Hemodynamic Assessment and Pharmacologic Probes as Tools to Analyze Cardiovascular Reactivity

Abstract

The blood pressure and heart rate responses to a laboratory task are most frequently used to assess an individual’s cardiovascular reactivity. Information from such observation is useful for general categorization and for the delineation of subgroups of hyper- and hyporesponders. Measurement of systemic and regional hemodynamics further complements reactivity studies by providing important information about qualitative differences which are not necessarily reflected in the overall magnitude of the blood pressure response. Hollenberg, Williams, and Adams (1981) engaged patients with borderline hypertension and normotensive control subjects in resolving Ravens progressive matrices. The blood pressure responses to this challenge were similar in both groups, but patients with borderline hypertension had a significant decrease of renal blood flow. This observation, that renal vasculature tends to overrespond to the mental stress, provided important inference as to how behavioral factors might lead to hypertension. As Light, Koepke, Obrist, and Willis (1983) suggest, mental stress might cause excessive salt retention in patients with borderline hypertension. It is not difficult to visualize how sodium retention might lead to hypertension. Another example of the differential behavior of local vasculature was provided by Mark, Lawton, and Abboud (1975). They observed that chronic salt loading does not alter the mean blood pressure in borderline hypertensive and normotensive subjects, but the forearm vascular resistance in normotensive individuals decreased whereas in patients with borderline hypertension it increased.