Showing papers by "Giuseppe Mancia published in 1992"

Persistent blood pressure increase induced by heavy smoking.

Abstract: Objective: To test the hypothesis that heavy smoking is associated with a persistent increase in blood pressureDesign: In 10 normotensive smokers asked to smoke one cigarette every 15 min for 1 h, blood pressure and heart rate were continuously monitored during the smoking period and during the prec

Evaluation of noninvasive blood pressure monitoring devices Spacelabs 90202 and 90207 versus resting and ambulatory 24-hour intra-arterial blood pressure.

Abstract: This study evaluated the accuracy of blood pressure values provided by the Spacelabs 90202 and 90207 devices in comparison with intra-arterial recording in 19 subjects at rest and in nine subjects in ambulatory conditions (Oxford method). At rest Spacelabs monitors reflected intra-arterial systolic blood pressure values very closely but overestimated to a considerable extent intra-arterial diastolic blood pressure (Spacelabs-intra-arterial differences, -0.8 +/- 9.2, NS, and 9.1 +/- 8.8 mm Hg, p less than 0.01, for systolic and diastolic blood pressures, respectively). In ambulatory conditions Spacelabs-intra-arterial average differences in 24-hour values were +0.4 +/- 5.1 mm Hg for systolic blood pressure (NS) and +14.0 +/- 2.9 mm Hg for diastolic blood pressure (p less than 0.01) when group data were considered. The performance of both Spacelabs devices was worse when assessed in individual subjects or for each hourly interval. In spite of these differences between noninvasive and intra-arterial absolute blood pressure values, however, Spacelabs 90202 and 90207 monitors were able to faithfully reflect directional hour-to-hour changes in intra-arterial blood pressure (chi 2 = 18.2 and chi 2 = 23.1 for systolic and diastolic blood pressures, respectively, p less than 0.01). No differences were found between the performance of the two Spacelabs devices. Thus, although the absolute accuracy of blood pressure values provided by these monitors in ambulatory subjects is still limited, they seem to be suitable for studies aimed at assessing 24-hour blood pressure profiles quantitatively as well as qualitatively.

Limited reproducibility of hourly blood pressure values obtained by ambulatory blood pressure monitoring: implications for studies on antihypertensive drugs.

Abstract: OBJECTIVE To assess the reproducibility of average hourly blood pressure values obtained by 24-h non-invasive ambulatory monitoring. PATIENTS Fifteen outpatients with essential hypertension. In all subjects antihypertensive treatment was withdrawn for 4 weeks before and during the 4 weeks of the study. METHODS The 24-h blood pressure was monitored by a SpaceLabs 5300 device (four readings per hour during the day and three readings per hour during the night) twice, at a 4-week interval. Systolic (SBP) and diastolic blood pressure (DBP) were averaged for each hour and for the whole 24-h period, and hourly and 24-h reproducibility was quantified by the standard deviation of the mean difference (SDD) between the values obtained in the two recordings. RESULTS The SDD of hourly SBP and DBP was much greater than that of the 24-h values and ranged widely between the hours of recording. The SDD of hourly SBP and DBP were also variably greater than the SDD of the 24-h value in another 14 untreated essential hypertensives in whom 24-h ambulatory blood pressure was monitored intra-arterially twice at a 4-week interval to calculate hourly average blood pressure on thousands rather than on three or four values per hour. CONCLUSION Reproducibility is less for hourly than for 24-h average blood pressure. This feature (which probably depends on behavioural differences between two recordings) suggests that ambulatory blood pressure measurement partly loses its advantages for reproducibility and reduction in trial size if the results are analysed over hourly periods.

Effects of graded vasoconstriction upon the measurement of finger arterial pressure.

