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Biomedical subjects

G Mancia

Publications and source records attributed to G Mancia.

At least 91 records · Page 5Linked to original sources
PubMed1999

Muscle and skin sympathetic nerve traffic during the "white-coat" effect.

BACKGROUND: Sphygmomanometric blood pressure measurements induce an alerting reaction and thus an increase in the patient's blood pressure and heart rate. Whether and to what extent this "white-coat" effect is accompanied by detectable changes in sympathetic nerve traffic has never been investigated. METHODS AND RESULTS: In 10 mild untreated essential hypertensives (age 37.9+/-3. 8 years, mean+/-SEM), we measured arterial blood pressure (by Finapres), heart rate (by ECG), and postganglionic muscle and skin sympathetic nerve activity via microneurography. Measurements were performed with the subject supine during (1) a 15-minute control period, (2) a 10-minute visit by a doctor unfamiliar to the patient who was in charge of measuring his or her blood pressure by sphygmomanometry, and (3) a 15-minute recovery period after the doctor's departure. The entire procedure was performed twice at a 45-minute interval to obtain, in separate periods, muscle or skin sympathetic nerve traffic recordings, whose sequence was randomized. The doctor's visit induced a sudden, marked, and prolonged pressor and tachycardic response, accompanied by a significant increase in skin sympathetic nerve traffic (+38.6+/-6.7%, P<0.01). In contrast, muscle sympathetic nerve traffic was significantly inhibited (-25. 5+/-4.1%, P<0.01). All changes persisted throughout the doctor's visit and, with the exception of skin sympathetic nerve traffic, showed a slow rate of disappearance after the doctor's departure. CONCLUSIONS: Thus, the pressor and tachycardic responses to the alerting reaction that accompanies sphygmomanometric blood pressure measurement is characterized by a behavior of the adrenergic nervous system that causes muscle sympathoinhibition and skin sympathoexcitation.

Adult↗
PubMed1999

Early impairment of large artery structure and function in type I diabetes mellitus.

AIMS/HYPOTHESIS: Diabetes mellitus is associated with an increased incidence of atherosclerosis. How early functional and structural alterations of large arteries that may preceded atherosclerosis occur in the course of this disease has, however, never been conclusively documented. METHODS: We evaluated arterial wall distensibility in the radial artery, common carotid artery and abdominal aorta in 133 patients (aged 35.4 +/- 0.9 years, means +/- SEM) with Type I (insulin-dependent) diabetes mellitus and no macrovascular complications. Arterial distensibility was derived from continuous measurements of arterial diameter through echotracking techniques and use of either the Langewouters (radial artery) or the Reneman (carotid artery and aorta) formula. The same echotracking techniques enabled us to obtain radial artery and carotid artery wall thickness. Data were compared with those from 70 age-matched normotensive control subjects. RESULTS: In diabetic patients arterial distensibility was consistently less (p < 0.01) than in control subjects, the reduction averaging 26%, 14% and 25% for the radial artery, carotid artery and aorta, respectively. This was accompanied by an increase (p < 0.01) in both radial and carotid artery wall thickness. The changes were more pronounced in patients with microalbuminuria, retinopathy or neuropathy or both. They were evident also in those without microvascular complications. This was the case also when subjects in whom diabetes was associated with hypertension (n = 30) were excluded from data analysis. Carotid and aortic wall abnormalities showed a relation with the duration of disease and blood pressure whereas radial artery abnormalities showed a relation with glycated haemoglobin. CONCLUSION/INTERPRETATION: Type I diabetes is characterised by diffuse arterial wall stiffening and thickening which progress with the severity of the disease but can clearly be seen also in the absence of any diabetic-related complication. This suggests that in diabetes stiffening and thickening are an early marker of vascular damage.

Adult↗
PubMed1999

Early effects of total paracentesis and albumin infusion on muscle sympathetic nerve activity in cirrhotic patients with tense ascites.

