Ethnic differences in skin microvascular function and their relation to cardiac target-organ damage.
BACKGROUND
People of Black African descent have increased risks of vascular target-organ damage not explained by greater blood pressures.


OBJECTIVE
To study ethnic differences in the microvasculature.


METHODS
Flow (flux) in microcirculatory skin vessels was assessed using laser Doppler fluximetry in 181 Afro-Caribbean and European men and women aged 40-65 years from the general population in London, UK. Flux in response to maximal heating (maximal hyperaemic response) was measured and minimum vascular resistance calculated. Peak flux and time to peak after an ischaemic stimulus were also measured. Target-organ damage was assessed using echocardiographic interventricular septal thickness (IVST).


RESULTS
In men, maximum hyperaemic response was attenuated in Afro-Caribbeans [109 arbitrary units (au), 25th and 75th percentiles 101, 117] compared with Europeans [165 (155, 179) au; P = 0.008]. Minimum vascular resistance was greater in Afro-Caribbeans, significantly so in men [(1.22 (1.18, 1.28) au/mmHg compared with 0.80 (0.77, 0.83) au/mmHg; P = 0.006]. Peak ischaemic response was attenuated in Afro-Caribbean men and women compared with Europeans (35.6 au compared with 49.5 au; P < 0.001) and time to peak was prolonged (14.1 s compared with 12.5 s; P = 0.07). These ethnic differences could not be accounted for by standard cardiovascular risk factors. IVST was greater in Afro-Caribbeans than in Europeans. Minimum vascular resistance and peak response accounted for a small proportion of this ethnic difference, in addition to conventional factors.


CONCLUSIONS
Afro-Caribbeans have poorer microvascular structure and function, unexplained by conventional risk factors, which may contribute to greater rates of vascular target-organ damage.
Strain
William D
WD
International Centre for Circulatory Health, Faculty of Medicine, Imperial College London at St Mary's, London, UK. d.strain@imperial.ac.uk
Chaturvedi
Nish
N
Leggetter
Sandra
S
Nihoyannopoulos
Petros
P
Rajkumar
Chakravarthi
C
Bulpitt
Christopher J
CJ
Shore
Angela C
AC
D000328:Adult; D000368:Aged; D044383:Black People; D005260:Female; D006801:Humans; D006973:Hypertension / Q000208:ethnology* / Q000473:pathology / Q000503:physiopathology*; D017379:Hypertrophy, Left Ventricular / Q000208:ethnology; D007511:Ischemia / Q000208:ethnology; D017078:Laser-Doppler Flowmetry; D008297:Male; D008833:Microcirculation / Q000473:pathology / Q000502:physiology; D008875:Middle Aged; D012307:Risk Factors; D012867:Skin / Q000098:blood supply*; D014655:Vascular Resistance; D044465:White People