Baroreflex sensitivity in essential and secondary hypertension

Baroreceptor reflex regulation has been shown to reset towards a higher blood pressure level and to operate with reduced sensitivity in hypertension. Whether this is secondary to elevated blood pressure or whether it plays a role in the development of hypertension is not known. In addition, only limited data exist on baroreflex sensitivity (BRS) in patients with long-lasting medically treated essential hypertension and in patients who have blood pressure elevation with similar severity, but of different etiology. The purpose of this study was to examine BRS in patients with different severity and forms of chronic, medically treated hypertension. Patients with renovascular hypertension (RVHT, n = 14), severe essential hypertension (SEHT, n = 36) and mild essential hypertension (MEHT, n = 29) as well as healthy age- and sex-matched control subjects were studied. BRS was measured with the phenylephrine method. BRS in the RVHT (3.7 +/- 0.6 ms/mmHg) and SEHT (7.6 +/- 0.8 ms/mmHg) groups did not differ from each other after age, gender and left ventricular mass index were taken into consideration. On the contrary, BRS in the RVHT (p = 0.008) and SEHT (p = 0.016) groups were lower than in the MEHT (8.5 +/- 1.2 ms/mmHg) group. BRS was also significantly reduced in the RVHT (P = 0.004) and SEHT groups (P = 0.006) when compared to the healthy age- and sex-matched controls. BRS in the MEHT group did not differ from the control subjects. In conclusion, BRS was equally impaired in patients wiih renovascular and severe essential hypertension, which was similar in severity but different in etiology. BRS in patients with long-lasting medically treated mild essential hypertension did not differ from the healthy subjects. Our study suggests that baroreflex dysfunction in hypertensive patients is related to the clinical severity of hypertension, rather than its etiology.