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Biomedical subjects

G Parati

Publications and source records attributed to G Parati.

At least 19 recordsLinked to original sources
PubMed2006

Baroreflex control of heart rate during sleep in severe obstructive sleep apnoea: effects of acute CPAP.

Baroreflex control of heart rate during sleep (baroreflex sensitivity; BRS) has been shown to be depressed in obstructive sleep apnoea (OSA), and improved after treatment with continuous positive airway pressure (CPAP). Whether CPAP also acutely affects BRS during sleep in uncomplicated severe OSA is still debatable. Blood pressure was monitored during nocturnal polysomnography in 18 patients at baseline and during first-time CPAP application. Spontaneous BRS was analysed by the sequence method, and estimated as the mean sequence slope. CPAP did not acutely affect mean blood pressure or heart rate but decreased cardiovascular variability during sleep. Mean BRS increased slightly during CPAP application (from 6.5+/-2.4 to 7.5+/-2.9 ms x mmHg(-1)), mostly in response to decreasing blood pressure. The change in BRS did not correlate with changes in arterial oxygen saturation or apnoea/hypopnoea index. The small change in baroreflex control of heart rate during sleep at first application of continuous positive airway pressure in severe obstructive sleep apnoea was unrelated to the acute resolution of nocturnal hypoxaemia, and might reflect autonomic adjustments to positive intrathoracic pressure, and/or improved sleep architecture. The small increase in baroreflex control of heart rate during sleep may be of clinical relevance as it was accompanied by reduced cardiovascular variability, which is acknowledged as an independent cardiovascular risk factor.

Adult↗
PubMed2005

Correlations of smoothness index and trough-to-peak ratio with left ventricular mass index changes induced by lercanidipine in hypertensive patients. A pilot trial.

AIM: The aim of this study was to determine the correlation of changes in left ventricular mass, with changes in office blood pressure (BP) and in 24-h ambulatory (ABP), with the trough-to-peak (T/P) ratio and with the smoothness index (SI), as induced by antihypertensive treatment with lercanidipine. METHODS: This was done through an observational, prospective, open, non-comparative, single centre, pilot study in patients naïve to antihypertensive therapy. All patients were treated with lercanidipine 10-20 mg/day plus hydrochlorothiazide 12.5-25 mg/day if treated BP exceeded an arbitrarily defined safety level (>160/100 mmHg) after 1 month on monotherapy. ABP monitoring was repeated after 1 month and after 6 months. Two-dimensional mode echocardiography was performed twice, at the beginning and end of the study. Seventeen patients were included in the final analysis (aged 45.8 +/- 10.7 years, 35% women). RESULTS: Treatment-induced changes in left ventricular mass index (LVMI) were not found to correlate neither with changes in office BP, with changes in ABP values, nor with T/P. However, a significant correlation was found between LVMI changes and SI at 6 months (r=0.50, P=0.039). CONCLUSION: The results of this study suggest that the SI has a higher predictive value, compared to other BP-derived parameters, for treatment-induced LVMI changes, in hypertensive patients treated with lercanidipine.

Adult↗
PubMed2004

Inflammatory response and the endothelium.

Antiphospholipid-mediated endothelium perturbation plays a role in antiphospholipid syndrome (APS)-associated vasculopathy. Antiphospholipid antibodies activate endothelium both in vitro and in vivo experimental models by inducing a pro-inflammatory/-coagulant phenotype; the antibodies recognize beta2 glycoprotein I (beta2GPI) on human endothelial cells (EC) from different parts of the vasculature. In spite of such large in vitro evidence, few studies have addressed the issue whether or not a comparable endothelial perturbation might be detectable in vivo. We investigated several indirect ex vivo parameters of endothelial dysfunction: plasma levels of soluble adhesion molecules (sADM), soluble thrombomodulin (sTM), von Willebrand factor (vWF) and tissue plasminogen activator (t-PA) by solid-phase assays. The study included: patients with primary antiphospholipid syndrome (n=32), with the syndrome secondary to non-active systemic lupus erythematosus (SLE, n=10), six patients with persistent antiphospholipid positivity at medium/high titre without any clinical manifestation of the syndrome. Fifty-two age and sex matched healthy subjects have been enrolled as controls. In addition, circulating endothelial cells identified by flow cytometry and the brachial artery flow-mediated vasodilation (FMV) were evaluated in 26 patients (20 primary and 6 lupus syndromes) and 30 healthy controls. Plasma levels of soluble adhesion molecules did not differ from controls, while a significant increase in von Willebrand factor titres (P<0.05) was found. No significant difference was found regarding the number of circulating endothelial cells and flow-mediated vasodilation. As a whole, these findings do suggest that antiphospholipid antibodies per se are not able to support a full-blown endothelial perturbation in vivo. As shown in antiphospholipid syndrome experimental animal models, a two-hit hypothesis is suggested.

