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Impact de l'ischémie sur les cinétiques cardiaques du Thallium-201 et du Technétium-99m-MIBI : étude sur le modèle de coeur isolé de lapin perfusé par du «sang reconstitué»

Abstract : 201T1 and 99mTc-MIBI are the most widely used myocardial perfusion tracers in clinical tomoscintigraphic imaging (SPECT). They are tracers with a cellular retention and it is not known if metabolic cellular disorders related to ischemia have an impact on their myocardial kinetics, thus, on the clinical information provided by SPECT. The aim of this study was : [1] to adapt on the isolated blood-perfused heart rnodel, a method of analysis of 201T1 and 99mTc-MIBI kinetics across the capillary membrane (co-dilution of a vascular reference tracer) and across the plasma membrane of myocytes (interstitial microdialysis); and [2] to analyse the impact of low-flow ischemia and of post-ischemic stunning on the two tracers kinetics across the capillary and plasma membranes. ln a 1st study, we showed that, for 201TI and 99mTc-MIBI, the myocardial retention fractions were enhanced in ischemia, because of the increase of initial extraction and the decrease of clearance rate of the tracers. These variations of the transcapillary kinetics are mechanically related to the coronary perfusion rate. In a 2nd then a 3rd study, with the use of microdialysis, we calculated the tracers concentration ratio between the lnterstitial and cellular spaces. We showed that low-flow lschemia was associated with a decrease of interstltial transit rate but it does not alter the ability of myocytes to uptake and retain the tracers. Theretore, we can suggest that the clinical information provided by 201TI or 99m--MIBI-SPECT is essentially dependent on coronary perfusion rate, without any major influence of the metabolic disorders associated with ischemia or post-ischemic stunning.
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http://docnum.univ-lorraine.fr/prive/SCD_T_2002_0328_AYALEW.pdf
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https://hal.univ-lorraine.fr/tel-01747033
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Submitted on : Thursday, March 29, 2018 - 10:49:49 AM
Last modification on : Wednesday, October 21, 2020 - 3:23:02 PM

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  • HAL Id : tel-01747033, version 1

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Adey Ayalew. Impact de l'ischémie sur les cinétiques cardiaques du Thallium-201 et du Technétium-99m-MIBI : étude sur le modèle de coeur isolé de lapin perfusé par du «sang reconstitué». Biologie animale. Université Henri Poincaré - Nancy 1, 2002. Français. ⟨NNT : 2002NAN10328⟩. ⟨tel-01747033⟩

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