597Left ventricular longitudinal contraction abnormality relates to subendocardial fibrosis in hypertensive rat with diastolic dysfunction

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Left ventricular (LV) longitudinal strain (LS) has been proposed as the marker of myocardial dysfunction in heart failure with persevered ejection fraction (HFPEF). However, underlying pathological status has not been fully clarified.Objective: To apply speckle tracking echocardiography (STE) in HFPEF rat and compare myocardial systolic deformation and pathophysiological measurements.Methods; STE was performed in Dahl salt-sensitive rat fed a high-salt (HT-group) or a low-salt diet (Control-group). At 14-weeks of age, LV circumferential strain (CS) and LS were measured using echocardiography system (Vevo2100). Time constant tau was meausred by left ventricular catheterization. Transmural myocardial distributionas of systolic wall stress, fiber angle, and %fibrosis were evaluated.Results: Blood pressure (173±33, 121±12 mm Hg, p<0.01) and LV mass (1.38±1.17, 1.10±0.17g, p<0.001) was significantly higher in HT-group than that in control-group. Subendocardial wall stress significantly correlated with the subendocardial %fibrosis (r=0.78, p<0.01). As shown in table, subendocardial and mid wall stress were higher and subendocardial fibrosis was greater in HT-group than that in control-group. While LVEF and CS did not differ, LS was smaller and tau was greater in HT-group than in control group.Conclusions: Longitudinal contraction abnormality correlated with subendocardial longitudinal fiber layer fibrosis, which reflecting elevated subendocardial wall stress in hypertensive heart with delayed relaxation.

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