Post on 01-Apr-2015
transcript
Imaging Endothelial Function
Imaging Endothelial Function
Andre DejamAndre Dejam
Endothelial Function
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Endothelial Dysfunction
10 20 30 40 50 60 70
endothelial dysfunction
Birth
geneticandintrauterinefactors
Age(years)
Early Diagnosis Diagnosis Therapy
atherothrombosis
Environmental factors and risk factors
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Imaging The Natural History of Atherosclerosis
IMT(structural)
FMD or Acetylcholine-mediated Dilation(functional)
stiffness(functional/structural)
Atherothrombosis
FMD- set up -
- longitudinal segment of the
brachial artery
- ~ 5 cm proximal of the
antecubital fossa
- anatomical landmarks
(Faszia, veins, arterial branches)
Brachial artery
Imaging the Brachial artery - location -
Time
Res
ting
Cuf
f def
latio
n
Mea
sure
men
t
GT
N
5 min after 60 s 10 min after 4 min
Cuf
f inf
latio
n
Mea
sure
men
t G
TN
Dila
tatio
n (
% )
0 -
Ischemia
Flow mediated dilation- Protocol -
NO
F low-M ediated-D ilation
reactive hyperemia
Ischämie
Makro Mikro
Brachial artery
FMD
What is the Diameter of the Brachial Artery - FMD -
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7.5 MHz 15 MHz
same individual, same location
Comparison of Ultrasound Transducers - 7.5 Mhz vs 15 Mhz -
good bad
Image Quality- An Important Contributor to Variability -
Imaging- Unclear Vessel Boundaries -
Nitric Oxide Dependence of FMD
FMD Decreases with Atherosclerotic Risk
Predictive value of FMD- Older Population -
Predictive value of FMD- Younger Population with no apparent CAD -
Clinical Measurement of Endothelial Dysfunction
Conduitarteries4 - 5 mm
Resistance vessels100-300 µm
Capillaries1-8 µm
Duplexsonography VOP Shaevitz-Transformator
Veins2 - 4 mm
Magnetic Resonance Angiography
Magnetic Resonance Angiography
Brachial Artery a Surrogate for Coronary arteries?
- Differences in microvascular architecture
- Pattern of blood flow and vascular resistance
- Metabolic regulation
- Receptor distribution of humeral regulation
- Stimuli for hyperemia
- Sympathetic innervation
Measurement of Coronary Blood Flow
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PET-scanning
UltrasoundMRI
Coronary angiography
Measurement of Coronary Blood Flow
Transthoracic Echocardiography
Transthoracic Echocardiography
Transthoracic Echocardiography
Transthoracic Echocardiography
Summary
- Endothelium plays a pivotal role in vascular homeostasis
- Endothelial function can be measured invasively or non- invasively
- Possible marker of early atherothrombosis
eNOSNO
1
NO
NOHb
MetHb + NO3-
SNO-Hb
2
3
NO
+ RSH
RSNO
+ O2-
OONO- NO2-+ OH
+ ½O2
+ H2O2
NO2-
HONO
NO3-OONO-
Transport and Storage of NO Bioactivity in Blood