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Biomedical subjects

R Asmar

Publications and source records attributed to R Asmar.

At least 55 records · Page 3Linked to original sources
PubMed2000

Self-measurement of blood pressure in clinical trials and therapeutic applications.

Self-measurement of blood pressure (SMBP) is increasingly used to assess blood pressure outside the medical setting. A prerequisite for the wide use of SMBP is the availability of validated devices providing reliable readings when they are handled by patients. This is the case today with a number of fully automated oscillometric apparatuses. A major advantage of SMBP is the great number of readings, which is linked with high reproducibility. Given these advantages, one of the major indications for SMBP is the need for evaluation of antihypertensive treatment, either for individual patients in everyday practice or in clinical trials intended to characterize the effects of blood-pressure-lowering medications. In fact, SMBP is particularly helpful for evaluating resistant hypertension and detecting white-coat effect in patients exhibiting high office blood pressure under antihypertensive therapy. SMBP might also motivate the patient and improve his or her adherence to long-term treatment. Moreover, SMBP can be used as a sensitive technique for evaluating the effect of antihypertensive drugs in clinical trials; it increases the power of comparative trials, allowing one to study fewer patients or to detect smaller differences in blood pressure than would be possible with the office measurement. Therefore, SMBP can be regarded as a valuable technique for the follow-up of treated patients as well as for the assessment of antihypertensive drugs in clinical trials.

Antihypertensive Agents↗
PubMed2000

[Validation of electronic automatic-measurement arterial blood pressure devices].

Validation of automatic devices for self blood pressure measurement is a necessity, as the mercury columns are no longer available. The European consensus meeting organized by the Group for blood pressure measurement and evaluation (GEM), from French Society of Hypertension held last June 1999 has defined a new international protocol for clinical validation of these devices. The main parts of this protocol are the following: the blood pressure is measured at the same arm with two observers simultaneously and then with the automatic device sequentially seven times among 38 patients. The evaluation is interrupted after the 15th patient if the pre-analysis fails defined criteria. Technical supports are available: A CD-rom from French society of HTA for the training and certification of observers, a special kit for the evaluation (2 mercury column's and a double stethoscope) and a specific software for data analysis created by the GEM.

Automation↗
PubMed2000

[Measuring arterial pressure].

Measuring the blood pressure is the basis of diagnosis and management of hypertension. The blood pressure is a variable, the single value of which cannot be considered to be representative of a given person. Therefore, different methods of measurement have been developed to take this variability into account or to limit its repercussions. Of these methods, the authors describe clinical measurement, self measurement and ambulatory blood pressure recording with their advantages and disadvantages, their indications and limitations. The type of information obtained by each method is different: the methods are not competitive but complementary. Clinical measurement is the reference but it has its limitations and causes of error which pose problems of its validity for assessing mean blood pressure in some patients. Traditional self measurement and ambulatory blood pressure recording seem to provide a more accurate evaluation of the blood pressure and are more closely correlated with target organ damage and cardiovascular morbidity and mortality. However, it remains to be determined if the use of these methods in the assessment of cardiovascular risk and management of hypertensive patients improve the long-term cardiovascular prognosis.

Blood Pressure↗
PubMed2000

[Microabluminuria in arterial hypertension. Measurement, variables, interpretation, recommendations].

Permanent hypertension is frequently associated with increased glomerular permeability to albumin at an early stage, indicating renal involvement and endothelial dysfunction. The definition of microalbuminuria is an urinary albumin excretion of 30-300 mg/24 hrs, confirmed on two occasions over a 3 month period. It may also be expressed in microgram/min, m/l or mg/mmol of creatinine. Radio-immunological, immunonephelometric methods and Elisa are specific and the most sensitive methods of measurement. There is a large intra-individual variability (25-60%) making it essential to repeat measurements always by the same technique. The prevalence of microalbuminuria is 5-8% in the general population and 6-24% in hypertensive patients. When present, it is a marker of increased cardiovascular risk. Clinical recommendations suggest adaptation of urinary collection according to the context: screening, diagnosis or clinical research. It is always necessary to start by dip-stick detection of proteinuria, haematuria or urinary infection. Clinical research requires repeated measurement of 24 hour microalbuminuria, sometimes divided into two periods of day and night, often associated with ambulatory blood pressure recordings and renal function tests. Studies of the effects of anti-hypertensive drugs on microalbuminuria could provide better evaluation. In conclusion, measurement of microalbuminuria remains a tool of clinical research allowing an assessment of cardiovascular and renal risk of hypertensive patients.

