Detection of Patent Foramen Ovale: Transcranial Doppler and Echocardiography Are Not Equivalent to Define a Large Shunt

BACKGROUND: The decision to close patent foramen ovale (PFO) depends on the size of PFO, the coexistence of interatrial septum aneurysm, and the importance of right-to-left shunt assessed by the number of bubbles on transcranial Doppler (TCD) and echocardiography after saline or glucose injection. The interventional threshold for the number of bubbles is considered to be the same for trans-thoracic and trans-esophageal echocardiography (TTE and TEE) and TCD. Our objective was to study whether the same thresholds can be used for TCD and echocardiography. PATIENTS AND METHODS: In this comparative, observational study, we modeled a linear relationship between the number of bubbles on TCD and echocardiography, which suggests a different threshold between TCD and TTE/TEE. RESULTS: = (7.2 (95% CI: -2.36-16.8) + (2.67 (95% CI: 1.85-3.49, p < 0.001)) × TTE/TEE). CONCLUSION: Different thresholds for the decision to close a PFO should be used for both techniques: 20 bubbles for echocardiography and 60 bubbles for TCD.