The evolution of diastolic dysfunction in the hypertensive disease

Abstract

To investigate the effects of cardiac remodelling on left ventricular (LV) diastolic function, as evaluated by tissue Doppler and blood-pool indices, with respect to loading as expressed by wall stress. Cardiac remodelling is the major pathophysiological result of increased blood pressure and manifests as changes in the size, shape, and function of the heart. We evaluated 90 hypertensive patients and 30 healthy volunteers. The hypertensive patients were divided into three groups: (i) HTN-N: normal remodelling (n= 30), (ii) HTN-CR: concentric remodelling (n= 30), and (iii) HTN-CH: concentric hypertrophy (n= 30). Mitral annular early diastolic (Ea) velocities were recorded. Filling pressures (E/Ea), relative wall thickness, LV mass index, DT, isovolumic relaxation time (IVRT), E/A ratio, and longitudinal wall stress (LWS) were also measured. Diastolic dysfunction (DD) was diagnosed based on published criteria. Progressive and increased incidence of DD with advancement of LV remodelling and an increase in LV mass was noted. Wall stress-loading was higher in the HTN-N group and lower in the HTN-CR and HTN-CH groups, despite the more deteriorated diastolic function in the latter groups. DD appeared early, even in the HTN-N group, which had a 36.6% incidence of DD compared to a 13% age-related incidence in the control group (P < 0.05). When the control group was used to define the reference values for septal Ea with the cut-off set as 2SD below the mean, the HTN-N, HTN-CR, and HTN-CH groups had abnormal diastolic function at 16.6, 26.6, and 56.6% incidence rates, respectively. Septal (Ea) was correlated with LVMI (r= -0.55), RWT (r= -0.56), Age (r= -0.52), BMI (r= -0.31), SBP (r= -0.54), PP (r= -0.55), and MAP (r= -0.39), all at P < 0.05. The correlations of blood-pool indices (DT, IVRT, and E/A) with the above parameters were less than that of tissue Doppler imaging (Septal and mean Ea). In a multivariate model, LVMI (beta= -0.25), SBP (beta = -0.26), and age (beta= -0.24) R(2)= 0.49 were found to be independent predictors of DD. DD appears early in hypertensive disease, before the onset of abnormal remodelling or LV hypertrophy. With progression of the remodelling process and the advance of LVH, diastolic function progressively deteriorates. Tissue Doppler indices are better correlated with clinical and echocardiographic parameters of LV remodelling compared to blood-pool indices.