of VSD. Materials and Methods: Thirty-four children with TOF (aged 14 months to 11 years, mean 40 months, median 29 months) were enrolled to be studied before total corrective surgery. The direct measurement by the surgeon during the operation is recognized as the true size of the VSD. The VSD diameters measured by echocardiography and angiocardiography pre-operatively and by the surgeon during the operation were compared to each other by linear regression analysis. Results: The VSDs were classified as perimembranous type in 25 patients and supracristal type in nine patients by surgery. The VSD diameters, which were measured by the surgeon during the operation, ranged from 5 to 20 mm (mean ± SD: 12.9 ± 3.13 mm). By echocardiographic study, the VSD diameters ranged from 8 to 16 mm (mean ± SD: 11.9 ± 2.25 mm). By angiocardiographic study, the VSD diameters were calculated to range from 8.3 to 17.5 mm (mean ± SD: 13.4 ± 2.41 mm). After statistical analysis, we found that: 1) the correlation between those measurements by echocardiography and those by the surgeon was statistically significant (r = 0.622, p < 0.0001), 2) the correlation between those measurements by angiocardiography and those by the surgeon was also noteworthy and significant (r = 0.428, p = 0.0116) and 3) the correlation between echocardiography and surgery was better than that between angiocardiography and surgery (r = 0.622, p < 0.0001 vs r = 0.428, p = 0.0116). Conclusion: Our study indicated that two-dimensional echocardiography provided an accurate, non-invasive assessment of malalignment of VSDs in patients with TOF.