Antiphospholipid Syndrome↗
PubMed2003

[Current trends in the treatment of arterial hypertension].

Today's approach to the treatment of patients with arterial hypertension is no longer based solely on reducing high pressure values but forms part of a broader context designed to reduce the overall cardiovascular risk. The very decision of whether to begin anti-hypertensive treatment or not depends both on the degree of hypertension and on the presence or otherwis of other risk factors, organ damage or associated pathological conditions. The present paper summarises recent indications provided by the guidelines issued in 2003 by the European Society of Hypertension and the European Society of Cardiology. The criteria for planning anti-hypertensive treatment in patients with a different level of cardiovascular risk are the subject of particularly concentrated discussion and the approach to the hypertens patient in special clinical conditions such as ageing, diabetes mellitus, the presence of renal, cerebrovascular or coronary pathology and pregnancy will be treated separately.

Algorithms↗
PubMed2001

Importance of smooth and sustained blood pressure control in preventing cardiovascular morbidity and mortality.

Current management guidelines in hypertension define the magnitude of blood pressure lowering required from antihypertensive therapy to favourably alter cardiovascular prognosis. In addition, however, the manner in which blood pressure is reduced also influences outcome, and antihypertensive therapy should induce smooth and sustained blood pressure control throughout the 24-h dosing interval. Ambulatory blood pressure recording techniques, in particular, have allowed the quantitative measurement of parameters such as the short-term variability of blood pressure, which correlates significantly with cardiovascular damage in patients with hypertension. The smoothness index has been developed as an index of the homogeneity of the blood pressure reduction obtained over the 24 hours by any given treatment during a long-term trial in patients with hypertension. This parameter is more predictive of a favourable effect of antihypertensive therapy (regression of left ventricular hypertrophy) during antihypertensive therapy than the widely used trough:peak ratio. The smoothness index is a useful new tool for comparing the quality of blood pressure lowering with different antihypertensive agents. For example, candesartan cilexetil, a potent and long-acting AT1-receptor blocker, increased the smoothness index by a significantly greater extent than the prototype AT1-receptor blocker, losartan, implying a more smooth and sustained antihypertensive effect.

Antihypertensive Agents↗
PubMed2001

Time versus frequency domain techniques for assessing baroreflex sensitivity.

BACKGROUND: Newer techniques to evaluate baroreflex sensitivity (BRS) are based on the analysis of blood pressure (BP) and heart rate (HR) time series in the time or frequency domain. These novel approaches are steadily gaining popularity, since they do not require injection of vasoactive substances, nor do they rely on a complex experimental set-up. AIM: This review outlines and compares some basic features of the latest methods to assess spontaneous baroreflex function. RESULTS: Modern techniques for the estimation of spontaneous BRS are based on a variety of signal processing schemes and derive information on the baroreflex function from different perspectives. Thus factors such as respiration and other non-stationary agents may have different influences on the estimates provided by each of these approaches. Notwithstanding such individual specificity, however, it has been observed that in several physiological and pathophysiological conditions these techniques often provide comparable information on BRS changes over time, particularly when the estimates are averaged over time windows of a few minutes. CONCLUSIONS: Due to the general agreement in the pattern of BRS among most modern methods, it seems reasonable to employ the most validated of these techniques, for which data obtained in several studies are already available.

Animals↗
PubMed2001

Twenty-four hour ambulatory blood pressure in the Hypertension Optimal Treatment (HOT) study.

