title: A new method for quantification of left ventricular systolic function using a corrected ejection fraction.
abstract: OBJECTIVE
  Left ventricular ejection fraction (EF) is a suboptimal measure of ventricular function. Recent mathematical modelling of left ventricular contraction has shown that the EF is determined by both myocardial shortening (strain) and by end-diastolic wall thickness. Increasing end-diastolic wall thickness resulted in augmented radial wall thickening. This may result in a significant 'overestimation' of ventricular systolic function as assessed by the EF. This study proposes a new measure of ventricular systolic function, the corrected EF (EF(c)) to allow for the presence of concentric left ventricular hypertrophy (LVH).
  
  
  RESULTS
  The study uses a new two-layer, three-dimensional mathematical model of ventricular contraction. Changes in end-diastolic wall thickness in addition to long-axis and mid-wall circumferential strain were modelled. Iso-strain lines were obtained where myocardial shortening (strain) is constant; EF increases with increasing end-diastolic wall thickness. The corrected EF is determined by following the iso-strain lines to the equivalent EF in the absence of hypertrophy (e.g. 9 mm thickness). For example, an individual with a mean end-diastolic wall thickness of 20 mm and measured EF of 60% has a corrected EF (EF(c)) of 37%.
  
  
  CONCLUSIONS
  The study shows that the EF is determined by absolute wall thickening and provides a nomogram for comparing EF when LVH is present. The EF(c) is a potential new measure of left ventricular systolic function. Its possible role will need validating in mortality trials.
authors.affiliation: Department of Cardiology, Taunton & Somerset Hospital, Musgrove Park, Taunton, TA1 5DA, UK. david.maciver@tst.nhs.uk
authors.forename: David H
authors.initials: DH
authors.lastname: Maciver
mesh_terms: D054143:Heart Failure, Systolic / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000175:diagnosis / Q000503:physiopathology*; D008953:Models, Anatomic; D008962:Models, Theoretical; D012680:Sensitivity and Specificity; D013318:Stroke Volume; D016277:Ventricular Function, Left / Q000502:physiology