Albuminuria↗
PubMed1999

[Microalbuminuria and arterial hypertension].

UNLABELLED: IMPACT OF HYPERTENSION ON THE KIDNEY: Permanent uncontrolled hypertension affects target organs, particularly the kidney. Infraclinical renal dysfunction can be detected by early measurements of microalbuminuria which is an expression of the increased glomerular permeability related to increased arterial pressure, endothelial dysfunction and hormonal factors. Trace albumin can be detected in the urine of normal subjects. Although the amount of albumin in the urine increases with exercise, output should not exceed 20 mg/24 h. DEFINITIONS: Microalbuminuria is defined as urinary excretion of albumin in the 30-300 mg/24 h or 20-200 micrograms/min range. Due to the wide variability, tests should be repeated 2 or 3 times to confirm the persistent nature of the microalbuminuria. In hypertensive patients, microalbuminuria can be reversible if blood pressure levels are normalized. Urinary secretion of albumin above 300 mg/24 h is considered to be a macroalbuminuria expressing a more severe renal condition. INCIDENCE: The incidence of microalbuminuria in patients with borderline hypertension is 12-15%, in those with mild or moderate hypertension, it is 15-30%, and in those with severe hypertension, the percentages exceed 50%. RISKS: Albuminuria is positively correlated with blood pressure levels measured in inpatients; the correlation is even tighter with ambulatory recordings. Microalbuminuria is a risk factor for cardiovascular disease and for the development of nephroangiosclerosis. It should be searched for in all patients with persistently high blood pressure. Monitoring urine albumin is an effective tool for assessing the efficacy of an antihypertensive treatment and is useful for preventing renal damage.

Adult↗
PubMed1999

A comparison of the efficacy and duration of action of candesartan cilexetil and losartan as assessed by clinic and ambulatory blood pressure after a missed dose, in truly hypertensive patients: a placebo-controlled, forced titration study. Candesartan/Losartan study investigators.

The purpose of this double-blind, forced titration study was to compare the antihypertensive effect duration of candesartan cilexetil, which has a longlasting binding to the human AT1-receptor, to that of losartan on ambulatory BP (ABP) not only during the 24-h dosing interval but also during the day of a missed dose intake. After a 4-week placebo lead-in period, 268 patients with sitting diastolic BP 95 to 110 mm Hg and mean awake ambulatory DBP > or =85 mm Hg were randomized to receive either 8 mg of candesartan, 50 mg of losartan, or placebo for a 4-week period. Thereafter, the doses were doubled in all patients for an additional 4-week period. Ambulatory BP monitoring was performed for 36 h after dosing and clinic BP measured 48 h after dosing. Candesartan cilexetil (16 mg) reduced ABP to a significantly greater extent than 100 mg of losartan, particularly for systolic ABP during daytime (P<.05), nighttime (P<.05), and 24-h (P<.01) periods, systolic (P<.01) and diastolic (P<.05) ABP between 0 and 36 h, and both systolic (P<.001) and diastolic (P<0.001) ABP during the day of a missed dose. Clinic BP at 48 h after dosing was significantly reduced exclusively with 16 mg of candesartan. The differences in BP reduction between 8 mg of candesartan and 50 mg of losartan were statistically significant for systolic ABP during daytime (P<.01), nighttime (P<.05), 24-h (P<.01), 0 to 36 h (P<.05) and during the day of missed dose (P<.05). Moreover, although losartan did not significantly reduce ambulatory BP in a dose-related manner, ambulatory systolic and diastolic BP reductions with 16 mg of candesartan were significantly greater (P<.01 and <.001) than those seen with 8 mg of candesartan during every period at the ABP supporting a dose-response relationship. In conclusion, this forced titration study in ambulatory hypertensive patients demonstrates that candesartan cilexetil provides significant dose-dependent reduction in both clinic and ambulatory BP in doses ranging from 8 to 16 mg once daily. Furthermore, candesartan cilexetil is superior to losartan in reducing systolic ABP and in controlling both systolic and diastolic ABP on the day of a missed dose. The differences observed between both agents are most likely attributable to a tighter binding to, and a slower dissociation from, the receptor binding site with candesartan cilexetil.

