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Biomedical subjects

G Mancia

Publications and source records attributed to G Mancia.

At least 289 records · Page 16Linked to original sources
PubMed1994

Alterations in neural cardiovascular control mechanisms with ageing.

AGEING AND MECHANISMS OF BLOOD PRESSURE CONTROL: Ageing is associated with functional and structural alterations to the cardiovascular system. Evidence is accumulating, however, that ageing also determines major changes in the effectiveness of mechanisms involved in blood pressure control and that this represents an important determinant of the cardiovascular changes that can be observed in the elderly. DIFFERENCES SEEN IN ELDERLY SUBJECTS: It has been observed that compared to young subjects, in the elderly (1) baroreceptor control of the heart rate and cardiac function is impaired; (2) baroreceptor modulation of the sympathetic drive to the peripheral circulation is impaired, particularly the speed of reflex adjustments to normal and abnormal stimuli; and (3) cardiopulmonary stretch receptors, which tonically inhibit sympathetic tone, the renal release of renin and vasopressin secretion, are impaired. These three factors may account, at least in part, for the raised blood pressure and sympathetic activity in the elderly. They certainly explain the reduced ability of elderly people to maintain blood pressure and blood volume homeostasis, and their increased blood pressure variability over 24 h. ASSOCIATION WITH HYPERTENSION: All these problems are exacerbated if ageing is associated with hypertension, and are highly relevant to antihypertensive treatment. Care should be taken that any antihypertensive drugs selected for treatment in the elderly do not aggravate these basic homeostatic problems.

Aged↗
PubMed1994

Hemodynamic and neural effects of urapidil and prazosin in essential hypertensives.

Assessment of the effects of antihypertensive drugs on sympathetic cardiovascular modulation is aimed not only at exploring the neural mechanisms of the hypotensive action of different pharmacological compounds but also at evaluating the effects of these drugs on neural cardiovascular homeostatic control. This paper, after reviewing the effects of different antihypertensive drugs on efferent postganglionic muscle sympathetic nerve activity directly assessed in man via the microneurographic technique, will report the preliminary results of a study we have recently performed in 12 untreated mild essential hypertensives. This study was aimed at examining the effects of a single oral administration of either the hybrid drug urapidil (30 mg) or the pure alpha-blocker prazosin (2 mg) on arterial blood pressure (Finapres technique), heart rate (electrocardiogram) and muscle sympathetic nerve activity (microneurography at the peroneal nerve). For similar blood pressure reductions, urapidil caused a lesser degree of tachycardia in comparison with prazosin (+5.1 +/- 1.2 vs +8.4 +/- 0.8 beats/min, p < 0.05) but superimposable increases in muscle sympathetic nerve traffic (+15.4 +/- 2.8 vs 17.5 +/- 3.5 bursts/min). These results suggest that the two drugs induce similar degrees of blood pressure reduction as well as of muscle sympathetic activation. Urapidil, however, is accompanied by less tachycardia than prazosin, presumably because of a selective drug's action on either parasympathetic or sympathetic modulation of heart rate, triggered by the stimulation of central 5HT1A-receptors.

Administration, Oral↗
PubMed1994

[The antihypertensive effects of the lisinopril-hydrochlorothiazide combination (Zestoretic) in elderly hypertensive patients. The results of a multicenter study. The Italian Zestoretic Study Group].

The present study was aimed at evaluating the effects of combined lisinopril-hydrochlorothiazide (Zestoretic) antihypertensive treatment on sphygmomanometric and 24-hour systolic and diastolic blood pressure values in 631 elderly patients (mean age +/- SD 68.8 +/- 5.8 years) with mild-to-moderate essential systolic-diastolic or isolated systolic hypertension. After a wash-out period of 4 weeks, patients received o.d. lisinopril combined with hydrochlorothiazide for a 6-week period. At the end of both periods, sphygmomanometric blood pressure was assessed 24 hours after dosing and 24-hour ambulatory blood pressure was performed, taking blood pressure readings every 15 minutes during day- and night-time. The drug induced in all elderly hypertensives clearcut and significant systolic and diastolic blood pressure reductions (average reduction amounting to 25 mmHg and 15 mmHg for systolic and diastolic blood pressure values respectively) without any significant heart rate change. The antihypertensive effect of combined lisinopril and hydrochlorothiazide was significant during the whole 24-hour monitoring period. This antihypertensive drug regimen was well tolerated, a low side effect profile being observed (10.3% of treated patients). Thus single daily administration of combined lisinopril-hydrochlorothiazide represents a safe and effective antihypertensive drug regimen.

