Neurovascular coupling in severe aortic valve stenosis.

Abstract

Aortic stenosis (AS) is characterized by obstruction of blood outflow from the left ventricle, which can impair target organ perfusion such as the brain. We hypothesized that hemodynamic changes in AS may lead to dysfunction of cerebral blood flow regulatory mechanisms. The aim of our study was to evaluate neurovascular coupling in patients with AS by Transcranial Doppler ultrasonography. Neurovascular coupling was assessed using visually evoked cerebral blood flow velocity responses (VEFR) calculated as relative blood flow velocity changes in the posterior cerebral artery upon visual stimulation. We analyzed peak systolic, mean and end diastolic VEFR in 54 patients with severe AS and 43 controls in 10 consecutive cycles of visual stimulation. Repeated-measures ANOVA test was used to compare cerebral hemodynamic data by group. Patients with AS had significantly higher peak systolic (12.9%±5.6% and 10.5%±4.5%; p=.009) and mean VEFR (14.4%±5.8% and 12.2%±4.9%; p=.021) compared to controls, whereas only a tendency for higher end diastolic VEFR was observed (16.7%±6.9% and 14.4%±6.2%; p=.061). We have shown for the first time that patients with severe AS exhibit higher VEFR than controls indicating dysregulation of neurovascular coupling, which can be one of the factors contributing to development of cognitive decline.