Unveiling the Value of Contrast Transthoracic Echocardiography Over Enhanced Transcranial Doppler for Right-to-Left Shunt Diagnosis During Synchronous Provocation Testing

Abstract

Objective: The results of right-to-left shunt (RLS) assessments are highly influenced by the methods used. This study aimed to compare the effectiveness of contrast transthoracic echocardiography (cTTE) and contrast transcranial Doppler (cTCD) in detecting RLS by conducting them simultaneously, employing the same provocations, timing, contrast-saline mixture, and posture.

Materials and Methods: This study was conducted at the Second Affiliated Hospital, School of Medicine, the Chinese University of Hong Kong, Shenzhen. A total of 237 patients who underwent both cTTE and cTCD simultaneously were included. The differences in RLS detection rates and the degree of shunting between the two examinations were assessed using the chi-square test and Wilcoxon rank-sum test. In addition, the timing of RLS appearance was compared between cTTE and cTCD examinations.

Results: The detection rate of RLS was higher with cTTE compared to cTCD (93.25% vs. 84.81%, X² = 8.64, p = 0.03); the difference was primarily observed in cases where RLS appeared after five cardiac cycles (X² = 17.496, p < 0.001). Regarding the detection of moderate/large shunts, cTTE outperformed cTCD (66.67% vs. 30.38%, X² = 62.468, p < 0.001); the difference in moderate/large shunt detection rates was primarily observed in cases where RLS appeared after five cardiac cycles (X² = 86.361, p < 0.001).

Conclusion: During the synchronous provocation testing, cTTE demonstrated superior performance over cTCD in detecting RLS and moderate/large RLS, particularly when RLS appeared after five cardiac cycles following full right atrial opacification.