Showing papers by "Giuseppe Mancia published in 1991"
TL;DR: The standard deviation of the mean difference (s.d.d.) between blood pressures obtained in each recording was taken as the reciprocal of blood pressure reproducibility, which was highest for office blood pressure and for single blood pressure readings taken from 24-h non-invasive recordings.
Abstract: Ambulatory blood pressure has been shown to be more reproducible than office blood pressure and thus to be more suited for studying the efficacy of antihypertensive drugs. In 34 untreated essential hypertensive subjects, we measured office and 24-h non-invasive or intra-arterial blood pressure twice
149 citations
TL;DR: The reduction in PI variance induced by SAD is paralleled by a reduction in all PI fluctuations identified by spectral analysis, not the case for the SAD-related increase in BP variance, which is accompanied by an increase, no change, or even a reduced in the different BP spectral components.
Abstract: Sinoaortic denervation (SAD) is accompanied by an increase in blood pressure (BP) and a reduction in pulse-interval (PI) variance. Little is known, however, about the effect of SAD on the complex BP and PI variability pattern, which is identified by spectral analysis. In nine unanesthetized cats in which intra-arterial BP was monitored before and 7-10 days after SAD, spectral powers (estimated by fast Fourier transform) were calculated for the low frequency (LF, 0.025-0.07 Hz), midfrequency (MF, 0.07-0.14 Hz), and high frequency (HF, 0.14-0.60 Hz) band. The very low frequency (VLF) BP and PI components (VLF less than 0.025 Hz) were also estimated. SAD increased systolic BP variance and decreased PI variance. The reduction of PI variance was paralleled by significant and marked reductions in all PI powers including the VLF components. In contrast, the increase in systolic BP variance was accompanied by a marked increase in LF power, a decrease in MF power, and no change in HF power. The VLF BP components increased after SAD for frequencies between 0.025 and 0.0012 Hz, whereas a sudden marked reduction was observed below 0.0012 Hz. Similar results were obtained for diastolic BP powers. Thus the reduction in PI variance induced by SAD is paralleled by a reduction in all PI fluctuations identified by spectral analysis. This is not the case for the SAD-related increase in BP variance, which is accompanied by an increase, no change, or even a reduction in the different BP spectral components.(ABSTRACT TRUNCATED AT 250 WORDS)
120 citations
Journal Article•
TL;DR: In this paper, a population sample of 328 subjects, aged 20-81 years, who reported themselves to be in good health, was investigated, and the ambulatory blood pressure was recorded over 24 hours, taking measurements at 20min intervals from 8 am to 10 pm, and at 45 min intervals from 10 pm to 8 am.
Abstract: Summary: In order to determine reference values for the ambulatory blood pressure, a population sample of 328 subjects, aged 20-81 years, who reported themselves to be in good health, was investigated. The ambulatory blood pressure was recorded over 24 h, taking measurements at 20 min intervals from 8 am to 10 pm, and at 45 min intervals from 10 pm to 8 am. Blood pressure was also measured by trained observers on each of two separate home visits (5 readings per visit). The ambulatory blood pressure in the 328 subjects averaged 118171 mmHg over 24 h, 124176 mmHg during the day (10 am-8 pm), and 108162 mmHg at night (0 am-6 am). Blood pressure measured by an observer at the occasion of the second home visit was 415 mmHg lower (P<0.001) than the daytime ambulatory blood pressure. The 95th centiles for the daytime ambulatory pressures were 144195 mmHg in 85 men below age 50; 154190 mmHg in 74 men aged 250 years; 132185 mmHg in 96 women below age 50; and 151191 mmHg in 73 women aged 250 years. The 95th centiles for the nighttime pressures in these four sex-age groups were 124179, 140183, 121170, and 132172 mmHg, respectively.
89 citations
Journal Article•
TL;DR: A population sample of 328 subjects, aged 20-81 years, who reported themselves to be in good health, was investigated, and reference values for the ambulatory blood pressure were determined.
