Coronary steal Revealing the diagnosis with quant

Authors: Mechteld Heijne Pieter G Raijmakers Hendrik J Harms Mark Lubberink Rick Halbmeijer Yolande E Appelman Paul Knaapen

Publish Date: 2010/07/07

Volume: 17, Issue: 6, Pages: 1118-1121

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Abstract

3D fusion of the parametric perfusion PET with the RCA derived from the CTCA during rest left and vasodilation right with corresponding colorscale of absolute perfusion ranging from 0 to 10 expressed in mL/minute/g of perfusable tissue The PET/CT stress images reveal a small perfusion defect during rest which expands to the inferior inferoseptal and inferolateral wall during vasodilationParametric polar map of absolute quantitative myocardial perfusion mL/minute/g of perfusable tissue at rest right upper quadrant stress left upper quadrant and flow reserve left lower quadrant A decreased flow reserve is displayed in inferior inferolateral and inferoseptal wall with according quantitative parametersDuring stress testing with vasodilators such as adenosine or dipyridamol generally a condition of luxury perfusion occurs ie vasomotor autoregulation is abolished and perfusion exceeds metabolic demand Consequently ischemia is not routinely observed during administration of these agents The principle to detect a flow limiting coronary stenosis is based on the relative impairment to increase perfusion during maximum vasodilation in comparison with myocardium subtended by a nonstenotic reference vessel irrespective of the myocardial metabolic demand at the time of the vasodilation study In the currently described patient however transmural ischemia was induced by adenosine which could not be attributed to increased metabolic demand as the ratepressure product remained stable during the stress study Instead maximum vasodilation induced a coronary steal syndrome of collateraldependent myocardium Studies have demonstrated that coronary collaterals are preexisting channels consisting of interconnecting anastomotic vessels IAVs rather than being actively formed1 During circumstances of a critical coronary stenosis or occlusion a pressure drop is created in the IAVs which cause dilatation of the IAVs and thereby induce a collateral circulation Under hyperemic conditions due to vasodilatoragents or exercise resistance in the normal coronary artery falls resulting in augmented perfusion in areas without a stenosis and a reduced collateral flow to the stenotic or occluded artery segment Since vasodilation in the latter area is already maximal coronary perfusion actually decreases in collateraldependent myocardium24 Although data are limited coronary steal may occur in as many as 10 of patients with coronary artery disease during pharmacological stress56In routine clinical practice however this phenomenon is not easily detected as a reduction in absolute levels of perfusion in the collateraldependent myocardium during vasodilation is a prerequisite to diagnose coronary steal syndrome78 The combination of PET/CT enables to measure absolute quantitative perfusion in combination with visualization of coronary anatomy As illustrated in the current case this new form of hybrid imaging therefore facilitates the identification of collateraldependent myocardium in a noninvasive mannerThis article is published under an open access license Please check the Copyright Information section for details of this license and what reuse is permitted If your intended use exceeds what is permitted by the license or if you are unable to locate the licence and reuse information please contact the Rights and Permissions team

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