DIURNAL BLOOD-PRESSURE VARIABILITY IN ESSENTIAL-HYPERTENSION AND VASCULAR REACTIVITY TO ISOMETRIC STRESS

The present study was designed to assess the hemodynamic conditions, b y means of impedance cardiography methods, and the relation existing b etween vascular reactivity to isometric stress (isometric handgrip tes t) and the day/night blood pressure variations, estimated by ABPM. Fif ty unselected untreated non-obese EEH adult subjects (WHO class I) wit h a duration of disease not exceeding 3 years were classified as dippe rs or non-dippers according to commonly accepted criteria. Twenty thre e normotensive volunteers acted as controls. SEP, DBP, HR, CI and SVRI were assessed at rest and after IHG test. At rest dippers, non-dipper s and controls showed comparable CI. SVRI were more enhanced in EEH th an in controls and, although not significantly, in non-dippers than in dippers. During IHG all subjects showed a significant rise of SEP, DB P and HR; CI variations were of comparable size in all groups while SV RI increases were not. Non-dippers showed a significant SVRI rise afte r IHG in comparison with resting values. In dippers and in controls SV RI increment was insignificantly different in comparison with resting values. Non-dippers showed a closest correlation between BP and SVRI r ise during IHG while dippers showed a less consistent-association. In conclusion, our data suggest that in adults with short duration EEH th e existence of non-dipper condition may be unrelated to myocardial hyp ertrophy. Blunted nocturnal BP fall is associated with vascular hyper- reactivity revealed by a bigger elevation of SVRI during IHG. These da ta suggest that EEH individuals may have a different proneness to beco me non-dippers and that vascular reactivity to stress may have a patho physiological role in the natural history of EEH.