TY - JOUR
T1 - Cerebral blood flow response to simulated hypovolemia in essential hypertension a magnetic resonance imaging study
AU - Neumann, Sandra
AU - Burchell, Amy E.
AU - Rodrigues, Jonathan C. L.
AU - Lawton, Christopher B.
AU - Burden, Daniel
AU - Underhill, Melissa
AU - Kobetić, Matthew D.
AU - Adams, Zoe H.
AU - Brooks, Jonathan C. W.
AU - Nightingale, Angus K.
AU - Paton, Julian F. R.
AU - Hamilton, Mark C. K.
AU - Hart, Emma C.
N1 - The online-only Data Supplement is available with this article at https://www.ahajournals.org/doi/suppl/10.1161/HYPERTENSIONAHA.119.13229.
Funding Information: This study was supported by the Wellcome Trust and the Bristol National Institute for Health Research (NIHR) Biomedical Research Centre. The views expressed are those of the authors and not necessarily those of the National Health Service, NIHR, or the Department of Health and Social Care.
PY - 2019/12
Y1 - 2019/12
N2 - Hypertension is associated with raised cerebral vascular resistance and cerebrovascular remodeling. It is currently unclear whether the cerebral circulation can maintain cerebral blood flow (CBF) during reductions in cardiac output (CO) in hypertensive patients thereby avoiding hypoperfusion of the brain. We hypothesized that hypertension would impair the ability to effectively regulate CBF during simulated hypovolemia. In the present study, 39 participants (13 normotensive, 13 controlled, and 13 uncontrolled hypertensives; mean age±SD, 55±10 years) underwent lower body negative pressure (LBNP) at -20, -40, and -50 mmHg to decrease central blood volume. Phase-contrast MR angiography was used to measure flow in the basilar and internal carotid arteries, as well as the ascending aorta. CBF and CO decreased during LBNP (P<0.0001). Heart rate increased during LBNP, reaching significance at -50 mmHg (P<0.0001). There was no change in mean arterial pressure during LBNP (P=0.3). All participants showed similar reductions in CBF (P=0.3, between groups) and CO (P=0.7, between groups) during LBNP. There was no difference in resting CBF between the groups (P=0.36). In summary, during reductions in CO induced by hypovolemic stress, mean arterial pressure is maintained but CBF declines indicating that CBF is dependent on CO in middle-aged normotensive and hypertensive volunteers. Hypertension is not associated with impairments in the CBF response to reduced CO.
AB - Hypertension is associated with raised cerebral vascular resistance and cerebrovascular remodeling. It is currently unclear whether the cerebral circulation can maintain cerebral blood flow (CBF) during reductions in cardiac output (CO) in hypertensive patients thereby avoiding hypoperfusion of the brain. We hypothesized that hypertension would impair the ability to effectively regulate CBF during simulated hypovolemia. In the present study, 39 participants (13 normotensive, 13 controlled, and 13 uncontrolled hypertensives; mean age±SD, 55±10 years) underwent lower body negative pressure (LBNP) at -20, -40, and -50 mmHg to decrease central blood volume. Phase-contrast MR angiography was used to measure flow in the basilar and internal carotid arteries, as well as the ascending aorta. CBF and CO decreased during LBNP (P<0.0001). Heart rate increased during LBNP, reaching significance at -50 mmHg (P<0.0001). There was no change in mean arterial pressure during LBNP (P=0.3). All participants showed similar reductions in CBF (P=0.3, between groups) and CO (P=0.7, between groups) during LBNP. There was no difference in resting CBF between the groups (P=0.36). In summary, during reductions in CO induced by hypovolemic stress, mean arterial pressure is maintained but CBF declines indicating that CBF is dependent on CO in middle-aged normotensive and hypertensive volunteers. Hypertension is not associated with impairments in the CBF response to reduced CO.
KW - Brain blood flow
KW - Cerebral blood flow
KW - Hypertension
KW - LBNP
KW - Lower body negative pressure
UR - http://www.scopus.com/inward/record.url?scp=85074965809&partnerID=8YFLogxK
U2 - 10.1161/HYPERTENSIONAHA.119.13229
DO - 10.1161/HYPERTENSIONAHA.119.13229
M3 - Article
C2 - 31656098
AN - SCOPUS:85074965809
VL - 74
SP - 1391
EP - 1398
JO - Hypertension
JF - Hypertension
SN - 0194-911X
IS - 6
ER -