Harmonic Imaging Improves Sensitivity at the Expense of Specificity in the Detection of Patent Foramen Ovale

UNLABELLED: Contrast echocardiography using agitated saline is widely employed to detect right to left shunt in patients with suspected patent foramen ovale (PFO). The sensitivity of fundamental transthoracic echocardiography (FTTE) is often limited by poor far-field resolution. The purpose of this study was to evaluate the test characteristics of harmonic imaging during transthoracic echocardiography (HTTE) for the detection of PFO. METHODS: Sixty-four patients referred for transesophageal echo (TEE) for clinical indications underwent FTTE and HTTE during saline contrast injections. RESULTS: TEE identified nine PFOs. For FTTE, the sensitivity was 78% and the specificity was 100%. For HTTE, the sensitivity was 100% and the specificity was 82%. All ten false positives with HTTE occurred after five cardiac cycles, suggesting transpulmonary transit of the bubbles. CONCLUSION: In the detection of PFO, HTTE improves sensitivity at the expense of specificity, particularly if the timing of contrast appearance in the left heart is ignored.