BACKGROUND AND AIMS: The Hypertension Optimal Treatment (HOT) study showed that when antihypertensive treatment reduces diastolic blood pressure well below 90 mmHg, there can be a further reduction of cardiovascular events, particularly myocardial infarction, with no evidence of a J-shaped curve at lower pressures. Office measurement, however, gives no information about blood pressure outside the office. This paper describes a HOT substudy in which patients underwent both office measurement and 24 h ambulatory blood pressure monitoring. METHODS: The mean age of the substudy population was 62 +/- 7 years. Substudy patients were treated for a median period of 2 years. All received the dihydropyridine calcium antagonist felodipine, while some also received an ACE-inhibitor, a beta-blocker or a diuretic. Average 24 h, day and night ambulatory blood pressure values were computed at baseline (n = 277) and during treatment (n = 347): 112 patients had been randomized to a target office diastolic blood pressure <or= 90 mmHg, 117 to <or= 85 mmHg and 118 to <or= 80 mmHg. Additional analyses included computation of: (1) trough-to-peak ratio and (2) the smoothness index (the ratio between the average of the 24 hourly blood pressure reductions after treatment and its standard deviation). RESULTS: Taking the subgroup as a whole, baseline 24 h average blood pressures (146 +/- 18/90 +/- 10 mmHg) were significantly and markedly lower than office blood pressures (170 +/- 14/105 +/- 3 mmHg, P < 0.01). Office, 24 h, day and night blood pressures were all significantly reduced by treatment, but there was a smaller fall in ambulatory, than in office pressures. The between group differences in office blood pressure were smaller than those observed in the overall HOT sample. Between-group differences in 24 h blood pressure were even smaller. Trough-to-peak ratios and smoothness indices were lowest in the highest blood pressure target group and highest in the lowest blood pressure target group. Office and ambulatory blood pressures were similar in the groups randomized to placebo (n = 170) or acetylsalicylic acid (n = 177). CONCLUSION: In conclusion, in the HOT study, treatment reduced not only office but also ambulatory blood pressure throughout the 24 h. The reduction was less marked for ambulatory than for office blood pressure.

Aged↗
PubMed2001

Relation between blood pressure variability and carotid artery damage in hypertension: baseline data from the European Lacidipine Study on Atherosclerosis (ELSA).

BACKGROUND: Baseline data from the European Lacidipine Study on Atherosclerosis (ELSA) have shown that carotid intima-media thickness (IMT) is not related to diastolic blood pressure (BP), but that it is related to clinic systolic (S) or pulse pressure (PP) and more so to their 24 h average values. The aim of the present study was to determine whether IMT independently relates to additional information obtained through ambulatory BP, in particular to SBP or PP variability. METHODS AND RESULTS: In 1663 hypertensive patients, after a wash-out period from antihypertensive treatment (mean age 56.2 +/- 7.65 years), IMT was assessed from 12 different carotid sites. Ambulatory BP measurements were performed every 15 min (day) and every 20 min (night). IMT values were positively related to 24 h, day and night average SBP and PP. There was some relationship of IMT with day-night or clinic-day SBP and PP differences. The most important finding, however, was that IMT values were related with 24 h SBP or PP standard deviation (P < 0.001), a measure of overall SBP or PP variability. The relationship was seen also by multiple regression analysis, the standard deviation for SBP or PP only following age and 24 h average SBP or PP in accounting for IMT values. CONCLUSIONS: This is the first demonstration from a large database that not only average 24 h PP and SBP values, but also 24 h BP fluctuations, are associated with, and possibly determinants of, the alterations of large artery structure in hypertension.

Aged↗
PubMed2001

Blood pressure variability as a risk factor.

Blood pressure variability is clinically relevant because of the evidence that the degree of blood pressure fluctuation may independently contribute to organ damage and to the cardiovascular risk of hypertensive patients. This review will focus on the evidence available to support this concept. As such, data obtained from cross-sectional studies, longitudinal studies in humans and experimental studies in animals will be discussed. The possibility of antagonizing an excessive degree of blood pressure variability by administering drugs to provide a long-lasting and smooth antihypertensive action will also be discussed, as will the usefulness of mathematical indices aimed at quantifying the homogeneity of the blood pressure reduction by treatment.

Animals↗
PubMed2001

Task Force II: blood pressure measurement and cardiovascular outcome.

