Seasonal variation in blood pressure (BP) has been described in some people, although the variation is small for both systolic and diastolic BPs. The aim of this study was to elucidate underlying haemodynamic and hormonal mechanisms that may occur to defend seasonal changes in BP. Participants were 27 men and 7 women with either normal BP or early hypertension. Measurements of haemodynamics (cardiac output by dual-gas rebreathing) and hormones (resting catecholamines, renin activity, and aldosterone by radioenzymatic assay or radioimmunoassay) were performed during the summer, fall, winter, and spring seasons. Student's paired t-test with Bonferroni modification and regression analyses were used to examine the data with a significance level of Po0.05. Systolic and diastolic BP remained relatively constant across seasons. Cardiac output and stroke volume significantly decreased 10 and 15%, respectively, from summer to winter, whereas heart rate and systemic vascular resistance significantly increased 5 and 11%, respectively. Plasma aldosterone (PA) significantly increased 59% from summer to winter, whereas plasma norepinephrine (PNE), plasma epinephrine, and plasma renin activity (PRA) increased 19, 2, and 17%, respectively (pNS for each). Across the four seasons, mean arterial pressure significantly correlated with PRA and PA, whereas systemic vascular resistance significantly correlated with PNE and PRA. There are dramatic counterregulatory haemodynamic and hormonal adaptations to maintain a relatively constant BP. Norepinephrine, PRA, and aldosterone have a function in mediating the changes in haemodynamics.
Objectives: To compare the effect of fixed-dose combinations (FiDC) versus free-dose combinations (FrDC) in hypertensive patients, in terms of reduction of blood pressure (BP) values and achievement of BP goals.Design and Method: Longitudinal retrospective cohort study in patients attended at our Hypertension Unit from january 2006 until september 2009. All consecutive hypertensive patients treated with monotherapy, who did not achieve BP goals, were included in the study. A second farmacological agent according to usual clinical practice was added in the initial visit with evaluation one year later.
Results:We included 169 hypertensive patients on monotherapy (90 men, 53,3 %, median age 57,7 years) and a BMI of 30,2 kg/m2. 84 patients initiated a second antiypertensive agent on a free basis, the resting 85 patients received a fixed-dosed combination. There were no statistically significant differences in age or initial office BP. The most prevalent combination strategies in both groups were ACEI/diuretics and ARB/ diuretics, accounting for almost 90 % of the combination treatment (86 % in the FrDC versus 94 % in the FiDC-group). In the FiDC-group arterial BP was reduced from initially 149/85 to 128/75 mmHg, in the FrDC-group from 147/84 to 134/77 mmHg. Differences between intitial and final systolic (20.6 vs. 12.2, p ¼ 0.001) and diastolic (10.1 vs. 6.8, p ¼ 0.029) BP were significantly greater in the FiDC than in the FrDC-group. The proportion of patients achieving blood pressure goals in the FiDC-group was significantly greater (88 %) than the corresponding proportion in the FrCD-group (69 %, p < 0,01). There were no statistical differences between groups in the number of antihypertensive drugs (2.12 FrDC versus 2.22 FiDC).
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