Showing papers by "Giuseppe Mancia published in 1998"

Baroreflex Control of Sympathetic Nerve Activity in Essential and Secondary Hypertension

Abstract: Studies performed in experimental animals and in humans have documented that high blood pressure markedly impairs baroreceptor control of heart rate. Whether a similar impairment also characterizes baroreceptor control of sympathetic activity modulating peripheral vasomotor tone is still unknown. In 28 untreated essential hypertensive subjects [14 of moderate and 14 of more severe degree, age 51.6+/-2.4 and 52.6+/-2.1 years (mean+/-SEM)] and in 13 untreated secondary hypertensives (renovascular or pheochromocytoma, age 50.1+/-4.6 years), we measured beat-to-beat arterial blood pressure (finger photoplethysmographic device), heart rate (electrocardiogram), and efferent postganglionic muscle sympathetic nerve activity (microneurography) at rest and during baroreceptor stimulation and deactivation induced by stepwise intravenous infusions of phenylephrine and nitroprusside, respectively. Data were compared with those obtained in 15 age-matched normotensive control subjects. Muscle sympathetic nerve activity (bursts per 100 heart beats) showed a progressive and significant (P<.01) increase from normotension (40.3+/-3.3) to moderate (55.6+/-4.1) and more severe essential hypertension (68.2+/-4.1), paralleling the progressive increase in blood pressure values. In contrast, muscle sympathetic nerve activity was not increased in secondary hypertensives (40.5+/-6.7) despite blood pressure values similar to or even greater than those of severe essential hypertensives. In both essential and secondary hypertensives, baroreceptor-heart rate control was displaced toward elevated blood pressure values and markedly impaired compared with normotensive subjects (average reduction, 38.5%). In contrast, the sympathoinhibitory and sympathoexcitatory responses to baroreceptor stimulation and deactivation were displaced toward elevated blood pressure values but similar in all groups. Thus, sympathetic activation characterizes essential but not secondary hypertension. Regardless of its nature, however, hypertension is not accompanied by an impairment of baroreceptor modulation of sympathetic activity.

Body weight reduction, sympathetic nerve traffic, and arterial baroreflex in obese normotensive humans

Abstract: Background —Previous studies have shown that sympathetic cardiovascular outflow is increased in obese normotensive subjects and that this increase is associated with a baroreflex impairment. The purpose of this study was to determine whether these abnormalities are irreversible or can be favorably affected by body weight reduction. Methods and Results —In 20 obese normotensive subjects (age, 31.3±1.7 years; body mass index, 37.6±0.9 kg/m 2 , mean±SEM), we measured beat-to-beat arterial blood pressure (Finapres technique), heart rate (ECG), postganglionic muscle sympathetic nerve activity (microneurography at a peroneal nerve), and venous plasma norepinephrine (high-performance liquid chromatography) at rest and during baroreceptor stimulation and deactivation induced by increases and reductions of blood pressure via stepwise intravenous infusions of phenylephrine and nitroprusside. Measurements were repeated in 10 subjects after a 16-week hypocaloric diet with normal sodium content (4600 to 5000 J and 210 mmol NaCl/d) and in the remaining 10 subjects after a 16-week observation period without any reduction in the caloric intake. The hypocaloric diet significantly reduced body mass index, slightly reduced blood pressure, and caused a significant and marked decrease in both muscle sympathetic nerve activity (from 50.0±5.1 to 32.9±4.6 bursts per 100 heart beats, P P P P P Conclusions —In obese normotensive subjects, a reduction in body weight induced by a hypocaloric diet with normal sodium content exerts a marked reduction in sympathetic activity owing to central sympathoinhibition. This can be due to the consequences of an increased insulin sensitivity but also to a restoration of the baroreflex control of the cardiovascular system with weight loss.