BACKGROUND/AIMS: Cirrhotic patients with ascites are characterized by a marked activation of the sympathetic and the renin-angiotensin-aldosterone system. Total paracentesis is associated with a short-lived suppression of the renin-angiotensin-aldosterone system. Little information exists as to whether this favourable effect is parallelled by sympathoinhibition. METHODS: In 16 Child C cirrhotic patients (age: 57.1+/-6.2 years, mean+/-SEM) with tense ascites we assessed the time course of the effects of total paracentesis followed by intravenous albumin (6-8 g/l of ascites) on beat-to-beat mean arterial pressure (Finapres), heart rate, plasma norepinephrine, epinephrine (high performance liquid chromatography) and muscle sympathetic nerve activity (microneurography, peroneal nerve). Measurements were obtained under baseline conditions, during staged removal of ascitic fluid (250 ml/min) and 24 h later. The patient remained supine throughout the study period. RESULTS: Total paracentesis (10.6+/-1.3 l) induced a decrease in mean arterial pressure (from 95.0+/-2.6 mmHg to 88.2+/-3.2 mmHg, p<0.01), in heart rate (from 82.5+/-3.3 beats/min to 77.1+/-2.8 beats/min, p<0.01) and a reduction in plasma norepinephrine values (from 782+/-133 pg/ml to 624+/-103 pg/ml, p<0.01), which were substantially maintained 24 h later. In eight patients muscle sympathetic nerve activity did not change during paracentesis (from 65+/-7.1 bursts/min to 65+/-7.4 bursts/min, p=NS), but a marked reduction was observed 24 h later (48.4+/-5.6 bursts/min, p<0.01). CONCLUSIONS: These data provide the first evidence that total paracentesis exerts an acute marked sympathoinhibitory effect. Whether this is a long-lasting phenomenon and to what extent plasma expansion with albumin contributes to this effects need to be further addressed.

Adult↗
PubMed1999

Current antihypertensive treatment: can we do better?

Results of various randomized, controlled clinical trials have shown that antihypertensive treatment is accompanied by reductions in morbidity and mortality caused by cardiovascular, cerebrovascular, and renal disease. Treatment confers a protective benefit against stroke, coronary artery disease, and heart failure, as well as against conditions previously considered unrelated to elevated blood pressure (eg, loss of cognitive function and dementia). Overall benefits of antihypertensive treatment are probably even greater than those shown in clinical trials. More rigorous blood pressure control in high-risk and multiple-risk patients provides even greater benefits. Because epidemiologic findings indicate that elevated systolic blood pressure (SBP) may be a greater risk factor for cardiovascular disease than elevated diastolic blood pressure (DBP), more attention should be paid to the control of SBP. Pulse pressure may be a better indicator of target-organ damage than either SBP or DBP, but further evaluation of its prognostic value is required. New monotherapies that can significantly reduce blood pressure, especially SBP, and confer protection on the target organs most affected by chronic hypertension may substantially add to current treatment.

Antihypertensive Agents↗
PubMed1999

Prediction of relapse or sustained response in biochemical responders by serum hepatitis C virus RNA monitoring during interferon therapy.

Normalization of serum aminotransferase levels is achieved in approximately 50% of chronic hepatitis C patients treated with interferon (IFN); however, in about one-half of these patients the hepatitis relapses after therapy. In this study we investigated the efficacy of serum hepatitis C virus (HCV) RNA monitoring during IFN therapy to predict the outcome of a biochemical end-of-treatment (ETR) response. Eighty patients with chronic hepatitis C received leucocyte (natural) IFN-alpha (13 patients) or recombinant IFN-alpha2a (67 patients). Antiviral therapy was given for 12 months to 43 (53.7%) responders and this group was analysed further. During follow-up, 15 relapsed and 28 showed a sustained response (median follow-up 50 months, range 39-67 months). Viraemia was monitored at baseline, and at months 1, 3, 6, 9 and 12 of treatment, by nested polymerase chain reaction (PCR) (sensitivity 10-100 copies ml-1). A combination of positive nested PCR and HCV RNA values at the 3rd and 6th months of treatment was 100% predictive of relapse (sensitivity, 66.6%; specificity, 100%). A combination of negative nested PCR and HCV RNA values at the 1st and 3rd months of treatment was 100% predictive of sustained response (sensitivity, 39.3%; specificity, 100%). In conclusion, serum HCV RNA monitoring is an appropriate and reliable tool for predicting early outcome of the biochemical ETR response after IFN discontinuation. This could be useful in the modulation of therapeutic management of chronic hepatitis C.

