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Biomedical subjects

A Zanchetti

Publications and source records attributed to A Zanchetti.

539 records · Page 30Linked to original sources
PubMedDate not supplied

Carotid sinus baroreceptor control of arterial pressure in renovascular hypertensive subjects.

We used the neck chamber technique to study carotid baroreceptor control of blood pressure in 18 renovascular hypertensive subjects. Carotid baroreceptors were stimulated or deactivated for 2 minutes by applying graded reductions or increases in the neck tissue pressure (NTP) outside the carotid sinuses. The sensitivity of the baroreflex was separately calculated for these two conditions by the coefficients of the linear regressions relating the changes in NTP to the resulting changes in mean arterial pressure (MAP, catheter measurement). Baroreceptor deactivation increased MAP, and the sensitivity of the baroreflex was 0.12 /+- 0.07 in an early (5 to 1 seconds) and 0.32 /+- 0.05 in a late (90 to 120 seconds) phase of the stimulus application. Baroreceptor stimulation reduced MAP, and the baroreflex sensitivity was in this instance 0.66 /+- 0.08 and 0.05 /+- 0.08 respectively. Both these sensitivities were significantly greater than those obtained for the baroreceptor deactivation. These response entirely reproduced those of essential hypertensive subjects, but differed from those of normotensive subjects in whom baroreflex sensitivity was greater for carotid baroreceptor deactivation than for stimulation. Our findings indicate that carotid baroreceptor control of blood pressure undergoes a marked resetting in renovascular hypertension. The similarity of the baroreflex between renovascular and essential hypertension suggests as secondary origin of the resetting in man.

Adult↗
PubMedDate not supplied

Twenty-four-hour hemodynamic profile during treatment of essential hypertension by once-a-day nadolol.

The effect of nadolol (N) on 24-hour blood pressure (BP) and heart rate (HR) values and on their variability was examined in ambulant patients with essential hypertension, using the Oxford method to obtain continuous intraarterial recording and a computer to have a beat-to-beat analysis of the data. The recording was carried out without treatment and after 10 days' administration of N once daily by mouth (dose range: 80-320 mg). After N, 24-hour BP and HR were reduced by 17 +/- 3% and 27 +/- 4% respectively as compared to before N, the effect being similar for both systolic and diastolic BP. The hypertension and bradycardia were significantly more marked during the day than during the night, neither showing any attenuation in the hours furthest from the administration of the drug. During N, there was a reduction in the 24-hour variation coefficient for HR but the reduction was limited to the longer term component of this phenomenon, the moment-to-moment variations remaining unaffected. The long- and short-term variation coefficients for BP were not modified under N. These findings suggest that N once a day can reduce BP for 24 hours in ambulant hypertensive patients. The lack of alteration in variability of BP and moment-to-moment HR suggests that the hypotension is achieved without interfering with the mechanisms involved in cardiovascular homeostasis.

Adrenergic beta-Antagonists↗
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Structural cardiovascular adaptation and the consequences for baroreflexes.

Changes in arterial baroreflex control of the circulation occur in experimental and in human hypertension. Hypertension can affect the afferent, the central, and the efferent portions of the baroreflex. Structural cardiovascular adaptation due to stiffening of the vascular wall is usually thought to influence the afferent component of the baroreflex, but it can also influence the effector component. Resetting of central mechanisms of the baroreflex also occurs. Cardiopulmonary baroreflexes appear to be enhanced in young spontaneously hypertensive rats (SHR) and in borderline hypertensive patients, probably because of reduced venous compliance that shifts blood to the cardiovascular compartments (atrium, ventricle) where the receptors are located. Progression of cardiac hypertrophy is likely to reverse this enhanced reflex activity. In hypertension the carotid sinus reflex appears to be readjusted in such a way as to protect against a further rise in blood pressure, rather than providing protection, as in normotension, against a fall in blood pressure. Thus the homeostatic functions of the reflex are maintained and readjusted to the needs of the hypertensive circulation. It is interesting to speculate that increased afferent inhibition from "volume" receptors in the cardiopulmonary area may represent a homeostatic attempt to buffer an early increase in sympathetic activity to the kidney.

Afferent Pathways↗
PubMedDate not supplied

The new WHO Expert Committee Report on Hypertension Control.