Abstract: In order to determine reference values for the ambulatory blood pressure, a population sample of 328 subjects, aged 20-81 years, who reported themselves to be in good health, was investigated. The ambulatory blood pressure was recorded over 24 h, taking measurements at 20 min intervals from 8 am to 10 pm, and at 45 min intervals from 10 pm to 8 am. Blood pressure was also measured by trained observers on each of two separate home visits (5 readings per visit). The ambulatory blood pressure in the 328 subjects averaged 118/71 mmHg over 24 h, 124/76 mmHg during the day (10 am-8 pm), and 108/62 mmHg at night (0 am-6 am). Blood pressure measured by an observer at the occasion of the second home visit was 4/5 mmHg lower (P less than 0.001) than the daytime ambulatory blood pressure. The 95th centiles for the daytime ambulatory pressures were 144/95 mmHg in 85 men below age 50; 154/90 mmHg in 74 men aged greater than or equal to 50 years; 132/85 mmHg in 96 women below age 50; and 151/91 mmHg in 73 women aged greater than or equal to 50 years. The 95th centiles for the nighttime pressures in these four sex-age groups were 124/79, 140/83, 121/70, and 132/72 mmHg, respectively.
72 citations
TL;DR: In 27 essential hypertensive outpatients, blood pressure was measured in the doctor's office and by 24-h ambulatory blood pressure monitoring after a 3-week wash-out period from antihypertensive treatment (Control) and following 4 weeks of placebo administration.
Abstract: Twenty-four-hour mean ambulatory blood pressure has been shown to be devoid of a placebo effect. However, whether this is the case for different periods within the 24 h has not been established. In 27 essential hypertensive outpatients, blood pressure was measured in the doctor's office and by 24-h ambulatory blood pressure monitoring after a 3-week wash-out period from antihypertensive treatment (Control) and following 4 weeks of placebo administration. Office systolic and diastolic blood pressures were reduced by placebo (-9.6 +/- 2.6 and -3.1 +/- 1.7 mmHg, P less than 0.01, respectively), whereas 24-h mean blood pressure values did not show any significant change. This was not the case for all 24-h subperiods, however, because during the initial 8h, systolic and diastolic blood pressures were slightly (-4.1 +/- 9.2 and -2.5 +/- 6.4 mmHg) but significantly (P less than 0.05) lower during placebo than during control. Similar findings were obtained in 14 additional essential hypertensive patients in whom neither placebo nor any other treatment was employed between the two office and 24-h blood pressure measurements. Thus, placebo treatment is associated with a blood pressure reduction in the initial portion of the ambulatory blood pressure profile, probably because of an attenuation of an initial transient alerting response to the procedure. Although so small as to leave the 24-h blood pressure mean unaffected, this may lead to some overestimation of the antihypertensive effect of treatment during an appreciable portion of the circadian blood pressure tracing.
70 citations
TL;DR: Arterial baroreceptor reflex control of blood pressure, studied by the neck chamber technique, has been found to be reset to more effectively buffer increases in blood pressure than blood pressure falls, but without any loss of overall reflex sensitivity.
Abstract: Both arterial baroreceptor reflexes and cardiopulmonary reflexes are modified in human hypertension. The arterial baroreceptor reflex regulation of heart rate, when tested by both vasoactive drug injection and the neck chamber technique, has been shown to be reset and blunted. Arterial baroreceptor reflex control of blood pressure, studied by the neck chamber technique, has been found to be reset to more effectively buffer increases in blood pressure than blood pressure falls, but without any loss of overall reflex sensitivity. Cardiopulmonary reflexes, tested by passive leg raising and by application of lower body negative pressure, are also blunted, and their dysfunction involves not only control of peripheral vasoconstriction but also that of renin release. These readjustments of arterial and cardiopulmonary reflexes make buffering of blood pressure falls or of blood volume changes less effective in hypertension. These readjustments appear to be a consequence, rather than a cause, of hypertension. In particular, the blunting of cardiopulmonary reflexes is induced more by left ventricular hypertrophy than by hypertension. It is very marked in hypertensive patients with echocardiographic evidence of left ventricular hypertrophy and very significantly improves when left ventricular hypertrophy is made to regress by prolonged antihypertensive therapy; significant blunting of cardiopulmonary reflexes has also been found in young athletes with marked left ventricular hypertrophy but normal blood pressure. Whether structural changes in the carotid and aortic wall and possibly in the heart are equally important in the readjustment of arterial baroreceptor reflexes is incompletely clarified at the moment, although there are indications that functional and structural modifications may both be involved.