Adult↗
PubMed1999

New drugs for the treatment of hypertension.

Despite the many outstanding favorable results achieved in the treatment of hypertension, several unmet goals of antihypertensive therapy remain, such as better blood pressure control, greater protection against the organ damage associated with hypertension, better tolerability, and ultimately a more effective prevention of cardiovascular disease. These unmet goals are the reasons why new antihypertensive drugs are synthesized and tested in the clinical practice. This paper briefly mentions the goals of new antihypertensive agents and examines the main pharmacological and clinical features of new classes of antihypertensive drugs, such as angiotensin II receptor blockers, central agents, vasopeptidase inhibitors, and endothelin antagonists. The results of experimental and clinical studies with these new drugs are reviewed, emphasizing some advantages and potential disadvantages of these drugs compared with traditional antihypertensive drugs.

Adrenergic beta-Antagonists↗
PubMed1999

Arterial stiffness.

BACKGROUND: Arterial stiffness is an important determinant of pulse pressure, and of left ventricular load and coronary perfusion pressure. ASSESSMENTS OF STIFFNESS: Precise quantification is elusive, since stiffness is different in different arteries and even in the same artery at different pressures. Proximal elastic arteries and peripheral muscular arteries respond differently to aging change and to drugs. Various other terms are used to express stiffness, such as distensibility and compliance. Various indirect indices are also used, including pulse wave velocity, characteristic impedance and augmentation index. INCREASES IN STIFFNESS: While the literature is confusing, it is well established that stiffness of central arteries increases with aging and with elevated blood pressure. Effects of other diseases and of vasoactive agents are less clear-cut.

Aging↗
PubMed1999

Sympathetic tone restrains arterial distensibility of healthy and atherosclerotic subjects.

BACKGROUND: Sympathetic activation induced by cold pressor test or cigarette smoking is accompanied by a marked reduction of radial artery distensibility. It is not known, however, whether arterial distensibility is under tonic sympathetic restraint, or whether this restraint involves arteries greater than the radial one in both normal and pathological conditions. METHODS: We studied the distensibility of radial artery by continuous ultrasonographic assessment of the changes in arterial diameter over the diasto-systolic pressure range (finger pressure measurement) in eight patients with a Dupuytren disease before and 20 min after ipsilateral brachial plexus anaesthesia. We also studied ultrasonographic distensibility of femoral artery in seven subjects before and 20 min after ipsilateral subarachnoid anaesthesia, performed before arthroscopic surgery, and in five patients with claudicatio intermittens before and 1 month after ipsilateral removal of the lumbar sympathectomy chain. In all three conditions, the contralateral artery served as control. RESULTS: The three interventions did not cause any significant alteration in blood pressure and heart rate. Radial artery distensibility was markedly increased by ipsilateral anaesthesia of the brachial plexus (+36%, P<0.01). This was the case also for femoral artery distensibility both following ipsilateral subarachnoid anaesthesia in healthy subjects (+47%, P<0.05) or ipsilateral sympathetic gangliectomy in patients with peripheral artery disease (+26%, P<0.05). In all three instances, the distensibility of the contralateral artery remained unaffected. CONCLUSIONS: These data indicate that the sympathetic nervous system exerts a marked tonic restraint of arterial distensibility. This restraint involves medium-size and large muscular arteries and can also be seen in subjects with peripheral artery disease. This stiffening influence may increase the traumatic effect of intravascular pressure on the vessel wall and favour atherosclerosis.

Adult↗
PubMed1999

Reliability and limitations of echocardiographic measurement of left ventricular mass for risk stratification and follow-up in single patients: the RES trial. Working Group on Heart and Hypertension of the Italian Society of Hypertension. Reliability of M-mode Echocardiographic Studies.