OBJECTIVE: To reach a consensus on the prognostic significance of new techniques of automated blood pressure measurement. METHODS: A Task Force on the prognostic significance of ambulatory blood pressure monitoring wrote this review in preparation for the Eighth International Consensus Conference (28-31 October 2001, Sendai, Japan). This synopsis was amended to account for opinions aired at the conference and to reflect the common ground reached in the discussions. POINTS OF CONSENSUS: (1) Prospective studies in treated and untreated hypertensive patients and in the general population have demonstrated that, even after adjusting for established risk factors, the incidence of cardiovascular events is correlated with blood pressure on conventional as well as ambulatory measurement. Ambulatory monitoring, however, significantly refines the prediction already provided by conventional blood pressure measurement. (2) White-coat hypertension is usually defined as an elevated clinic blood pressure in the presence of a normal daytime ambulatory blood pressure. Event-based studies in hypertensive patients have convincingly demonstrated that the risk of cardiovascular disease is less in patients with white-coat hypertension than in those with higher ambulatory blood pressure levels even after controlling for concomitant risk factors. Based on prognostic evidence, white-coat hypertension can now be defined as a conventional blood pressure that is persistently equal to or greater than 140/90 mmHg with an average daytime ambulatory blood pressure of below 135/85 mmHg. The issue of whether or not white-coat hypertension predisposes to sustained hypertension needs further research. (3) There is a growing body of evidence showing that a decreased nocturnal fall in blood pressure (<10% of the daytime level) is associated with a worse prognosis, irrespective of whether night-time dipping is studied as a continuous or a class variable. (4) Intermittent techniques of ambulatory blood pressure monitoring are limited in terms of quantifying short-term blood pressure variability. Proven cardiovascular risk factors such as old age, a higher than usual blood pressure and diabetes mellitus are often associated with greater short-term blood pressure variability. After adjusting for these risk factors, some - but not all - studies have nevertheless reported an independent and positive relationship between cardiovascular outcome and measures of variability of daytime and night-time blood pressure, for example standard deviation. (5) Reference values for ambulatory blood pressure measurement in children are currently based on statistical parameters of blood pressure distribution. In children and adolescents, functional rather than distribution-based definitions of ambulatory hypertension have yet to be developed. (6) Several studies of gestational hypertension have shown that, compared with office measurement, ambulatory blood pressure monitoring is a better predictor of maternal and fetal complications. Pregnancy is a special indication for ambulatory monitoring so that the white-coat effect can be measured and pregnant women are not given antihypertensive drugs unnecessarily. (7) Ambulatory pulse pressure and the QKD interval are measurements obtained by ambulatory monitoring that to some extent reflect the functional characteristics of the large arteries. The QKD interval is correlated with left ventricular mass, and ambulatory pulse pressure is a strong predictor of cardiovascular outcome. (8) Under standardized conditions, the self-measurement of blood pressure is equally as effective as ambulatory blood pressure monitoring in identifying the white-coat effect, but further studies are required to elucidate fully the prognostic accuracy of self-measured blood pressure in comparison with conventional and ambulatory blood pressure measurement. CONCLUSIONS: Ambulatory blood pressure measurement refines the prognostic information provided by conventional blood pressure readings obtained in the clinic or the doctor's office. Longitudinal studies of patients with white-coat hypertension should clarify the transient, persistent or progressive nature of this condition, particularly in paediatric patients, in whom white-coat hypertension may be a harbinger of sustained hypertension and target-organ damage in adulthood. Finally, the applicability, cost-effectiveness and long-term prognostic accuracy of the self-measurement of blood pressure should be evaluated in relation to conventional blood pressure measurement and ambulatory monitoring.

Adult↗
PubMed2001

Dynamic modulation of baroreflex sensitivity in health and disease.

Assessment of arterial baroreflex function in humans through laboratory tests has provided a great deal of information of pathophysiological and clinical relevance. Indeed, the sensitivity of the baroreceptor-heart rate reflex quantified through these laboratory methods was shown to predict the risk of cardiovascular events and death from myocardial infarction, heart failure, and in diabetic patients. This traditional approach, however, does not provide information on daily life baroreflex cardiovascular control. Modern techniques, based on computer analysis of spontaneous blood pressure and heart rate fluctuations, are now available and allow baroreflex sensitivity to be assessed under real-life conditions with no need for external stimulation. In particular, these methods offer the possibility of investigating the dynamic modulation of baroreflex sensitivity occurring either on a minute-to-minute basis or over 24 hours.

Baroreflex↗
PubMed2001

Baroreflex effectiveness index: an additional measure of baroreflex control of heart rate in daily life.

In healthy subjects, progressive beat-to-beat increases or decreases in systolic blood pressure (SBP) ramps are not always accompanied by baroreflex-driven lengthening or shortening in pulse interval (PI) ramps, respectively. This phenomenon has been quantified by a new index, the baroreflex effectiveness index (BEI), defined as the ratio between the number of SBP ramps followed by the respective reflex PI ramps and the total number of SBP ramps observed in a given time window. Specificity of BEI was shown in eight cats by a -89% reduction of BEI after sinoaortic denervation. In 14 healthy humans, the 24-h average BEI value was 0.21, with a marked day-night modulation ( approximately 0.25 day, approximately 0.15 night) in counterphase with modulation of baroreflex sensitivity (BRS). Our analysis indicates that 1) in normal subjects, arterial baroreflex can induce beat-by-beat PI changes in response to only 21% of all SBP ramps, possibly because of central inhibitory influences or of interferences at sinus node level by nonbaroreflex mechanisms and 2) BEI provides information on the baroreflex function that is complementary to BRS.

