Oscillatory Cerebral Blood Flow Is Associated With Impaired Neurocognition and Functional Hyperemia in Postural Tachycardia Syndrome During Graded Tilt. Issue 3 (March 2015)

• Record Type: Journal Article
• Authors: Stewart, Julian M.; Del Pozzi, Andrew T.; Pandey, Akash; Messer, Zachary R.; Terilli, Courtney; Medow, Marvin S.
• Is Part Of: Hypertension. Volume 65:Issue 3(2015:Mar.)
• Publication Date: 2015-03
• Subjects: Hypertension -- Periodicals; Hypertension -- Treatment -- Periodicals; 616.132005
• DOI: 10.1161/HYPERTENSIONAHA.114.04576
• Languages: English
• ISSNs: 0194-911X

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <p>We hypothesize that upright cognitive impairment in patients with postural tachycardia syndrome (POTS) is caused by reduced cerebral blood flow (CBF). The CBF velocity (CBF<sub>v</sub>) measured by transcranial Doppler ultrasound decreased excessively during 70° tilt in a minority of patients with intermittent hyperpnea/hypocapnia. Incremental tilt showed no difference in mean CBF<sub>v</sub>. But N-back memory tasking indicated progressive compromised memory, reduced functional hyperemia, and reduced neurovascular coupling. Orthostasis caused slow oscillations in CBF<sub>v</sub> linked to oscillations in arterial pressure in patients with POTS. We also hypothesize that oscillatory CBF<sub>v</sub> degrades neurovascular coupling. We performed 2-back testing when subjects were in supine position and during incremental tilts to 15°, 30°, 45°, and 60° in 11 patients with POTS and 9 controls. Oscillatory arterial pressure, oscillatory CBF<sub>v</sub>, and neurovascular coupling were similar in supine position. The oscillatory arterial pressure increased by 31%, 45%, 67%, and 93% in patients with POTS during tilt and remained unchanged in the controls. Oscillatory CBF<sub>v</sub> increased by 61%, 82%, 161%, and 264% in patients with POTS during tilt and remained unchanged in the controls. Functional hyperemia decreased from 4.1% to 3.0%, 1.1%, 0.2%, and to 0.04% in patients with POTS, but it was unchanged at 4% in the controls. Percent correct N-back responses decreased from 78% to 33% in patients with POTS, whereas they remained at 89% in the controls. In patients with POTS, oscillatory CBF<sub>v</sub> was linearly correlated with functional hyperemia (<italic>r</italic><sup>2</sup>=0.76). Increased oscillatory CBF is associated with reduced neurovascular coupling and diminished cognitive perf ormance in patients with POTS.</p> </sec> </abstract>