Abstract: Objective To assess the effects of incremental phenylephrine infusion rates and subsequent graded vasoconstriction upon the performance of the Ohmeda Finapres. Design Blood pressure in eight hypertensive patients in the finger and the brachial artery was recorded simultaneously. Systolic blood pressure (SBP), diastolic blood pressure (DPB) and mean arterial pressure (MAP) were compared as well as additional waveform characteristics like the pressure at moment of the dicrotic notch and calculation of the pulsatile-systolic areas. Results Before phenylephrine infusion SBP and DBP were higher in the finger. At maximal infusion (1.6 micrograms/kg/min) the increase in brachial SBP was significantly underestimated by Finapres. Thus, the computed sensitivities of baroreflex control for SBP differed significantly between the two measurements. Under control conditions, the shape of the finger waveform differed from the brachial-artery waveform in terms of: (1) a more peaked appearance; (2) a dicrotic notch (Pnotch) which is located at a lower percentage of pulse pressure; and (3) a larger pulsatile-systolic area. At maximal infusion rates finger Pnotch increased whilst intrabrachial Pnotch did not. In contrast, the brachial and finger pulsatile-systolic areas changed fully in parallel. Conclusions Phenylephrine infusion caused a significant, and clinically important, underestimation of the increase in brachial SBP when assessed by Finapres, whereas MAP and DBP and pulsatile-systolic area track intra-arterial pressure reliably.

Ambulatory blood pressure monitoring in elderly patients with isolated systolic hypertension.

Abstract: Objectives: This study compared clinic and ambulatory blood pressure measurement and the reproducibility of these measurements in older patients with isolated systolic hypertension (Isti). Patients: Eighty-seven patients aged 260 years with ISH on clinic measurement were followed in the placebo run-in phase of the Syst-Eur trial. Methods: Clinic blood pressure was defined as the mean of two blood pressure readings on each of three clinic visits (six readings in total). Ambulatory blood pressure was measured over 24 h using non-invasive ambulatory blood pressure monitors. Results: Daytime ambulatory systolic pressure was, on average, 21 mmHg lower than the clinic blood pressure, whereas diastolic pressure was, on average, similar with both techniques of measurement. In the 42 patients who had repeat measurements, clinic blood pressure levels and the amplitude of the diurnal blood pressure profile (fitted by Fourier analysis) were equally reproducible. However, both were less reproducible than ambulatory blood pressure levels. The repeatability coefficients, expressed as per cent of near gaximum variation (four times the standard deviation of a given measurement), were 52% and 45% for the clinic systolic and diastolic pressures, 56010 and 42% for the amplitude of the diurnal profile, and 29% and 26% for mean 24-h pressures. Conclusions: In older patients with ISH, clinic and ambulatory systolic blood pressure measurements may differ largely: the prognostic significance of this difference remains to be elucidated. Furthermore, in these patients the level of pressure is more reproducible by daytime ambulatory blood pressure measurement than by clinic measurement.

Reflex cardiovascular control in congestive heart failure.

Abstract: This article reviews evidence that the reflex control of the cardiovascular system provided by negative feedback mechanisms is impaired in congestive heart failure (CHF). The impairment involves vagal and sympathetic modulation of the heart exerted by arterial baroreceptors. It also affects baroreceptor control of blood pressure and peripheral vascular resistance, as well as the cardiopulmonary receptor's ability to modulate sympathetic activity. The degree of such impairment is most marked in severe CHF but is also apparent, to a minor degree, in mild heart failure. Reflex impairment is due to a reduction in the receptor signal, but other factor under investigation are probably also involved. Digoxin and other pharmacologic treatments of CHF improve reflex function, thereby facilitating a reduction in the elevated sympathetic activity and a stepping up of the reduced vagal activity typical of CHF. This may be relevant to a patient's prognosis.

Cigarette smoking and the adrenergic nervous system.

Abstract: The acute increase in blood pressure and heart rate that accompanies cigarette smoking is associated with a rise in plasma catecholamines and it is thus believed to result from stimulation of the adrenergic nervous system. We have employed direct recording of efferent post-ganglionic sympathetic nerve activity by the microneurographic technique from the peroneal nerve to determine whether this stimulation occurs centrally or peripherally. It was shown that during cigarette smoking blood pressure, heart rate, plasma norepinephrine and epinephrine do increase markedly. Sympathetic nerve activity, however, shows a concomitant specular reduction. Thus peripheral (adrenal gland stimulation, reduction in norepinephrine reuptake, reduction in catecholamine clearance, etc.) rather than central mechanisms explain the adrenergic involvement in the acute hemodynamic effect of smoking, the central sympathetic drive being inhibited rather than excited probably as a result of arterial baroreceptor stimulation.