Adult↗
PubMed2001

Cardiovascular effects of an earthquake: direct evidence by ambulatory blood pressure monitoring.

The increased cardiovascular mortality during an earthquake has been related, among other factors, to a sympathetically mediated increase in heart rate and blood pressure. However, this is supported only by indirect evidence collected after an earthquake, whereas for obvious technical difficulties, no data are available on the acute blood pressure and heart rate effects during an earthquake. In a patient undergoing 24-hour ambulatory blood pressure monitoring (Spacelabs 90207), we had the opportunity to directly record the acute blood pressure and heart rate changes induced by an earthquake (magnitude 4.7 according to the Richter scale) that struck central Italy in March 1998. Systolic blood pressure rose to 150 mm Hg, diastolic blood pressure rose to 122 mm Hg, and heart rate rose to 150 bpm at the time of the strongest tremor. Prequake blood pressure levels were restored only 1 hour later, but blood pressure remained characterized by a pronounced variability throughout the following 6 hours. Thus, a sympathetically mediated combined increase in blood pressure and heart rate may represent an important pathophysiological mechanism responsible for the increased frequency of cardiovascular events during an earthquake. The associated increase in blood pressure variability might further contribute to the increase in cardiovascular risk typical of this condition. Our case report further supports the usefulness of ambulatory blood pressure monitoring to assess the blood pressure and heart rate effects of sudden daily life events, the actual cardiovascular impact of which can hardly be quantified through traditional measurements.

Adult↗
PubMed2001

Potassium depletion and salt sensitivity in essential hypertension.

To evaluate the actual role of potassium depletion on blood pressure, 11 hypertensive patients were placed on a 10-day isocaloric diet providing a daily potassium intake of either 18 or 80 mmol, with each subject serving as his or her own control; the intake of sodium (220 mmol/day) and other minerals was kept constant. On day 11 each patient was also subjected to central volume expansion by water immersion associated with either normal or low potassium intake. After a 10-day period of low potassium intake, systolic blood pressure increased (P < 0.02) by 5 mm Hg, whereas serum potassium decreased (P < 0.001) by 0.9 mmol/L; no significant changes in urinary sodium and a marked increase in urinary calcium excretion (P < 0.001) were found during the 10-day low potassium intake. PRA (P < 0.02) and plasma aldosterone (P < 0.04) concentrations also decreased during low potassium intake in hypertensive patients. Even though an identical natriuretic response was found during the water immersion experiments with either high or low potassium in the whole hypertensive group, the evaluation of hypertensive subjects in relation to salt sensitivity enabled us to disclose pronounced differences in the natriuretic and calciuretic response. In fact, although an impaired natriuretic ability and moderate calcium loss were particularly found during water immersion in those hypertensive subjects exhibiting a lower salt sensitivity index, a predominant calcium depletion appeared to be the most important consequence of potassium depletion in the hypertensive subjects with a higher salt sensitivity index. By confirming that potassium depletion may exacerbate essential hypertension, our data also suggest that not only sodium restriction, but also potassium and calcium supplementation, could be particularly advisable in salt-sensitive hypertensive patients.

Adult↗
PubMed2001

[Blood pressure variability].

This review deals with a number of issues related to blood pressure variability. These include: historical aspects, with reference to the first pioneering observations; methodological aspects, focusing on the different methods for quantifying blood pressure variability; description of the characteristics of blood pressure variability over the 24 hours; mechanisms involved in determining the different magnitude of this phenomenon in different subjects, such as behavioral factors, central and reflex neural influences, humoral and mechanical factors; blood pressure variability as a probe to assess spontaneous baroreflex sensitivity; effects of aging and hypertension on blood pressure variability, with a discussion of the clinical relevance of this phenomenon in the prognostic evaluation of patients; effects of drugs on blood pressure variability. Finally methodological aspects related to the use of noninvasive ambulatory blood pressure monitoring in the assessment of blood pressure variability are discussed.

Aging↗