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Biomedical subjects

G Mancia

Publications and source records attributed to G Mancia.

At least 271 records · Page 15Linked to original sources
PubMed1994

Clinical trials with ambulatory blood pressure monitoring: fewer patients needed? Syst-Eur Investigators.

We have tested the concept that fewer patients are needed in trials of antihypertensive treatment if blood pressure is measured by ambulatory monitoring rather than by conventional sphygmomanometry. 233 patients (> or = 60 years old) with isolated systolic hypertension were randomly allocated placebo (n = 119) or active treatment (n = 114). Blood pressure measurements were compared by Wilcoxon's test and blood pressure profiles by ANOVA. With either method of measurement, the same number of patients (40 in each treatment group) was required to show a reduction after 1 year in clinic (13/8 mm Hg) or average blood pressure over 24 h (9/5 mm Hg). To detect that the decrease in systolic pressure was not steadily maintained through the day, 40 patients in each treatment group were needed for blood pressure profiles made up of 4-hourly or 2-hourly means and 60 for profiles of 1-hourly means. For diastolic pressure, the corresponding numbers were 80, 100, and more than the number of available patients, respectively. We conclude that parallel-group trials focusing on the average blood pressure over 24 h, rather than on conventionally measured blood pressure, cannot economise on sample size. Moreover, trials studying the full course of blood pressure throughout the day, require more--not fewer--patients than studies of only the conventional or average 24 h blood pressure.

Aged↗
PubMed1994

Blood pressure reduction and end-organ damage in hypertension.

VALUE OF AMBULATORY BLOOD PRESSURE MONITORING: Studies that have used ambulatory blood pressure monitoring techniques have shown that the average 24-h or daytime blood pressure values are more closely related to the end-organ damage associated with hypertension than are isolated office readings. IMPORTANCE OF BLOOD PRESSURE VARIABILITY IN PROGNOSIS: More recently, blood pressure variability, measured as the overall 24-h blood pressure standard deviation, has been shown to have a significant relationship to end-organ damage in hypertensive patients. The potential clinical relevance of blood pressure variability has been strengthened in a recent prospective study. The possible prognostic value of blood pressure variability has practical implications for antihypertensive treatment; it may mean, for example, that the optimal antihypertensive drug should reduce not only the mean 24-h values but also the degree of fluctuation in blood pressure. This is more likely to occur with long-acting drugs, which induce a more balanced reduction in blood pressure throughout the 24 h. USE OF THE TROUGH:PEAK RATIO: A proposed measure of a balanced 24-h blood pressure effect is the trough:peak ratio of the blood pressure fall. This ratio can be obtained by clinic blood pressure measurements but ambulatory blood pressure monitoring offers some distinct advantages. One of these advantages is that by revealing the possibility of an excessive fall in blood pressure at the time of the peak effect or an uncontrolled rise at the trough, ambulatory monitoring can also reveal the possible impact of pharmacological treatment on 24-h blood pressure variability.

Antihypertensive Agents↗
PubMed1994

Clinical value of ambulatory blood pressure monitoring.

This report reviews the evidence for and against clinical use of ambulatory blood pressure monitoring (ABPM) on a large scale. Such monitoring is supported by a number of data, among which is that the end-organ damage associated with hypertension correlates more with 24-h average blood pressure than with clinic blood pressure, the correlation becoming even closer with addition of blood pressure variability values. However, the evidence thus far collected is largely cross-sectional. Furthermore, ABPM devices have limited accuracy and the procedure has a high cost. Therefore, while prospective studies on the prognostic value of ambulatory blood pressure are awaited, use of this approach should be restricted to a limited number of clinical circumstances (e.g., identification of white-coat hypertension) and used only in specialized centers.

Blood Pressure Monitoring, Ambulatory↗
PubMed1994

Ambulatory and home blood pressure normality: the Pamela Study.

Ambulatory blood pressure monitoring (ABPM) is increasingly used in the clinical evaluation of hypertension. However, a number of limitations restrict its routine use. One of the limitations is a lack of definite conclusions about ambulatory blood pressure normality, because of the shortcomings of previous studies on this issue. In the present study we describe a survey from a large sample of subjects within the age range of 25-64 years. It was found that 24-h average systolic and diastolic blood pressures are markedly lower than clinic blood pressure, and for daytime average and home blood pressure as well. In addition, it was found that the clinic ambulatory or home blood pressure disparity is related to the baseline clinic blood pressure (i.e., it increases with increasing clinic blood pressure values) and that the three pressures (ambulatory, home, clinic) are closely related to each other, thereby allowing the application of correction factors to obtain information on ambulatory or home blood pressure normality. This results in an upper normality limit for 24-h average blood pressure and home blood pressure of around 120 mm Hg systolic and 77 mm Hg diastolic pressure.

