Flow Mediated Slowing FMS
For a long time, the clinical research community looked for a more automized and operator-independent, technically less demanding test replacing the FMD procedure, at least for certain applications.
In 2006, Katarina Naka was the first to report about “Flow-mediated changes in Pulse Wave Velocity: a new clinical measure of endothelial function” in the European Heart Journal [9].
FMS Testing Procedure
Flow Mediated Slowing or FMS testing mimics the FMD test procedure leveraging on its underlying physiological principles. While post-occlusive hyperemia leads to NO activated tone modulation and vessel diameter increase, pulse wave velocity (PWV) in the stimulated limb decreases. As PWV is inversely related to Distensibility, a widening of brachial artery cross section will cause a drop in brachial PWV. The coupling of acute flow-mediated relaxation of conduit artery tone with PWV reduction or “slowing” in both arms and legs – independent from blood pressure, was documented [9]. Post-occlusive brachial hyperemia, induced flow-mediated slowing of bPWV, is measured between the wrist and the upper arm. In normal healthy subjects the immediate drop from pre-occlusive levels is quite significant (up to 20%) and sustained at an 8-10% level for up to 10 min. Whereas in patients with cardio-vascular disease, where endothelial function and flow-mediated vasodilation are known to be compromised, the PWV slowing (FMS) is substantially reduced, particularly when observed over a longer post-occlusive phase of some minutes. It was also shown that administration of vaso-active agents in the brachial artery was leading to an ipsilateral PWV slowing, while the simultaneously measured PWV on the contralateral side remained unaffected [10].
While relying on the proven FMD testing procedure by applying a brachial occlusion, the FMS test does neither require expensive imaging equipment nor the expertise of a physician or skilled ultrasound technologist but more importantly is entirely operator independent, making it an inexpensive and reproducible exam which can be applied not only in special labs but virtually anyplace.
EndoCheck FMS Test Innovation
Over the past 15+ years, VICORDER®, a small vascular testing device, has proven its reliability, and user-friendliness, documented in numerous studies.
A thoroughly validated testing instrument for the evaluation of Arterial Stiffness, Vicorder has been expanded by a new application, EndoCheck FMS. Based on the ground laying evidence of the FMS coupling with endothelial function, the new test protocol was developed for automated, operator-independent testing of brachial PWV (bPWV) based on prior and recent validation [10, 11, 12].
An automated procedure guides the operator through a standardized test, measuring brachial PWV before and after occlusion of the brachial artery. Real-time analysis of PWV data is displayed, and the complete test meticulously recorded for review at any time. The target parameter FMS, the ratio of bPWV before and post brachial artery occlusion, and its absolute change in m/s is displayed at the end of test.
Test duration – as in conventional FMD - is typically 10 minutes (baseline, five minutes of occlusion, and three minutes of post-occlusive response recording). User-adjustable variables ensure adaptation to the needs of the test environment and purpose. The occlusion cuff can be placed at upper, mid or forearm, depending on the applied protocol.
The Endocheck FMS test has been applied in clinical and epidemiological studies, but also in hospital departments and outpatient clinics.
For more info on VICORDER® EndoCheck FMS measurement click here.