Evaluation of the antihypertensive effect of once-a-day trandolapril by 24-hour ambulatory blood pressure monitoring

Abstract: The aim of this study was to evaluate the effects of trandolapril on 24-hour blood pressure in patients with mild-to-moderate essential hypertension. After a washout period of 4 weeks, 42 patients were randomized to receive 2 mg of trandolapril once dairy and 20 to receive placebo in a double-blind fashion for 6 weeks. This was followed by a second washout period of 4 weeks. At the end of each period, clinic blood pressure was assessed at 24 hours after the last dose and 24-hour ambulatory blood pressure was measured noninvasively, taking blood pressure readings every 15 minutes during the day and every 20 minutes during the night. Two patients were dropped out before any blood pressure evaluation under treatment. Analysis of ambulatory blood pressure was performed in 48 patients who met the criteria for the minimal number of ambulatory blood pressure data (2 values per hour during the day and 1 value per hour in the night). In the trandolapril-treated group (n = 41) clinic systolic/diastolic blood pressures were 159.8 ± 2.0/ 102.4 ± 0.8, 146.8 ± 2.3/94.8 ± 1.1, and 155.7 ± 2.0/99.2 ± 0.7 mm Hg in the pretreatment, treatment, and post-treatment periods, respectively. The corresponding values for 24-hour mean blood pressure (n = 31) were 139.5 ± 1.9 91.2 ± 1.5, 131.0 ± 2.0 84.3 ± 1.2, and 139.7 ± 1.8 90.9 ± 1.1 mm Hg. The differences between the lower treatment, versus the higher pre- and post-treatment, values were all statistically significant (p

Sympathomoderating influence of benazepril in essential hypertension

Abstract: OBJECTIVE In essential hypertension, captopril attenuates forearm vasoconstriction reflexly induced by deactivation of cardiopulmonary and arterial baroreceptors, thus exerting a sympathomoderating effect. We investigated whether this is a common effect of angiotensin converting enzyme (ACE) inhibitors. METHODS AND DESIGN Cardiopulmonary and arterial baroreceptors were deactivated by progressively reducing central venous pressure (CVP) through progressively greater lower body negative pressures in eight untreated mild essential hypertensives on a moderately low-sodium diet (50 mmol/l per day). This deactivation was performed after oral administration of the non-sulphidrylic ACE inhibitor benazepril (10 mg) and placebo according to a double-blind randomized crossover experimental design. RESULTS After placebo, the reduction in CVP increased forearm vascular resistance (FVR; mean arterial pressure: plethysmographic forearm blood flow ratio). After benazepril, baseline blood pressure (beat-to-beat finger pressure) and FVR were significantly reduced whilst plasma angiotensin II was suppressed and PRA increased (both measured by radioimmunoassay). The FVR increases induced by progressive CVP reduction were less than after placebo administration, and the overall difference was statistically significant. Benazepril did not affect the reflex FVR reduction observed by increasing CVP through leg raising, nor the reflex changes in plasma norepinephrine measured by high-performance liquid chromatography accompanying the changes in FVR. CONCLUSIONS Benazepril attenuates sympathetic vasoconstriction as does captopril. This effect (which is mainly operative during an increased sympathetic drive and exerted through a reduction of adrenoceptor responsiveness) is thus likely to be a class- rather than a compound-related feature.

Cardiopulmonary receptor and arterial baroreceptor reflexes after acute myocardial infarction

Abstract: The baroreceptor-heart rate reflex in human is impaired 2 days after a myocardial infarction but it improves 10 days after the acute coronary event. This study investigated whether (1) the baroreceptor-heart rate reflex improvement takes the reflex back to normal, and (2) the cardiopulmonary reflex is affected by myocardial infarction. In subjects studied 8 to 11 days after a transmural anterior or inferior myocardial infarction the baroreceptor-heart rate reflex sensitivity (slope of the linear regression between negative neck chamber pressures and lengthenings in RR interval) was similar to that seen in control subjects (-6.2 +/- 0.8 vs -6.0 +/- 0.6 ms/mm Hg, mean +/- SEM) and did not change when reassessed 10 days later. In contrast, the cardiopulmonary reflex sensitivity (changes in forearm vascular resistance induced by changing central venous pressure through nonhypotensive lower body suction and leg raising) was markedly less in subjects studied 8 to 11 days after myocardial infarction than in control subjects; the reduction amounted to 58.1 +/- 8% (p less than 0.01). The cardiopulmonary reflex sensitivity greatly improved when reassessed 28 to 45 days later. Thus, the baroreflex is normal about 10 days after myocardial infarction. This condition markedly impairs the cardiopulmonary reflex, but the impairment is also transient.