Adult↗
PubMed1994

Hypertension--when is the clinical problem solved? When patients are rendered normotensive.

Hypertension is usually symptomless and associated with little or no alterations in well-being. However, conclusive evidence demonstrates that hypertension is a major risk factor for cardiovascular disease. A reduction of the elevated blood pressure with antihypertensive medication can reduce this risk, but not to that of a normotensive patient. Furthermore, antihypertensive treatment is more effective against stroke and congestive heart failure than against coronary heart disease. Antihypertensive treatment is costly due to its extensive use and life-long indication. Future progress in this area will aim to identify those hypertensive patients at greatest risk of cardiovascular disease, in order to limit treatment to those patients who may benefit most. This paper will consider the effects of blood pressure reduction on cardiovascular morbidity and mortality, the differing effects of antihypertensive treatment on the complications of hypertension, and how antihypertensive therapy can be optimized.

Antihypertensive Agents↗
PubMed1994

Mechanisms responsible for sympathetic activation by cigarette smoking in humans.

BACKGROUND: The pressor and tachycardic effects of cigarette smoking are associated with an increase in plasma catecholamines, suggesting the dependence of these effects on adrenergic stimulation. Whether the stimulation occurs at a central or a peripheral level and whether reflex mechanisms are involved is unknown. METHODS AND RESULTS: In nine normotensive healthy subjects (age, 33.0 +/- 3.5 years, mean +/- SEM), we measured blood pressure (Finapres device), heart rate (ECG), calf blood flow and vascular resistance (venous occlusion plethysmography), plasma norepinephrine and epinephrine (high-performance liquid chromatography assay), and postganglionic muscle sympathetic nerve activity (microneurography from the peroneal nerve) while subjects were smoking a filter cigarette (nicotine content, 1.1 mg) or were in control condition. Cigarette smoking (which raised plasma nicotine measured by high-performance liquid chromatography from 1.0 +/- 0.9 to 44.2 +/- 7.1 ng/mL) markedly and significantly increased mean arterial pressure (+13.2 +/- 2.3%), heart rate (+30.3 +/- 4.7%), calf vascular resistance (+12.1 +/- 4.9%), plasma norepinephrine (+34.8 +/- 7.0%), and plasma epinephrine (+90.5 +/- 39.0%). In contrast, muscle sympathetic nerve activity showed a marked reduction (integrated activity -31.8 +/- 5.1%, P < .01). The reduction was inversely related to the increase in mean arterial pressure (r = -.67, P < .05), but the slope of the relation was markedly less (-54.1 +/- 7.5%, P < .05) than that obtained by intravenous infusion of phenylephrine in absence of smoking. The hemodynamic and neurohumoral changes were still visible 30 minutes after smoking and occurred again on smoking a second cigarette. Sham smoking was devoid of any hemodynamic and neurohumoral effect. CONCLUSIONS: These data support the hypothesis that in humans the sympathetic activation induced by smoking depends on an increased release and/or a reduced clearance of catecholamines at the neuroeffector junctions. Central sympathetic activity is inhibited by smoking, presumably via a baroreceptor stimulation triggered by the smoking-related pressor response. The baroreflex is impaired by smoking, however, indicating that partial inability to reflexly counteract the effect of sympathetic activation is also responsible for the pressor response.

Adult↗
PubMed1994

Physical training and baroreceptor control of sympathetic nerve activity in humans.

In nine sedentary subjects (16.5 +/- 0.4 years, mean +/- SEM) we measured blood pressure (Finapres device), heart rate (electrocardiogram), and postganglionic muscle sympathetic nerve activity (microneurography from the peroneal nerve) at rest and during intravenous infusion of phenylephrine and nitroprusside. These measurements were performed before and after 10 weeks of endurance training (2 h/d, 5 d/wk) that increased maximum oxygen consumption from 34.8 +/- 2.1 to 40.4 +/- 1.8 mL/kg per minute (P < .02). Basal mean blood pressure and muscle sympathetic nerve activity were lower after than before endurance training (86.5 +/- 2.6 versus 97.5 +/- 1.8 mm Hg, P < .05, and 14.0 +/- 1.8 versus 21.2 +/- 2.3 bursts per minute, P < .02), and the changes in these variables were closely related (r = .95, P < .01). Similar mean blood pressure increases induced by phenylephrine caused greater reductions in heart rate and muscle sympathetic nerve activity after than before endurance training (-8.6 +/- 0.8 versus -6.1 +/- 1.1 beats per minute, P = NS, and -78.0 +/- 4.6% versus -53.6 +/- 4.8%, P < .05). Likewise, similar mean blood pressure reductions induced by nitroprusside caused greater increases in heart rate and muscle sympathetic nerve activity after than before endurance training (18.6 +/- 3.0 versus 12.4 +/- 2.4 beats per minute, P < .05, and 128.1 +/- 26% versus 63.2 +/- 11%, P < .02). No alteration in hemodynamics, oxygen consumption, muscle sympathetic nerve activity, and baroreceptor reflex sensitivity occurred in four other age-matched sedentary subjects studied before and after a 10-week observation period without endurance training.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Beta-adrenergic blocking treatment and 24-hour baroreflex sensitivity in essential hypertensive patients.