Risk factors associated with alterations in carotid-intima-media thickness in hypertension: baseline data from the European lacidipine study on atherosclerosis

Abstract: Background The possibility that calcium antagonists exert an anti-atherosclerotic action at least partly independently of the blood-pressure-lowering effect is supported by results of a large number of experimental studies and can now be investigated by quantitative B-mode ultrasound imagining of the carotid artery walls. Design The European Lacidipine Study on Atherosclerosis (ELSA) is a prospective, randomized, double-blind, multinational trial comparing effects of 4-year treatment based on the long-acting, highly lipophilic calcium antagonist lacidipine with those of treatment based on the β-blocker atenolol on the development of carotid artery wall alterations in patients (aged 45-75 years) with mild-to-moderate hypertension (systolic blood pressure 150-210 mmHg and diastolic blood pressure 95-115 mmHg). While the intervention study is progressing, this article summarizes baseline data obtained from the whole cohort of 2259 patients randomly allocated to treatment Methods Baseline ultrasound data were obtained from two replicate examinations performed shortly before random allocation to treatment by certified sonographers at 23 referral centres and read at the ultrasound coordinating centre at the Wake Forest University School of Medicine. Intima-media thickness was measured at up to 12 different sites in the carotid artery tree and expressed as the mean of the maxima at these sites (M max ), the mean of the maxima at four sites in the distal common carotid artery and bifurcation (CBM max ) and the maximum intima-media thickness (T max ). Baseline demographic and clinical measurements were performed by investigators in 410 peripheral clinical units and 24 h ambulatory blood pressure monitorings read and validated by members of a centralized unit at the University of Milan. The statistical analysis centre at the Technische Universitat Munchen received and analysed all baseline data, by calculating means ± SD, medians and ranges and performing correlation (Spearman correlation coefficients) and multiple regression analyses. Results Prevalence of carotid artery wall alterations among the hypertensive patients randomly allocated to treatment in the ELSA was very high: 82% had T max ≥ 1.3 mm ('plaques' according to protocol) and 17% had T max ≥ 1.0 and <1.3 mm ('thickening'), with a median of two plaques per patient We found significant correlations between ultrasound measurements and the following demographic and clinical variables: age, sex, systolic blood pressure and pulse pressure (both clinic and ambulatory), concentrations of total, high-density lipoprotein and low-density lipoprotein cholesterol and triglycerides, smoking habit and duration of hypertension. We found no significant correlation to diastolic blood pressure and glucose concentration. A multiple regression analysis indicated significant variables in the following rank order: age, 24 h ambulatory pulse pressure, sex, low-density lipoprotein cholesterol concentration, triglyceride concentration, smoking and clinic systolic blood pressure. Conclusions Analysis of baseline data from the ELSA has shown that there is an extremely marked prevalence of carotid artery wall alterations among mild-to-moderate, middle-aged hypertensive patients.

Dissociation Between Muscle and Skin Sympathetic Nerve Activity in Essential Hypertension, Obesity, and Congestive Heart Failure

Abstract: —Essential hypertension, obesity, and congestive heart failure are characterized by an increase in muscle sympathetic nerve activity. Whether in these conditions skin sympathetic nerve activity is also increased has never been systematically examined, however. In 10 untreated mild essential hypertensive, 12 untreated normotensive obese, 10 mild (New York Heart Association class II) heart failure, and 10 normotensive lean healthy control subjects, we measured beat-to-beat arterial blood pressure (Finapres technique), body mass index, and postganglionic sympathetic nerve activity in skeletal muscle and skin areas (microneurographic technique, peroneal nerve). The muscle and skin nerve measurements were made in a randomized sequence. All data were obtained with the subject supine in a quiet, semidark environment at constant temperature over two periods of 30 minutes each, separated by a 20- to 30-minute interval. Blood pressure was increased only in hypertensive and body mass index only in obese subjects. Muscle sympathetic nerve activity quantified as bursts/min was markedly and significantly ( P

Reproducibility and clinical value of nocturnal hypotension: prospective evidence from the SAMPLE study. Study on Ambulatory Monitoring of Pressure and Lisinopril Evaluation

Abstract: ObjectiveTo assess whether modifications in the night-time blood pressure fall caused by antihypertensive treatment predict the regression of end-organ damage of hypertension.MethodsThe analysis was performed in patients with essential hypertension and echocardiographically detected left ventricular

Heart rate as marker of sympathetic activity.

