Time-course changes in left ventricular geometry and function during the development of hypertension in Dahl salt-sensitive rats

Serial changes of left Ventricular (LV) geometry and function during the de velopment of hypertension were studied in 50 Dahl salt-resistant (DR) and 8 8 Dahl salt-sensitive (DS) rats fed an 8% NaCl diet beginning at the age of 6 weeks. Echocardiography at 6, 8, 11, 13, 14, 15, and 18 weeks and in viv o invasive hemodynamic determination at 6, 8, 11, 14, and 18 weeks were per formed. After 11 weeks, 33 DS rats were observed for survival analysis. The survival analyses showed that the incidence of death was 57.6% due to hear t failure, 27.3% due to stroke, and 15.2% due to sudden death. However, dea th in the early stages of hypertension was due almost entirely to sudden de ath or stroke. A high value of relative wall thickness (RWT) and a small en d-diastolic dimension were predictive of sudden death and stroke, but LV ma ss (LVM) was not. Concerning the change in LV geometric patterns, LVM conti nued to increase to 18 weeks. The RWT increased or remained at a plateau up to 13 weeks, and then progressively decreased after 13 weeks. In contrast, LV function was hyperdynamic between 8 and 11 weeks when compared to DR ra ts. However, after 13 weeks, all hemodynamic Variables of DS rats deteriora ted progressively, and all DS rats died of heart failure. Thus, our study i ndicates that the cardiovascular events associated with the progression of hypertension vary widely according to the stage of hypertension and that RW T is more sensitive in predicting LV conditions than LVM in hypertension.