Response to Letter by Tsivgoulis et al
We wish to thank Dr Tsivgoulis and colleagues for their kind appreciation of our article, and we are pleased to answer their questions.
During TCD testing, blood pressure and heart rate were not systematically investigated. However, no patients reported subjective complaints that could be attributable to orthostatic intolerance, and heart rate, as recorded on the spectral display, did not change appreciably from the recumbent to the upright position. As a matter of fact, in 16 patients during normal breathing, RLS was undetectable while recumbent and apparent only in upright position (in 3 of them with a bubble load of 28, 31 and 33 bubbles respectively). However, in all these 16 patients the Valsalva maneuver had disclosed RLS while recumbent, and in 13 of them the postural difference during normal breathing ranged between 1 and 7 bubbles. Therefore, although our study was not powered to assess postural sensitivity in detecting RLS, because we studied only patients with echocardiography-confirmed shunts, we do not believe that changing posture significantly increases the likelihood of finding in upright position a shunt missed while the patient is recumbent. Moreover, in our extended database which includes also negative cases (unpublished data, 2007) there are no patients with negative Valsalva strain while recumbent who exhibits a shunt while standing.
From these considerations we would suggest that testing patients during both normal breathing and Valsalva maneuver in the recumbent position is sufficient to confirm or exclude a RLS and repeat testing in upright position during normal breathing may be warranted only in positive (while recumbent) cases to better qualify postural spontaneous variations that may be important, as emphasized by Tsivgoulis et al in a number of conditions.
Finally, we completely agree with Tsivgoulis et al on the need to perform a prospective multicenter study of testing protocols with different body positions, although the limited availability of machines equipped with Power M-Mode may pose some difficulty in integrating data among different participating centers.