We dynamically evaluated the effects of beta-blockade on the sensitivity of arterial baroreflex control of heart rate in 10 mild or moderate essential hypertensive patients in whom blood pressure was recorded intra-arterially for 24 hours in ambulatory conditions. Twenty-four-hour baroreflex sensitivity was assessed by both (1) a time-domain approach based on the calculation of the slope of the regression line between linearly related progressive increases in systolic blood pressure and pulse interval (+PI/+SBP sequences) and decreases in systolic blood pressure and pulse interval (-PI/-SBP sequences) and (2) a frequency-domain approach, ie, the ratio between the spectral powers of pulse interval and systolic blood pressure around 0.1 Hz (alpha coefficient). Data were obtained before and after 1 month of administration of either acebutolol (n = 5) or labetalol (n = 5). Before treatment, the 24-hour average slopes of the +PI/+SBP and -PI/-SBP sequences were 4.36 +/- 0.32 and 4.05 +/- 0.27 ms/mm Hg, respectively, while the alpha coefficient was 7.78 +/- 0.7 ms/mm Hg. After beta-blockade, these values were increased by 25.3 +/- 6.8%, 25.0 +/- 8.0%, and 32.1 +/- 9.3%, respectively (P < .01 for all values). Thus, beta-blockers potentiate baroreflex sensitivity in daily life. Time-domain and frequency-domain methods yielded superimposable results in dynamically evaluating 24-hour baroreflex sensitivity and its changes after beta-blockade.

Acebutolol↗
PubMed1994

Clinical use of ambulatory blood pressure monitoring: a critical appraisal.

Traditional sphygmomanometric techniques are heavily affected by the 'white-coat' effect and cannot be used to assess blood pressure variability over the 24h period. These limitations can be overcome in part using ambulatory monitoring, which (1) quantifies both the mean and the variability of blood pressure over 24h, including blood pressure fluctuations between day and night, (2) does not trigger any alerting reaction in the patient, (3) provides reproducible 24h blood pressure means and (4) allows the action of antihypertensive drugs to be assessed over 24h without interference from a placebo effect. Moreover, ambulatory blood pressure values are more closely related to the end-organ damage associated with hypertension than are isolated clinic readings. However, the limited accuracy of ambulatory monitoring in ambulant individuals, the lack of normal reference values for 24h blood pressure and the need for a longitudinal demonstration of the prognostic value of the technique do not permit the recommendation of its widespread use in clinical hypertension. Although the clinical use of ambulatory monitoring should be restricted to selected cases, there is general agreement on its usefulness in clinical pharmacology trials and in studies aimed at assessing cardiovascular regulation through the analysis of 24h blood pressure and heart rate fluctuations.

Antihypertensive Agents↗
PubMed1994

Coronary vascular reactivity and calcium antagonist therapy in patients with angina.

In patients with severe coronary atherosclerotic disease, the angiotensin-converting enzyme inhibitor captopril attenuates the vasoconstriction induced by the cold pressor test and diving (two stimuli that cause reflex sympathetic activation) via removal of the facilitating effect of angiotensin II on sympathetic drive. However, whether calcium antagonists also have this effect is not clear. We evaluated the effects of a single 11-mg intravenous dose of the dihydropyridine calcium antagonist amlodipine on the coronary vascular response to the cold pressor test, a 30-s application of the dive reflex and cigarette smoking (whose effects on the coronary circulation also involve the sympathetic nervous system). In 13 normotensive male patients with severe stenoses of the left anterior descending coronary artery, the cold pressor test and diving reflex increased mean arterial pressure and rate-pressure product and caused a marked and significant rise in coronary vascular resistance (+ 12.1 +/- 4.8% and +30.4 +/- 6.8%, respectively). Mean arterial pressure, rate-pressure product, and coronary vascular resistance also increased markedly during smoking. Amlodipine caused a reduction in baseline mean arterial pressure, an increase in baseline coronary blood flow, and a marked fall in baseline coronary vascular resistance (-19.2 +/- 3.1%; p < 0.01). The coronary vascular responses to the cold pressor test and the diving reflex were unchanged with amlodipine. However, the smoking-induced increase in coronary vascular resistance was significantly attenuated after amlodipine (+3.2 +/- 2.7% vs. +16.8 +/- 7.2%; p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Amlodipine↗
PubMed1994

Blood pressure variability and organ damage.