Abstract: OBJECTIVE To determine the value of the supine heart rate as a marker of sympathetic tone by assessing, in a large group of subjects, the relationships between this parameter and two other indices of sympathetic activity, plasma norepinephrine and sympathetic nerve traffic. PATIENTS AND METHODS We studied 243 subjects aged 50.0+/-12.1 years (mean +/- SD). Of these, 38 were normotensive healthy controls, 113 subjects had untreated essential hypertension, 27 were obese normotensives and 65 had congestive heart failure. In each subject, over a 10 min supine period, we measured mean arterial pressure (Finapres), heart rate (electrocardiogram), venous plasma norepinephrine (high-performance liquid chromatography) and efferent postganglionic muscle sympathetic nerve activity (microneurography at a peroneal nerve). RESULTS In the whole study group, supine heart rate was correlated with both plasma norepinephrine (r = 0.32, P < 0.0001) and muscle sympathetic nerve activity (r = 0.38, P < 0.0001). This was also the case in the normotensive obese subjects and the heart failure subjects considered separately. Heart rate values were greater in the obese and the heart failure patients than in controls (75.1+/-13.0 and 78.2+/-13.0 versus 69.2+/-11.6 beats/min; P < 0.05 and P < 0.001, respectively), as were plasma norepinephrine (362.7+/-202 and 400.3+/-217 versus 230.4+/-126 pg/ml; P < 0.01 and P < 0.001, respectively) and muscle sympathetic nerve activity (44.1+/-14.7 and 55.3+/-14.3 versus 27.8+/-11.0 bursts/min; P < 0.001 for both). In contrast, in the essential hypertensive subjects, no significant relationship was found between these three indices of sympathetic activity. Furthermore, in the hypertensives, the heart rate was not increased, at variance with the sympathetic nerve traffic, which was greater than in controls (36.2+/-10.0 versus 27.8+/-11.0 bursts/min, P < 0.001). CONCLUSIONS These data suggest that the supine heart rate can be regarded as a marker of intersubject differences in sympathetic tone, and that this is the case both in the general population and in those with cardiovascular diseases. Its value for this purpose is limited, however, and the limitations may be more evident in essential hypertension than in conditions such as obesity and heart failure.

Seasonal variations in home and ambulatory blood pressure in the PAMELA population. Pressione Arteriose Monitorate E Loro Associazioni

Abstract: ObjectiveClinic blood pressure values are known to change according to seasonal influences. We therefore examined home and 24 h ambulatory blood pressure values to determine whether these measurements are also affected by the seasons.Design and methodsIn 2051 subjects of the Pressione Arteriose Moni

The smoothness index: a new, reproducible and clinically relevant measure of the homogeneity of the blood pressure reduction with treatment for hypertension.

Abstract: ObjectiveTo introduce a new method, the smoothness index, for assessing the homogeneity of 24 h blood pressure reduction by antihypertensive treatment and to compare it with the trough: peak ratio; and to assess the ability of both indices to predict a reduction in the left ventricular mass index in

Difference Between Clinic and Daytime Blood Pressure Is Not a Measure of the White Coat Effect

Abstract: The purpose of the present study was to evaluate whether the difference between blood pressure measured in the clinic or physician's office and the average daytime blood pressure accurately reflects the blood pressure response of the patient to the physician ("white coat effect" or "white coat hypertension"). We studied 28 hypertensive outpatients (mean age, 41.8+/-11.2 years; age range, 21 to 64 years) of 35 consecutive patients attending our hypertension clinic, in whom (1) continuous noninvasive finger blood pressure was recorded before and during the visit, (2) blood pressure was measured according to the Riva-Rocci-Korotkoff method (mercury sphygmomanometer) with the patient in the supine position, and (3) daytime ambulatory blood pressure was monitored with a SpaceLabs 90207 device. The peak blood pressure increase recorded directly during the visit was compared with the difference between clinic and daytime average ambulatory blood pressures. Compared with previsit values, peak increases in finger systolic and diastolic blood pressures during the visit to the clinic were 38.2+/-3.1 and 20.7+/-1.6 mm Hg, respectively (mean+/-SEM, P<.01 for both). Daytime average systolic and diastolic blood pressures were 135.5+/-2.5 and 89.2+/-1.9 mm Hg, with both lower than the corresponding clinic blood pressure values (146.6+/-3.6 and 94.9+/-2.2 mm Hg, P<.01). These differences, however, were <30% of the peak finger blood pressure increases during the physician's visit, to which these increases showed no relation. Although the visit to the physician's office was associated with tachycardia (9.0+/-1.6 bpm, P<.01), there was no difference between clinic and daytime average heart rates. These data indicate that the clinic-daytime average blood pressure difference does not reflect the alerting reaction and the pressure response elicited by the physician's visit and thus is not a reliable measure of the white coat effect.

