title: Relationship between cardiac function and resting cerebral blood flow: MRI measurements in healthy elderly subjects.
abstract: Although both impaired cardiac function and reduced cerebral blood flow are associated with ageing, current knowledge of the influence of cardiac function on resting cerebral blood flow (CBF) is limited. The aim of this study was to investigate the potential effects of cardiac function on CBF. CBF and cardiac output were measured in 31 healthy subjects 50-75 years old using magnetic resonance imaging techniques. Mean values of CBF, cardiac output and cardiac index were 43.6 ml per 100 g min(-1), 5.5 l min(-1) and 2.7 l min(-1) m(-2), respectively, in males, and 53.4 ml per 100 g min(-1), 4.3 l min(-1) and 2.4 l min(-1) m(-2), respectively, in females. No effects of cardiac output or cardiac index on CBF or structural signs of brain ageing were observed. However, fractional brain flow defined as the ratio of total brain flow to cardiac output was inversely correlated with cardiac index (r(2) = 0.22, P = 0.008) and furthermore lower in males than in females (8.6% versus 12.5%, P = 0.003). Fractional brain flow was also inversely correlated with cerebral white matter lesion grade, although this effect was not significant when adjusted for age. Frequency analysis of heart rate variability showed a gender-related inverse association of increased low-to-high-frequency power ratio with CBF and fractional brain flow. The findings do not support a direct effect of cardiac function on CBF, but demonstrates gender-related differences in cardiac output distribution. We propose fractional brain flow as a novel index that may be a useful marker of adequate brain perfusion in the context of ageing as well as cardiovascular disease.
authors: Functional Imaging Unit, Section of Clinical Physiology and Nuclear Medicine, Department of Diagnostics, Glostrup Hospital, Copenhagen University Hospital, Glostrup, Denmark; Department of Clinical Physiology, Nuclear Medicine and PET, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark; Center for Healthy Aging, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors: Otto M
authors: OM
authors: Henriksen
authors: Lars T
authors: LT
authors: Jensen
authors: Katja
authors: K
authors: Krabbe
authors: Henrik B W
authors: HB
authors: Larsson
authors: Egill
authors: E
authors: Rostrup
mesh_terms: D000367:Age Factors; D000368:Aged; D000375:Aging; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001783:Blood Flow Velocity; D002302:Cardiac Output; D002560:Cerebrovascular Circulation; D003430:Cross-Sectional Studies; D005260:Female; D006321:Heart / Q000294:innervation*; D006339:Heart Rate; D006801:Humans; D056784:Leukoencephalopathies / Q000175:diagnosis* / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D055420:Perfusion Imaging / Q000379:methods*; D011237:Predictive Value of Tests; D012720:Severity of Illness Index; D012737:Sex Factors; D013997:Time Factors
keywords: brain ageing; brain perfusion; cardiac output; gender; heart rate variability