Effects of Posture on Right-to-Left Shunt Detection by Contrast Transcranial Doppler

Abstract

Background and Purpose-There is controversy about the optimal patient position for the detection of right-to-left shunt (RLS). The study was performed to investigate which patient position best detects RLS during contrast-enhanced transcranial Doppler. Methods-We prospectively evaluated consecutive patients with ischemic stroke or TIA referred to our Noninvasive Cerebrovascular Laboratory for suspected paradoxical embolism. The standard protocol for RLS detection recommended by the International Consensus Criteria was followed. Each patient was examined at rest and after Valsalva maneuver in 4 positions: supine, right lateral decubitus, right lateral leaning, and upright sitting, in random order. RLS was graded 0 (no microbubbles [mB] detected), 1 (1-10 mB), 2 (Ͼ10 mB but no curtain), and 3 (curtain, shower of mB). Blood pressure, heart rate, and neurological symptoms were monitored. Data were analyzed using SPSS version 17. Results-RLS

Effects of Patient Position on Right-to-Left Shunt Detection by Contrast Transcranial Doppler

“…A later study evaluated 240 cases of patients with ischemic stroke or TIA (Agustin et al 2011). RLS was detected in at least one position in 89 of 240 patients (37.1%).…”

Body Positions in the Diagnosis of Right-to-Left Shunt by Contrast Transcranial Doppler

“…A VM was considered successful if the Doppler peak-flow velocity of the MCA decreased by 25% (Fig. 1, arrow) (Agustin et al 2011;Jauss and Zanette 2000). The time to appearance of the first MB in the MCA was noted (Jauss and Zanette 2000).…”

“…Numerous positions have been used to improve the sensitivity and accuracy of c-TCD, including sitting upright, right lateral decubitus, right lateral leaning, recumbent and standing. Higher MB counts or higher frequency of RLS in the standing position at rest (Caputi et al 2008) or in the upright sitting position with the VM (Agustin et al 2011;Lao et al 2007), which are all erect postures, have been reported. It has also been argued (Agustin et al 2011;Telman et al 2003) that the erect posture allows MBs in the right atrium to rise to the PFO and pass easily into the left atrium because the right atrium is relatively higher than the right ventricle.…”

“…Higher MB counts or higher frequency of RLS in the standing position at rest (Caputi et al 2008) or in the upright sitting position with the VM (Agustin et al 2011;Lao et al 2007), which are all erect postures, have been reported. It has also been argued (Agustin et al 2011;Telman et al 2003) that the erect posture allows MBs in the right atrium to rise to the PFO and pass easily into the left atrium because the right atrium is relatively higher than the right ventricle. However, patients with severe migraine or stroke patients with hemiplegia or vertigo may not be able to sit or stand, and an alternative to erect postures is needed.…”

“…Research has revealed the supine position is not the best, however (Agustin et al 2011;Caputi et al 2008;Lao et al 2007;Schwarze et al 1999;Telman et al 2003), when using number of MBs or rate of RLS detection as the criterion for diagnosis. Numerous positions have been used to improve the sensitivity and accuracy of c-TCD, including sitting upright, right lateral decubitus, right lateral leaning, recumbent and standing.…”