Ambulatory blood pressure monitoring and clinical characteristics of the true and white-coat resistant hypertension.

The resistant hypertension has been differentiated in true resistant hypertension and white-coat resistant hypertension by using ambulatory blood pressure monitoring. White-coat resistant hypertension was defined as high clinic blood pressure, despite triple treatment for at least 3 months, but day-time blood pressure values < 135/85 mmHg. The aim of this study was to evaluate the presence of different clinical characteristics between two types of resistant hypertension. The study group consisted of 49 patients with essential hypertension, resistant to an adequate and appropriate triple-drug therapy, that included a diuretic, with all 3 drugs prescribed in near maximal doses and that had persistently elevated clinic blood pressure (> 140/90 mm Hg), for at least 3 months. They represented the 2% of 2500 hypertensive outpatients that referred at our Hypertension Unit. Patients with white-coat resistant hypertension (n=19) were older (p<0.05) than those with true resistant hypertension (n=30). The sodium intake (p<0.05) and alcohol intake (p<0.05) were significantly higher in patients with true resistant hypertension than in those with white-coat resistant hypertension. The renin plasma activity and plasma aldosterone were higher (p<0.05) in patients with true resistant hypertension than in those with white-coat resistant hypertension with normal plasma electrolyte balance. There were no significant differences in mean values of office systolic and diastolic blood pressures between white coat resistant hypertensives and true resistant hypertensives (165+17 vs 172+28 and 98+12 vs 102+14 mmHg). Day-time and night-time ambulatory 24-h-systolic and diastolic blood pressures were significantly higher in the true resistant hypertensive patients when compared with white-coat resistant hypertensives (153+15 vs 124+10 mmHg and 97+9 vs 76+6 mmHg all p<0.001). Day-time and night-time ambulatory 24-h-heart rate were significantly higher in the true resistant hypertensive patients when compared with white-coat resistant hypertensives (79+11 vs 71+9 beats/min; p<0.01; 68+9 vs 60+6 beats/min, p<0.001). The ABP readings were analysed by a Fourier series with 4 harmonics. According to the runs test both two groups of patients showed a circadian rhythm for both systolic and diastolic blood pressure. The nocturnal fall in SBP, DBP and HR was not different in both groups of patients. In conclusion, our findings showed that true resistant hypertensive patients were characterized both by higher heart rate and higher plasma renin activity values as an expression of a possible increased sympathetic activity. Thus, the combination of ABPM with the assessment of the clinical characteristics allow to differentiate better the true drug-resistant hypertension from the white coat resistant hypertension.

Baroreflex control of heart rate is impaired in pre-eclampsia.

Autonomic nervous dysfunction, such as parasympathetic and sympathetic impairment, has been suggested as possible cause of pre-eclampsia, but the studies are not conclusive. Our purpose was to assess non-invasively if pre-eclampsia is associated with a decreased baroreflex function. Nine women with pre-eclampsia (PE), eight normotensive pregnant women, and seven healthy normotensive non-pregnant women were studied. Continuous finger blood pressure was recorded by a Portapres device in the left lateral recumbent position and active standing. Baroreflex gain was evaluated by cross-spectral analysis of systolic blood pressure and pulse interval. The result was that baroreflex gain at rest was lower in pre-eclamptic women both compared to non-pregnant and healthy pregnant subjects (P<0.05). Moreover, a decrease of the baroreflex sensitivity was present in all pregnant women in the orthostatic position (P<0.05). In conclusion pregnancy per se is associated with a decrease in the baroreflex control of the heart, whereas in pre-eclampsia, the baroreflex sensitivity is impaired further.

Blood pressure and heart rate in young thalassemia major patients.

The analysis of blood pressure (BP) and heart rate (HR) variability is currently used to investigate the mechanisms responsible for cardiovascular control; therefore, we assessed whether an impairment of 24-h BP and HR profiles and sympathovagal interaction modulating cardiovascular function was present in patients with thalassemia major (TM) in preclinical phase of heart disease. Nine beta-thalassemic patients 18 years old without clinical signs of cardiac failure and 9 age- and sex-matched controls were studied. Twenty-four-hour-ambulatory BP and HR were measured using the SpaceLabs 90207 device. A truncated Fourier series with four harmonics was used to describe the diurnal blood pressure profile. Mean 24-h ambulatory systolic BP, diastolic BP, and mean arterial pressure were significantly lower in TM patients than in normal subjects (P < .05). A significantly higher nighttime HR value was found in TM patients (P < .05). More than 40% of the TM patients did not show a significant diurnal BP and HR rhythm. In TM patients, the overall amplitude of systolic BP, diastolic BP, and HR was significantly lower than in controls (P < .01). The night/day differences of systolic BP, diastolic BP, and HR were significantly lower in TM patients than in normals (P < .01). Furthermore, we performed power spectral analysis on short-term continuous finger BP and HR data in supine position and during passive head-up tilt. Total spectral power of systolic BP was significantly lower in patients than controls (P < .05). Low-frequency (LF) power of systolic BP and diastolic BP and LF/high-frequency (HF) ratio of HR were significantly lower during tilt in TM patients compared to controls (P < .05). High-frequency power of HR was significantly higher in patients than controls (P < .05). The baroreflex gain assessed by alpha-index was the same in supine position but was higher in TM patients during passive tilt (P < .05). An inverse relationship between LF/HF ratio of HR and hemoglobin levels in TM patients was found. Finally, plasma norepinephrine levels were significantly lower in thalassemics (P < .005). In young TM patients in a preclinical stage of heart disease, these findings demonstrated abnormal 24-h BP and HR rhythms and a decreased short-term variability of BP and HR, in particular in the LF range, showing a diminished sympathetic activity.