Adult↗
PubMed1999

Task force VI: Self-monitoring of the blood pressure.

BACKGROUND: Self-monitoring of the blood pressure by patients at home or in other nonclinical settings has become increasingly common in recent years. This phenomenon has been fueled in part by the increase in availability of automatic sphygmomanometers, which are now both affordable and easy for patients to use. BENEFITS OF SELF-MONITORING: Self-monitoring of the blood pressure can be an important adjunct to management of hypertension. The technique allows patients to participate more in their care. Self-measured values of blood pressure are more likely to be representative of the average daily blood pressure than is a clinic measurement and may be better related to hypertensive involvement of target organs and cardiovascular morbidity than is the clinic blood pressure. Finally, the self-monitoring of blood pressure has the potential to reduce the costs of hypertension-related care. LIMITATIONS OF SELF-MONITORING: There are several issues that prevent the more widespread use of self-monitoring of the blood pressure in clinical practice. First, devices marketed for use by patients have advanced technically during the 1990s, but many have not been subjected to rigorous clinical validation for precision and reliability (e.g. in terms of Association for the Advancement of Medical Instrumentation and British Hypertension Society guidelines). It is recommended that devices for measuring blood pressure used by patients at home be subjected to the same validation processes as those that are applied to ambulatory recordings. Second, although the upper limits of normal for self-monitored blood pressure of a general population can be defined statistically (it is approximately 135/85 mmHg), it is not yet possible to determine the normal self-monitored blood pressure because these values must be linked to classical clinical cardiovascular endpoints or outcomes. Third, the relationships among self-monitored, clinic, and ambulatory blood pressures are defined for some populations but their behaviors according to age, sex, ethnicity, and treatment status require further study. Fourth, several different schedules for self-monitoring of the blood pressure by patients have been used in clinical research and practice. It will be necessary to determine the optimal schedule and number of recordings required when patients perform self-monitoring of the blood pressure. Fifth, self-monitoring of the blood pressure in clinical trials of antihypertensive therapies is certainly feasible but has typically not been included in their design, either by investigators or by the pharmaceutical sponsors. Sixth, there have been data suggesting that self-monitoring of the blood pressure reduces the comprehensive costs associated with hypertension care on an annual basis. However, since most work on the economic impact of self-monitoring of the blood pressure has been performed in managed-care environments in the USA, it is not known whether this reduction in health-care costs would be applicable to other types of practice environments on a worldwide basis. CONCLUSIONS: Self-monitoring of the blood pressure is at present useful as an adjunct measurement for the management of hypertensive patients and might provide benefits in clinical trials of antihypertensive therapy. Nevertheless, the available data on self-monitoring of the blood pressure are inadequate as grounds for clinicians to make primary diagnostic or therapeutic decisions and should not override the blood pressure obtained by clinical measurement or via ambulatory monitoring.

Blood Pressure↗
PubMed1999

Aortic pulse wave velocity as a marker of cardiovascular risk in hypertensive patients.

