Link between cerebral blood flow and autonomic function in survivors of internal carotid artery occlusion.

PURPOSE

Symptomatic internal carotid artery occlusion (ICAO) is an important cause of cerebral ischemia with poor long-term outcome. Reductions in baroreflex function is reported in carotid atherosclerosis and implicated in increased risk of recurrent cardiovascular events. A distributed network of forebrain regions can exert modulatory influences over the cardio-vagal and baroreflex functions. The successful clinical translation of these approaches offers insights into underlying modulatory mechanisms and to possible therapeutic strategy.

METHODS

This study enrolled 20 symptomatic ICAO survivors, 20 patients with small vessel disease (SVD) as risk control, and 20 healthy controls. All underwent a standardized evaluation of cardiovascular autonomic function testing that included baroreflex sensitivity (BRS), Valsalva ratio (VR), and heart rate response to deep breathing (HR_DB). The regional cerebral blood flow (rCBF) of the central autonomic network (CAN) was obtained from arterial spin-labeling magnetic resonance imaging. Parameters of autonomic function between symptomatic ICAO survivors with and those without recurrent cardiovascular events were compared.

RESULTS

Valsalva ratio and HR_DB levels were significantly higher in the control group, followed by the SVD and ICAO groups (p=0.009 and p=0.007, respectively). Spontaneous BRS and BRS during the early phase II of Valsalva maneuver levels were both significantly higher in the control group, followed by the SVD and ICAO groups (p<0.001 and p=0.042, respectively). The rCBF of CAN inversely correlated with spontaneous BRS.

CONCLUSION

Autonomic dysregulation, including reduced BRS and impaired cardio-vagal function in the convalescent stage ICAO, can persist for a long time. Reduced BRS is inversely correlated with CAN activity.