Aged↗
PubMed1994

Ambulatory pressure decreases on long-term placebo treatment in older patients with isolated systolic hypertension. Syst-Eur Investigators.

OBJECTIVE: This long-term study investigated the widely accepted hypothesis that ambulatory pressure does not decrease in patients given placebo. METHODS: One hundred and twelve older (> or = 60 years) outpatients with isolated systolic hypertension were recruited. Treatment consisted of a placebo during a 3-month baseline period and long-term follow-up. RESULTS: At baseline, on placebo treatment, clinic systolic/diastolic (SBP/DBP) blood pressure (+/- SD) averaged 176 +/- 12/86 +/- 7 mmHg and 24-h SBP/DBP 151 +/- 15/81 +/- 10 mmHg. These pressures were unaltered in 51 patients in whom the baseline measurements were repeated after a further month on placebo. After the 112 patients had received placebo for 1 year (median), clinic SBP/DBP fell by 6.6 +/- 15.9 (P < 0.001)/1.4 +/- 7.4 (P = 0.06)mmHg and 24-h SBP by 2.4 +/- 10.7 mmHg (P < 0.05), whereas 24-h DBP did not change significantly. The 24-h SBP decreased more with higher baseline level and longer follow-up (5-21 months). CONCLUSIONS: These findings in older patients with isolated systolic hypertension suggest that in long-term studies the ambulatory pressure may slightly but significantly decrease on a placebo. Like those using conventional sphygmomanometry, long-term studies using non-invasive ambulatory monitoring require a placebo-controlled design.

Aged↗
PubMed1994

[Variability of heart rate in hypertensive patients: clinical and physiopathological implications].

Heart rate variability has been investigated in essential hypertension by studies combining 24-hour ambulatory blood pressure and heart rate monitoring techniques. These studies have shown a clear circadian pattern of heart rate fluctuations. By means of spectral analysis it has also been possible to describe the changes over the 24 hours of specific heart rate fluctuations occurring at various frequencies, which, at least in mild to moderate hypertensives, are not different from those of normotensive subjects. Laboratory studies have also shown the important role exerted by arterial baroreflexes in modulating heart rate variability. Finally, recent methods have been developed to dynamically monitor changes in baroreflex sensitivity in daily life conditions through the time domain or frequency domain analysis of spontaneous blood pressure and heart rate fluctuations.

Activities of Daily Living↗
PubMed1994

[Neurohumoral mechanisms in cardiocirculatory decompensation].

Congestive heart failure is characterized by profound alterations in systemic haemodynamics as well as in neurohumoral profile with activation of the sympathetic nervous system, reninangiotensin axis, plasma vasopressin and atrial natriuretic peptides, i.e. factors involved in homeostatic control of the cardiovascular system. The sympathetic stimulation, which has been documented by a variety of methodological approaches (plasma norepinephrine measurement, norepinephrine spillover technique, microneurographic recording of efferent post-ganglionic muscle sympathetic nerve traffic) is already evident in the initial stages of the disease (NYHA classes I-II) and more manifest in severe heart failure (NYHA classes III-IV). Although representing in mild heart failure a compensatory mechanism aimed at preserving cardiac output, the sympathetic and neurohumoral activation, which can be likely ascribed to arterial baroreceptor dysfunction, may represent, in the clinical course of the disease, a maladaptative phenomenon. Thus pharmacological treatment of heart failure should be aimed not only at improving systemic haemodynamics but also at reversing neurohumoral activation and baroreflex impairment. Recent experimental clinical evidence suggests that these therapeutical goals can be satisfactorily achieved by digitalis glycosides and ACE-inhibitors.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1994

Effects of amlodipine on coronary hemodynamics and vascular responses to sympathetic stimulation in patients with coronary heart disease.

