Autonomic nervous system activity in dipper and non dipper essential hypertensives, what about gender differences?

Objectives : 1) To compare the autonomic nervous system activity parameters obtained from a photoplethysmographic recording in dipper and non dipper h ypertensives. 2) To look for an interaction between dipper/non dipper statu s and gender. Methods : Prospective study involving 245 untreated hypertensives (51 +/- 1 3 years, 146 men, 99 women). All of the patients underwent a 24-hour ambula tory blood pressure measurement (ABPM) as well as an echocardiography for l eft: ventricular mass index determination (LVMI) and a photoplethysmographi c recording of blood pressure (BP). Nondippers were defined as those whose nocturnal decrease in systolic BP (SBP) and/or diastolic BP (DBP) was < 10% of daytime BP. Spectral powers were obtained from the photoplethysmographi c recording using a fast Fourier transform over the low frequency band (LF) and the high frequency band (HF). Baroreflex sensitivity (BRS) was evaluat ed by the sequences method. Results : Of the 245 patients, 159 were dippers (98 men, 61 women) and 86 w ere non dippers (48 men and 38 women). Clinic BP was significantly higher i n non dippers than in dippers (168/101 vs 161/98 mmHg; p<0.01 for SEP and p <0.05 for DBP) whereas daytime ABPM and LVMI were not different, whatever t he gender. LF spectral powers were significantly lower in non dippers than in dippers for SEP (respectively 25+/-11% vs 30+/-13%; p<0.01) for DBP (res pectively 35+/-4% vs 41+/-15%; p<0.01) and for HR (respectively 34+/-15% vs 38+/-15%; p=0.03). They showed a positive correlation with the nocturnal S EP fall (r=0.21, p<0.001 for SEP and DBP spectral powers, r=0.19; p<0.005 f or HR spectral power) and with the nocturnal DBP fall, too (r=0.19; p<0.005 for SEP spectral power, r=0.20; p<0.002 for DBP spectral power, r=0.19; p< 0.005 for HR spectral power). HF spectral powers tended to be higher in non dippers than in dippers but in a non significative way. BRS was roughly th e same in dippers and non dippers (7.5+/-2.7 vs 7.0+/-3.1 ms/mmHg, NS). The interaction between non dipper/dipper status and sex was non significant w hatever the LF spectral power. Conclusions : 1) The greater the nocturnal BP fall, the higher the sympathe tic activity indexes. 2) This relationship was found both in males and fema les.