A left to right shunt through an iatrogenic atrial septal defect(ASD) is known to occur after percutaneous mitral valvuloplasty(PMV), however, its hemodynamic significance as well as methods for the quantitation and follow-up evaluation have not been well established.

In order to compare the feasibilities of noninvasive diagnostic methods for the detection and quantitation of the left-to-right shunt after PMV. 35 patients(age 37±10 years) undertook either radionuclide angiography or transesophageal echocardiography or both within a week after PMV. Qp/Qs was calculated by Fick's oxygen method during cardiac catheterization and by indicator dilution method during radionuclide angiography. The left-to-right shunt was also quantified with transesophageal echocardiography(TEE) by calculating shunt flow rate(Q=2 πr²Vr) using isovelocity surface area.

TEE was the most sensitive to detect ASD(16 among 27 patients, 59%) compared to either RI angiography(5 among 27 patients, 18%, Qp/Qs>1.5) or cardiac catheterization(4 among 35 patients, 11%, oxygen step-up>7%). Calculated shunt flow rate by TEE showed significant linear correlation to the Qp/Qs by cardiac catheterization(r=0.73, p<0.001). Also there was a significant correlation between Qp/Qs by radionuclide angiography and by cardiac catheterization(r=0.49, p<0.01).

Both radionuclide angiography and TEE appear useful for the detection and quantitation of the left to right shunt after PMV. Since TEE seems to be not only more sensitive to detect the presence of the ASD than either radionuclide angiography or cardiac catheterization but useful to quantify the left-to-right shunt, it appears to be useful method for the follow-up evaluation after PMV.