Noninvasive Hemodynamic Measurements

Abstract

It has been well established that effective blood pressure (BP) lowering, using various antihypertensive agents with different mechanisms of action, lowers the risk for cardiovascular morbidity and mortality.1–4 However, when hypertensive populations are partitioned into subgroups by race, sex, geography, and age, differences in BP responses to single antihypertensive drugs emerge, albeit at the group level, that have been used to guide therapy for individuals within these contrasted groups.1,5,6 With respect to race, perhaps the most widely used group characteristic used to guide individual therapy, we5 and Sehgal6 have argued that the observed racial differences in BP response overlap to such a large degree that, by far, the greatest source of variation in BP response is within rather than between groups. This observation renders the use of group characteristics as grossly suboptimal criterion on which to base therapy for all individuals of a group. The inaccuracy of blanket extrapolation of group characteristics to predict BP responses for individuals is also likely to be true for traits such as geographic residence, age, and sex. Thus, the findings reported by Smith et al7 in this issue of Hypertension were very encouraging. These investigators showed that consideration of hemodynamic parameters, as determined noninvasively by impedance cardiography (IC) (BioZ, Cardiodynamics), in the selection of antihypertensive therapy in primary care practice settings improved rates of BP control and normalization of selected hemodynamic parameters in drug-treated hypertensives with BP >140/90 mm Hg. They …