NONINVASIVE ASSESSMENT OF BAROREFLEX CONTROL IN BORDERLINE HYPERTENSION - COMPARISON WITH THE PHENYLEPHRINE METHOD

In this study, we examined the sensitivity of two recently developed n oninvasive baroreflex measurement techniques to assess baroreflex cont rol in hypertension. We assessed baroreflex sensitivity noninvasively from covariations of systolic pressure and RR interval using spectral analysis and sequence detection. The non-invasive estimates of baroref lex control were compared with estimates derived from phenylephrine-in duced increases in systolic pressure and RR interval in normotensive s ubjects (n=27) and borderline hypertensive subjects (n=15). Baroreflex sensitivity was significantly reduced in the borderline hypertensive group relative to the normotensive group when assessed with the use of either the non-invasive or invasive methods to index baroreflex contr ol. In addition, estimates obtained from the non-invasive methods were significantly correlated with baroreflex sensitivity assessed with th e phenylephrine method (spectral: r=.48, P <.001; sequence: r=.50, P < .001). These findings suggest that spectral analysis and the sequence method provide viable alternatives to the pharmacological approach for estimation of baroreflex sensitivity in hypertension.