Cardiac parasympathetic hyperresponsiveness in spontaneously hypertensive rats.

Abstract: The bradycardic response to baroreceptor stimulation is impaired in human and experimental hypertension. Because this bradycardia mainly depends on the vagus, this may reflect a reduced cardiac parasympathetic responsiveness, which would parallel the reduced cardiac adrenergic responsiveness observed in hypertension. To test this hypothesis, 12-week-old spontaneously hypertensive rats (n = 12) and normotensive Wistar-Kyoto rats (n = 11) were anesthetized with ketamine and underwent bilateral vagotomy. Cardiac parasympathetic responsiveness was assessed from the bradycardia induced by 1) graded electrical stimulation of the right efferent vagus (1-16 Hz) and 2) graded intravenous injections of methacholine (1-8 micrograms.kg-1). The slope of the linear regression between the bradycardiac response and the applied stimulus was taken as the measure of cardiac parasympathetic responsiveness. To identify the onset of possible alterations in cardiac parasympathetic responsiveness in hypertension, the study was extended to younger (8-week-old) spontaneously hypertensive (n = 11) and Wistar-Kyoto (n = 13) rats. With vagal stimulation, cardiac parasympathetic responsiveness was greater in 12-week-old spontaneously hypertensive rats than in 12-week-old Wistar-Kyoto rats (24.8 +/- 5.4 versus 10.1 +/- 1.2 beats per minute per hertz, mean +/- SEM, p less than 0.035). This was also the case with methacholine (18.8 +/- 3.5 versus 13.1 +/- 4.4 beats per minute per microgram per kilogram, p less than 0.045). In contrast, cardiac parasympathetic responsiveness was similar, with both vagal stimulation and methacholine, when tested in the younger spontaneously hypertensive and Wistar-Kyoto groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in arterial compliance induced by physical training in hammer-throwers.

Abstract: OBJECTIVE Physical training induces multiple changes in the cardiovascular system which allow an increased performance along with increased oxygen consumption. The present study was designed to investigate whether the changes include an increase in arterial compliance. METHODS AND DESIGN In six normotensive right-handed hammer-throwers (aged 21.3 +/- 1.8 years, mean +/- SE) we measured radial artery diameter continuously via a new non-invasive echo-tracking device, and beat-to-beat blood pressure. Arterial compliance was calculated by an arctangent model. In each subject measurements were made from both the left and the right arm. The data were compared with those obtained in six age-matched normotensive controls. RESULTS Compared to the controls, the hammer-throwers had similar blood pressure, a lower heart rate and plasma norepinephrine and a higher left ventricular mass index and radial artery diameter. In the athletes, right radial artery compliance was significantly greater than either right or left radial artery compliance in the sedentary subjects (+61 and 63%, P < 0.05). It was also significantly greater than contralateral radial artery compliance (+53 +/- 8%, P < 0.05). CONCLUSIONS Physical training is accompanied by an increase in arterial compliance. In our hammer-throwers this increase was mainly evident in the more highly trained arm, suggesting that local mechanisms are involved in this phenomenon.

Changes in 24 hour blood pressure and in cardiac and vascular structure in normotensive subjects with parental hypertension.

Abstract: Subjects with family history of hypertension represent a suitable model to investigate the mechanisms responsible for early cardiovascular structural and functional changes occurring in essential hypertension. In our study we have addressed the factors involved in determining the mild elevation in office blood pressure frequently observed in normotensive subjects with hypertensive parents. In 15 normotensive subjects with both parents hypertensive (FH++) and in 15 normotensive subjects with one parent hypertensive (FH+−) we found no evidence of a hyperreactivity to stress as compared to the responses of 15 normotensive subjects with no parental hypertension (FH–). On the contrary FH++ subjects were characterized by a significant although mild increase in their blood pressure values recorded either at rest and in ambulatory conditions over the 24 hours, including night sleep. FH++ and FH+− subjects also showed a greater left ventricular mass thickness and a greater minimal forearm vascular resistence than ...

