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A prospective transesophageal echocardiographic study to assess a new type of left atrial spontaneous contrast at rest and during respiratory manoeuvres.

BACKGROUND
Recent observations suggest that a spontaneous echocardiographic contrast with fast motion (FEC) mimicking intravenous contrast can be seen in the left atrium in the absence of intravenous contrast injection.


OBJECTIVE
To assess the incidence of FEC and to evaluate the differentiating features between FEC and injected saline contrast.


STUDY DESIGN
Prospective cohort study.


SETTING
Tertiary referral centre.


PATIENTS AND METHODS
Transesophageal echocardiography was performed in 91 consecutive patients with a mean age of 58+/-15 years. Patients with mechanical valves and congenital heart disease were excluded. Images of the right atrium, left atrium and pulmonary veins were obtained in the absence of an intravenous catheter during quiet respiration, cough and the Valsalva manoeuvre. The same procedure was repeated during injection with agitated saline after venous cannulation.


RESULTS
In the absence of intravenous cannulation, FEC was detected in eight patients (9%) during quiet respiration, 36 patients (40%) during cough and 55 patients (60%) during the Valsalva manoeuvre. During the Valsalva manoeuvre, FEC was detected in the right atrium in 41 patients (45%) and in the left atrium in 33 patients (36%) (P=0.15). FEC was not related to a history of embolic event, left atrial smoke or patent foramen ovale. Intra- and interobserver agreements in the detection of FEC were 96% and 90%, respectively.


CONCLUSIONS
FEC can be observed frequently in the left atrium during cough or the Valsalva manoeuvre, and awareness of FEC is important to avoid the erroneous diagnosis of patent foramen ovale.