Dihydropyridines (DHPs) exert a powerful coronary vasodilator action, but whether they actually affect the coronary vasomotor effects elicited by an increase in cardiac sympathetic drive is controversial. We assessed the effects of the DHP calcium antagonist amlodipine on coronary hemodynamics and vascular response to sympathetic activation in patients with coronary heart disease. In the control condition, mean arterial pressure (MAP, aortic catheter), heart rate (HR, ECG), rate-pressure product (RPP), coronary sinus blood flow (CBF, thermodilution) and coronary vascular resistance (CVR) (ratio between MAP and CBF) were measured in all our case series (13 patients with angiographically documented severe coronary artery disease) before and during a 2-min cold pressor test (CPT) and a 30-s diving (D) and, in the 8 patients of this case series who were smokers, also before and during smoking a cigarette (S, nicotine content 1.0 mg for 10 min). The same protocol used in control condition was repeated 30 min after intravenous (i.v.) bolus administration of 11 mg amlodipine. CPT, diving, and smoking increased MAP and RPP and caused a marked and significant increase in CVR (+12.1 +/- 4.8, +30.4 +/- 6.8, and +16.8 +/- 7.2%, respectively). Amlodipine reduced MAP, increased CBF, and caused a marked decrease in CBF. The drug did not modify responses to CPT and diving or pressure and HR responses to smoking, whereas the smoking-induced increase in coronary vascular resistance was attenuated after amlodipine administration (+3.2 +/- 2.7%, p < 0.05 vs. control condition). Thus, amlodipine does not attenuate the sympathetic coronary vasoconstrictor effects of CPT and diving.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[The trough-to-peak ratio in the evaluation of an antihypertensive drug].

The trough-to-peak ratio (T/P) is more and more frequently employed to assess in a simple fashion the duration and the homogeneity of the antihypertensive effect of a drug over a between-dose interval. This paper emphasizes that to provide reliable data T/P should be calculated only when there is a clearcut antihypertensive effect and that other important features are its within-individual reproducibility and an acceptable value (> 50%) in most individual patients. T/P can be assessed by sphygmomanometric measurements obtained at the end of the between-dose interval and at or near the maximal effect of the drug within the dose interval. It is more and more common, however, to assess T/P by ambulatory blood pressure monitoring which, although characterized by a number of limitations (e.g. low reproducibility of blood pressure values within the 24 hours), allows to avoid a parallel placebo group and to simplify the study design. While a high T/P suggests that the dose and the between-dose interval of a drug is capable to provide an adequate therapeutic coverage a low T/P indicates that the therapeutic coverage is insufficient. The posology must then be changed (more frequent and/or greater doses) to avoid an insufficient protection against hypertension.

Antihypertensive Agents↗
PubMed1994

Acute effects of smoking on radial artery compliance in humans.

OBJECTIVE: To clarify whether the acute and marked increase in blood pressure associated with smoking is accompanied by an alteration in arterial compliance. DESIGN: Arterial compliance was measured in 13 subjects before and after smoking a cigarette with a nicotine content of 1.2 mg, or before and after sham smoking. Measurements were obtained with the subjects at rest and after prolonged brachial artery occlusion (12 min). METHODS: Compliance was measured using an echo-tracking system capable of continuously providing (300 readings/s) radial diameter data and, with the addition of a photoplesythmographic device, blood pressure measurement. RESULTS: Acute cigarette smoking caused a pressor and tachycardic response, and decreased markedly both resting radial artery diameter and compliance, at blood pressure values identical to those before smoking. The marked increase in radial artery diameter and compliance brought about by local ischaemia was unaffected by smoking, and no changes were observed both at rest and after ischaemia as a result of sham smoking. CONCLUSIONS: Smoking causes a marked reduction in radial artery compliance, and the effect is independent of the increase in blood pressure. However, the marked increase in compliance due to ischaemia is not modified by smoking.

Adult↗
PubMed1994

Blood pressure variability: clinical implications and effects of antihypertensive treatment.

HYPOTHESIS ON RELATIONSHIP BETWEEN BLOOD PRESSURE VARIABILITY AND END-ORGAN DAMAGE: Several studies have shown that the cardiovascular complications of hypertension are more closely related to ambulatory 24-h or daytime average blood pressure than to office readings. A few studies have also provided evidence that in hypertensive patients, not only average ambulatory blood pressure but also the degree of blood pressure variability is significantly and independently related to the end-organ damage associated with hypertension. LIMITATIONS OF PREVIOUS STUDIES: A common limitation of previous studies is that they were based on cross-sectional or retrospective observations, so that the correlative evidence they provide does not allow the relationship between blood pressure variability and end-organ damage to be interpreted causally. EVIDENCE FROM RECENT STUDIES: Recent evidence from follow-up observations has strongly supported the hypothesis that blood pressure variability is prognostically important in hypertensive patients. These findings suggest that optimal antihypertensive treatment should aim not only to reduce mean blood pressure levels, but also to reduce the degree of blood pressure fluctuation. EFFECTS OF ANTIHYPERTENSIVE DRUGS: Unfortunately, while most new antihypertensive drugs seem to be effective in reducing 24-h mean blood pressure levels, they are frequently unable to reduce 24-h blood pressure variability, which is often increased during treatment when expressed in normalized units. The development of drugs that guarantee a constant and uniform reduction in blood pressure over 24 h may, in principle, offer a further advantage by preventing the increase in 24-h blood pressure fluctuations that may follow the administration of short-acting antihypertensive agents. TROUGH: PEAK MEASUREMENTS OF BLOOD PRESSURE: The trough: peak ratio, proposed as an arithmetic indicator of the duration of the antihypertensive effect of a drug, may be a useful measure of the occurrence of a smooth reduction in blood pressure over 24 h. The possibility of obtaining an additional reduction in cardiovascular risk for hypertensive patients by minimizing the net trough: peak effect of antihypertensive drugs is thus an important issue for future studies.