Effect of chronic angiotensin converting enzyme inhibition on sympathetic nerve traffic and baroreflex control of the circulation in essential hypertension.

Abstract: BackgroundHuman studies have shown that the blood pressure lowering effects of angiotensin converting enzyme inhibitors are accompanied by a reduction in plasma norepinephrine levels. Whether this is due to central or peripheral mechanisms is unknown, however.ObjectiveTo evaluate the effects of chro

Limitations of the difference between clinic and daytime blood pressure as a surrogate measure of the 'white-coat' effect. Syst-Eur investigators

Abstract: BackgroundThe difference between clinic and ambulatory average daytime blood pressures is frequently taken as a surrogate measure of the ‘white-coat effect’ (i.e. the pressor reaction triggered in the patient by the physician's visit).ObjectiveTo assess the reproducibility of this difference and its

Antihypertensive treatment : past, present and future

Abstract: THE PAST Guidelines for pharmacological and non-pharmacological approaches to the treatment of hypertension were first published in 1977 and were subsequently revised in the 1980s. They were largely based on the approach known as 'stepped care', which suggests that antihypertensive treatment should be started with the initial use of a thiazide diuretic, followed by the addition of a second, third and fourth drug if no satisfactory therapeutic success is obtained. This approach was reviewed in the guidelines that followed, which indicated that pharmacological treatment should be started in a more liberal fashion by selecting the antihypertensive drug from among four rather than two classes (diuretics, beta-blockers, angiotensin converting enzyme inhibitors and calcium antagonists). THE PRESENT The latest guidelines issued in 1993 by the World Health Organization/International Society of Hypertension and by the Joint National Committee contain innovative aspects on how to treat high blood pressure. They share common features, such as lifelong treatment of hypertension, attention to overall cardiovascular risk profile, initiation of treatment with lifestyle changes and subsequently with monotherapy, but they also have differences, such as goal blood pressure, initial blood pressure values to be treated and first-choice drug. For example, according to the World Health Organization/International Society of Hypertension guidelines first-choice drugs include five classes of drug, whereas the Joint National Committee guidelines advocate two classes of drug for first choice. THE FUTURE It is likely that the 'stepped care' approach for hypertension treatment will continue to be employed in the future, although greater attention will be devoted to the need for combination drug treatment. Greater importance will be also given to the non-pharmacological antihypertensive approaches, as well as to baseline blood pressure values at which drug treatment should be started.

Nitric Oxide–Dependent Vasodilation in Young Spontaneously Hypertensive Rats

Abstract: —Conflicting evidence exists on the possible impairment of tonic nitric oxide (NO)–mediated vasodilation as a causative factor in the genesis of human as well as experimental hypertension. We evaluated the tonic NO-dependent vasodilation from the pressor response to NO synthesis inhibition by N G-monomethyl-l-arginine (L-NMMA) in 9 conscious, chronically instrumented spontaneously hypertensive rats (SHR) at 12 weeks of age, ie, during the early established hypertensive stage. Nine age-matched Wistar-Kyoto rats (WKY) were used as controls. The pressor responses to L-NMMA (100 mg · kg−1 IV bolus plus 1.5 mg · kg−1 · min−1 infusion for 60 minutes) as well as to non–NO-dependent pressor stimuli, namely, vasopressin (2, 4, and 8 ng · kg−1) and phenylephrine (0.5, 1, and 2 μg · kg−1) given as IV boluses, were assessed both under control conditions and during suppression of autonomic reflexes by hexamethonium (30 mg · kg−1 IV bolus+1.5 mg · kg−1 · min−1 infusion). Rather than being reduced, the pressor responses to L-NMMA were 39% and 71% larger in the control and areflexic conditions, respectively, than those observed in WKY (both P <0.01). A similar pattern was observed for the pressor responses to vasopressin (+37% and +68% in the control and areflexic conditions, respectively; both P <0.01) and phenylephrine, (+20% and +52%; both P <0.05). Additional groups of 6-week-old prehypertensive SHR (n=11) and age-matched WKY (n=11) were subjected to an identical protocol: in these animals, the pressor responses to L-NMMA were similar in each strain, as were the pressor responses to vasopressin and phenylephrine in both control and areflexic conditions. In conclusion, our observations indicate that during the developmental phase of hypertension in the SHR model, namely, during the prehypertensive as well as the early established hypertensive stage, NO-dependent vasodilation is preserved (if not enhanced) so that a putative impairment of this function provides no significant pathogenic contribution to the onset of hypertension in this experimental model.