A new WHO Expert Committee Report on Hypertension Control has recently been prepared. This paper is not intended to be a detailed summary of this report. It rather intends to identify the principal issues where the new report differs from the previous 1978 WHO report, to point out the aspects where it has substantially incorporated the recommendations made on the 1993 WHO/ISH guidelines, and to mention the issues that have been developed in this report more extensively than in previous WHO or WHO/ISH documents.

Adolescent↗
PubMedDate not supplied

Antiatherosclerotic effects of antihypertensive drugs: recent evidence and ongoing trials.

The issue as to whether antihypertensive drugs may exert some antiatherosclerotic effect, at least partly independent of blood pressure lowering, has been explored in several experimental models of atherosclerosis, and a large body of evidence has been obtained in favor of a specific antiatherosclerotic action of calcium antagonists and ACE-inhibitors. On the clinical side, several studies are investigating the problem in hypertensive patients in whom progression of carotid intima-media thickness (IMT) and atherosclerotic plaques is explored by sensitive quantitative B-mode ultrasound techniques. The MIDAS has indicated a slower progression, at least in the first six months, of carotid plaques in isradipine treated patients than in diuretic-treated ones. However, MIDAS as a pioneer study has been particularly valuable in giving information on the rate of growth of IMT in hypertensive patients and on the best end-point to use in carotid ultrasound trials. Baseline data of the ongoing studies ELSA and VHAS have so far provided evidence of the very high prevalence of carotid atherosclerosis among hypertensive patients, an observation that makes the evaluation of the antiatherosclerotic action of some antihypertensive agents even more important. Finally, the PHYLLIS trial using a factorial design, beside exploring the antiatherosclerotic action of an ACE-inhibitor vs a diuretic, intends to evaluate the possible benefits of associating antihypertensive therapy with lipid lowering by a statin on the progression of carotid atherosclerosis.

Aged↗
PubMedDate not supplied

Carotid artery wall alterations as intermediate end points.

Carotid artery wall alterations can now be measured in a quantitative, well reproducible way by B-mode ultrasound. The thickness of the intima-media complex (IMT) is commonly measured at three levels along the carotid tree. Well standardized protocols to use in randomized prospective trials are available. It is argued that IMT measurements can be used as intermediate end points of antihypertensive treatment trials as 1) IMT alterations are frequent in hypertension and closely correlated to systolic and pulse pressures; 2) IMT alterations are predictive of an increased risk of cardiovascular events; 3) changes in IMT occur during antihypertensive treatment; 4) at least one study has shown differential effects of different antihypertensive agents on IMT (VHAS: verapamil better than chlorthalidone); 5) in this study a greater effect on IMT has been accompanied by a reduced cardiovascular event rates. Larger studies are desirable to confirm these conclusions.

Aged↗
PubMedDate not supplied

Ambulatory blood pressure monitoring.

This paper will briefly summarize the available evidence on the diagnostic and prognostic relevance of a number of parameters derived from the analysis of 24 hour ambulatory blood pressure recordings. These parameters include the 24 h average blood pressure values, the difference between daytime and nighttime blood pressure, the difference between clinic blood pressure and daytime average blood pressure as a surrogate measure of the "white coat effect", and 24 hour blood pressure variability as quantified by the standard deviation of the 24 hour average value.

Blood Pressure↗
PubMedDate not supplied

Behavioural stress blunts the creatinine clearance increase induced by a protein load in healthy subjects.

BACKGROUND: The aim of this study was to investigate how behavioural states related to different levels of stress affected the increments of glomerular filtration rate induced by an acute protein load. METHODS: Thirteen healthy subjects were enrolled. Each subject was studied from 9:00 h to 15:00 h on two consecutive days. In random order, after a protein meal (1.2 g/kg b.w. of protein), each subject was required to remain in a relaxing, sitting position (resting period, R), or to solve graphical and mathematical problems (behavioural stress period, S). Mean blood pressure (MBP) and heart rate (HR) were monitored by an ambulatory blood pressure device. Urine samples collected in each period were used to measure glomerular filtration rate (GFR, creatinine clearance) and urinary sodium excretion (UNa+V). RESULTS: Significant decreases in MBP and HR were observed during the resting period after the protein load, which significantly increased GFR. There was also a large increase of UNa+V. During S, the GFR changes were no longer seen whereas the increse of UNa+V was maintained. HR and MBP did not change compared to the prestimulus period. CONCLUSIONS: We conclude that in healthy subjects behavioural stress can blunt the increase in GFR that follows a protein load, presumably by neuro-humoral activated mechanisms. In our experimental conditions, behavioural stress did not affect UNa+V.

