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A Comparison of Different Time Windows for the Detection of Cardiac Right-To-Left Shunt Using Contrast-Enhanced Transcranial Doppler Ultrasonography

Author(s): Hui-Qin Wang, Kang-Ding Liu, Xiao-Cong Wang, Chuang Li, Ying-Qi Xing


Contrast-enhanced transcranial Doppler ultrasonography (c-TCD) is highly sensitive for detecting cardiac right-to-left shunt (RLS). However, the time window to be used with c-TCD for cardiac shunt detection is yet to be standardized. The aim of our study was to standardize the time window to enable easy and widespread use of c-TCD for cardiac shunt detection.


A total of 239 consecutive patients with suspected cardiac RLS were subjected to simultaneous c-TCD and contrast-enhanced transthoracic echocardiography (c-TTE). We evaluated time windows of 15-, 20-, 25-, 30-, 35-, and 40-s duration for c-TCD. Receiver operating characteristic (ROC) curve analyses and Spearman’s rho rank correlations were performed for the different time windows to calculate the areas under the curve (AUCs) and 95% confidence intervals (95% CIs).


The AUC, and thus the diagnostic accuracy, was highest for the 25-s window (AUC, 0.746; 95% CI, 0.684–0.809). The 15-s window (0.667; 95% CI, 0.598–0.737; P < 0.05) had the least AUC. Spearman’s rho rank correlation identified the 25-s window (rho, 0.627; 95% CI, 0.534–0.708) as having the strongest correlation between c-TCD and c-TTE.


The 25-s window is ideal for c-TCD-aided detection of cardiac RLS.

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