Hemodilution Reduces Clinic and Ambulatory Blood Pressure in Polycythemic Patients

Abstract: Limited information is available for humans on whether blood viscosity affects total peripheral resistance and, hence, blood pressure. Our study was aimed at assessing the effects of acute changes in blood viscosity on both clinic and 24-hour ambulatory blood pressure (BP) values. In 22 normotensive and hypertensive patients with polycythemia, clinic and 24-hour ambulatory BPs were measured before and 7 to 10 days after isovolumic hemodilution; this was performed through the withdrawal of 400 to 700 mL of blood, with concomitant infusion of an equivalent volume of saline-albumin solution. Hematocrit, plasma renin activity, plasma endothelin-1, right atrial diameter (echocardiography), and blood viscosity were measured under both conditions. Plasma renin activity and right atrial diameter were used as indirect markers of blood volume changes. Plasma endothelin-1 was used to obtain information on a vasomotor substance possibly stimulated by our intervention, which could counteract vasomotor effects. Isovolumic hemodilution reduced hematocrit from 0.53+/-0.05 to 0.49+/-0.05 (P<.01). Plasma renin activity, plasma endothelin-1 and right atrial diameter were unchanged. Clinic blood pressure was reduced by hemodilution (systolic, 144.3+/-5.4 to 136.0+/-3.9 mm Hg[mean+/-SEM]; diastolic, 87.0+/-2.8 to 82.1+/-2.6 mm Hg, P<.05 for both) and a reduction was observed also for 24-hour average ABP (systolic, 133.6+/-2.9 to 129.5+/-2.7 mm Hg; diastolic, 80.0+/-2.0 to 77.3+/-1.7 mm Hg, P<.05 for both). The reduction was consistent in hypertensive patients (n = 12), whereas in normotensive patients (n = 10) it was small and not significant. Both clinic and 24-hour average heart rates were unaffected by the hemodilution. Thus, in polycythemia, reduction in blood viscosity without changing blood volume causes a significant fall in both clinic and 24-hour ambulatory BPs; this is particularly true when, as can often happen, blood pressure is elevated. This emphasizes the importance this variable may have in the determination of blood pressure and the potential therapeutic value of its correction when altered.

Reproducibility and Clinical Value of the Trough-to-Peak Ratio of the Antihypertensive Effect: Evidence From the Sample Study

Abstract: The objectives of our study were to assess the reproducibility of the trough-to-peak ratio (T/P) and to see whether a high T/P is accompanied by more organ protection or vice versa. The study included 175 (mean+/-SD age, 51+/-9 years) subjects with mild-moderate essential hypertension who had echocardiographic evidence of left ventricular (LV) hypertrophy taken from the SAMPLE study (Study on Ambulatory Monitoring of Blood Pressure and Lisinopril Evaluation), an open-label multicenter study. The study included a 3-week washout pretreatment period, a 12-month treatment period with lisinopril (n=84) or lisinopril plus hydrochlorothiazide (n=91) once daily, and a 4-week placebo follow-up period. Results of 24-hour ambulatory blood pressure monitoring and echocardiographic determination of left ventricular mass index (LVMI) were obtained before and after 3 and 12 months of treatment. T/Ps were computed in each patient by dividing the systolic and diastolic blood pressure changes at trough (changes in the last 2 hours of the monitoring period) by those at peak (average of the 2 adjacent hours with the maximal blood pressure reduction between the 2nd and 8th hour from drug intake) after 3 and 12 months of treatment. Average 24-hour blood pressure was similarly reduced at 3 and 12 months. Trough blood pressure changes at 3 and 12 months were closely correlated, as were the corresponding peak blood pressure changes. However, the 3- and 12-month T/Ps correlated to a lesser degree (r /=0.5 or <0.5, the regression of LVMI was similar. In conclusion, peak and trough blood pressure changes are reproducible and predict the regression of LVMI induced by treatment as well as average 24-hour blood pressure. T/Ps are less reproducible, and their value does not predict regression of organ damage by antihypertensive treatment.