OBJECTIVE: To investigate the clinical reliability of repeated measurements of left ventricular mass in a single patient. DESIGN: We used test-retest reliability analysis, within-class correlation and interval of agreement measures. METHODS: Two M-mode tracings (three consecutive cycles) were recorded in the same session and 3-10 days apart (5+/-2 days; mean +/- SD) in 261 participants (age 45+/-13 years, body mass index 24.7+/-3.6 kg/m2; 131 hypertensive and 130 normotensive; 50% of each group women) in 16 centres in Italy. The two tracings were read by two observers in each centre, after classification by a three-order quality score (1 = poor, 2 = sufficient, 3 = optimal). RESULTS: The average quality score was 2.11+/-0.71 (21% poor, 50% sufficient, 29% optimal). Left ventricular mass values ranged from 56 to 419 g (170+/-61 g). On the same day, within-observer 90% interval of agreement between tracing 1 and tracing 2 was -28 to +22 g (-17 to +11% of tracing 1). For day-to-day test-retest within-observer variability (average three cycles), the 90% interval of agreement was -30 to +35 g (-18 to +18%). This variability decreased to -13 to +12% at the 80% interval of agreement and -12 to +11% at the 75% interval of agreement. The 90% interval of agreement of test- retest between-observer variability was -26 to 30 g (-19 to +15%). A negligible regression toward the mean was identified. Categorical consistency of retest in the identification of hypertensive patients with left ventricular hypertrophy, classified in the first study, was 87% (k = 0.87). CONCLUSIONS: Measurement of left ventricular mass in single patients allows reliable risk stratification on the basis of the presence of left ventricular hypertrophy. The probability of a true change in left ventricular mass over time is maximized for a single-reader difference greater than 18% of the initial value, although differences of 10-13% might also have clinical relevance.

Adolescent↗
PubMed1999

Task force II: Ambulatory blood pressure monitoring in population studies.

Ambulatory blood pressure (ABP) has only rarely been employed in population studies because of the difficulty posed by the greater complexity of this technique. The cross-sectional studies that have been published, however, have allowed a number of conclusions to be drawn. One, 24h average blood pressure of populations is significantly but not closely related to office blood pressure, which thus can not predict accurately daily-life values of blood pressure. Two, 24h average blood pressure is usually less than office blood pressure, the discrepancy increasing with the increase in office values and being of magnitude several mmHg at the office blood pressure of 140/90 mmHg (systolic/diastolic) Three, ABP in women is somewhat less than that in men and ABP for both sexes increases less with aging than does office blood pressure. Four, a circadian profile of blood pressure consisting in values that are much lower at night than are those during daytime characterizes both sexes and all ages with the possible exception of individuals aged 75 years and more, in whom the nocturnal hypotension appears to be attenuated. A similar attenuation has been found for blacks in comparison with whites. The upper limit of normality of ABP has not yet been defined conclusively, although 24h average values </=125/80 mmHg are almost invariably regarded as normal. Normality of ABP should be defined, however, by longitudinal population studies in which ambulatory values are related to prognosis. One of these studies has already been published and others will be completed in the near future.

Blood Pressure Monitoring, Ambulatory↗
PubMed1999

Blood Pressure Monitoring. Task force V: White-coat hypertension.

TERMINOLOGY: Two terms are in current use to describe patients whose blood pressures are high only in a medical setting (white-coat hypertension and isolated office or clinic hypertension). The term white-coat effect is also commonly used to describe the pressor response to the clinic setting. DEFINITIONS: White-coat hypertension is generally defined as a persistently elevated clinic blood pressure in combination with a normal ambulatory blood pressure (ABP). There is disagreement regarding the optimal cutoff point for ABP. The white-coat effect is operationally defined as the difference between the clinic blood pressure and daytime ABP. PREVALENCE OF WHITE-COAT HYPERTENSION: This varies according to the definition of white-coat hypertension and the population studied, but is approximately 20% among mild hypertensives, and increases with age. METABOLIC AND BIOCHEMICAL ASPECTS: Authors of some studies have suggested that white-coat hypertension is associated with metabolic abnormalities such as hyperlipidemia that lead to an increase in cardiovascular risk, but most have not found this. TARGET-ORGAN DAMAGE: Several measures of target-organ damage have been compared among normotensives, white-coat hypertensives, and sustained hypertensives; these include left ventricular mass, microalbuminuria, and carotid atherosclerosis. In general, target-organ damage in white-coat hypertension is less than that in sustained hypertension, but in some studies it has been found to be more prevalent than in normotensives. MORBIDITY AND MORTALITY: Authors of a relatively small number of prospective studies have concluded that white-coat hypertensives have a lower risk of morbidity than do sustained hypertensives, but a larger number have drawn the more general conclusion that, when there is a discrepancy between the clinic blood pressure and ABP, the prognosis is more closely related to the ABP. MANAGEMENT: When white-coat hypertensives are prescribed antihypertensive medication there is usually a decrease in clinic blood pressure, but little or no change in ABP. Thus drug treatment is not necessarily indicated. Another issue is the follow-up of white-coat hypertensives; there is general agreement that blood pressure outside the office should be monitored indefinitely. Some patient may have been wrongly classified as white-coat hypertensives, and others may progress to develop sustained hypertension.

