Left ventricular torsion shear angle volume analysis in patients with hypertension: a global approach for LV diastolic function

Abstract

BackgroundTorsion shear angle φ is an important measure of left ventricular (LV) systolic and diastolic functions. Here we provide a novel index utilizing LV normalized torsion shear angle volume loop to assess LV diastolic functional properties. We defined the area within loop as torsion hysteresis area, and hypothesized that it may be an important global parameter of diastolic function. We evaluated the changes to increased during early diastole as a potential measure of LV suction.MethodsSixty resistant hypertension patients (HTN), forty control volunteers were studied using cardiovascular magnetic resonance with tissue tagging. Volumetric and torsional parameters were evaluated.ResultsHTN demonstrated concentric remodeling with preserved ejection fraction. HTN had significantly decreased normalized early filling rate, early diastolic mitral annulus velocity and E/A (1.33 ± 1.13 vs. 2.19 ± 1.07, P < 0.0001) vs. control. Torsion hysteresis area was greater (0.11 ± 0.07 vs. 0.079 ± 0.045, P < 0.001) and peak at early diastole was higher (10.46 ± 8.51 vs. 6.29 ± 3.85, P = 0.002) than control. Torsion hysteresis area was significantly correlated with E/A (r = −0.23, P = 0.025). Thirteen HTN patients had both E/A ratio < 1.12 (Control mean E/A-1SD) and torsion hysteresis area > 0.12 (Control mean torsion hysteresis area + 1SD).ConclusionsTorsion hysteresis area and peak early diastolic were significantly increased in hypertensive concentric remodeling. The loop takes into account the active and passive recoil processes of LV diastolic and systolic phases, therefore provides a new global description of LV diastolic function.

Left Ventricular Torsion Shear Angle Volume Approach for Non-Invasive Evaluation of Diastolic Dysfunction in Preserved Ejection Fraction

“…9 We previously proposed a novel CMR approach to assess LVDD; it utilizes normalized LV torsion shear angle volume (normalized φ is indicated as φ 0 , and normalized LV volume is indicated as V 0 ). 10 We found that the ratio of φ 0 change to increase in V 0 during early diastolic phase (Àdφ 0 /dV 0 ) was significantly increased in the hypertensive cohort, indicating reduced LV filling to the same changes of untwist when compared with the control cohort. 10 Here we sought to evaluate the relationship of CMR-obtained Àdφ 0 / dV 0 index to high-fidelity invasively measured markers of LV diastolic function in clinically stable patients with preserved LVEF and assess diagnostic accuracy in identifying invasively proved LVDD.…”

“…LV volumes in the present study cohort were in the normal range, 33 and LV volumes seemed not to play any role in the Àdφ 0 /dV 0 increase in our previous study. 10 Additional studies incorporating pressure and volume overload condition on Àdφ 0 /dV 0 can further elucidate this mechanism. Our participant cohort represents a particularly challenging patient population who frequently present with heart failure risk factors and limited signs and symptoms suggesting LVDD.…”

“…The CMR parameters were slice thickness of the imaging planes 8 mm with 0 interslice gap, field of view 40 cm, scan matrix 2569128, flip angle 45°, repetition/echo times 3.8/1.6 milliseconds, and number of reconstructed cardiac phases 20. Tagged CMR was done at baseline and post-NTG on exact slice prescriptions as above by applying grid tagging to the short-axis views and stripe tagging to long-axis views using spatial modulation of magnetization encoding gradients method as previously described 10,13 with the following parameters: prospective ECG triggering, repetition/echo times 8.0/4.2 milliseconds, views per segment 8 to 10, tag spacing 7 mm, and number of reconstructed cardiac phases 20. Because the tag lines faded with time due to T1 relaxation, tagged image-derived parameters were valid only throughout systole and the first 67% of diastole.…”

“…Peak twist rate and peak diastolic untwist rate were measured. 10 Peak twist per length at end systole and peak untwist per length rate were then calculated by dividing the peak end-systolic twist and peak untwist by the distance between the apical and basal slices at end diastole. 9,19 Torsion shear angle φ(t) at timeframe t was computed as 9,20 :…”

A graph theoretic approach for computing 3D+time biventricular cardiac strain from tagged MRI data

“…The myocardium in both ventricles was segmented using endocardial and epicardial contours constructed with a dual-contour propagation technique developed by our group (Feng et al, 2009; Zha et al, 2015) and used in several clinical studies (Ahmed et al, 2012a; Pat et al, 2010b; Gupta et al, 2015; Ahmed et al, 2010; Dillon et al, 2012; Schiros et al, 2014, 2012; Ahmed et al, 2012b). This technique uses manually-drawn contours in time frames near end-diastole (ED) and end-systole (ES) to automatically propagate contours to all remaining time frames using non-rigid registration.…”