Doppler evaluation of left to right shunt (Qp/Qs) in patients with isolated ventricular septal defect (Vsd)

A prospective observational study was carried out in the department of cardiology, Bangabandhu Sheikh Mujib Medical University (BSMMU) in collaboration with the department of cardiology, Combined Military Hospital (CMH), Dhaka from January 2000 to October 2001. All the patients were clinically evaluated. ECG & Doppler echocardiography were done.All the patients underwent cardiac catheterization. Complex congenital heart disease & cyanotic heart disease patients were excluded from the study. Doppler estimated pulmonary to systemic blood flow ratio (Qp/Qs) was done by conventional (velocity time integral method) method. In cardiac catheterization Qp/Qs ratio derived from oximetric data which has become a well established part of clinical practice. Doppler derived Qp/Qs were compared with catheter derived Qp/Qs. 30 patients with VSD were included. In those patients Doppler derived Qp/Qs ranged from maximum 4.5 to minimum 1.10. Mean (+/-SD) was 1.88+/-0.86 In patients with VSD mean (+/-SD) Qp/Qs at catheterization was 1.80+/-0.80. Qp/Qs ranged from maximum 4.10 to minimum 1.1 In those patients the correlation coefficient for invasively determined Qp/Qs versus Doppler estimated Qp/Qs was .92 (standard error of estimate SEE] = 0.19) & the line of regression passed close to the origin. The results of this study demonstrate that The Doppler technique allows the noninvasive evaluation of Qp/Qs with a high degree of accuracy & allows determination of the stage of VSD by the consecutive assessment of shunt magnititude.