Imaging Endothelial Function Andre Dejam
Endothelial Function
Endothelial Dysfunction endothelial dysfunction Birth genetic and intrauterine factors Age (years) Early DiagnosisDiagnosis Therapy atherothrombosis Environmental factors and risk factors
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 Resting Cuff deflation MeasurementGTN 5 min after 60 s 10 minafter 4 min Cuff inflation Measurement GTN Dilatation ( % ) 0 - Ischemia Flow mediated dilation - Protocol -
NO F low- M ediated- D ilation reactive hyperemia Ischämie MakroMikro Brachial artery FMD
What is the Diameter of the Brachial Artery - FMD -
7.5 MHz 15 MHz same individual, same location Comparison of Ultrasound Transducers 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 Conduitarteries mm Resistance vessels µm Capillaries 1-8 µm Duplexsonography VOPShaevitz- Transformator Veins mm
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 PET-scanning UltrasoundMRI Coronary angiography
Measurement of Coronary Blood Flow
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
eNOS NO 1 NOHb MetHb + NO 3 - SNO-Hb 2 3 NO + RSH RSNO + O 2 - OONO - NO OH + ½O 2 + H 2 O 2 NO 2 - HONO NO 3 - OONO - Transport and Storage of NO Bioactivity in Blood