Open AccessHemodynamic variability and cerebrovascular control after transient cerebral ischemia
Author(s) -
Allan Philip D.,
Faulkner James,
O'Donnell Terrence,
Lanford Jeremy,
Wong Laikin,
Saleem Saqib,
Woolley Brandon,
Lambrick Danielle,
Stoner Lee,
Tzeng YuChieh
Publication year - 2015
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.12602
Subject(s) - cerebral blood flow , hyperventilation , medicine , hypocapnia , hemodynamics , cardiology , middle cerebral artery , hypercapnia , anesthesia , ischemia , acidosis
We investigated if hemodynamic variability, cerebral blood flow ( CBF ) regulation, and their interrelationships differ between patients with transient ischemic attack ( TIA ) and controls. We recorded blood pressure ( BP ) and bilateral middle cerebral artery flow velocity ( MCA v) in a cohort of TIA patients ( n = 17), and age‐matched controls ( n = 15). Spontaneous fluctuations in BP and MCA v were characterized by spectral power analysis, and CBF regulation was assessed by wavelet phase synchronization analysis in the very low‐ (0.02–0.07 Hz), low‐ (0.07–0.20 Hz), and high‐frequency (0.20–0.40 Hz) ranges. Furthermore, cerebrovascular CO 2 reactivity was assessed as a second metric of CBF regulation by inducing hypercapnia with 8% CO 2 inhalation followed by hyperventilation driven hypocapnia. We found that TIA was associated with higher BP power (group effect, P < 0.05), but not MCA v power ( P = 0.11). CBF regulation (assessed by wavelet phase synchronization and CO 2 reactivity) was intact in patients (all P ≥ 0.075) across both hemispheres (all P ≥ 0.51). Pooled data (controls and affected hemisphere of patients) showed that BP and MCA v power were positively correlated at all frequency ranges ( R 2 = 0.20–0.80, all P < 0.01). Furthermore, LF phase synchronization index was a significant determinant of MCA v power ( P < 0.05), while VLF and HF phase synchronization index, and TIA were not (all P ≥ 0.50). These results indicate that CBF stability and control is maintained in TIA patients, but BPV is markedly elevated. BPV attenuation may be an important therapeutic strategy for enhancing secondary stroke prevention in patients who suffer a TIA .