The trough:peak ratio and the smoothness index in the evaluation of control of 24 h blood pressure by treatment in hypertension.

Abstract: The duration and homogeneity of the antihypertensive effect of a drug are commonly quantified by computation of the trough:peak ratio (T/P) from 24 h ambulatory blood pressure recordings [i.e. the ratio of the reduction in blood pressure at the end of the interval between doses (trough) and the reduction in blood pressure at the time of the maximal effect of a drug (peak)]. Although it is widely employed, this index has a lot of limitations: it makes use of only a small portion of a 24 h blood pressure recording; individual T/P values do not have a normal distribution, unless responders at peak are selected; it bears no relation to 24 h blood pressure variability; peak changes in blood pressure are affected by a placebo effect and thus T/P needs correction for effects of placebo; peak and trough changes in blood pressure are reproducible over time but T/P is not; and, finally, it was shown in the SAMPLE study that T/P is not correlated to changes in left ventricular mass induced by treatment, and thus has a limited clinical value.

Effects of Isolated Systolic Hypertension and Essential Hypertension on Large and Middle-sized Artery Compliance

Abstract: Background: Systolic hypertension of the elderly is characterized by a reduction in arterial compliance. Whether and to what extent this involves arteries of various structure and size is not well known. Objective: To study carotid and radial artery compliance in systolic hypertension of the elderly, compared to essential hypertension and normotension. Methods

Lack of autonomic contributions to tonic nitric oxide-mediated vasodilatation in unanesthetized free-moving rats.

Abstract: OBJECTIVE To clarify the controversial issue of whether autonomic influences modulate vascular nitric oxide-mediated vasodilatation or even directly contribute to production of nitric oxide (NO) via nitroxidergic fibers. METHODS Chronic venous and arterial catheters were implanted in Wistar-Kyoto rats (n = 65) for continuous blood pressure measurement, drug administration and blood sampling. Tonic NO-dependent vasodilatation in the conscious free-moving animal was evaluated as the pressor response to inhibition of NO synthesis by intravenous L-monomethylarginine (a 100 mg/kg intravenous bolus plus 0.5 mg/kg per min infusion for 30 min). Experiments were performed under control conditions, chemical sympathectomy by 6-hydroxy-dopamine, ganglionic blockade by hexamethonium, and surgical denervation of sino-aortic baroreceptors. RESULTS Baseline mean arterial pressure was 100+/-4 mmHg (mean +/- SEM) in control rats and 73+/-3, 62+/-5, and 105+/-10 mmHg in sympathectomized, ganglion-blocked, and denervated rats, respectively. The peak increase in mean arterial pressure after administration of L-monomethylarginine was 38+/-3 mmHg in control rats and 51+/-3, 50+/-6, and 63+/-10 mmHg in sympathectomized, ganglion-blocked, and denervated rats, respectively. Epinephrine and norepinephrine levels in rats of separate groups of unanesthetized control, sympathectomized and ganglion-blocked animals were measured by high-performance liquid chromatography from an arterial blood sample, the results indicating drastic reductions in levels of both catecholamines in the ganglion-blocked (but not in the sympathectomized) rats compared with those in the control rats. CONCLUSIONS Tonic NO-dependent vasodilatation can normally be maintained in the unanesthetized unrestrained rat irrespective of autonomic or humoral adrenergic influences.

Methods to quantify sympathetic cardiovascular influences

Abstract: This paper will critically review the main features of the various techniques (plasma noradrenaline assay. noradrenaline spillover technique, microneurographic recording of postganglionic muscle sympathetic nerve and power spectral analysis of blood pressure and heart rate signals in specific bands) currently employed to assess sympathetic cardiovascular control in humans. After highlighting the advantages and limitations of each approach, the paper will describe some of the results obtained by employing the above mentioned techniques to detect abnormalities in ympathetic cardiovascular tone in physiological and pathological conditions.

