Right-to-left shunt detection via synchronized contrast transcranial Doppler combined with contrast transthoracic echocardiography: A preliminary study.

Abstract

Background: Patent foramen ovale (PFO)-related right-to-left shunts (RLSs) have been implicated in cryptogenic stroke and migraine, with larger shunts posing a higher risk. When used individually to detect RLS, contrast transcranial Doppler (cTCD) and contrast transthoracic echocardiography (cTTE) may yield false-negative results. Further, the literature exposes gaps regarding the understanding of the limitations of cTCD and cTTE, presents conflicting recommendations on their exclusive use, and highlights inefficiencies associated with nonsynchronous testing.

Aim: To investigate the accuracy of multimodal ultrasound to improve diagnostic efficiency in detecting PFO-related RLSs.

Methods: We prospectively enrolled four patients with cryptogenic stroke (n = 1), migraine (n = 2), and unexplained dizziness (n = 1) who underwent synchronized cTCD combined with cTTE. The participants were monitored and followed-up for 24 months.

Results: cTTE identified moderate and large RLSs in patients with recurrent cryptogenic stroke and migraines, whereas cTCD revealed only small RLSs. Moderate and large RLS were confirmed on combined cTTE and cTCD. After excluding other causes, both patients underwent PFO occlusion. At 21- and 24-month follow-up examinations, neither stroke nor migraine had recurred. cTTE revealed a small RLS in a third patient with unexplained dizziness and a fourth patient with migraines; however, simultaneous cTCD detected a large RLS. These patients did not undergo interventional occlusion, and dizziness and headache recurred at the 17- and 24-month follow-up examinations.

Conclusion: Using cTTE or cTCD may underestimate RLS, impairing risk assessments. Combining synchronized cTCD with cTTE could enhance testing accuracy and support better diagnostic and therapeutic decisions.