LAUSR

PURPOSE To investigate the characteristics of left ventricular multidirectional strain during different stages of heart dysfunction and the possible morphological basis in spontaneously hypertensive rats (SHR). MATERIALS AND METHODS SHRs and Wistar-Kioto (WKY) rats (control group) were randomly divided into cages and observed for 3-25 months. Conventional echocardiographic measurements, myocardial strain, LV+dp/dtmax and LVEDP, and histological collagen volume fraction (CVF) were observed in all rats. RESULTS According to LVEF and LVEDP, SHRs were divided into Normal cardiac function group (group A), Diastolic dysfunction group (group B1), and Systolic dysfunction group (group B2). In group A, myocardial strain and CVF showed no difference compared to the control group. In group B1, global longitudinal strain(GLS) and endocardial longitudinal strain (SL-endo) were significantly lower than those in group A(P < 0.05), global circumferential and radial strain(GCS,GRS) had no difference but a decreasing trend in SC-endo (P > 0.05), while CVF-endo was significantly increased(P < 0.05). In group B2, global and layer-specific strain decreased significantly, along with the increased CVF-endo and CVF-epi (all P < 0.05). The decrease of GLS and SL-endo were moderately correlated with the increase of CVF-endo. The reduction of LVEF was correlated with the decrease of GCS, SC-endo and GRS, in which the highest correlation was with SC-endo(r=0.65，P<0.01). CONCLUSION Pathological myocardial fibrosis associated with hypertension develops from the inner to outer layer of myocardium, which is coincident with the impairment of myocardial multi-directional deformation, where longitudinal strain is involved firstly and LVEF declines when all directions of strain are reduced.