Effects of Prolonged Immobilization of the Limb on Radial Artery Mechanical Properties

Abstract: Physical training is associated with an increase in arterial distensibility. Whether the effect of training on this variable is evident also for ordinary levels of exercise or no exercise is unknown, however. We have addressed this issue by investigating the effect on radial artery distensibility of prolonged monolateral immobilization of the ipsilateral limb versus the following resumption of normal mobility. We studied 7 normotensive subjects (age, 25.4+/-3.0 years; systolic/diastolic blood pressure, 119+/-9/68+/-6 mm Hg, mean+/-SE) in whom 1 limb had been immobilized for 30 days in plaster because of a fracture of the elbow. At both the day after plaster removal and after 45 days of rehabilitation, radial artery distensibility was evaluated by an echo-tracking device (NIUS-02), which allows arterial diameter to be measured noninvasively and continuously over all pressures from diastole to systole (finger monitoring), with the distensibility values being continuously derived from the Langewouters formula. In both instances, the contralateral arm was used as control. Immediately after removal of the plaster, radial artery distensibility was markedly less in the previously immobilized and fractured limb compared with the contralateral limb (0.4+/-0.1 versus 0.8+/-0.1, 1/mm Hg 10(-3), P<0.05). After rehabilitation, the distensibility of the radial artery was markedly increased in the previously fractured limb (0.65+/-0.1 1/mm Hg 10(-3), P<0.05), whereas no change was seen in the contralateral limb. Thus, complete interruption of physical activity is associated with a marked reduction of arterial distensibility, indicating that even an ordinary level of activity plays a major role in modulation of arterial mechanical properties.

The International Nifedipine GITS Study of Intervention as a Goal in Hypertension Treatment (INSIGHT) trial

Abstract: Several trials have shown that antihypertensive drug treatment decreases cardiovascular morbidity and mortality rates. They have also shown, however, that the risk is not decreased to the level of nonhypertensive patients. Trials are therefore underway to determine whether the benefits achieved by older drugs, such as diuretics and beta blockers, can be enhanced by using newer classes of antihypertensive agents, such as calcium antagonists, angiotensin-converting enzyme (ACE) inhibitors, and angiotensin II receptor antagonists. Among these trials, the International Nifedipine GITS Study of Intervention as a Goal in Hypertension Treatment (INSIGHT) is of special interest because it is the first study to address, in a prospective fashion, the prognostic influence of antihypertensive treatment (nifedipine GITS vs a combined thiazide and potassium-sparing diuretic) in hypertensive patients with concomitant risk factors such as hypercholesterolemia, cigarette smoking, diabetes, and left ventricular hypertrophy. This article briefly describes the rationale and design of the INSIGHT trial and cites the substudies and the preliminary data available.

Early and late sympathetic activation in hypertension

Abstract: In several experimental animal models of hypertension, sympathetic factors have been shown to be involved in the development and/or maintenance of high blood pressure. Although the information available on this issue in man is more scarce, recent evidence clearly indicates the participation of adrenergic mechanisms in the early and late phases of the hypertensive process. In addition, several cardiovascular risk factors frequently associated with hypertension, such as obesity, insulin-resistance, cigarette smoking, and the atherogenic process, are also characterized by alterations in sympathetic cardiovascular drive. This contributes to a further activation of the sympathetic nervous system thus favoring the development of the end organ damage (e.g. cardiac and vascular hypertrophy) associated with the hypertensive state.

Arterial distensibility in cardiovascular diseases.

Abstract: Several pathological conditions affecting the cardiovascular system are characterized by a dysfunction of the viscoelastic properties of the arterial vessels and, in particular, of arterial distensibility and compliance. These alterations have pathophysiological and clinical relevance because both distensibility and compliance play a key role in cardiovascular homeostatic control by modulating a number of important parameters, such as arterial impedence, cardiac afterload and myocardial oxygen consumption. This paper, after briefly mentioning the technical progress recently achieved in the assessment of arterial compliance in man, will examine the alterations in this vascular function which take place in hypertension, hypercholesterolemia, diabetes and congestive heart failure. It will also discuss the mechanisms potentially responsible for these alterations and the effects of cardiovascular drugs commonly employed in the treatment of these diseases.