Making measurements from a left ventricular M-mode. Making measurements from a left ventricular M-mode. Right parasternal short-axis view of the left ventricle at the level of the chordae tendinae, used to obtain a left ventricular M-mode. IVSd Interventricular septal diameter in diastole, IVSs Interventricular septal diameter in systole, LVFWd Left ventricular free wall diameter in diastole, LVFWs Left ventricular free wall diameter in systole, LVIDd Left ventricular internal diameter in diastole, LVIDs Left ventricular internal diameter in systole, FS per cent Fractional shortening Nuala Summerfield In Practice 2018;40:7-11 Copyright © British Veterinary Association. All rights reserved.