Antihypertensive Agents↗
PubMed1994

Ambulatory blood pressure monitoring in the diagnosis of hypertension and evaluation of antihypertensive drug efficacy.

Ambulatory blood pressure monitoring is invaluable in the assessment of the efficacy of antihypertensive drug treatment because it allows the reduction of blood pressure to be confirmed within the context of daily life. It also allows the determination of whether treatment produces an even blood pressure reduction over the 24-hour period or whether it is characterized by an uneven profile, for example, a precipitous fall early after administration of the drug and a later return towards elevated blood pressure values. A lack of information on prognostic and normal values does not permit quantification of the optimal blood pressure reduction to be achieved throughout the monitoring period. It is agreed, however, that the decrease should take into consideration both the elevated daytime and the reduced night-time blood pressures, and that peak blood pressure values associated with physical and emotional activities as well as the overall variability of blood pressure should also be reduced. Finally, ambulatory blood pressure monitoring is virtually devoid of the placebo effect, and the 24-hour average blood pressure data derived by this method are more reproducible than isolated blood pressure values taken by sphygmomanometry. This offers distinct advantages for studies designed to evaluate the antihypertensive effect of new drugs.

Antihypertensive Agents↗
PubMed1994

Increase in blood pressure reproducibility by repeated semi-automatic blood pressure measurements in the clinic environment.

OBJECTIVE: To evaluate whether increasing the number of blood pressure readings obtained in the clinic environment increases the blood pressure reproducibility. PATIENTS: Thirteen mild essential hypertensive patients studied in the outpatient clinics, following withdrawal of antihypertensive treatment for 4 weeks. METHODS: The systolic and diastolic blood pressures were measured three times, using a mercury sphygmomanometer, with the patient in the sitting position. Measurements were then performed with the patient in the lying position using an oscillometric device (SpaceLabs 90202 or 90207). The device was operated semi-automatically at 3-min intervals until 25 readings had been collected. The same procedure was repeated 4 weeks later. The systolic blood pressure, diastolic blood pressure and heart rate were averaged by considering a progressively greater number of readings, from 1 to 25. The reciprocal of the standard deviation (1/SD) of the mean difference after 4 weeks was taken as the measure of reproducibility. RESULTS: 1/SD increased progressively as the number of semi-automatic blood pressure readings from which the average was calculated increased. For a similar number of blood pressure readings the reproducibility was similar for semi-automatic readings to that for automatic readings obtained by 24-h ambulatory blood pressure monitoring. CONCLUSION: Multiple blood pressure readings obtained semi-automatically in the outpatient clinics increase blood pressure reproducibility and make the value similar to that obtained by ambulatory blood pressure monitoring. The advantage of an increase in reproducibility for studies on antihypertensive drugs thus depends on the number of readings, and can also be obtained by semi-automatic measurements in the clinic environment.

Adult↗
PubMed1993

Calcium antagonists in the treatment of arterial hypertension.

Calcium antagonists are widely used antihypertensive agents whose hemodynamic effects consist of a reduction in blood pressure and peripheral vascular resistance that is associated, in case of short-term administration, with a reflex increase in heart rate and cardiac output. These compounds exert several additional positive effects besides blood pressure reduction. Among them, calcium antagonists exert their antihypertensive effect without negatively interfering with both central and reflex neural control of circulation. The only change in baroreflex function observed during the administration of these compounds is a resetting of the baroreflex toward the lower blood pressure values achieved by treatment. New calcium antagonists of the dihydropyridine type are characterized by a greater vascular selectivity, and by the ability to exert a persistent blood pressure reduction throughout the 24 hours when administered in a single oral dose. The latter feature can be properly assessed by means of ambulatory blood pressure monitoring techniques.

Calcium Channel Blockers↗
PubMed1993

Impairment of the arterial baroreflex during symptomatic and silent myocardial ischemia in humans.