Large artery damage is a major contributory factor to cardiovascular morbidity and mortality of patients with hypertension. Pulse wave velocity (PWV), a classic evaluation of arterial distensibility, has never been ascertained as a cardiovascular risk marker. To determine the factors influencing aortic PWV and the potential predictor role of this measurement, we studied a cohort of 710 patients with essential hypertension. Atherosclerosis alterations (AA) were defined on the basis of clinical events. Calculation of cardiovascular risks, by use of Framingham equations, was performed in subjects without AA. PWV was higher in the presence of AA (14.9+/-4.0 versus 12.4+/-2.6 m/s, P<0.0001), even after adjustments on confounding factors and was the first determinant (P<0.0001) of the extent of atherosclerosis assessed as the sum of the atherosclerotic sites. In patients without AA, all cardiovascular risks increased constantly with PWV. Furthermore, at a given age, aortic PWV was the best predictor of cardiovascular mortality. The odds ratio of being in a high cardiovascular mortality risk group (>5% for 10 years) for patients in the upper quartile of PWV was 7.1 (95% confidence intervals 4.5 to 11.3). The presence of a PWV >13 m/s, taken alone, appeared as a strong predictor of cardiovascular mortality with high performance values. This study shows that aortic PWV is strongly associated with the presence and extent of atherosclerosis and constitutes a forceful marker and predictor of cardiovascular risk in hypertensive patients.

Age Factors↗
PubMed1999

Plasma homocysteine, aortic stiffness, and renal function in hypertensive patients.

Hyperhomocysteinemia has been associated with both vascular structure alterations and vascular clinical end points. To assess the relation between plasma homocysteine, structure and function of large arteries, and the presence of clinical vascular disease, we investigated a population of 236 hypertensive patients. We estimated arterial stiffness by measuring the carotid-femoral pulse wave velocity. Total plasma homocysteine was determined by fluorometric high-performance liquid chromatography. The presence of cardiovascular disease was defined on the basis of clinical events, including coronary heart disease, cerebrovascular disease, and peripheral vascular disease. In this population, pulse wave velocity was positively correlated with homocysteine, even after adjustments for age, mean blood pressure, extent of atherosclerosis, and creatinine clearance (P=0.016). Analysis of variance showed statistically significant differences between the mean values of homocysteine, creatinine clearance, and pulse wave velocity according to the extent of atherosclerosis, with an increase in these 3 parameters concomitant with an increase in the number of vascular sites involved with atherosclerosis. In conclusion, in hypertensive patients the levels of homocysteine are strongly and independently correlated to arterial stiffness measured by aortic pulse wave velocity. Plasma homocysteine, creatinine clearance, and aortic pulse wave velocity are higher in patients presenting with clinical vascular disease. These results suggest that the evaluation of aortic distensibility and homocysteine levels can help in cardiovascular risk assessment in hypertensive populations.

Adult↗
PubMed1999

Changes in arterial structure and function under trandolapril-verapamil combination in hypertension.

BACKGROUND AND PURPOSE: Converting enzyme inhibition and calcium blockade alter large arteries in hypertension. However, the heterogeneity of the response according to the site of cardiovascular measurements has never been investigated. METHODS: In a double-blind study, we compared for 180 days 3 hypertensive patient groups treated with verapamil, trandolapril, or their combination. Using echo-Doppler technique and applanation tonometry, we independently measured mean pressure, local pulse pressure, arterial diameter, and distensibility at 3 arterial sites (brachial and common carotid arteries and abdominal aorta), as well as cardiac and carotid wall structure. RESULTS: Mean and pulse pressure decreased significantly to a greater extent with the drug combination. Regarding arterial and cardiac hemodynamics, significant and similar changes were noted in the 3 groups: decreases in abdominal aorta and carotid but not brachial diameter; increases in carotid artery, abdominal aorta, and brachial distensibility even after adjustment to mean blood pressure reduction; and more substantial regression of cardiac mass than carotid wall thickness. CONCLUSIONS: This study shows that both compounds and more significantly combination therapy decreased mean and pulse pressures measured independently and that the changes in diameter, thickness, and stiffness were influenced primarily by the site of cardiovascular measurements, resulting in a predominant increase in distensibility of muscular arteries, little change in carotid wall thickness, but a significant regression of cardiac hypertrophy.

Adult↗
PubMed1998

Assessment of the acute arterial effects of converting enzyme inhibition in essential hypertension: a double-blind, comparative and crossover study.