58 citations
TL;DR: It is concluded that sympathetic nerve activity normally exerts an antagonistic effect on the baroreceptor-heart rate reflex and this phenomenon is much more pronounced in SHR than in WKY rats and may contribute to the barorceptor reflex impairment typical of the former animals.
Abstract: In both animals and humans, stimuli leading to sympathetic activation are accompanied by an impairment of the baroreceptor-heart rate reflex. To determine whether sympathetic activity normally interferes with this reflex function we examined in conscious Wistar-Kyoto (WKY) rats the effect of chemical sympathectomy by 6-hydroxydopamine on the bradycardic response to baroreceptor stimulation induced by raising blood pressure via intravenous phenylephrine boluses; control rats received vehicle. Spontaneously hypertensive rats were also studied because in these animals there is both a baroreceptor reflex impairment and a sympathetic overactivity. Baroreceptor reflex sensitivity, calculated as the ratio of the peak increase in pulse interval to the peak increase in mean arterial pressure, was 75% greater in sympathectomized WKY rats than in control WKY rats (1.28 +/- 0.15 versus 0.73 +/- 0.10 msec/mm Hg, mean +/- SEM; p less than 0.01). The sympathectomy-induced increase in sensitivity was even larger in spontaneously hypertensive rats (SHR) (1.26 +/- 0.12 versus 0.44 +/- 0.06 msec/mm Hg in sympathectomized SHR versus control SHR, +186%; p less than 0.01) so that the impaired baroreceptor reflex sensitivity observed in control SHR as compared with control WKY rats (-40%, p less than 0.01) was no longer detectable in the sympathectomized groups. To establish whether the sympathectomy-induced potentiation of the reflex was due to an increase in cardiac responsiveness to vagal stimuli, we subjected separate groups of anesthetized, vagotomized SHR and WKY rats to graded electrical stimulation of the right efferent vagus. The bradycardic effects of vagal stimulation, however, were similar in sympathectomized and control animals.(ABSTRACT TRUNCATED AT 250 WORDS)
44 citations
TL;DR: The bradycardic responses to graded electrical stimulations of the right efferent vagus and to graded bolus intravenous injections of acetylcholine in anesthetized, vagotomized rats suggest the more general conclusion that aging has complex and diversified effects rather than simply and uniformly depressing biological functions.
Abstract: Aging impairs sympathetic and parasympathetic cardiac control. Although the reduced sympathetic responses are known to depend on an age-related cardiac beta-adrenoceptor dysfunction, the hypothesis of a parallel cardiac muscarinic receptor dysfunction underlying the reduced parasympathetic responses has never been tested. We therefore measured the bradycardic responses to graded electrical stimulations of the right efferent vagus and to graded bolus intravenous injections of acetylcholine in anesthetized, vagotomized rats of young (16 wk) and old (103 wk) age. Unexpectedly, the bradycardia was markedly larger (greater than 2-fold) in old than in young rats with both the electrical and the pharmacological stimulus. This indicates that at variance with its effects on beta-adrenergic receptor responsiveness, aging not only fails to impair but actually enhances cardiac muscarinic receptor responsiveness. It also suggests the more general conclusion that aging has complex and diversified effects rather than simply and uniformly depressing biological functions.
39 citations
TL;DR: Older rats showed a marked reduction of the bradycardic and tachycardic baroreflex response to intravenous boluses of phenylephrine and nitroprusside, and the preservation of the peak pressor response to CCO in old rats was independent of chemoreceptor activation, aorticbaroreceptors or cerebral ischemia.