Antihypertensive Agents↗
PubMed1999

Effect of sinoaortic denervation on frequency-domain estimates of baroreflex sensitivity in conscious cats.

In animals and humans, baroreceptor modulation of the sinus node in daily life can be studied by identification of the number of sequences in which systolic blood pressure (SBP) and pulse interval (PI) linearly decrease or increase for several beats. It is also studied by power spectral analysis of SBP and PI in regions where their powers are coherent, although, in contrast to the sequence method, whether this frequency-domain method specifically reflects the baroreceptor-heart rate reflex has not been adequately tested. We recorded intra-arterial BP for approximately 3.5 h in eight conscious cats, first intact and then 7-10 days after sinoaortic denervation (SAD). Sensitivity of baroreceptor-heart rate reflex was assessed in 120-s segments by the square root of the ratio of PI and SBP spectral powers (alpha) in the regions around 0.1 (MF) and 0.3 (HF) Hz, and coherence between PI and SBP spectral powers in MF and HF regions was computed. SAD increased overall SBP variability and reduced PI variability throughout the frequency range examined. SAD markedly reduced (P < 0.01) both alpha-MF (-65.6%) and alpha-HF (-79. 9%) and consistently reduced the number of coherent segments [i.e., where coherence (K2) > 0.5] and average coherence values in the MF region. In the HF region, however, SAD did not alter the number of coherent segments, and although average coherence value throughout the HF band was reduced, in restricted portions of the band (different between animals), a high coherence value survived denervation. No significant changes were seen in any measured variables in five sham-operated cats. Thus the frequency-domain method specifically reflects baroreflex modulation of heart rate in the MF region only. In the HF region, in contrast, baroreflex and nonbaroreflex influences on the sinus node both contribute to a variable degree to determination of heart rate responses to BP oscillations. If used to study baroreflex function in daily life, this method should use the coefficient derived from MF data.

Animals↗
PubMed1999

Fluctuations of radial artery distensibility throughout the menstrual cycle.

Estrogen administration has a number of favorable cardiovascular effects, and recent evidence suggests that these include an increase in arterial distensibility. Whether this is also the case for the physiological changes in estrogen production during the menstrual cycle has never been determined, however. In 21 premenopausal healthy women, we continuously measured radial artery diameter and blood pressure by an echo-tracking device and a beat-to-beat finger device, respectively. Arterial distensibility was calculated as distensibility/blood pressure curve. The measurements were made during the follicular, ovulatory, and luteal phases of the menstrual cycle. As expected, compared with the follicular phase, plasma estradiol, follicle-stimulating hormone, luteinizing hormone, and prolactin were increased in the ovulatory phase, whereas progesterone was increased in the luteal phase, together with antidiuretic hormone. Radial artery distensibility was increased in the ovulatory and reduced in the luteal phase, the changes being independent of the small, concomitant blood pressure changes. The arterial wall stiffening seen in the luteal phase was associated with a reduction in the flow-dependent endothelial dilatation of the radial artery as assessed by the hyperemia after short-term ischemia of the hand. Thus, the natural menstrual cycle is characterized by alterations in radial artery distensibility. The mechanisms responsible for this phenomenon remain to be clarified. It is possible, however, that the greater arterial distensibility of the ovulatory phase is due to an estrogen-dependent reduction in vascular smooth muscle tone, whereas the arterial stiffening of the luteal phase depends on vascular smooth muscle contraction due to more complex hormonal phenomena, ie, an endothelial impairment due to estrogen reduction but also to an increase in progesterone and antidiuretic hormone levels.

Adult↗