In subjects with essential hypertension, angiotensin-converting enzyme (ACE) inhibition increases arterial diameter, compliance and distensibility of peripheral muscular arteries in association with blood pressure reduction. Whether pulse pressure amplification is modified by ACE inhibition and whether changes in compliance and distensibility are due to a drug effect on the arterial wall, to the blood pressure reduction or to a combination of both factors, is largely ignored. In a randomised, double-blind crossover trial, we used the ACE inhibitor quinapril as a marker to evaluate the changes in: pulse pressure amplification (applanation tonometry), carotid compliance and distensibility (echo-tracking technique), and aortic distensibility (measured from pulse wave velocity). Quinapril decreased in the same extent carotid and brachial pulse pressure, thus causing a resetting of pulse pressure amplification toward normal values. Carotid compliance and distensibility as well as aortic distensibility increased significantly. Based on three-way analysis of variance, it was shown that, whereas the changes in carotid stiffness were exclusively due to blood pressure reduction and not to a drug-induced relaxation of the arterial wall, the changes in aortic distensibility were due to the combination of both factors. Thus, using an atraumatic non-invasive procedure, it was possible to show that: (i) ACE inhibition is able to maintain pulse pressure amplification, an important factor contributing to reduce the afterload of the heart; and (ii) ACE inhibition alters the hypertensive arterial wall in a very heterogeneous manner, with a maximal drug effect on muscular large arteries like the abdominal aorta, and not on elastic arteries like the carotid artery and the thoracic aorta.

Adult↗
PubMed1998

Twenty-four hour antihypertensive efficacy of indapamide, 1.5-mg sustained release: results of two randomized double-blind controlled studies.

The antihypertensive efficacy of a 1.5-mg sustained-release formulation (SR 1.5) of indapamide, a diuretic related to thiazide, has been pointed out by using conventional sphygmomanometric measurement 24 h after dosing in clinic, in two large European randomized, double-blind, controlled studies (2 and 3 months). One of these studies was then extended to 12 months, as a complementary open study. Quality-controlled ambulatory blood pressure monitoring (ABPM) data for a total of 216 patients from these studies are presented, including subgroups of hypertensives and responders. Indapamide SR 1.5 achieves an adequate 24-h blood pressure control by significantly reducing the 24-h, diurnal, and nocturnal blood pressures versus baseline, confirming the sphygmomanometric data. The benefit at 2 and 3 months is maintained at 1 year, which confirms the long-term efficacy of SR 1.5 mg. The trough-to-peak ratio--not previously calculated for a diuretic according to international guidelines--meets Food and Drug Administration requirements and confirms the 24-h efficacy of indapamide SR 1.5.

Adolescent↗
PubMed1998

Recent advances on large arteries in hypertension.

The most classic hemodynamic concept explaining the increased mean arterial pressure in hypertension reflects an increased total peripheral resistance dynamically and an increased wall-to-lumen ratio to suppress smaller arteries. However, a more current consideration takes into account not only that steady component but also the pulsatile component of blood pressure, a point that importantly modifies the traditional hemodynamic definition. Whereas mean arterial pressure is almost constant along the arterial tree, the pulse pressure increases markedly from the more central to the peripheral arteries, indicating that in vivo each artery should be characterized according to its own blood pressure curve. This important concept implies major modifications in the methods used to investigate the relationships between mechanical factors and large artery structure and function. It therefore seems reasonable that in hypertension the large arteries should no longer be considered as passive conduits but rather in terms of their active behavioral response to the mechanical forces to which they are subjected. New investigational aspects in hypertension therefore now involve not only genetic, cellular, and molecular mechanisms but also transductional hemodynamic mechanisms reflecting changing patterns in the extracellular matrix that influence structural remodeling of the vessels.

Animals↗
PubMed1998

Prevalence of cardiovascular risk factors in a French population.

