Latin American Consensus Statement for the Use of Contrast-Enhanced Transcranial Ultrasound as a Diagnostic Test for Detection of Right-to-Left Shunt

Abstract

Background: The role of patent foramen ovale is a field of debate and current publications have increasing controversies about the patients’ management in young undetermined stroke. Work up with echocardiography and transcranial Doppler (TCD) can aid the decision with better anatomical and functional characterization of right-to-left shunt (RLS). Medical and interventional strategy may benefit from this information. Summary: a group of experts from the Latin American participants of the Neurosonology Research Group (NSRG) of World Federation of Neurology created a task force to review literature and describe the better methodology of contrast TCD (c-TCD). All signatories of the present consensus statement have published at least one study on TCD as an author or co-author in an indexed journal. Two meetings were held while the consensus statement was being drafted, during which controversial issues were discussed and voted on by the statement signatories. The statement paper was reviewed and approved by the Executive Committee of the NSRG of the World Federation of Neurology. The main objective of this consensus statement is to establish a standardization of the c-TCD technique and its interpretation, in order to improve the informative quality of the method, resulting in expanding the application of TCD in the clinical setting. These recommendations optimize the comparison of different diagnostic methods and encourage the use of c-TCD for RLS screening and complementary diagnosis in multicenter studies.

Comparison of Unilateral Middle Cerebral Artery and Bilateral Middle Cerebral Artery Monitoring for Right-to-Left Shunt Detection by Contrast-Enhanced Transcranial Doppler

“…The first injection was performed during normal respiration (rest), and the second injection was performed 5 s prior to the start of a 10-s Valsalva maneuver which reduced the mean MCA velocity by at least 25%. The duration of the Valsalva maneuver was 10 s ( 3 ). The presence and number of Mb and the time lag between the injection and the appearance of the first bubble (in seconds) were recorded.…”

“…Contrast-enhanced transcranial Doppler is a reliable and reproducible method for detecting RLS with high sensitivity and specificity ( 2 ). The Latin American common statement on c-TCD for the diagnosis of RLS recommends monitoring the MCA and mentions that unilateral or bilateral monitoring may result in important bilateral disagreements regarding the outcomes of c-TCD assessments ( 3 ). However, at present, there are no reports on c-TCD findings or associations with outcomes of unilateral versus bilateral MCA monitoring.…”

Comparison of right-to-left shunt characteristics in cryptogenic embolic ischemic stroke and non-cardioembolic ischemic stroke

“…Patients were classified into three levels: no MBs, negative test for RLS; ≤10 MBs, small or non-significant RLS; >10 MBs or significant RLS. Although there are some cut-off variations, the consensus seems to be that RLS is present if multiple MBs are detected (more than one) and is considered significant whenever more than 10 MBs are detected 21,22,23,24…”

Diagnosis of Patent Foramen Ovale: The Combination of Contrast Transcranial Doppler, Contrast Transthoracic Echocardiography, and Contrast Transesophageal Echocardiography

“…The first injection was performed at rest, and the test was repeated after asking the subject to perform a VM, and the MCA Doppler spectrum was recorded for 25 seconds. The agitated saline solution was injected 5 seconds prior to the start of VM maintaining for more than ten seconds [17]. To avoid possible misinterpretation of the Doppler examinations, VM was performed 3 times with a 5-minute interval, and we regarded one in which the most HITS were recorded from the MCA as the final result.…”