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Early diastolic left ventricular (LV) untwisting has been evaluated as a manifestation of LV recoil, reflecting the release of elastic energy stored during systole. The primary goal of this study was to characterize the relationship between systolic strain (e.g., circumferential strain and the shear strains that comprise twist) with the resulting early diastolic shear strain rates, including the rate of untwisting. A further goal was to characterize these relationships regionally from apical to basal locations. Cardiac magnetic resonance imaging tissue tagging was used to measure circumferential strain, global and regional (apex, mid, basal) twist ([theta]), and circumferential-longitudinal ([[member].sub.CL]) and circumferential-radial ([[member of].sub.CR]) shear strains along with the corresponding untwisting rates (d[theta]/dt and diastolic shear strain rates (d[member of]/dt in 32 healthy males (33 [+ or -] 7 yr). LV untwisting rates and shear strain rates measured during early diastole varied significantly with the measurement location from apex to base (P < 0.001) but demonstrated significant linear correlation with their corresponding preceding systolic strains (P < 0.001). Untwisting rates and diastolic shear strain rates were not significantly correlated with circumferential systolic strain or endsystolic volume (P > 0.05). Normalization of the untwisting rates to the peak twist (d[theta]/[dt.sub.Norm] = -13.6 [+ or -] 2.1 [s.sup.-1]) or shear strain rates to peak systolic shear strain (d[[member of].sub.CL]/[dt.sub.Norm] = -15.0 [+ or -] 5.4 [s.sup.-1], and d[[member of].sub.CR]/[dt.sub.Norm] = -14.2 [+ or -] 7.7 [s.sup.-1]) yielded a uniform measure of early diastolic function that was similar for all shear strain and twist components and for all locations from apex to base. These findings support a linear model of torsional recoil in the healthy heart, where diastolic shear strain rates (e.g., untwisting rates) are linearly related to the corresponding preceding systolic shear stain component. Furthermore, these findings suggest that torsional recoil is uncoupled from end-systolic volumes or the associated strains, such as circumferential strain. relaxation; torsion; untwisting doi: 10.1152/ajpheart.00353.2010.

Left ventricular (LV) active relaxation begins before aortic valve closure and is largely completed during isovolumic relaxation (IVR), before mitral valve opening. During IVR, despite closed mitral and aortic valves, indirect assessments of LV volume have suggested volume increases during this period. The aim of this study is to measure LV volume throughout IVR and to determine the sources of any volume changes. For 10 healthy individuals (26.0 [+ or -] 3.8 yr), magnetic resonance imaging was used to measure time courses of LV volume, principal myocardial strains (circumferential, longitudinal, radial), and LV twist. Mitral leaflet motion was observed using echocardiography. During IVR, LV volume measurements showed an apparent increase of 4.6 [+ or -] 1.5 ml (5.0 [+ or -] 2.0% of the early filling volume change), the LV untwisted by 4.5 [+ or -] 1.9[degrees] (36.6 [+ or -] 18.0% of peak systolic twist), and changes in circumferential, longitudinal, and radial strains were +0.87 [+ or -] 0.64%, +0.93 [+ or -] 0.57%, and - 1.46 [+ or -] 1.66% (4.2 [+ or -] 3.3%, 5.9 [+ or -] 3.3%, and 5.3 [+ or -] 7.5% of peak systolic strains), respectively. The apparent changes in volume correlated (P < 0.01) with changes in circumferential, longitudinal, and radial strains (r = 0.86, 0.69, and -0.37, respectively) and untwisting (r = 0.83). The closed mitral valve leaflets were observed to descend into the LV throughout IVR in all subjects in apical four- and three-chamber and parasternal long-axis views by 6.0 [+ or -] 3.3, 5.1 [+ or -] 2.4, and 2.1 [+ or -] 5.0 mm, respectively. In conclusion, LV relaxation during IVR is associated with changes in principal strains and untwisting, which are all correlated with an apparent increase in LV volume. Since closed mitral and aortic valves ensure true isovolumic conditions, the apparent volume change likely reflects expansion of the LV myocardium and the inward bowing of the closed mitral leaflets toward the LV interior. diastolic function; active relaxation; mitral valve leaflets doi: 10.1152/ajpheart.00131.2010.

Left ventricular (LV) systolic function increases with passive heat stress (HS); however, less is known about diastolic function. Eight healthy subjects (24.0 [+ or -] 2.0 yr of age) underwent whole body passive heating 1[degrees]C above baseline (BL). Cardiac magnetic resonance imaging was used to measure biventricular volumes, function, filling velocities, volumetric flow rates, and LV twist and strain at BL and after 45 min of HS. Passive heating reduced left atrial volume (-17.6 [+ or -] 11.7 ml, P < 0.05), right and LV end-diastolic volumes (-22.7 [+ or -] 11.0 and -25.7 [+ or -] 24.9 ml, respectively; P < 0.05), and LV stroke volume (-6.7 [+ or -] 6.8 ml, P < 0.05) from BL. LV ejection fraction (EF), end-systolic elastance, septal and lateral mitral annular systolic velocities, circurnferential strain, and peak LV twist increased with HS (P < 0.05). Right ventricular stroke volume, EF, and systolic tissue velocities were unchanged with HS (P > 0.05). Early LV diastolic tissue and blood velocities and strain rates were maintained with HS, whereas untwisting rate increased significantly from 166.4 [+ or -] 46.9 to 268.7 [+ or -] 76.8[degrees]/s (P < 0.05). The major novel finding of this study was that, secondary to an increase in peak LV twist and untwisting rate, early diastolic blood and tissue velocities and strain rates are maintained despite a reduction in filling pressure. hyperthermia; cardiac magnetic resonance imaging; biventricular function doi:10.1152/ajpheart.00987.2009

