Complementarity of Contrast Transcranial Doppler and Contrast Transesophageal Echocardiography for the Detection of Patent Foramen ovale in Stroke Patients

Abstract

All studies concerning the detection of patent foramen ovale (PFO) have compared transthoracic or transesophageal echocardiography (c-TEE) to transcranial Doppler ultrasound after contrast injection (c-TCD), but combining both techniques in the search of PFO has received no consideration. Our study aims to substantiate this claim in 37 patients with cryptogenic stroke. It includes two protocols for the detection of PFO to assess the complementarity of c-TCD and c-TEE performed simultaneously or separately. Firstly, we used a standardized protocol, performing c-TCD alone. Secondly, we used a standardized and a simultaneous protocol which associated c-TCD with c-TEE. When c-TCD and/or c-TEE found right-to-left shunts, they were classified as: minimal, intermediate and massive. c-TCD revealed all PFO detected by c-TEE in 24 patients out of 37 (65%). Furthermore, c-TCD was positive for a PFO in 5 other patients whereas c-TEE was negative. The degree of right-to-left interatrial shunting varied according to the protocol: c-TCD performed alone found 15 massive, 4 intermediate and 5 minimal shunts whereas 10, 9 and 5, respectively, were detected by c-TCD when it was combined with c-TEE. In contrast, c-TEE revealed 8 massive, 8 intermediate and 8 minimal shunts. c-TCD can identify minimal shunts missed by c-TEE and could be more relevant to detect massive shunts, particularly when not performed simultaneously with c-TEE because no sedation is required for c-TCD alone as opposed to c-TEE: thus patients are more cooperative and produce a better Valsalva strain. c-TEE confirms pulmonary shunts suspected by c-TCD and determines the morphologic characteristics of the interatrial septum. While previous studies opposed c-TEE against c-TCD for the detection of a PFO, we think that both techniques are complementary and that it is interesting to associate them, particularly when they are deferred, to increase the ability of detecting PFO and to specify the degree of right-to-left shunting.

Contrast Transcranial Doppler Ultrasound in the Detection of Right-to-Left Shunts

“…Some authors believe that a high number of MES and their early occurrence may help to discriminate cardiac from noncardiac shunts or clinically relevant from irrelevant shunts. 18,19,21,22 Our results, however, show that in individual cases, discrimination based only on the number of MES or their occurrence is not feasible. Additionally, shunts not noted on TEE can allow considerable and early transit of microbubbles.…”

Controlled Contrast Transcranial Doppler and Arterial Blood Gas Analysis to Quantify Shunt Through Patent Foramen Ovale

“…11 Its sensitivity approaches 90% and specificity approaches 92% compared with c-TEE. 12 c-TCD does not require sedation of the patient, thus ensuring better collaboration during the Valsalva maneuver (VM).…”

Quantification of Microspheres Appearance in Brain Vessels

“…These characteristics make TCD testing with agitated saline at least equivalent to echocardiography for detection of right-to-left shunts such as patent foramen ovale. [17][18][19][20][21][22] Experimental data suggest that perflutren-lipid S larger than 5 are eliminated from the circulation by adhesion in capillaries, 23 whereas air S cannot be detected without a shunt (these are filtered out by lung capillaries of 8 to 12 diameter). Therefore, a theoretical overlap for the 5 to 8 range in both size groups becomes negligible ( Figure 1A).…”