Abstract: The effect of aging on arterial baroreceptor control of heart rate and blood pressure was evaluated in unanesthetized normotensive rats aged 5-6 (young), 12-16 (adult) and 75-90 (old) weeks. Each rat was chronically implanted with arterial and venous femoral catheters and with bilateral balloon-in-cuff occluders around the common carotid arteries. Baroreceptor control of heart rate was assessed by the bradycardic and tachycardic response to intravenous boluses of phenylephrine and nitroprusside, respectively. Carotid baroreceptor control of blood pressure was assessed by a 12-s bilateral common carotid occlusion (CCO). All baroreflex responses were similar in young and adult rats. Compared with the young group, old rats showed a marked reduction of the bradycardic and tachycardic baroreflex response (-42% and -46%, respectively, P less than 0.05). The initial pressor responses to CCO were also impaired in the old animals (3 s: -63%, 6 s: -54%; both P less than 0.01), whereas the peak pressor response (9 and 12 s) was virtually identical in the young and old groups. The preservation of the peak pressor response to CCO in old rats was independent of chemoreceptor activation, aortic baroreceptors or cerebral ischemia. Thus, aging impairs baroreceptor control of heart rate but alters baroreceptor control of blood pressure, as assessed by the pressor response to CCO, only in its fast-developing component, leaving its longer-term component unaffected.
35 citations
34 citations
TL;DR: Although naturally occurring stress may markedly increase blood pressure, 24-hour blood pressure variations also depend on factors that are not related to emotional stimuli, and the study of cardiovascular responses to stress in humans encounters several problems, regardless of the method used.
Abstract: Cardiovascular effects of stress in humans are often assessed by application of physical or emotional stimuli in a laboratory environment Although this method provides important information, these procedures have several limitations First, blood pressure and heart rate responses to laboratory stressors are characterized by a limited within-subject reproducibility Second, there is poor correlation between blood pressure and heart rate responses to different stressors, which implies that individual reaction to stress may be estimated differently according to the test used Finally, these responses bear only a limited relation to 24-hour or daytime blood pressure variability, that is, they reflect to only a limited extent the tendency of blood pressure to vary during daily activities If assessed by techniques that allow blood pressure to be continuously recorded for 24 hours in ambulatory subjects, blood pressure variability represents a possible approach to observation of cardiovascular reactivity away from an artificial laboratory environment However, whether blood pressure variability should be expressed as a percentage or in absolute values is controversial Furthermore, although naturally occurring stress may markedly increase blood pressure, 24-hour blood pressure variations also depend on factors that are not related to emotional stimuli Thus, the study of cardiovascular responses to stress in humans encounters several problems, regardless of the method used
TL;DR: The stress inherent in usual blood pressure-measuring procedures is responsible for considerable overestimations of patients' blood pressures, and there are means by which this can be minimized, although a residual error is likely to remain in most subjects.
Abstract: Blood pressure assessment by a physician elicits an alerting reaction and a pressor response in the patient. The magnitude and time course of this response are described for a large number of hypertensive subjects in whom the assessments were performed during ambulatory intra-arterial blood pressure monitoring. In nearly all of the subjects, the physician's visit was accompanied by blood pressure and heart rate increases that peaked within 4 minutes and then declined. The response was characterized by a relatively high average value; a large between-subject variability; no relation with patient age, baseline hemodynamic values, and responses to laboratory stressors; and no attenuation with multiple repetition of the physician's visit. On the other hand, the increase in blood pressure was considerably less when blood pressure assessment was made by a nurse than when it was made by a physician; in both instances, a 10-minute wait was associated with marked reduction of the initial response. Thus, the stress inherent in usual blood pressure-measuring procedures is responsible for considerable overestimations of patients' blood pressures. There are means by which this can be minimized, although a residual error is likely to remain in most subjects. Whether the stress-devoid blood pressure is a better prognostic index than the stress-related one remains unknown.
TL;DR: Evidence is reported that in both conscious rats and humans aging is associated with a fall in the baroreceptor ability to rapidly cause blood pressure changes, but that the more long-term carotidbaroreceptor control of blood pressure remains similar to that observed in younger individuals.
