We ascertained the presence of PFO and EV using cTEE and transthoracic contrast echocardiography (cTTE) in 292 consecutive patients (age 42 ± 12 years) with cryptogenic stroke. A diagnosis of PFO was based on the observation of right-to-left shunting of contrast bubbles or by color Doppler with pulse repetition frequency of 20–30 cm/s. An EV with a diameter of > 1.5 cm in the bicaval view was considered large.
Overall 204 patients (70 % ) had evidence of a right-to-left shunt by either contrast echo method. Shunting was demonstrated more frequently by color Doppler than by cTEE, either spontaneously (133 vs. 92; p = 0.01) or during provocative maneuvers (166 vs. 184; p = 0.01). The sensitivity of color Doppler was significantly higher than that of cTEE (90 % vs. 81 % ; p = 0.01). A large EV was found in 37 patients, 31 (84 % ) of whom had a PFO. The presence of a large EV did not significantly influence the sensitivity of color Doppler for detecting shunting through a PFO, but the sensitivity of cTTE and cTEE was significantly reduced (from 88 % to 42 % , p < 0.001).
Color Doppler TEE is more accurate than traditional cTEE for PFO diagnosis and is not negatively influenced by the presence of an EV, provided that a low pulse repetition frequency is used.