Imaging Endothelial Function Andre Dejam. Endothelial Function.

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