Effects of rilmenidine on 24-h rhythmicity of blood pressure and spontaneous baroreflex sensitivity in essential hypertensive subjects.
OBJECTIVE
To study the effects of the centrally acting imidazoline-like compound rilmenidine on the circadian and short-term cardiovascular rhythms derived from continuous blood pressure (BP) recordings in patients with mild essential hypertension.


METHODS
This was a single-center, open study. Recordings were obtained from eight subjects, using a Portapres during two 24-h hospitalizations: the first after the inclusion visit and the second 4 weeks after starting rilmenidine treatment (1 or 2 mg/day). For circadian analysis of cardiovascular variables, 10 min were selected every hour to obtain 24 periods per subject for each session. Spontaneous baroreflex sensitivity (BRS) was estimated using the sequence technique and the cross-spectral analysis between systolic BP and interbeat intervals.


RESULTS
Rilmenidine significantly reduced the overall systolic and diastolic BP and heart rate (P < 0.001). The effects of rilmenidine on BP and heart rhythm were marked during the daytime. Rilmenidine reduced the low-frequency (LF) component of systolic BP variability throughout the 24 h. The highest values of spontaneous BRS were observed at night. Rilmenidine increased the BRS obtained by the slope of the sequence method throughout the 24-h period (P < 0.001). The LF gain was significantly increased with rilmenidine during the day and the night.


CONCLUSIONS
Rilmenidine may differentially affect the baroreflex-dependent (phasic or reflex) and the baroreflex-independent (tonic) autonomic outflow. The 24-h approach reinforced this concept, since indexes of BRS were increased throughout the 24-h period while BP was reduced during the daytime.
Finta
Ervin
E
Department of Internal Medicine, Szent Imre Hospital, Budapest, Hungary.
Laude
Dominique
D
Alföldi
Sándor
S
Farsang
Csaba
C
Elghozi
Jean-Luc
JL
D000328:Adult; D000704:Analysis of Variance; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D017704:Baroreflex / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects*; D002940:Circadian Rhythm / Q000187:drug effects*; D015986:Confounding Factors, Epidemiologic; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000453:epidemiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010080:Oxazoles / Q000627:therapeutic use*; D000077769:Rilmenidine; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome
D000959:Antihypertensive Agents; D010080:Oxazoles; D000077769:Rilmenidine