Should a FixedExternal Reference System BeUsed toAnalyze LeftVentricular WallMotion

SUMMARY Toinvestigate whether a fixed external reference system should be used to most accuratelydescriberegional left ventricularwall motion,we used vectorsto analyze a simplemodelofventricular contrac- tion. Ifmeasuredin a fixed external reference system, motion ofimplantedradiopaquemidwallmarkers may containtranslational as well as contractile components. Therefore, comparisonsofdifferent reference systems that use markermotionmeasured in a fixedreference system asa standardwill bebiasedunless propercorrec- tions are included. Weconcludethatevidence to datedoes not indicatethatthe use of a fixed reference system is superior to other methods for analyzing regional ventricular wall motion. THE USEof contrast, ventriculography to quantifyleft ventricular segmental wall motionhas resulted inthe development of methods to measure regional endocardial movement. As the methods have prolif- erated, the accuracy ofthese alternative approaches in separating abnormal, from normal wall motion has