Several studies have now shown that hypertension-induced end-organ damage is more closely related to 24-h average blood pressure than to clinic measurements. Furthermore, the degree of variability of blood pressure during a 24-h period bears a relation to organ damage that is independent of average blood pressure value. The measurement of blood pressure variability is a complex task, however, because data from automatic ambulatory blood pressure monitoring should be interpreted with caution, especially if the interval between blood pressure measurements is more than 15 min, and different types of blood pressure variability (e.g., short-term and long-term) can make calculation of variability by standard deviation of 24-h blood pressure values difficult, which further complicates measurement procedures and interpretation. Evidence is growing to suggest that blood pressure variability in hypertension is clinically significant. We have recently shown that over a 7.5-year period, end-organ damage is independently related to the initial blood pressure variability. Although information on the effect of antihypertensive treatment on 24-h blood pressure variability is limited, the available data suggest more of an effect on 24-h average blood pressure levels than on 24-h blood pressure changes. Further studies should investigate treatment effects on different types of blood pressure variability and the impact of treatment on patient protection and prognosis.

Antihypertensive Agents↗
PubMed1994

[Hemodynamics and pressure variability in isolated systolic hypertension].

Isolated systolic hypertension is a common feature in aged individuals and it has been associated with an increased cardiovascular mortality and morbidity. More recently it has been shown that this condition is characterized by peculiar abnormalities of arterial vessels. For example isolated systolic hypertension is associated with a reduction in arterial compliance evident both in muscle arteries, like the radial one, and in elastic arteries, like the carotid one. On the other side cardiovascular homeostasis is markedly deranged and blood pressure variability more marked than in age matched normotensive subjects. Finally, 24-hour blood pressure monitoring has allowed to exclude that isolated systolic hypertension might be merely linked to an exaggerated alarm reaction, showing that blood pressure is elevated along the whole 24-hour blood pressure profile.

Hemodynamics↗
PubMed1994

[Physiopathologic and clinical features of hypertensive cardiopathy].

Several studies, performed during the past 20 years in different experimental animal models of hypertension and in men, have allowed to clarify important pathophysiological and clinical aspects of the hypertensive cardiovascular disease, i.e. the pathological condition characterized by marked structural and functional alterations of the heart induced by arterial hypertension. Epidemiological studies have indeed clearly shown that the prevalence of left ventricular hypertrophy in large hypertensive population samples is markedly high (40-50%) and that the electrocardiographic evidence of cardiac hypertrophy adversely affects patient's prognosis, by significantly increasing cardiovascular morbidity (myocardial infarction, congestive heart failure and cardiac arrhythmias) and mortality (sudden death). It has also been shown that cardiac hypertrophy is characterized by profound functional alterations in myocardial contractility and impairs neural reflex responses to beta-adrenergic stimulation and to deactivation of cardiopulmonary volume receptors, which are involved in physiological conditions in blood volume homeostasis control. Finally, several interventional studies have unequivocally shown that antihypertensive drugs may allow to obtain, even following 3-6 months of treatment, along with a blood pressure reduction, a clearcut regression of cardiac hypertrophy. By improving cardiovascular hemodynamics and neural control of circulation, regression of cardiac structural alterations is associated with a significant reduction in the patient's cardiovascular risk profile.

Humans↗
PubMed1994

Ambulatory blood pressure monitoring in the evaluation of antihypertensive drugs.

CLINIC VERSUS AMBULATORY BLOOD PRESSURE MEASUREMENT: Clinic blood pressure measurements do not give the best estimate of the efficacy of antihypertensive drugs because (1) they provide readings for one time-point only, (2) they are subject to a 'white-coat' effect and also show a significant placebo effect and (3) they are poorly reproducible. Ambulatory blood pressure monitoring overcomes these problems and offers the possibility of obtaining reliable, reproducible and detailed information on the time-course and magnitude of the effect of antihypertensive treatment on blood pressure over 24 h. MEAN 24-H VERSUS MEAN HOURLY AMBULATORY BLOOD PRESSURE VALUES: Compared with mean 24-h values, reproducibility is poorer for mean hourly ambulatory values, which show greater variability when tested under different conditions. Thus, caution must be exercised when the effects of antihypertensive drugs on hourly blood pressure profiles are analysed and the trough:peak ratio is calculated. FURTHER PROBLEMS WITH AMBULATORY MONITORING: There are further reasons for caution: (1) ambulatory blood pressure readings can be inaccurate, (2) there is only preliminary information on normal reference values and (3) there have been no longitudinal studies demonstrating the prognostic value of ambulatory blood pressure monitoring, which introduces uncertainty into attempts to evaluate the optimal effect of antihypertensive treatment by this method. CONCLUSIONS: These limitations do not detract from the use of ambulatory blood pressure monitoring in drug studies, but they do suggest that this measurement technique should not be used routinely for assessing antihypertensive treatment in clinical practice.

Antihypertensive Agents↗