fNIRS Monitoring During Carotid Artery Stenting for Outcomes Prediction

Carotid artery stenting (CAS) is the minimally invasive treatment for carotid artery stenosis patients. However, the expanded stents can stimulate the carotid sinus during the CAS, resulting in hypotension. Decompensated hypotension might cause hypoperfusion of the brain tissue, leading to ischemic stroke. Functional near-infrared spectroscopy (fNIRS) is a wearable device that continuously monitors the variation of hemodynamic response during CAS. This study investigates the correlation of fNIRS signals with the occurrence of hypotension and the resulting dysfunction. The recorded fNIRS signals showing the variation in oxygenated hemoglobin concentration (△[OxyHb]) of 6 channels are analyzed. The average of a specific time frame, 12.29s epoch, is calculated for comparison. Three types of patients who underwent the CAS are reported. Type I had no hypotension; Type II experienced hypotension but with no dysfunction; and Type III experienced hypotension and the resulting dysfunction (cannot move the limbs). We found the average of △[OxyHb] is lower than one µM (in absolute value) for the signals of both hemispheres of Types I and II cases. However, the average of [OxyHb] is larger than one µM of the affected side for a Type III case after the stent expands. During the CAS, the average of △[OxyHb] of the recorded fNIRS signal can indicate complications after the stent expands completely. When the average is larger than one µM and lasts over 1 min after the stent releasement, dysfunction can appear due to hypotension affecting the cortex’s hemodynamics.