title: Left ventricular torsion and longitudinal shortening: two fundamental components of myocardial mechanics assessed by tagged cine-MRI in normal subjects.
abstract: Cardiac magnetic resonance imaging (Cardiac MRI) has become a gold standard diagnostic technique for the assessment of cardiac mechanics, allowing the non-invasive calculation of left ventricular long axis longitudinal shortening (LVLS) and absolute myocardial torsion (AMT) between basal and apical left ventricular slices, a movement directly related to the helicoidal anatomic disposition of the myocardial fibers. The aim of this study is to determine AMT and LVLS behaviour and normal values from a group of healthy subjects. A group of 21 healthy volunteers (15 males) (age: 23-55 y.o., mean: 30.7 ± 7.5) were prospectively included in an observational study by cardiac MRI. Left ventricular rotation (degrees) was calculated by custom-made software (Harmonic Phase Flow) in consecutive LV short axis planes tagged cine-MRI sequences. AMT was determined from the difference between basal and apical planes LV rotations. LVLS (%) was determined from the LV longitudinal and horizontal axis cine-MRI images. All the 21 cases studied were interpretable, although in three cases the value of the LV apical rotation could not be determined. The mean rotation of the basal and apical planes at end-systole were -3.71° ± 0.84° and 6.73° ± 1.69° (n:18) respectively, resulting in a LV mean AMT of 10.48° ± 1.63° (n:18). End-systolic mean LVLS was 19.07 ± 2.71%. Cardiac MRI allows for the calculation of AMT and LVLS, fundamental functional components of the ventricular twist mechanics conditioned, in turn, by the anatomical helical layout of the myocardial fibers. These values provide complementary information about systolic ventricular function in relation to the traditional parameters used in daily practice.
authors.affiliation: Cardiac Imaging Unit, Cardiology Department, Hospital de la Santa Creu i Sant Pau, c/Sant Antoni Mª Claret, 167, 08025 Barcelona, Spain. fcarreras@santpau.cat
authors.forename: Francesc
authors.initials: F
authors.lastname: Carreras
authors.forename: Jaume
authors.initials: J
authors.lastname: Garcia-Barnes
authors.forename: Debora
authors.initials: D
authors.lastname: Gil
authors.forename: Sandra
authors.initials: S
authors.lastname: Pujadas
authors.forename: Chi Hion
authors.initials: CH
authors.lastname: Li
authors.forename: Ramon
authors.initials: R
authors.lastname: Suarez-Arias
authors.forename: Ruben
authors.initials: R
authors.lastname: Leta
authors.forename: Xavier
authors.initials: X
authors.lastname: Alomar
authors.forename: Manel
authors.initials: M
authors.lastname: Ballester
authors.forename: Guillem
authors.initials: G
authors.lastname: Pons-Llado
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012016:Reference Values; D013030:Spain; D054159:Torsion, Mechanical; D016277:Ventricular Function, Left; D055815:Young Adult