Adult↗
PubMedDate not supplied

An Italian chart for cardiovascular risk prediction. Its scientific basis.

A risk chart for primary prediction of major coronary and cerebrovascular events based on Italian population data was created. Material from three Italian population studies was available: the Italian Rural Areas of the Seven Countries Study (no. 1712), the Gubbio Study (no. 3061) and the ECCIS Study (no. 4998) for a total of 9771 men and women aged 35 to 74 years and followed-up from 5 to 15 years, for a total of over 55,000 person/years. Sex, age, diabetes, cigarette smoking, systolic blood pressure and serum cholesterol were selected as risk factors, while the endpoint was established as the occurrence of the first major coronary or cerebrovascular event in 10 years. The accelerated failure time model was used as the predictive model. Two models were adopted, i.e., for relatively younger subjects (45-59 years) and for relatively older subjects (60-74 years). Both produced highly significant coefficients for each of the selected risk factors. The two models carried a satisfactory discriminating power, with 40% to more than 50% of all events located in the upper quintile of the estimated risk. Sex, age (6 classes), diabetes, cigarette smoking (4 classes), systolic blood pressure (4 classes) and serum cholesterol (5 classes) were considered for the creation of a risk map derived from multivariate models. A total of 1920 cells were filled with different colors corresponding to 6 classes of absolute risk. A similar set of cells was filled with another color scale for the estimate of the relative risk versus subjects of the same age and sex carrying Italian mean levels of risk factors. The chart is being distributed to the Italian medical profession as a practical tool to select high-risk individuals for the primary prevention of major cardiovascular diseases.

Aged↗
PubMedDate not supplied

[Hypertension and cardiovascular damage].

All major randomized trials of antihypertensive therapy have used cardiovascular events as endpoints. This approach has provided important information, but has also led to a few inappropriate conclusions. In particular, no sound information is available on the ability of antihypertensive therapy to prevent the cardiovascular lesions upon which events are superimposed. However, particularly in mild to moderate hypertensives, the primary goal of therapy is prevention of cardiovascular lesions rather than prevention of premature death. Sensitive and quantitatively reliable methods for evaluation of organ damage in hypertension are now available. For instance, the quantitative evaluation of coronary plaques has recently been employed in therapeutic trials of coronary artery disease; non-invasive methods (such as quantitative ultrasonography of carotid artery walls) can be employed in large trials of antihypertensive therapy to answer the question whether some class of antihypertensive drugs, such as calcium-antagonists) may be more effective in prevention and/or regression of atherosclerotic plaques than traditional antihypertensive agents.

Animals↗
PubMedDate not supplied

Felodipine, a new vasodilating drug: blood pressure, cardiac, renal, and humoral effects in hypertensive patients.

We studied the antihypertensive action of felodipine, a new dihydropyridine vasodilator interfering with intracellular calcium mechanisms, in 11 patients with essential hypertension whose supine blood pressure averaged 181/109 mm Hg after 5 days of placebo administration. Felodipine, 12.5 mg t.i.d., for 3 days, caused a marked reduction (-39/-19 mm Hg) of supine systolic and diastolic pressures. Doses of 25 and 50 mg t.i.d., for three consecutive days, caused only a slight further reduction of blood pressure. At the highest dose tested all patients had their supine blood pressure brought down to values below 150 mm Hg systolic and 90 mm Hg diastolic at all six daily measurements. The antihypertensive effect was of the same magnitude when the patients lay supine or stood upright. Lowering of blood pressure was accompanied by tachycardia, which was quite moderate after the 12.5 mg t.i.d. dose, but more conspicuous with the two higher doses. There was some increase in plasma renin activity and in plasma aldosterone. A significant decrease in renal sodium and water excretion occurred only during administration of the highest dose of 50 mg t.i.d., when reduction in blood pressure was pronounced and there were reflex increases in plasma renin activity and plasma aldosterone.

Aldosterone↗