Variability in arterial diameter and compliance: compliance modulation reserve.

Abstract: BACKGROUND Some antihypertensive drugs are known to increase arterial compliance in hypertensives; how far compliance can be increased is unknown. DESIGN We studied eight mildly hypertensive patients to determine how far radial artery compliance can be acutely increased, i.e. the extent of the compliance modulation reserve. METHODS We evaluated radial artery compliance by a new technique, assessing it throughout the cardiac cycle before and after the intra-arterial infusion of a vasodilator agent (papaverine). RESULTS Before papaverine, compliance decreased progressively through diastolic to systolic blood pressure values. This was the case also during the papaverine infusion. However, over the full systolo-diastolic pressure range, compliance was increased by about 40% with papaverine. CONCLUSIONS In hypertensive subjects radial artery compliance can be markedly increased on a acute basis, indicating that those antihypertensive drugs that improve compliance have a considerable reserve to act upon.

Effect of detraining on the cardiopulmonary reflex in professional runners and hammer throwers

Abstract: In professional athletes with marked cardiac hypertrophy, reflex influences originating from cardiopulmonary receptors are impaired. To determine whether the reflex is restored after termination of physical training and regression of cardiac hypertrophy 8 former athletes (age 31 +/- 6 years, mean +/- SD) who stopped agonistic activity for 5 +/- 1 years were compared with 15 sedentary subjects (27 +/- 7 years) and 19 active professional athletes (22 +/- 7 years). Cardiopulmonary receptor stimulation and deactivation were obtained by increasing and reducing left ventricular end-diastolic diameter (echocardiography) through leg raising and nonhypotensive lower body negative pressure, respectively. Left ventricular mass index (echocardiography) was markedly and significantly (p less than 0.01) greater in athletes (135 +/- 6 g/m2) than in former athletes (105 +/- 4 g/m2) whose value was similar to that of sedentary subjects (98 +/- 4 g/m2). The reduction in forearm vascular resistance and plasma norepinephrine induced by increasing left ventricular end-diastolic diameter was 24 and 23% less in athletes than in former athletes whose responses were similar to those of sedentary subjects. This was the case also for the responses induced by reducing left ventricular end-diastolic diameter. In contrast, the hemodynamic responses to cold pressor test were similar in the 3 groups. It is concluded that the impairment of the cardiopulmonary reflex observed in athletes is largely reversible when physical training is terminated. This may be due to regression of left ventricular hypertrophy.

Ambulatory blood pressure monitoring and antihypertensive treatment

Abstract: This paper outlines the advantages of ambulatory blood pressure monitoring (ABPM) in the evaluation of the efficacy of antihypertensive drugs. The main advantage is that ABPM allows the antihypertensive effect of a drug or drug regimen to be determined in daily life conditions and to uncover whether the treatment employed is associated with untoward hypotensive episodes. Furthermore, ABPM facilitates the design of studies on antihypertensive drug efficacy because the 24 h mean blood pressure is devoid of a placebo effect and its reproducibility is much greater than office blood pressure. This has permitted demonstration of the efficacy of several antihypertensive drug regimens, including diuretic studies, based on relatively small numbers of subjects. A further advantage of ABPM is that it allows drug treatment efficacy to be evaluated in relation to blood pressure variability, another possible determinant of the organ damage related to hypertension.

The neck chamber technique.