UNLABELLED: STUDY ON THE IDENTIFICATION OF CARDIOVASCULAR RISK FACTORS: Identification of cardiovascular risk factors and the estimation of their prevalence in different populations is an important aim of preventive medicine. We analysed the data from 58,803 volunteers who were subjected to systematic health examinations in the Centre d'Investigations Préventives et Cliniques in Paris during the period January 1991 to December 1993. In this report we present some results concerning the prevalence of the major cardiovascular risk factors and their associations with sex, age and the presence of hypertension. CONCLUSIONS: The present study clearly shows that before the age of 55 years, the prevalence of risk factors is higher in men than in women, whereas in postmenopausal women the risk-profile increases rapidly, reaching the level of men after the age of 65 years. The presence of multiple risk factors is much higher in hypertensive than in normotensive individuals. We also observed that more than two-thirds of the treated hypertensives had systolic/diastolic blood pressure levels of > 140/90 mmHg. These observations could contribute to the debate regarding the evaluation of global risk and therapeutic strategies in cardiovascular disease prevention.

Adult↗
PubMed1998

[Cardiovascular risk and ambulatory blood pressure measurement of arterial pressure].

Many studies have demonstrated that elevation of blood pressure is proportional to the risk of developing cardiovascular accidents. The relationship between blood pressure and cardiovascular risk varies according to whether diastolic, systolic or pulse pressure is considered. Several other parameters are involved in the determinism of the blood pressure risk such as age, gender, ethnic group, etc. These elements emphasize the importance of considering the various blood pressures as well of the patient's risk factors and clinical characteristics for global evaluation of the cardiovascular risk. As blood pressure is an eminently variable parameter and as the essential element of evaluation of the blood pressure risk is based on its determination, it is important to measure blood pressure accurately and precisely. Clinical measurement of BP constitutes the reference method, but presents several limits and several causes of error which raise the problem of its validity to evaluate a given patient's mean blood pressure. Ambulatory blood pressure monitoring during 24 hours of usual activity appears to more accurately evaluate the blood pressure load likely to induce organic lesions, as several studies have demonstrated its superiority over occasional measurement to evaluate the risk and cardiovascular prognosis of HT. However, whether its application in the evaluation of the global cardiovascular risk and therapeutic management can improve the prevention strategy and long-term cardiovascular prognosis has yet to be determined.

Blood Pressure Monitoring, Ambulatory↗
PubMed1998

[Efficacy and safety of indapamide 1.5 mg sustained release coated tablets in the therapy of arterial hypertension].

OBJECTIVE: In line with international recommendations concerning the need to decrease the doses of antihypertensives, a low dose form (1.5 mg) of indapamide, sustained release coated tablet (SR), has been developed in order to optimize the efficacy-safety ratio while maintaining a once daily dosage. The objective of this study was to evaluate the benefit obtained by reviewing the results of two clinical trials conducted according to a similar methodology. PATIENTS AND METHODS: European randomized double-blind trials were conducted in a total of 690 hypertensive patients. The first trial was conducted in 285 patients treated for 2 months and the second trial was conducted in 405 patients treated for 3 months. The second study was extended to 9 months under open-label conditions in order to obtain a follow-up of one year with clinical and ambulatory blood pressure monitoring. The average patient characteristics on inclusion were, in the two studies: age: 53 and 57 years, 44% and 57% of men, diastolic blood pressure (DRP): 100.6 and 102.5 mmHg, systolic blood pressure (SBP): 161.0 and 164.5 mmHg. RESULTS: The first dose-ranging study demonstrated the antihypertensive efficacy of indapamide 1.5 mg SR; the study second confirmed the equivalent efficacy with the 2.5 mg immediate release form of indapamide and a greater than 50% reduction of the number of patients presenting a serum potassium less than 3.4 mmol/l. The long-term study verified the absence of therapeutic escape. Clinical safety data assessed the absence of effects of indapamide on carbohydrate and lipid metabolism. CONCLUSION: Indapamide 1.5 mg sustained release coated tablet presents an optimized antihypertensive efficacy/safety ratio in line with international recommendations concerning the use of low-dose antihypertensives and diuretics as first-line treatment for hypertension.

Antihypertensive Agents↗