Effect of Patient Position on Detection of Patent Foramen Ovale by Simultaneously Performed Transcranial Doppler and Transesophageal ECHO

Background
Embolization through a patent foramen ovale (PFO) is an important cause of cryptogenic stroke and its detection and quantification are critical for further treatment of stroke patients.

Objective
The purpose of the study was to observe the correlation between a Transcranial Doppler (TCD) performed simultaneously with a Transesophageal echocardiogram (TEE) and the relationship to right or left lateral decubitus position of patients during injection of agitated saline.

Patients and Methods
31 stroke patients were examined with TEE and TCD performed simultaneously. Patients with a known embolic source or without an adequate sonographic window were excluded. Both the neurologist and the cardiologist were blinded to each other`s results doing the procedure. Four intravenous injections of agitated saline were injected via an antecubital vein to each patient, 2 with the injections in the left and 2 in the right decubitus position.

Results
In 24 cases PFO was excluded both by TEE and TCD. In 7 cases PFO was diagnosed both by TCD and TEE, but the quantification of the shunt by TCD differed depending on the patient`s position with a trend toward a more accurate quantification of the shunt`s size with the patient in left decubitus position and a false minimalization of the shunt`s quantification with the patient in the right decubitus position. Coughing during TEE increased the number of bubbles recorded by TCD.

Conclusion
Our results suggest a relationship between a lateral decubitus positioning of patients and the quantification of PFO but a larger study sample is necessary to clarify this point.