New method for quantification of atrial septum defect shunting by echocardiography

Abstract

Abstract Background Atrial septum defect (ASD) is a common congenital heart disease. Echocardiography is the preferred method for detection and characterization of ASD. Accurate quantification of shunting is pivotal, but often requires right heart catheterization (RHC). In the present study, we introduce a new non-invasive method for accurate quantification of the ASD shunt by combined transesophageal- (TEE) and transthoracic (TTE) echocardiography. Shunt by RHC was used as a reference method. Method In 22 adults with secundum ASD, left ventricular (LV) stroke volume (SV) was measured by the pulsed Doppler method using 2D TTE. The shunt volume passing through the ASD was quantified as the ASD area measured by planimetry from 3D TEE, multiplied with the time velocity integral (TVI) of the PW Doppler obtained at the center of the ASD by TEE. Finally, the ratio of the pulmonary to systemic shunt (Qp:Qs) was calculated as (LVSV+ASDvolume)/LVSV. Shunt by RHC was assessed by the Fick’s principle. Results Mean shunt was 2.2±0.7 (±SD) by echocardiography and 2.1±0.7 by RHC, with a mean difference of -0.1±0.4 (Figure 1). The correlation between shunt measured by RHC and echocardiography was strong (r=0.86, p<0.0001; Figure 2). Conclusion The present study demonstrates that ASD shunting can be quantified accurately by combining TTE and TEE, suggesting a new non-invasive approach in settings where RHC is not feasible or available.Figures