Purpose Conventional calculation of myocardial strain requires tissue-tracking. A surrogate for strain called global fractional shortening (GFS) is proposed based on changes in dimensions of endocardial and epicardial surfaces without tissue-tracking. Methods Three-dimensional endocardial and epicardial left ventricular surfaces traced at end-diastole and end-systole using conventional steady-state free precession cine images were used to calculate GFScc (circumferential), GFSll (longitudinal), and GFSrr (radial) using fractional length changes in each direction over the heart surface. GFS values were validated using finite element models (FEM) and in vivo using tagging-derived strains ( εcc,εll,εrr) in patients with a wide range of ejection fraction (EF) and diagnosis (n = 32). GFS was also measured in 31 patients with Fabry disease and matched healthy controls. Results GFS values were within 3% of average FEM-derived Lagrangian strains and had good agreement in vivo ( GFScc = −14 ± 4%, εcc = −14 ± 4%, R2 = 0.85; GFSll = −12 ± 4%, εll = −12 ± 4%, R2 = 0.72; GFSrr = 46 ± 21%). εrr could not be measured reliably from tagging. Compared with healthy controls with matched EF, patients with Fabry disease had significantly increased GFScc (Endo) (−28 ± 3% versus −25 ± 2%), decreased GFScc(Epi) (−10 ± 2% versus −11 ± 2%) and decreased GFSll for all components. Conclusion GFS yields similar values to conventionally measured strains without requiring tissue-tracking. Compared with controls, patients with Fabry disease have significant differences in several GFS components. Magn Reson Med 73:586-596, 2015. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Although several investigations have demonstrated that prolonged aerobic exercise results in decreased left ventricular (LV) function, few have examined the impact of an acute bout of high-intensity exercise on right ventricular (RV) and LV systolic and diastolic function. Cardiac magnetic resonance imaging with tagging was used to study the impact of high-intensity interval exercise on biventricular function in 9 endurance-trained (ET; Vo(2)max 69 +/- 7 ml/kg/min) and 9 normally active (NA; Vo(2)max 44 +/- 9 ml/kg/min) men. Subjects underwent baseline cardiac magnetic resonance imaging assessments (pre) and then performed an average of 14 1-minute intervals at 97 +/- 11% (NA) and 99 +/- 6% (ET) of peak power output, separated by 2 minutes of recovery at 21 +/- 6% (NA) and 21 +/- 9% (ET) of peak power output. After exercise, 2 cardiac magnetic resonance imaging assessments (post 1 at 6.2 +/- 2.6 minutes and post 2 at 38.4 +/- 3.8 minutes) were completed. RV and LV ejection fractions, twist, basal and apical rotation rates, rate of untwisting, circumferential strain, and timings were examined. No significant change in RV and LV ejection fractions, twist, untwisting rate, or strain after exercise occurred in the NA group. In the ET group, RV ejection fraction (pre 56 +/- 4%, post 1 54 +/- 4%, post 2 54 +/- 3%) and LV ejection fraction (pre 62 +/- 4%, post 1 59 +/- 4%, post 2 58 +/- 4%) were decreased at post 1 and post 2, while untwisting rate, apical rotation rate, and circumferential strain were decreased at post 2 (all p values <0.05). In conclusion, biventricular systolic and diastolic dysfunction occurred after 14 minutes of high-intensity exercise in ET athletes, a phenomenon not observed in NA subjects., (Copyright (c) 2010 Elsevier Inc. All rights reserved.)

Left ventricular (LV) rotation is the dominant deformation during relaxation and links systole with early diastolic recoil. LV torsion and untwisting rates during submaximal exercise were compared between heart transplant recipients (HTRs), young adults and healthy older individuals to better understand impaired diastolic function in HTRs. Two dimensional and colour M-mode echocardiography with speckle-tracking analysis were completed in eight HTRs (age: 61 +/- 9 years), six recipient age-matched (RM, age: 60 +/- 11 years), and five donor age-matched (DM, age: 35 +/- 8 years) individuals (all males) at rest and during submaximal cycle exercise. LV peak torsion, peak rate of untwisting and peak intraventricular pressure gradients (IVPGs) were examined. LV torsion increased with exercise in DMs (6.5 +/- 5.6 deg, P < 0.05), but not in RMs (-2.6 +/- 7.0 deg) or HTRs (-0.9 +/- 4.4 deg). The change from rest to exercise in the peak rate of untwisting was significantly greater for DMs (-2.1 +/- 0.5 rads s(-1), P < 0.05) compared to RMs (-0.7 +/- 1.3 rads s(-1)) and HTRs (-0.2 +/- 0.9 rads s(-1)). The amount of untwisting occurring prior to mitral valve opening substantially declined with exercise in RMs and HTRs only. The change in IVPGs was 1.3-fold greater in DMs versus HTRs or RMs (P > 0.05). Peak LV torsion and untwisting are blunted during exercise in HTRs and RMs compared to DMs. These factors may contribute to the impaired diastolic filling found in HTRs during exercise. Similarities between HTRs and RMs during exercise suggest functional accelerated ageing of the cardiac allograft.