Abstract: Since the first description of the neck chamber technique for stimulating carotid baroreceptors by Ernsting and Parry in 1957, a number of different neck collars have been realized, among which the simplified version devised by Eckberg and coworkers in 1975 and the neck chamber described by Ludbrook and coworkers in our Institute in 1977. At variance with Eckberg's type, the "Milan neck chamber" completely surrounds the neck and allows the application of both positive and negative pressures to the neck by means of a system of double rubber valves that prevents air leakage from the chamber. The main advantage of this technique, as compared to infusion of vasoactive drugs, is the possibility it offers to study baroreflex control not only of heart rate, but also of peripheral resistance and blood pressure through neck chamber induced changes in carotid transmural pressure. In recent years a systematic evaluation of the neck chamber technique has allowed to clarify the following issues: 1) application of positive pressure to the neck, although increasing internal jugular venous pressure and thereby reducing the pressure gradient from the arterial versus the venous side of head circulation, does not reduce cerebral blood flow; 2) changes in pressure within the neck chamber do not seem to reduce blood flow to the carotid bodies, at least to a degree which might lead to chemoreceptor stimulation; 3) there is a linear relation between changes in neck chamber pressure and changes in tissue pressure adjacent to the carotid sinus. The transmission of pressure to pericarotid tissues is complex, however.(ABSTRACT TRUNCATED AT 250 WORDS)

Twenty-four hour blood pressure monitoring and end-organ damage.

Abstract: Ambulatory blood pressure monitoring (ABPM) over 24 hours has become quite common. Evidence suggests that the mean 24-hour measurement is more closely associated with end organ damage, including end-points such as left ventricular hypertrophy (LVH), than is a single blood pressure measurement taken in the doctor's office. Clinicians disagree about the particular significance of blood pressure measurements obtained during exercise, blood pressure variability, and blood pressure load (a measurement above 140/90 over 24 hours). However, the morning peak in blood pressure appears to be associated with the highest incidence of coronary events, and end organ damage may be greater in subjects in whom nocturnal blood pressure falls only slightly from a diurnal baseline (non-dippers). From now, ABPM serves mainly as a research tool. Longitudinal controlled studies are needed to compare the value of ABPM to office blood pressure readings in terms of how these measurements can predict cardiovascular end-points or, more realistically, surrogate end-points, such as the development or regression of LVH.

Clinical value of blood pressure measurements: focus on ambulatory blood pressures.

Abstract: Because clinic blood pressure values are compromised by 2 major limitations—the alerting reaction to clinic measurements and the spontaneous blood pressure variability—they have only a limited correlation with average 24-hour blood pressure values. Whether the latter should be employed routinely in substitution for, or in addition to, traditional blood pressure measurements has not yet been determined, however. To date, average 24-hour blood pressure values have been shown to correlate more closely than clinic blood pressure values with the organ damage of hypertension. A correlation with organ damage has been shown also for a number of blood pressure values within the 24 hours. Nevertheless, the clinical importance of 24-hour blood pressure and blood pressure variability has never been confirmed by prospective controlled studies. This information needs to be obtained before this approach is routinely employed in the clinical practice.

Twenty-four-hour blood pressure and antihypertensive treatment.

Abstract: Normal values for 24-hour blood pressure (BP) have not been well characterized. However, it is believed that the maintenance of normal blood pressure control is a desirable feature of an antihypertensive agent. This is particularly important with respect to the drug's ability to (1) maintain circadian variation, albeit from a lower baseline, (2) lower BP throughout the 24 hours, (3) avoid the development of postural hypotension, (4) avoid decreases in BP sufficient to precipitate an ischemic event, (5) and to reduce BP variability toward the normal BP limits.

The Study Group of Quinapril in Arterial Hypertension. The Steering Committee

Abstract: The efficacy and safety of the treatment of arterial hypertension with the ACE-inhibitor quinapril, were evaluated in a multicentre study conducted in Italy. The study, lasting 14 weeks, after a preliminary wash-out period, allowed response-based titration of quinapril dose from 10 mg to 40 mg once a day, with provision to combine additional hydrochlorothiazide (12.5 to 25 mg), in case of persistently high diastolic pressure levels. The efficacy sample included 1267 patients: at therapy week 14, 78.6% of patients were treated with quinapril alone. Global response rate (intent-to-treat) was 83.3%, with a mean reduction of diastolic pressure of 15.8 mmHg (95% confidence interval from 15.5 to 16.2 mmHg). 91 patients reported 126 associated adverse events (7.0%); the most frequently reported event was cough (2.7%). First-dose hypotension was rarely reported (1.3%), even in elderly and diabetic patients.