OBJECTIVES: The aim of this study was to assess whether transient episodes of symptomatic or silent myocardial ischemia after baroreceptor modulation of heart rate. BACKGROUND: Animal and human studies have shown that myocardial infarction is accompanied by an impairment of the baroreceptor influences on the sinus node. However, whether this also occurs during transient myocardial ischemia has never been documented. METHODS: In 12 patients undergoing coronary angiography, systolic blood pressure (intraarterial catheter) was reduced by an intravenous bolus of nitroglycerin during a spontaneous episode of transient chest pain and myocardial ischemia (ST segment depression on the electrocardiogram) and 30 min after recovery. The slope of the linear regression between the decrease in systolic blood pressure and the RR interval shortening was taken as the measure of baroreflex sensitivity. RESULTS: During ischemia, baroreflex sensitivity was 1.3 +/- 0.3 ms/mm Hg (mean +/- SEM), whereas after recovery it was markedly and significantly greater (2.6 +/- 0.5 ms/mm Hg, p < 0.01). Similar results were obtained in eight other patients who experienced a silent ischemic episode either spontaneously or during coronary angioplasty. The reduction in baroreflex sensitivity was similarly pronounced during inferior (10 patients) and anterior (10 patients) ischemia, and its magnitude showed little or no relation to the ischemia-dependent changes in blood pressure and heart rate. CONCLUSIONS: Transient myocardial ischemia is associated with marked baroreflex impairment. The impairment occurs even during symptomless ischemic episodes and is therefore not related to pain or to other nonspecific influences on the baroreflex.

Baroreflex↗
PubMed1993

Clinical value of ambulatory blood pressure monitoring.

Although office blood pressure measurement may be predictive of cardiovascular complications, it still has several limitations: first, the accuracy of its predictions is limited; second, the stress reaction it causes may lead to an overestimation of the need for treatment and to an underestimation of the therapeutic response in some patients; and third, because of this 'white-coat' reaction and the wide variation in blood pressure over 24 h, office blood pressure can only be an approximate reflection of 24-h average blood pressure values both during and in the absence of treatment. The alternative method of ambulatory blood pressure monitoring may represent a valuable approach in the clinical management of hypertension. Values derived by this method are largely devoid of the consequences of the 'white-coat' reaction and are more closely correlated to the organ damage associated with hypertension than those derived from office blood pressure measurement. However, longitudinal studies are needed to demonstrate whether ambulatory blood pressure monitoring is truly prognostically superior to the traditional method, and to determine precisely which are the blood pressure values within the 24-h period on which to base the diagnosis of hypertension to assess more accurately the efficacy of antihypertensive treatment. However, there is the suggestion that optimal blood pressure control probably consists of an even reduction of both daytime and night-time values, and that the wide variations in blood pressure that occur throughout 24 h should probably also be reduced and maintained on a long-term basis.

Blood Pressure Determination↗
PubMed1993

Isobaric compliance of the radial artery is increased in patients with essential hypertension.

OBJECTIVES: Hypertension is known to decrease arterial elasticity and systemic compliance. However, the arterial tree is not a homogeneous system, and whether a distal medium-sized artery such as the radial artery behaves like proximal arteries has not been determined. The aims of the present study were, first, to characterize non-invasively the mechanical properties of the radial artery through the determination of the pressure-diameter curve, the distensibility-pressure curve and the compliance-pressure curve, and, secondly, to compare untreated hypertensive patients with normotensive subjects. METHODS: A new high-precision echo-tracking device was developed which allows the diameter of peripheral arteries to be measured continuously. By relating the changes in internal diameter (cross-sectional changes) to those in blood pressure, the cross-sectional arterial compliance could be determined. PARTICIPANTS: Seventy-eight untreated mild or moderate essential hypertensive patients aged 24-78 years were compared with 44 normotensive subjects aged 22-81 years. In order to increase the database and provide independent assessments of the variables examined, the cross-sectional study was performed independently using a standardized procedure in three different research centres. RESULTS: The major finding was that diameter, distensibility and compliance of the radial artery of hypertensive patients were not significantly different from those of normotensive controls when the two populations were studied at their mean arterial pressure. Furthermore, when the two populations were compared for the same level of blood pressure, using distensibility--and compliance--pressure curves, it was clear that isobaric distensibility and compliance of hypertensives were not significantly lower than those of normotensives, being either unchanged or higher. CONCLUSIONS: These findings are in contrast with the well-known decrease in compliance of proximal large arteries due to hypertension. Whether such a difference between proximal large arteries and distal medium-sized arteries may be related to the structural vascular changes observed with long-standing hypertension is still difficult to analyse in humans, and requires further investigation.

Adult↗