Abstract: Baroreceptor control of heart rate is markedly reduced in elderly subjects. However, the effects of aging on baroreceptor control of blood pressure and on the vascular and neurohumoral influences of volume cardiopulmonary receptors are unknown. In this paper we report evidence that in both conscious rats and humans aging is associated with a fall in the baroreceptor ability to rapidly cause blood pressure changes, but that the more long-term carotid baroreceptor control of blood pressure remains similar to that observed in younger individuals. Early and late cardiopulmonary receptor modulation of vascular resistance is impaired by aging, which also reduces the influence of this reflex on renin secretion. These dynamic and steady-state alterations in reflex cardiovascular control account for several hemodynamic abnormalities of the advanced age.
TL;DR: It is shown that cardiogenic reflexes are markedly depressed in subjects with left ventricular hypertrophy (LVH) due to hypertension and that this is also the case when, in normotensive subjects, LVH is caused by prolonged physical training.
Abstract: In man, cardiac receptors exert a continuous restraint on sympathetic activity. Reflexes originating from the heart also restrain renin and vasopressin secretion, thereby being involved both in blood pressure and in blood volume homeostasis. We have shown that these reflexes are markedly depressed in subjects with left ventricular hypertrophy (LVH) due to hypertension and that this is also the case when, in normotensive subjects, LVH is caused by prolonged physical training. In both instances, the cardiogenic reflex impairment is associated with derangement of blood pressure homeostasis. Either spontaneous regression of LVH by physical training cessation or antihypertensive treatment is followed by a marked improvement of the cardiogenic reflex. Thus, LVH also affects the 'afferent' function of the heart. 'Physiological', as well as pathological, hypertrophy has a similar adverse effect. This effect is reversible, however, and the reflex function can be restored by regression of hypertrophy.
TL;DR: The most useful methods appear to be the measurement of plasma noradrenaline and direct recording of sympathetic nerve traffic and a combination of these two methods may represent the ideal approach.
Abstract: Evaluation of sympathetic cardiovascular influences has important physiological, pathophysiological and clinical implications. This paper reviews some of the methods employed to measure these influences in man, along with their advantages and disadvantages. The most useful methods appear to be the measurement of plasma noradrenaline (particularly when modified to calculate spillover rate of noradrenaline) and direct recording of sympathetic nerve traffic. With the former, despite the technological advances in measurement, certain methodological problems remain, such as the separation of noradrenaline secretion from clearance. With the latter technique peripheral muscle and skin sympathetic activity can be measured separately but the question of regional vascular variability has still to be resolved. A combination of these two methods may represent the ideal approach. This review considers the complex problems associated with attempts to precisely quantify sympathetic cardiovascular influences in man.
Journal Article•
TL;DR: In this paper, the structural and functional organ abnormalities associated with hypertension are more closely correlated to 24-h blood pressure mean values than to clinic or other conventional sphygmomanometric blood pressures.
Abstract: Ambulatory blood pressure monitoring has both advantages and disadvantages in clinical practice. The structural and functional organ abnormalities associated with hypertension are more closely correlated to 24-h blood pressure mean values than to clinic or other conventional sphygmomanometric blood pressures. Furthermore, an additional relationship can be seen between the incidence and severity of these abnormalities and the magnitude of day and night blood pressure changes or 24-h blood pressure variability. However, controlled prospective studies are still required to demonstrate that ambulatory blood pressure data are superior or add to the prognostic value of clinic blood pressure. Moreover, ambulatory blood pressure normalcy has not yet been properly defined. This suggests caution in the practical use of this technique, which should be limited to special groups of subjects (those with a possible alerting reaction to conventional blood pressure assessments, in whom home blood pressure measurements are unreliable) and should only be used by clinicians with expertise in the field.
TL;DR: The evidence justifying the use of angiotensin-converting enzyme (ACE) inhibitors as first-line antihypertensive drugs is examined to suggest that this may be the case as several effects of ACE inhibitors in hypertension are potentially nephroprotective and cardioprotective.
Abstract: This article examines the evidence justifying the use of angiotensin-converting enzyme (ACE) inhibitors as first-line antihypertensive drugs. ACE inhibitors are as effective as traditional antihypertensive agents and, in addition, exert their blood-pressure-lowering effect with near optimal hemodynamic alterations. These drugs have a good tolerance and safety profile although they induce cough in an appreciable number of patients. They can be safely associated with other antihypertensive agents to provide therapeutic benefit in a large proportion of the hypertensive population