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![Page 1: Ethnic differences in aortic pulse wave velocity occur in the descending aorta independent of blood pressure and may be related to vitamin D MR Rezai,](https://reader036.fdocuments.in/reader036/viewer/2022062715/56649d9d5503460f94a8783a/html5/thumbnails/1.jpg)
Ethnic differences in aortic pulse wave velocity occur in the
descending aorta independent of blood pressure and may be related
to vitamin D
MR Rezai, SG Anderson, N Sattar, J Finn, F Wu & JK Cruickshank*
Cardiovascular & Endocrine SciencesUniversity of Manchester & Glasgow Royal Infirmary
*Now @ King’s College & St Thomas’ Hospital,
London
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Background
• Increasing evidence suggests that vitamin D may have an important role in modifying risk of cardiometabolic outcomes.
• Cross-sectional & prospective studies (and meta-analyses of these) have shown an independent inverse association between blood 25-OH vitamin D and CVD risk factors including BP, diabetes and dyslipidemia
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Meta-analysis of CVD incidence and mortality
About 50% increased risk of CVD incidence and mortality in the lowest
compared to the highest categories of vitamin D (pooled HR = 1.54 [1.22–
1.95])
Grandi et al. 2010. Prev Med. 51(3-4):228-33
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Reduced odds (24%) of hypertension for the highest vs. the lowest category of vitamin D
Burgaz et al 2011. Journal of Hypertension. 29(4):636-45
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Most of Northern Europe vitamin D deplete or deficient through winter -
and beyond• Setting - North West Britain (2009-2010)
• Population – 724 General Medicine OPD clinic attendees
assessed for vitamin D status
• Vitamin D deficiency - 75% with vit D <40 ng/ml **
• Vitamin D deplete - 23% <20 ng/ml#; 33% were South
Asian
• 10% & 15% overtly vitamin D deficient## and South Asian
**’recommended’ #’deplete’ ## <10ng/ml
Data courtesy of Prof R Malik
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Study Aims & Hypotheses
i. To Calibrate the Arteriograph against MR
ii. To examine the role of vitamin D on arterial stiffness - & its relation to ethnic differences in CVD
Hypotheses:
• Vitamin D would correlate closely with PWV, in relation to vascular risk
• People with melanised skin (eg: South Asian & Caribbean-origin), for given BP levels, have stiffer arteries in line with Vitamin D levels, independent of other Risk Factors
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Study participants
• 198 men aged 40 to 80 years of AfC,
SA, and European origin previously
recruited to the European Male
Ageing Study*.
• The participants had to be free of
severe chronic or acute disease
*N Engl J Med 2010; 363:123-135
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The Arteriograph device was used to measure arterial stiffness indices, including
total aPWV• Measurements were
performed ≥2 times on
the left arm after ≥5
minutes of rest supine
after BP measurement.
• The difference in time
between the beginning of
the 1st wave and 2nd
(reflected wave) is divided
into the distance from
sternal notch to pubic
symphysis.
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Arteriograph aPWV estimates calibrated with MRI-derived
Aortic Lengths• Comparison of MR-derived total aortic lengths
indicated an over estimate of real aortic path
using external landmarks.
• Mean difference 7cms (SD 2.8)
• Transit times similar
• Consequently, we recalculated Arteriograph
aPWV using transit times measured by device
and length of aortic path estimated by a
regression model from MR
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Study Characteristics by ethnicity
S Asian (n=65)
Af-C’bean (n=64)
European (n=62)
Age (yr) 55±10 54±10 56±8 SBP 124±15 < 129±16 126±13 DBP (mmHg) 78±10 < 82±11 81±8 PP 46±
9 48±10 45±7
HR (bpm) 68±11 > 64±8 > 61±8 BMI 27±3 28±5 27±4
ArterialStiffness PWV (m/s) 8.1±1.5 > 7.2±1.2 < 7.8±1.
4 central BP 125±19 127±20 124±12
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Vitamin D levels by Ethnic group & regression results for PWV
Ethnic effect diminished / absentP<0.01 lower
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MRI sub-study
• Randomly selected MRI study
participants (n=47) consisting of 16
Caribbean, 13 Pakistani, and 18
European men
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Regional MR PWV derived from sagittal views
(3 aortic paths - P1P2, P2P3, and P1P3)
• The MR protocol for PWV
measurement used a 1.5-T Philips
Intera scanner to acquire 2
consecutive transverse images:
– One from aortic arch at
level of pulmonary artery
– The other 2cm above the
aortic bifurcation.
P1P1
P2
AV
Bif
P3
P1
P2
AV
Bif
P3
desPWV
arcPWV
P2
P3
Bif
aoP
WV
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Regional PWV profiles across ethnicity.
Age-SBP adjusted mean desPWVMR in SAs was 0.7 m/s (0.3 m/s) and 0.8 m/s (0.3 m/s) greater than in AfCs and Europeans, respectively
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Are the larger sample PWV data by Arteriograph replicated by MR?
Hypertension – Aug 2011
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Summary
• Consistent with CVD risk among UK Caribbean, South
Asian and Europeans…
– SA men had higher (descending) aPWV, despite slightly
lower distending BPs, using a single point arm based
device (calibrated via MR)
– These changes were confirmed on an MR imaged sub-
sample
– Plasma vitamin D levels are related to aPWV & account
for much of the ethnic difference in aPWV
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THANK YOU
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Abdominal aorta (bifurcation)
Aortic arch1
2
3
1 2
3
Abdominal aorta (bifurcation)
Aortic arch1
2
1
2
33
1 2
3
Flow curves from 3 sections(Transit time derived from P1P2, P2P3 and P1P3)
-35-30-25-20-15-10-505
101520253035404550556065707580859095
100105110115120125130135140145150155160165170175180185190195200205210215220225230235240
Asce Aorta flow [ml/s]
Desc Aort flow [ml/s]
Above Bifurc. Flex Coil flow [ml/s]1
2
3
-35-30-25-20-15-10-505
101520253035404550556065707580859095
100105110115120125130135140145150155160165170175180185190195200205210215220225230235240
Asce Aorta flow [ml/s]
Desc Aort flow [ml/s]
Above Bifurc. Flex Coil flow [ml/s]1
2
3
Arrival times of the aortic pulse waves were computed from the 3 flow-time curves recorded at the 3 points: P1, P2, and P3
10% of the slope of the flow wave from each site
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Multiple regression model: risk factors related to aortic
stiffness = Pulse Wave Velocity (R2=0.36).
B
Per / 1 unit
SE B β Sig.
Constant -0.68 1.02 0.5
Age 0.05 0.01 0.35 <0.001 SBP 0.02 0.01 0.26 <0.001 HR 0.02 0.01 0.17 0.01
Diabetes 0.63 0.28 0.16 0.02 LDL/HDL Ratio 0.10 0.11 0.06 0.34
Smoking 0.31 0.17 0.11 0.07 Sth Asian # 0.73 0.23 0.25 0.001 European # 0.57 0.21 0.19 0.008
# vsAf C’beans
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Abdominal aorta (bifurcation)
Aortic arch1
2
3
1 2
3
Making PWV measures by MRI