الفهرس 
Left Ventricular structure and MechanicsOnly 14 pages are availabe for public view
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Abstract
Several imaging techniques has been developed for evaluation of LV diastolic dysfunction. However there is no single noninvasive method can provides a direct measurement of LV relaxation [124]. Echocardiographic assessment of LV filling using Doppler flow velocity of the LV inflow in conjunction with pulmonary venous (PVs) flow and mitral annulus velocity measurements using DTI have been used to identify patients with LV diastolic dysfunction, all these indices are load-dependent, measuring events that occur after MVO. Accordingly, evaluation of the earlier stages of LV relaxation including LV untwisting has become an important alternative. LV twisting and untwisting play a major role in LV mechanics [197]. LV untwisting process is the result of active and passive mechanisms with about 40 to 70% of LV recoil occur during IVRT, [198], high levels of stored potential energy from the active systolic twist are transformed into kinetic energy [29], adding a passive component to rapid early diastolic untwisting., hence, the evaluation of LV twisting and untwisting especially untwisting during IVRT may provide new pathophysiological insights in diastolic function[29]. A novel non-invasive methods to assess earlier stages of LV relaxation has been developed, 2D-STI has allowed LV untwisting to be evaluated non-invasively.
This study was conducted to assess LV untwisting during IVRT in patients with diastolic dysfunction.
Patients and methods:-
70 patients proved to have diastolic dysfunction, and 25 age and sex matched apparently healthy volunteers as controls were recruited from May of 2017 to October of 2018. The study included patients with diastolic dysfunction with normal EF. Patient suffering from arrhythmia, valvular lesions, history of ischemic heart disease (ECG changes and/or wall motion abnormality), bundle branch block, congenital heart disease, or cardiomyopathies were excluded. All individuals were subjected to full history taking, thorough clinical examination, 12 lead Electrocardiogram, transthoracic echocardiography (TTE), and STI.
TTE was done using a commercially available echo-cardiographic instrument (E9, GE Medical Systems, and Milwaukee, WI). LV end diastolic dimension and volume (LVIDd, and EDV), end systolic dimension and volume (LVID and ESV), fractional shortening (FS), ejection fraction (EF), and septal and posterior wall thickness (IVS and LVPW) were measured. Patients were identified to have diastolic dysfunction according to Doppler mitral flow pattern and DTI as either of the following: Grade 1 or abnormal relaxation pattern (E/A ratio <0.8 , e’<8 cm/s, and E/e’<8), Grade II or pseudo-normalized filling pattern (0.8 <E/A<2, e’<8 cm/s, and E/e’ ratio of 8-14), or Grade III or restrictive filling pattern (E/A >2, e’<8 cm/s , and E/e’>14). from the apical 4 chamber view with the ECG connected to the patient. Using DTI the IVRT was estimated as the interval between the end of S wave and the onset of e’ [124].
STI was used for assessment of LV rotational mechanics through scanning and recording from left para-sternal short axis view of both basal and apical planes to quantify basal and apical LV rotations using the same machine and probe with a probe frequency range 1.7-4.0 MHz at a high frame rate (range 80-110 frame/s). Basal level was identified as the plane showing tips of mitral valve leaflets at its center with full-thickness myocardium surrounding the mitral valve. Apical level was defined just proximal to the level of LV apical luminal obliteration at end-systole. Three consecutive cardiac cycles were digitally saved in a cine-loop format. Off-line analyses was done by an independent echocardiographer who was not involved in the image acquisition. The regions of interest were adjusted to include all myocardial thickness without including the pericardium. The endocardial borders of both basal and short axis planes were manually traced and subsequently tracked by the software. After processing, curves of basal and apical LV rotation, twist, peak untwist velocity (PUTV), UT rate were automatically generated by the software (Excel; Microsoft Corporation, Redmond, WA). The percentage of untwisting (%UT) was defined as (%dpTW - UTMVO), the untwist rate (UT rate) during IVRT was defined as the (%dpTW - UTMVO)/IVRT, where UTMVO is untwisting at MVO and TW is the peak LV twist at end-systole [20].
Statistical analysis: Data were fed to the computer and analyzed using IBM SPSS software package version 20.0. (Armonk, NY: IBM Corp) Qualitative data were described using number and percent. The Kolmogorov-Smirnov test was used to verify the normality of distribution Quantitative data were described using mean, standard deviation. Significance of the obtained results was judged at the 5% level. The used tests were: 1 - Chi-square test, 2 - Fisher’s Exact or Monte Carlo correction, 3 - Student t-test, 4 - Mann Whitney test, 5 - Pearson coefficient, 6 - Spearman coefficient Results:-
Of included subjects there was no significant difference between patients and controls as regard to Sex and age (P≥0.05), Increased prevalence of hypertension and diabetes mellitus (P≤0.001) (table 1), and significantly higher LA diameter (p<.001), and LV walls thickness (P<0.01) among patients. Nonsignificant difference was noted as regard to LVIDd, LVIDs, EDV, ESV, SV, FS and EF between patients and controls. There was a significant difference in transmitral Flow Doppler parameters; E wave (P<0.001), A wave (P<0.02), and E/A ratio (P<0.001), and DTI derived e’ velocity (P<0.001), a’ velocity (P<0.001), e’/a’ (P<0.001) and E/e’ (P <0.001 respectively). Weak but statistically significant longer IVRT (P <0.044). Patients had a significantly higher apical rotation (14.23 ± 6.47 vs. 8.12 ± 4, P <0.01), Tw (18.99 ± 6.52 vs. 11.32 ± 3.75, P <0.001), and PUTV (-113.1 ± 40.15 vs. -98.7 ± 24.39, P ≤0.02), nonsignificant difference in basal rotation (P>0.05). The %UT (0.27± 0.08 vs. 0.47 ± 0.06, P ≤0.001) and UT rate (0.37 ± 0.11 vs. 0.67 ± 0.10, p ≤0.001) were significantly reduced among patients compared controls. Both of the %UT and UT rate were inversely correlating with LV wall thickness, Tw, age, and the presence DM and/or hypertension (p<0.05). The UT rate was positively correlating with e’ velocity and IVRT. The %UT and UT rate showed no correlation with E, A, E/A ratio, a’, and E/e’ ratio, PUTV, LV apical rotation and LV basal rotation among all patients (p>0.05 for all).